Author name code: mein ADS astronomy entries on 2022-09-14 author:"Mein, Pierre" OR author:"Mein, Nicole" ------------------------------------------------------------------------ Title: The SLED project and the dynamics of coronal flux ropes Authors: Malherbe, Jean-Marie; Mein, Pierre; Sayède, Frédéric; Rudawy, Pawel; Phillips, Kenneth; Keenan, Francis; Rybák, Jan Bibcode: 2022AdSpR..70.1562M Altcode: Investigations of the dynamics of the hot coronal plasma are crucial for understanding various space weather phenomena and making in-depth analyzes of the global heating of the solar corona. We present here numerical simulations of observations of siphon flows along loops (simple semi-circular flux ropes) to demonstrate the capabilities of the Solar Line Emission Dopplerometer (SLED), a new instrument under construction for imaging spectroscopy. It is based on the Multi-channel Subtractive Double Pass (MSDP) technique, which combines the advantages of filters and slit spectrographs. SLED will observe coronal structures in the forbidden lines of FeX 6374 Å and FeXIV 5303 Å, and will measure Doppler shifts up to 150 km s-1 at high precision (50 m s-1) and cadence (1 Hz). It is optimized for studies of the dynamics of fast evolving events such as flares or Coronal Mass Ejections (CMEs), as well as for the detection of high-frequency waves. Observations will be performed with the coronagraph at Lomnický Štít Observatory (LSO), and will also occur during total solar eclipses as SLED is a portable instrument. Title: Non-LTE Inversion of Prominence Spectroscopic Observations in Hα and Mg II h&k lines Authors: Jejčič, Sonja; Heinzel, Petr; Schmieder, Brigitte; Gunár, Stanislav; Mein, Pierre; Mein, Nicole; Ruan, Guiping Bibcode: 2022ApJ...932....3J Altcode: We continued our investigation of the plasma characteristics of a quiescent prominence that occurred on 2017 March 30. The prominence was observed simultaneously by several instruments, including the Interface Region Imaging Spectrograph (IRIS) and the Multichannel Subtractive Double Pass (MSDP) spectrograph operating at the Meudon solar tower. We focused on IRIS Mg II h&k and MSDP Hα spectra, selecting 55 well-coaligned points within the prominence. We computed an extensive grid of 63,000 isothermal and isobaric 1D-slab prominence models with a non-LTE (i.e., departures from the local thermodynamic equilibrium) radiative transfer code. We then performed a 1.5D spectral inversion searching for an optimal model that best fits five parameters of the observed profiles (observables), namely, the integrated intensity of the Hα and Mg II k lines, the FWHM of both lines, and the ratio of intensities of the Mg II k and Mg II h lines. The latter is sensitive to temperature. Our results show that the prominence is a low-temperature structure, mostly below 10,000 K, with some excursions to higher values (up to 18,000 K) but also rather low temperatures (around 5000 K). The microturbulent velocity is typically low, peaking around 8 km s-1, and electron density values are of the order of 1010 cm-3. The peak effective thickness is 500 km, although the values range up to 5000 km. The studied prominence is rather optically thin in the Hα line and optically thick in the Mg II h&k lines. Title: The Solar Line Emission Dopplerometer project Authors: Malherbe, Jean-Marie; Mein, Pierre; Sayède, Frédéric; Rudawy, Pawel; Phillips, Kenneth; Keenan, Francis; Rybák, Jan Bibcode: 2022ExA....53...83M Altcode: 2021ExA...tmp..125M; 2021arXiv211001645M Observations of the dynamics of solar coronal structures are necessary to investigate space weather phenomena and global heating of the corona. The profiles of high temperature lines emitted by the hot plasma are usually integrated by narrow band filters or recorded by classical spectroscopy. We present in this paper details of a new transportable instrument (under construction) for imaging spectroscopy: the Solar Line Emission Dopplerometer (SLED). It uses the Multi-channel Subtractive Double Pass (MSDP) technique, which combines the advantages of both filters and narrow slit spectrographs, i.e. high temporal, spatial and spectral resolutions. The SLED will measure at high cadence (1 Hz) the line-of-sight velocities (Doppler shifts) of hot coronal loops, in the forbidden lines of FeX 6374 Å and FeXIV 5303 Å. It will follow the dynamics of fast evolving events of solar activity such as flares or Coronal Mass Ejections (CMEs), and also study coronal heating by short period waves. Observations will be performed with the coronagraph at the Lomnický Štít Observatory (LSO, in Slovakia) or during total eclipses. The SLED will also observe the dynamics of solar prominences in Hα 6563 Å or He D3 5876 Å lines when mounted on the Białków coronagraph (near Wrocław, Poland). It is fully compatible with polarimetric measurements by various techniques. Title: Five decades of solar research at the Mic du Midi Turret-Dome (1960-2010). Part 1: Overview of instrumentation and observations Authors: Roudier, Th.; Malherbe, J. -M.; Rozelot, J. -P.; Mein, P.; Muller, R. Bibcode: 2021JAHH...24..585R Altcode: The Pic du Midi Turret-Dome, known as 'Lunette Jean Rösch'or LJR ('lunette' for refractor in French), was scientifically active during five decades between 1960 and 2010. It was dedicated to high spatial resolution observations in solar astronomy. We review fifty years of advances in solar instrumentation and solar physics made by this instrument in various domains, which took advantage of the good seeing at Pic du Midi. First, we summarize some of the LJR results in broad-band and wide-field imagery of the photosphere; as this topic was the initial goal and has been the most important contribution of the refractor, details will be provided in Part 2. Then, we present spectro-polarimetric instrumentation and observations with narrow slit and imaging spectroscopy of the photosphere and the chromosphere. The Turret-Dome also housed an original spectro-coronagraph, and observations of the high temperature coronal plasma are highlighted. Finally, we describe progress in the determination of the solar shape with the heliometer. The LJR remained active until the launch of the Hinode and Solar Dynamics Observatory satellites (in 2006 and 2010, respectively). Title: Spectro-imagery of an active tornado-like prominence: Formation and evolution Authors: Barczynski, Krzysztof; Schmieder, Brigitte; Peat, Aaron W.; Labrosse, Nicolas; Mein, Pierre; Mein, Nicole Bibcode: 2021A&A...653A..94B Altcode: 2021arXiv210604259B Context. The dynamical nature of fine structures in prominences remains an open issue, including rotating flows in tornado prominences. While the Atmospheric Imaging Assembly imager aboard the Solar Dynamics Observatory allowed us to follow the global structure of a tornado-like prominence for five hours, the Interface Region Imaging Spectrograph, and the Multichannel Subtractive Double Pass spectrograph permitted to obtain plasma diagnostics of its fine structures.
Aims: We aim to address two questions. Firstly, is the observed plasma rotation conceptually acceptable in a flux rope magnetic support configuration with dips? Secondly, how is the plasma density distributed in the tornado-like prominence?
Methods: We calculated line-of-sight velocities and non-thermal line widths using Gaussian fitting for Mg II lines and the bisector method for Hα line. We determined the electron density from Mg II line integrated intensities and profile fitting methods using 1D non-LTE radiative transfer theory models.
Results: The global structure of the prominence observed in Hα, and Mg II h, and k line fits with a magnetic field structure configuration with dips. Coherent Doppler shifts in redshifted and blueshifted areas observed in both lines were detected along rapidly-changing vertical and horizontal structures. However, the tornado at the top of the prominence consists of multiple fine threads with opposite flows, suggesting counter-streaming flows rather than rotation. Surprisingly we found that the electron density at the top of the prominence could be larger (1011 cm−3) than in the inner part of the prominence.
Conclusions: We suggest that the tornado is in a formation state with cooling of hot plasma in a first phase, and following that, a phase of leakage of the formed blobs with large transverse flows of material along long loops extended away from the UV prominence top. The existence of such long magnetic field lines on both sides of the prominence would stop the tornado-like prominence from really turning around its axis.

Movies are available at https://www.aanda.org Title: Four Decades of Advances from MSDP to S4I and SLED Imaging Spectrometers Authors: Mein, P.; Malherbe, J. -M.; Sayède, F.; Rudawy, P.; Phillips, K. J. H.; Keenan, F. P. Bibcode: 2021SoPh..296...30M Altcode: 2021arXiv210103918M The Multichannel Subtractive Double Pass (MSDP) is an imaging spectroscopy technique, which allows observations of spectral line profiles over a 2D field of view with high spatial and temporal resolution. It has been intensively used since 1977 on various spectrographs (Meudon, Pic du Midi, the German Vacuum Tower Telescope, THEMIS, Wrocław). We summarize previous developments and describe the capabilities of a new design that has been developed at Meudon and that has higher spectral resolution and increased channel number: Spectral Sampling with Slicer for Solar Instrumentation (S4I), which can be combined with a new and fast polarimetry analysis. This new generation MSDP technique is well adapted to large telescopes. Also presented are the goals of a derived compact version of the instrument, the Solar Line Emission Dopplerometer (SLED), dedicated to dynamic studies of coronal loops observed in the forbidden iron lines, and prominences. It is designed for observing total solar eclipses, and for deployment on the Wrocław and Lomnicky peak coronagraphs respectively for prominence and coronal observations. Title: Spectral inversion of H-alpha and MgII lines in quiescent prominences Authors: Heinzel, Petr; Schmieder, Brigitte; Ruan, Guiping; Mein, Pierre; Gunár, Stanislav; Jejcic, Sonja; Mein, Nicole Bibcode: 2021cosp...43E1764H Altcode: Recent spectral analysis of simultaneous H-alpha (MSDP) and MgII lines (IRIS) (Guiping et al. 2019) has revealed certain bifurcation in resulting models. Two solutions were found from the line inversions using the non-LTE modeling: relatively high kinetic temperature and low non-thermal motions or temperatures mostly compatible with standard ones plus non-thermal motions of the order of 16 km/sec. Here we will present an improved spectral line inversion technique which clearly prefers the latter solution. Strong non-thermal motions are then interpreted as a mixture of microturbulence and the line-of-sight dynamics of prominence fine-structure threads. A detailed multithread modeling with the 2D non-LTE code and stochastic distributions of threads (position, dynamics) is now in progress and we will show our preliminary results. Title: Active tornado in a prominence observed in H-alpha with MSDP and Mg II with IRIS Authors: Barczynski, Krzysztof; Schmieder, Brigitte; Mein, Pierre; Labrosse, Nicolas; Mein, Nicole; Peat, Aaron Bibcode: 2021cosp...43E.973B Altcode: Large prominences with highly dynamic plasma features expand outwards in the solar atmosphere, often in loop or arch-shape or as a tornado. The origin of the rotating flow in prominence tornadoes is not fully understood yet. We aim to find an answer to two long-standing questions: what is the nature of the plasma flow and rotation in the prominence, and the role of the magnetic field configuration in the prominence dynamics? To this aim, we use observations from the Atmospheric Imaging Assembly (AIA) imager aboard the Solar Dynamics Observatory (SDO) to follow the plasma dynamics related to magnetic field. Simultaneous observations from the Interface Region Imaging Spectrograph (IRIS) and the Multi subtractive Double pass spectrograph (MSDP) allow us to study the plasma properties (intensity, Doppler velocity, non-thermal line broadening) of a tornado-like structure. We calculate line-of-sight velocities and non-thermal line width using Gaussian fitting for Mg II lines (IRIS) and a bisector method for H$\alpha$ line (MSDP). We determine the electron density and temperature from Mg II line integrated intensities using radiative transfer theory. We find that the red and blue Doppler-shifted areas present a coherent position in H$\alpha$ and Mg II h\&k lines along the fast-evolving prominence features. The EUV observations suggest long magnetic field lines on the sides of the prominence. The tornado-like at the top of the prominence consists of multiplefine threads with opposite flows, all of them being supported in dips of long magnetic field lines. From time to time, condensed blobs escape along these field lines. We conjecture that micro or macro turbulence exists at the top of the prominence and could form the small threads giving the impression of rotation. Title: Raymond Michard and his solar physics group at Paris-Meudon Observatory Authors: Mein, Pierre; Mein, Nicole Bibcode: 2020JAHH...23..582M Altcode: During the second half of the twentieth century, an important Solar Research Department was developed in the Paris-Meudon Observatory thanks to Raymond Michard. After several years devoted to theoretical studies about stellar atmospheres at the Institut d'Astrophysique de Paris Michard joined the Paris-Meudon Observatory in 1954. He replaced Lucien d'Azambuja as Director of the Solar Section, and succeeded to attract new young scientists, while building new high-performance instruments in good sites such as Pic du Midi. He became Director of the Solar and Planetary Department in 1968. All topics of solar physics were investigated, providing many results about coronal physics, solar activity and flares, but also fine structures of the quiet Sun. Michard knew that the best research involved successful collaborations. Eclipse missions, international cooperation and access to space instruments were developed. Participation to the European JOSO association prepared the future THEMIS telescope. In 1971 Michard left the Solar Department to be successively the President of Paris Observatory and then Nice Observatory. But his Solar Physics group in Meudon went on working with topics and means that he had successfully initiated. Title: Diagnostics of the Prominence Plasma from Hα and Mg II Spectral Observations Authors: Ruan, Guiping; Jejčič, Sonja; Schmieder, Brigitte; Mein, Pierre; Mein, Nicole; Heinzel, Petr; Gunár, Stanislav; Chen, Yao Bibcode: 2019ApJ...886..134R Altcode: The goal of this paper is to derive the physical conditions of the prominence observed on 2017 March 30. To do so, we use a unique set of data in Mg II lines obtained with the space-borne Interface Region Imaging Spectrograph (IRIS) and in Hα line with the ground-based Multi-Channel Subtractive Double Pass spectrograph operating at the Meudon solar tower. Here, we analyze the prominence spectra of Mg II h and k lines, and the Hα line in the part of the prominence which is visible in both sets of lines. We compute a grid of 1D NLTE (i.e., departures from the local thermodynamical equilibrium) models providing synthetic spectra of Mg II k and h, and Hα lines in a large space of model input parameters (temperature, density, pressure, and microturbulent velocity). We compare Mg II and Hα line profiles observed in 75 positions of the prominence with the synthetic profiles from the grid of models. These models allow us to compute the relationships between the integrated intensities and between the optical thickness in Hα and Mg II k lines. The optical thickness τ Hα is between 0.05 and 2, and {τ }Mg{{II}}{{k}}} is between 3 and 200. We show that the relationship of the observed integrated intensities agrees well with the synthetic integrated intensities for models with a higher microturbulence (16 km s-1) and T around 8000 K, ne = 1.5 × 1010 cm-3, p = 0.05 dyne. In this case, large microturbulence values could be a way to take into account the large mixed velocities existing in the observed prominence. Title: Bidirectional Reconnection Outflows in an Active Region Authors: Ruan, Guiping; Schmieder, Brigitte; Masson, Sophie; Mein, Pierre; Mein, Nicole; Aulanier, Guillaume; Chen, Yao Bibcode: 2019ApJ...883...52R Altcode: We report on bidirectional coronal reconnection outflows reaching ±200 km s-1 as observed in an active region with the Si IV and C II spectra of the Interface Region Imaging Spectrograph (IRIS). The evolution of the active region with an emerging flux, a failed filament eruption, and a jet is followed in Solar Dynamical Observatory (SDO)/Atmospheric Imaging Assembly (AIA) filters from 304 to 94 Å, IRIS slit jaw images, and SDO/Helioseismic and Magnetic Imager movies. The bidirectional outflow reconnection is located at a bright point visible in multiwavelength AIA filters above an arch filament system. This suggests that the reconnection occurs between rising loops above the emergence of magnetic bipoles and the longer, twisted magnetic field lines remnant of the failed filament eruption one hour before. The reconnection occurs continuously in the corona between quasi-parallel magnetic field lines, which is possible in a 3D configuration. The reconnection also triggers a jet with transverse velocities around 60 km s-1. Blueshifts and redshifts along its axis confirm the existence of a twist along the jet, which could have been transferred from the filament flux rope. The jet finally blows up the material of the filament before coming back during the second phase. In the Hα Dopplergrams provided by the MSDP spectrograph, we see more redshift than blueshift, indicating the return of the jet and filament plasma. Title: Exploration of long-period oscillations in an Hα prominence Authors: Zapiór, M.; Schmieder, B.; Mein, P.; Mein, N.; Labrosse, N.; Luna, M. Bibcode: 2019A&A...623A.144Z Altcode: 2019arXiv190300230Z Context. In previous work, we studied a prominence which appeared like a tornado in a movie made from 193 Å filtergrams obtained with the Atmospheric Imaging Assembly (AIA) imager aboard the Solar Dynamics Observatory (SDO). The observations in Hα obtained simultaneously during two consecutive sequences of one hour with the Multi-channel Subtractive Double Pass Spectrograph (MSDP) operating at the solar tower in Meudon showed that the cool plasma inside the tornado was not rotating around its vertical axis. Furthermore, the evolution of the Dopplershift pattern suggested the existence of oscillations of periods close to the time-span of each sequence.
Aims: The aim of the present work is to assemble the two sequences of Hα observations as a full data set lasting two hours to confirm the existence of oscillations, and determine their nature.
Methods: After having coaligned the Doppler maps of the two sequences, we use a Scargle periodogram analysis and cosine fitting to compute the periods and the phase of the oscillations in the full data set.
Results: Our analysis confirms the existence of oscillations with periods between 40 and 80 min. In the Dopplershift maps, we identify large areas with strong spectral power. In two of them, the oscillations of individual pixels are in phase. However, in the top area of the prominence, the phase is varying slowly, suggesting wave propagation.
Conclusions: We conclude that the prominence does not oscillate as a whole structure but exhibits different areas with their own oscillation periods and characteristics: standing or propagating waves. We discuss the nature of the standing oscillations and the propagating waves. These can be interpreted in terms of gravito-acoustic modes and magnetosonic waves, respectively.

Movie attached to Fig. 2 is available at https://www.aanda.org Title: On the Dynamic Nature of a Quiescent Prominence Observed by IRIS and MSDP Spectrographs Authors: Ruan, Guiping; Schmieder, Brigitte; Mein, Pierre; Mein, Nicole; Labrosse, Nicolas; Gunár, Stanislav; Chen, Yao Bibcode: 2018ApJ...865..123R Altcode: Quiescent solar prominences are generally considered to have a stable large-scale structure. However, they consist of multiple small-scale structures that are often significantly dynamic. To understand the nature of prominence plasma dynamics we use the high spatial, temporal, and spectral resolution observations obtained by Interface Region Imaging Spectrograph (IRIS) during a coordinated campaign with the Multichannel Subtractive Double Pass spectrograph at the Meudon Solar Tower. Detailed analysis of the IRIS observations of Mg II lines, including the analysis of Dopplershift and line width obtained with two different methods (quantile method and Gaussian-fit method) are discussed in the frame of the dynamic nature of the structures. Large-scale coherent blueshift and redshift features are observed in Mg II lines and Hα exhibiting a slow evolution during 1:40 hr of observations. We explain the presence of several significantly asymmetric peaks in the observed Mg II line profiles by the presence of several prominence fine structures moving with different velocities located along the line of sight (LOS). In such a case, the decrease of the intensity of individual components of the observed spectra with the distance from the central wavelength can be explained by the Doppler dimming effect. We show that C II line profiles may be used to confirm the existence of multi-components along the LOS. Title: Dynamics in quiescent prominences observed by the IRIS and MSDP spectrographs Authors: Gunár, Stanislav; Schmieder, Brigitte; Ruan, Guiping; Mein, Pierre; Heinzel, Petr Bibcode: 2018cosp...42E1314G Altcode: Quiescent solar prominences are generally considered to be stable. However, these prominences consist of a multitude of small-scale structures or threads that are often significantly dynamic. To understand the nature of the plasma dynamics we use the high spatial, temporal and spectral resolution observations obtained by IRIS during coordinated campaign with the MSDP spectrograph at the Meudon Solar Tower. Mg II h and k lines observed by IRIS represent a good diagnostic tool for investigation of the prominence fine structure dynamics, as they are optically thick under the prominence conditions. We will present detailed IRIS observations of Mg II lines. We explain significant asymmetries in the observed Mg II spectra by the presence of several threads located along the line of sight with different velocities. In such a case, the decrease of the intensity of individual components of the observed spectra with the distance from the central wavelength can be explained by the Doppler dimming effect. To interpret the observed Mg II profiles in terms of dynamics we use 1D or 2D radiative transfer models including a prominence-corona transition region. We also show that the H-alpha line which is optically thinner than the Mg II doublet is an important constrain for the radiative transfer radiation modelling. Title: Prominence/Tornado plasma parameters Authors: Schmieder, Brigitte; Mein, Pierre; Zapior, Maciej; Labrosse, Nicolas; Lopez Ariste, Arturo Bibcode: 2018cosp...42E3025S Altcode: We present a comparison of the plasma physical parameters in prominences and tornadoes using IRIS data and ground based polarimetry measurements obtained with THEMIS. Mg II lines give a good diagnostics of the temperature and optical thickness of the structures. The Stokes parameters from the He D3 line allow to distinguish the behaviour of the magnetic field in typical prominences and atypical prominences (e.g. bubbles, eruptive prominence). We concentrate on the Dopplershifts in a tornado observed in transition region lines and in Halpha. Our results support the existence of oscillations in tornadoes but not rotation.A reconstruction of the 3D geometry of a helical prominence obtained by following the trajectory of kernels yields surprising results. The loops are shown to be quasi-horizontal structures with no curvature.We conclude that it is important to take into account the 3D structure of the prominence to study the dynamics of the prominence plasma. Title: Prototype of S4EI (spectral sampling with slicer for stellar and extragalactical instrumentation): a new generation 3D Spectro-imager Authors: Sayède, F.; Puech, M.; Mein, P.; Galicher, R.; Malherbe, J. -M.; Amans, J. -P. Bibcode: 2018SPIE10702E..54S Altcode: S4EI (Spectral Sampling with Slicer for Stellar and Extragalactical Instrumentation) is a new concept for extending Multichannel Subtractive Double Pass (ie S4I - Spectral Sampling with Slicer for Solar Instrumentation) to night-time astronomy. The Multichannel Subtractive Double Pass (MSDP) spectrographs have been widely used in solar spectroscopy because of their ability to provide an excellent compromise between field of view and the spatial and spectral resolutions. Compared with other spectrographs, MSDP can deliver simultaneous monochromatic images without any time-scanning requirements (as the standard Fabry-Perot), with limited loss of flux. Spatial resolution is the same as for an Imager given by the telescope: it can be very high. It is based on new generation reflecting plane image slicers working with large apertures specific to night-time telescopes. The resulting design could be potentially very attractive and innovative for different domains of astronomy, e.g., the simultaneous spatial mapping of accurately flux-calibrated emission lines between OH sky lines in extragalactic astronomy or the simultaneous imaging of stars, exoplanets and interstellar medium. The determination of physical and chemical properties of galaxies needs to observe several emission lines at different wavelengths. The combination of these lines gives access to the distribution in dust, star formation rate, metallicity, the kinematics or even to the electron density of the gas in the galaxies. The spatial resolution of MSDP allows, like the 3D or integral field spectrographs the construction of spatial distribution maps. The advantage of S4EI is that by measuring simultaneously the different lines, the relative errors of the flux calibration between the different wavelengths of the lines are potentially limited by the uncertainty of the calibration source used, which is expected to significantly reduce the associated errors and thus increase the precision and accuracy of estimates. Title: Prominence and tornado dynamics observed with IRIS and THEMIS Authors: Schmieder, Brigitte; Levens, Peter; Labrosse, Nicolas; Mein, Pierre; Lopez Ariste, Arturo; Zapior, Maciek Bibcode: 2017SPD....4820104S Altcode: Several prominences were observed during campaigns in September 2013 and July 2014 with the IRIS spectrometer and the vector magnetograph THEMIS (Tenerife). SDO/AIA and IRIS provided images and spectra of prominences and tornadoes corresponding to different physical conditions of the transition region between the cool plasma and the corona. The vector magnetic field was derived from THEMIS observations by using the He D3 depolarisation due to the magnetic field. The inversion code (PCA) takes into account the Hanle and Zeeman effects and allows us to compute the strength and the inclination of the magnetic field which is shown to be mostly horizontal in prominences as well as in tornadoes. Movies from SDO/AIA in 304 A and Hinode/SOT in Ca II show the highly dynamic nature of the fine structures. From spectra in Mg II and Si IV lines provided by IRIS and H-alpha observed by the Multi-channel Subtractive Double Pass (MSDP) spectrograph in the Meudon Solar Tower we derived the Doppler shifts of the fine structures and reconstructed the 3D structure of tornadoes. We conclude that the apparent rotation of AIA tornadoes is due to large-scale quasi-periodic oscillations of the plasma along more or less horizontal magnetic structures. Title: Hα Doppler shifts in a tornado in the solar corona Authors: Schmieder, B.; Mein, P.; Mein, N.; Levens, P. J.; Labrosse, N.; Ofman, L. Bibcode: 2017A&A...597A.109S Altcode: 2016arXiv161202232S Context. High resolution movies in 193 Å from the Atmospheric Imaging Assembly (AIA) on the Solar Dynamic Observatory (SDO) show apparent rotation in the leg of a prominence observed during a coordinated campaign. Such structures are commonly referred to as tornadoes. Time-distance intensity diagrams of the AIA data show the existence of oscillations suggesting that the structure is rotating.
Aims: The aim of this paper is to understand if the cool plasma at chromospheric temperatures inside the tornado is rotating around its central axis.
Methods: The tornado was also observed in Hα with a cadence of 30 s by the MSDP spectrograph, operating at the Solar Tower in Meudon. The MSDP provides sequences of simultaneous spectra in a 2D field of view from which a cube of Doppler velocity maps is retrieved.
Results: The Hα Doppler maps show a pattern with alternatively blueshifted and redshifted areas of 5 to 10'' wide. Over time the blueshifted areas become redshifted and vice versa, with a quasi-periodicity of 40 to 60 min. Weaker amplitude oscillations with periods of 4 to 6 min are superimposed onto these large period oscillations.
Conclusions: The Doppler pattern observed in Hα cannot be interpreted as rotation of the cool plasma inside the tornado. The Hα velocity observations give strong constraints on the possible interpretations of the AIA tornado. Title: Height formation of bright points observed by IRIS in Mg II line wings during flux emergence Authors: Grubecka, M.; Schmieder, B.; Berlicki, A.; Heinzel, P.; Dalmasse, K.; Mein, P. Bibcode: 2016A&A...593A..32G Altcode: Context. A flux emergence in the active region AR 111850 was observed on September 24, 2013 with the Interface Region Imaging Spectrograph (IRIS). Many bright points are associated with the new emerging flux and show enhancement brightening in the UV spectra.
Aims: The aim of this work is to compute the altitude formation of the compact bright points (CBs) observed in Mg II lines in the context of searching Ellerman bombs (EBs).
Methods: IRIS provided two large dense rasters of spectra in Mg II h and k lines, Mg II triplet, C II and Si IV lines covering all the active region and slit jaws in the two bandpasses (1400 Å and 2796 Å) starting at 11:44 UT and 15:39 UT, and lasting 20 min each. Synthetic profiles of Mg II and Hα lines are computed with non-local thermodynamic equlibrium (NLTE) radiative transfer treatment in 1D solar atmosphere model including a hotspot region defined by three parameters: temperature, altitude, and width.
Results: Within the two IRIS rasters, 74 CBs are detected in the far wings of the Mg II lines (at +/-1 Å and 3.5 Å). Around 10% of CBs have a signature in Si IV and CII. NLTE models with a hotspot located in the low atmosphere were found to fit a sample of Mg II profiles in CBs. The Hα profiles computed with these Mg II CB models are consistent with typical EB profiles observed from ground based telescopes e.g. THEMIS. A 2D NLTE modelling of fibrils (canopy) demonstrates that the Mg II line centres can be significantly affected but not the peaks and the wings of Mg II lines.
Conclusions: We conclude that the bright points observed in Mg II lines can be formed in an extended domain of altitudes in the photosphere and/or the chromosphere (400 to 750 km). Our results are consistent with the theory of heating by Joule dissipation in the atmosphere produced by magnetic field reconnection during flux emergence. Title: Fast inversion of Zeeman line profiles using central moments. II. Stokes V moments and determination of vector magnetic fields Authors: Mein, P.; Uitenbroek, H.; Mein, N.; Bommier, V.; Faurobert, M. Bibcode: 2016A&A...591A..64M Altcode: Context. In the case of unresolved solar structures or stray light contamination, inversion techniques using four Stokes parameters of Zeeman profiles cannot disentangle the combined contributions of magnetic and nonmagnetic areas to the observed Stokes I.
Aims: In the framework of a two-component model atmosphere with filling factor f, we propose an inversion method restricting input data to Q , U, and V profiles, thus overcoming ambiguities from stray light and spatial mixing.
Methods: The V-moments inversion (VMI) method uses shifts SV derived from moments of V-profiles and integrals of Q2, U2, and V2 to determine the strength B and inclination ψ of a magnetic field vector through least-squares polynomial fits and with very few iterations. Moment calculations are optimized to reduce data noise effects. To specify the model atmosphere of the magnetic component, an additional parameter δ, deduced from the shape of V-profiles, is used to interpolate between expansions corresponding to two basic models.
Results: We perform inversions of HINODE SOT/SP data for inclination ranges 0 <ψ< 60° and 120 <ψ< 180° for the 630.2 nm Fe I line. A damping coefficient is fitted to take instrumental line broadening into account. We estimate errors from data noise. Magnetic field strengths and inclinations deduced from VMI inversion are compared with results from the inversion codes UNNOFIT and MERLIN.
Conclusions: The VMI inversion method is insensitive to the dependence of Stokes I profiles on the thermodynamic structure in nonmagnetic areas. In the range of Bf products larger than 200 G, mean field strengths exceed 1000 G and there is not a very significant departure from the UNNOFIT results because of differences between magnetic and nonmagnetic model atmospheres. Further improvements might include additional parameters deduced from the shape of Stokes V profiles and from large sets of 3D-MHD simulations, especially for unresolved magnetic flux tubes. Title: Magnetic Field and Plasma Diagnostics from Coordinated Prominence Observations Authors: Schmieder, B.; Levens, P.; Dalmasse, K.; Mein, N.; Mein, P.; Lopez-Ariste, A.; Labrosse, N.; Heinzel, P. Bibcode: 2016ASPC..504..119S Altcode: We study the magnetic field in prominences from a statistical point of view, by using THEMIS in the MTR mode, performing spectropolarimetry of the He I D3 line. Combining these measurements with spectroscopic data from IRIS, Hinode/EIS as well as ground-based telescopes, such as the Meudon Solar Tower, we infer the temperature, density, and flow velocities of the plasma. There are a number of open questions that we aim to answer: - What is the general direction of the magnetic field in prominences? Is the model using a single orientation of magnetic field always valid for atypical prominences? %- Does this depend on the location of the filament on the disk (visible in Hα, in He II 304 Å) over an inversion line between weak or strong network ? - Are prominences in a weak environment field dominated by gas pressure? - Measuring the Doppler shifts in Mg II lines (with IRIS) and in Hα can tell us if there are substantial velocities to maintain vertical rotating structures, as has been suggested for tornado-like prominences. We present here some results obtained with different ground-based and space-based instruments in this framework. Title: Understanding the Mg II and Hα Spectra in a Highly Dynamical Solar Prominence Authors: Heinzel, P.; Schmieder, B.; Mein, N.; Gunár, S. Bibcode: 2015ApJ...800L..13H Altcode: Mg ii h and k and Hα spectra in a dynamical prominence have been obtained along the slit of the Interface Region Imaging Spectrograph (IRIS) and with the Meudon Multi-channel Subtractive Double Pass spectrograph on 2013 September 24, respectively. Single Mg ii line profiles are not much reversed, while at some positions along the IRIS slit the profiles show several discrete peaks that are Doppler-shifted. The intensity of these peaks is generally decreasing with their increasing Doppler shift. We interpret this unusual behavior as being due to the Doppler dimming effect. We discuss the possibility to interpret the unreversed single profiles by using a two-dimensional (2D) model of the entire prominence body with specific radiative boundary conditions. We have performed new 2D isothermal-isobaric modeling of both Hα and Mg ii lines and show the ability of such models to account for the line profile variations as observed. However, the Mg ii line-center intensities require the model with a temperature increase toward the prominence boundary. We show that even simple one-dimensional (1D) models with a prominence-to-corona transition region (PCTR) fit the observed Mg ii and Hα lines quite well, while the isothermal-isobaric models (1D or 2D) are inconsistent with simultaneous observations in the Mg ii h and k and Hα lines, meaning that the Hα line provides a strong additional constraint on the modeling. IRIS far-UV detection of the C ii lines in this prominence seems to provide a direct constraint on the PCTR part of the model. Title: Open questions on prominences from coordinated observations by IRIS, Hinode, SDO/AIA, THEMIS, and the Meudon/MSDP Authors: Schmieder, B.; Tian, H.; Kucera, T.; López Ariste, A.; Mein, N.; Mein, P.; Dalmasse, K.; Golub, L. Bibcode: 2014A&A...569A..85S Altcode: 2014arXiv1407.3171S Context. A large prominence was observed by multiple instruments on the ground and in space during an international campaign on September 24, 2013, for three hours (12:12 UT -15:12 UT). Instruments used in the campaign included the newly launched (June 2013) Interface Region Imaging Spectrograph (IRIS), THEMIS (Tenerife), the Hinode Solar Optical Telescope (SOT), the Solar Dynamic Observatory's Atmospheric Imaging Assembly (SDO/AIA), and the Multichannel Subtractive Double Pass spectrograph (MSDP) in the Meudon Solar Tower. The movies obtained in 304 Å with the EUV imager SDO/AIA, and in Ca II line by SOT show the dynamic nature of the prominence.
Aims: The aim of this work is to study the dynamics of the prominence fine structures in multiple wavelengths to understand their formation.
Methods: The spectrographs IRIS and MSDP provided line profiles with a high cadence in Mg II h (2803.5 Å) and k (2796.4 Å) lines along four slit positions (IRIS), and in Hα in a 2D field of view (MSDP). The spectropolarimetry of THEMIS (Tenerife) allowed us to derive the magnetic field of the prominence using the He D3 line depolarization (Hanle effect combined with the Zeeman effect).
Results: The magnetic field is found to be globally horizontal with a relatively weak field strength (8-15 Gauss). On the other hand, the Ca II movie reveals turbulent-like motion that is not organized in specific parts of the prominence. We tested the addition of a turbulent magnetic component. This model is compatible with the polarimetric observations at those places where the plasma turbulence peaks. On the other hand, the Mg II line profiles show multiple peaks well separated in wavelength. This is interpreted by the existence of small threads along the line of sight with a large dispersion of discrete values of Doppler shifts, from 5 km s-1 (a quasi-steady component) to 60-80 km s-1. Each peak corresponds to a Gaussian profile, and not to a reversed profile as was expected by the present non-LTE radiative transfer modeling. This is a very surprising behavior for the Mg II line observed in prominences.
Conclusions: Turbulent fields on top of the macroscopic horizontal component of the magnetic field supporting the prominence give rise to the complex dynamics of the plasma. The plasma with the high velocities (70 km s-1 to 100 km s-1 if we take into account the transverse velocities) may correspond to condensation of plasma along more or less horizontal threads of the arch-shape structure visible in 304 Å. The steady flows (5 km s-1) would correspond to a more quiescent plasma (cool and prominence-corona transition region) of the prominence packed into dips in horizontal magnetic field lines. The very weak secondary peaks in the Mg II profiles may reflect the turbulent nature of parts of the prominence.

Movies are available in electronic form at http://www.aanda.org Title: The S4I prototype, a beam-slicer dedicated to the new generation Multichannel Subtractive Double Pass for EST imaging spectropolarimetry Authors: Sayède, Frédéric; Mein, Pierre; Malherbe, Jean-Marie; Amans, Jean-Philippe; Crussaire, Daniel; Lecocguen, Regis Bibcode: 2014SPIE.9147E..6FS Altcode: For the future European Solar Telescope (EST) the Observatoire de Paris proposes a new generation of MSDP, an imaging spectro-polarimetry instrument. To validate this new generation, we develop a plane micro-mirrors beam slicer prototype that is tested and validated on an optical bench and on existing telescopes. The prototype called S4I (Spectral Sampling with Slicer for Solar Instrumentation) is built and tested at the Observatoire de Paris. It validates the opto-mechanical feasibility of the new beam slicer. After a complete description of the system, we present the first images. We evaluate the performances of the prototype and compare them to the requirements for the beam-slicer dedicated to the future EST. Title: S4EI (Spectral Sampling with Slicer for Stellar and Extragalactical Instrumentation), a new-generation of 3D spectro-imager dedicated to night astronomy Authors: Sayède, Frédéric; Puech, Mathieu; Mein, Pierre; Bonifacio, Piercarlo; Malherbe, Jean-Marie; Galicher, Raphaël.; Amans, Jean-Philippe; Fasola, Gilles Bibcode: 2014SPIE.9147E..3OS Altcode: Multichannel Subtractive Double Pass (MSDP) spectrographs have been widely used in solar spectroscopy because of their ability to provide an excellent compromise between field of view and spatial and spectral resolutions. Compared with other types of spectrographs, MSDP can deliver simultaneous monochromatic images at higher spatial and spectral resolutions without any time-scanning requirement (as with Fabry-Perot spectrographs), and with limited loss of flux. These performances are obtained thanks to a double pass through the dispersive element. Recent advances with VPH (Volume phase holographic) Grisms as well as with image slicers now make MSDP potentially sensitive to much smaller fluxes. We present S4EI (Spectral Sampling with Slicer for Stellar and Extragalactical Instrumentation), which is a new concept for extending MSDP to night-time astronomy. It is based on new generation reflecting plane image slicers working with large apertures specific to night-time telescopes. The resulting design could be potentially very attractive and innovative for different domains of astronomy, e.g., the simultaneous spatial mapping of accurately flux-calibrated emission lines between OH sky lines in extragalactic astronomy or the simultaneous imaging of stars, exoplanets and interstellar medium. We present different possible MSDP/S4EI configurations for these science cases and expected performances on telescopes such as the VLT. Title: Proper horizontal photospheric flows in a filament channel Authors: Schmieder, B.; Roudier, T.; Mein, N.; Mein, P.; Malherbe, J. M.; Chandra, R. Bibcode: 2014A&A...564A.104S Altcode: Context. An extended filament in the central part of the active region NOAA 11106 crossed the central meridian on Sept. 17, 2010 in the southern hemisphere. It has been observed in Hα with the THEMIS telescope in the Canary Islands and in 304 Å with the EUV imager (AIA) onboard the Solar Dynamic Observatory (SDO). Counterstreaming along the Hα threads and bright moving blobs (jets) along the 304 Å filament channel were observed during 10 h before the filament erupted at 17:03 UT.
Aims: The aim of the paper is to understand the coupling between magnetic field and convection in filament channels and relate the horizontal photospheric motions to the activity of the filament.
Methods: An analysis of the proper photospheric motions using SDO/HMI continuum images with the new version of the coherent structure tracking (CST) algorithm developed to track granules, as well as the large scale photospheric flows, was performed for three hours. Using corks, we derived the passive scalar points and produced a map of the cork distribution in the filament channel. Averaging the velocity vectors in the southern hemisphere in each latitude in steps of 3.5 arcsec, we defined a profile of the differential rotation.
Results: Supergranules are clearly identified in the filament channel. Diverging flows inside the supergranules are similar in and out of the filament channel. Converging flows corresponding to the accumulation of corks are identified well around the Hα filament feet and at the edges of the EUV filament channel. At these convergence points, the horizontal photospheric velocity may reach 1 km s-1, but with a mean velocity of 0.35 km s-1. In some locations, horizontal flows crossing the channel are detected, indicating eventually large scale vorticity.
Conclusions: The coupling between convection and magnetic field in the photosphere is relatively strong. The filament experienced the convection motions through its anchorage points with the photosphere, which are magnetized areas (ends, feet, lateral extensions of the EUV filament channel). From a large scale point-of-view, the differential rotation induced a shear of 0.1 km s-1 in the filament. From a small scale point-of-view, any convective motions favored the interaction of the parasitic polarities responsible for the anchorages of the filament to the photosphere with the surrounding network and may explain the activity of the filament.

Two movies are available in electronic form at http://www.aanda.org Title: Dynamics of a prominence observed in Mg II lines by IRIS Authors: Schmieder, Brigitte; Mein, Pierre; Dalmasse, Kévin; Tian, Hui; Kucera, Therese; Lopez-Ariste, Arturo Bibcode: 2014cosp...40E2927S Altcode: In September 2013 several prominences were observed with the IRIS spectrograph during a 60 day-long international program. We will present one set of observations obtained using multiple instruments on September 24. SDO/AIA and IRIS slit jaws provided images of the prominence corresponding to different physical conditions of the transition region between the cool plasma and the corona. The vector magnetic field was derived from THEMIS (Tenerife) observations using the He D3 depolarisation due to the magnetic field. The inversion code (CPA) takes into account the Hanle and the Zeeman effects. Movies from SDO/AIA in 304 A and Hinode/SOT in Ca II show the dynamics of the fine structures in the plane of the sky. From Mg II and Si IV line spectra observed by IRIS and H-alpha observed by the Multi-channel subtractive spectrograph (MSDP) in the Meudon solar tower we derived the Dopplershifts of the fine structures. The profiles of the Mg II lines are narrow (FHWM =0.15 A) and not reversed, contrary to the predictions of the theoretical models (Paletou et al 1993). We could resolve the velocity of several structures along the LOS with Dopplershifts as high as 60 km/s. Title: Dynamics in the filament of september 17 2010 and in its channel Authors: Mein, Nicole; Mein, Pierre; Schmieder, Brigitte; Malherbe, Jean-Marie; Roudier, Thierry Bibcode: 2014IAUS..300..451M Altcode: Dynamics of a filament is investigated in Hα. Counterstreaming flows are observed along the filament. Photospheric horizontal motions have been computed by using a Coherent Structure Tracking algorithm in the filament environment. Title: Proper horizontal photospheric flows below an eruptive filament Authors: Schmieder, Brigitte; Mein, Pierre; Mein, Nicole; Roudier, Thierry; Chandra, Ramseh Bibcode: 2014cosp...40E2926S Altcode: An analysis of the proper motions using SDO/HMI continuum images with the new version of the coherent structure tracking (CST) algorithm developed to track the granules as well as the large scale photospheric flows, was perfomed during three hours in a region containing a large filament channel on September 17, 2010. Supergranules were idenfied in the filament channel. Diverging flows inside the supergranules are similar in and out the filament channel. Using corks, we derived the passive scalar points and produced maps of cork distribution. The anchorage structures with the photosphere (feet) of the filament are located in the areas of converging flows with accumulations of corks. Averaging the velocity vectors for each latitude we defined a profile of the differential rotation. We conclude that the coupling between the convection and magnetic field in the photosphere is relatively strong. The filament experienced the convection motions through its feet. On a large scale point-of-view the differential rotation induced a shear of 0.1 km/s in the filament. On a small scale point-of-view convection motions favored the interaction/cancellation of the parasitic polarities at the base of the feet with the surrounding network explaining the brightenings,/jets and the eruption that were observed in the EUV filament. Title: Multi-purpose grating spectrograph for the 4-meter European Solar Telescope Authors: Calcines, A.; Collados, M.; Feller, A.; Gelly, B.; Grauf, B.; Hirzberger, J.; López Ariste, A.; Lopez, R. L.; Mein, P.; Sayéde, F. Bibcode: 2012SPIE.8446E..6TC Altcode: This communication presents a family of spectrographs designed for the European Solar Telescope. They can operate in four different configurations: a long slit standard spectrograph (LsSS), two devices based on subtractive double pass (TUNIS and MSDP) and one based on an integral field, multi-slit, multi-wavelength configuration. The combination of them composes the multi-purpose grating spectrograph of EST, focused on supporting the different science cases of the solar photosphere and chromosphere in the spectral range from 3900 Å to 23000 Å. The different alternatives are made compatible by using the same base spectrographs and different selectable optical elements corresponding to specific subsystems of each configuration. Title: The S4I prototype: a beam-slicer system dedicated to the new generation multichannel subtractive double pass for EST imaging spectropolarimetry Authors: Sayède, Frédéric; Mein, Pierre; Amans, Jean-Philippe; Moity, Jacques Bibcode: 2012SPIE.8446E..6ZS Altcode: For the future European Solar Telescope (EST) the Observatoire de Paris proposes a new generation of MSDP: an imaging spectro-polarimetry instrument. To validate this new generation, we develop a beam slicer prototype that will be tested and validated on an optical bench and on existing telescopes. The prototype called S4I (Spectral Sampling with Slicer for Solar Instrumentation) is under construction and tested at the Observatoire de Paris. It validates the opto-mechanical feasibility of the new beam slicer. The manufacture is now complete: we give a description of the whole system. We give also some results of the first tests. Title: Velocity Vector, Ionization Degree, and Temperature of Prominence Fine Structures Observed by Hinode/SOT Authors: Schmieder, B.; Mein, P.; Chandra, R.; Molodij, G.; Heinzel, P.; Berlicki, A.; Schwartz, P.; Fárník, F.; Labrosse, N.; Anzer, U.; Watanabe, T. Bibcode: 2012ASPC..454..107S Altcode: Prominences have been successfully observed by Hinode in April 2007 exhibiting a strong dynamics of their fine structures. The dynamics of a prominence is a challenge to understand the formation of cool prominence plasma embedded in the hot corona. Combining simultaneous observations obtained in Hα with Hinode/SOT and the MSDP spectrograph operating at the Meudon solar tower, velocity vectors have been derived. The Doppler-shifts of bright threads are of the same order as the velocities measured perpendicular to the line of sight. This suggests that the vertical structures of the prominence could be a pile up of dips in magnetic field lines viewed in 3D. Using Hα, Hinode/XRT and TRACE data, the hydrogen ionization degree has been determined to be 0.5-0.8, and the optical thickness in Hα between 0.2 and 1.3. The Extreme Ultraviolet Imaging Spectrometer (EIS) on Hinode produced images of the prominence in 11 selected lines with formation temperatures between log(T) = 4.7 and log(T) = 6.1. We comment on the absorption, emissivity blocking and emission involved for interpreting the different structures of the prominence in terms of the temperature and density. Title: Prominence fine-structure dynamics as inferred from 2D non-LTE models Authors: Gunar, Stanislav; Schmieder, Brigitte; Mein, Pierre; Heinzel, Petr Bibcode: 2012cosp...39..683G Altcode: 2012cosp.meet..683G 2D multi-thread prominence fine structure models are able to produce synthetic Lyman spectra in very good agreement with spectral observations by SOHO/SUMER including the spectral line asymmetries. The synthetic differential emission measure curves derived from these models are also in a good agreement with observations. Now we show that these models are also able to produce synthetic H-alpha line profiles in very good agreement with observations which allows us to analyze not only the physical parameters of the prominence fine-structure plasma but also some aspects of its dynamical behaviour. We compare the synthetic H-alpha spectra with the observed spectra of the April 26, 2007 prominence using three statistical parameters: the line integrated intensity, the line full-width at the half-maximum (FWHM), and the Doppler velocity derived from shifts of the line profiles. This statistical analysis allows us to conclude that the overall statistical distribution of the LOS velocities in the April 26, 2007 prominence at the time of the observations was below +/-15 km/s and in the prominence core was close to +/-10 km/s. In combination with the analysis of the Lyman spectra we determine several physical parameters of the observed prominence fine structures which show that the April 26, 2007 prominence was relatively less massive. We are also able to put some constrains on the prominence core temperature that might be relatively low, reaching values below 6000 K. Title: Dynamics of quiescent prominence fine structures analyzed by 2D non-LTE modelling of the Hα line Authors: Gunár, S.; Mein, P.; Schmieder, B.; Heinzel, P.; Mein, N. Bibcode: 2012A&A...543A..93G Altcode:
Aims: We analyze the dynamics of the prominence fine structures of a quiescent prominence observed on April 26, 2007 during a coordinated campaign of several spaceborne and ground-based instruments. We use Lyman spectra observed by SOHO/SUMER and the Hα line spectra obtained by MSDP spectrograph working at the Meudon Solar Tower.
Methods: We employ the 2D multi-thread prominence fine-structure modelling that includes randomly distributed line-of-sight (LOS) velocities of individual threads to derive models producing synthetic Lyman lines in good agreement with the SOHO/SUMER observations. We then use these models to produce synthetic Hα line spectra that we compare with the observed spectra using three statistical parameters: the line integrated intensity, the line full-width at half-maximum (FWHM), and the Doppler velocity derived from shifts of the line profiles.
Results: We demonstrate that the 2D multi-thread models that produce synthetic Lyman spectra in agreement with observations also generate synthetic Hα spectra in good agreement with the observed ones. The statistical analysis of the FWHM and Doppler velocities of the synthetic Hα line profiles show that the overall LOS velocities in the April 26, 2007 prominence at the time of the observations were below 15 km s-1 and in the prominence core were close to 10 km s-1. In combination with the analysis of the Lyman spectra, we determine several physical parameters of the observed prominence fine-structures that show that the April 26, 2007 prominence had a relatively low-mass weakly magnetized structure. We are also able to impose some constraints on the prominence core temperature, which may be relatively low, with values below 6000 K.
Conclusions: The combination of 2D non-LTE prominence fine-structure modelling with the statistical analysis of the observed and synthetic Lyman and Hα spectra allows us to analyze the influence of the model input parameters and the velocity fields on the synthetic Hα line profiles, thus determine the overall dynamics of the observed prominence as well as the physical parameters of its plasma.

Appendix A is available in electronic form at http://www.aanda.org Title: Inversion of Zeeman Line Profiles Using Central Moments Authors: Mein, P.; Uitenbroek, H.; Mein, N.; Bommier, V.; Faurobert, M. Bibcode: 2012EAS....55...83M Altcode: A new inversion method derived from central moments of Zeeman line profiles (ICM), is used to determine magnetic field vectors (Mein et al. 2011). Two quantities A1 and A2 combining moments of profiles I ± S (S = Q,U,V) are nearly linear functions of the longitudinal and transverse components and lead to the field components through very fast iterations. Optimized exponents reduce noise effects. The ICM inversion does not require Milne Eddington approximation and can be used in a wide range of solar models. Title: New generation Multichannel Subtractive Double Pass for imaging spectropolarimetry - The S4I prototype Authors: Sayede, F.; Mein, P.; Amans, J. -P.; Moity, J. Bibcode: 2012EAS....55..385S Altcode: Imaging spectropolarimetry is a powerful tool in solar physics. Multichannel Subtractive Double Pass (MSDP) spectrographs can produce simultaneous 2D images in a number of wavelengths covering several line profiles with the following advantages: - Contrary to long slit spectroscopy, the spatial resolution can reach the diffraction limit. - Contrary to narrow band filters, full line profiles are recorded at the same time without any image motion and differential seeing effect. MSDP spectrographs use an entrance window instead of the usual long slit. A new generation MSDP using slicers made of mirrors instead of prisms is proposed for the future 4 m class European Solar Telescope. We describe the beam slicer prototype S4I (Spectral Sampling with Slicer for Solar Instrumentation) that will be tested soon at the 14 m spectrograph of the Meudon Solar Tower. Title: Magnetic Field Structures in a Facular Region Derived from THEMIS and Hinode Vector Magnetic Field Authors: Guo, Y.; Schmieder, B.; Bommier, V.; Mein, P. Bibcode: 2012ASPC..456...55G Altcode: In order to compare vector magnetic fields obtained by two spectral polarimeters (THEMIS/MTR and Hinode SOT/SP) and two inversion codes (UNNOFIT and MELANIE), we observed a facular region in the active region NOAA 10996 on 2008 May 23. We found that they give consistent results concerning the distributions of field strengths, azimuth and inclination angles. SOT/SP could resolve small magnetic polarities with sizes of 1'' to 2'', and detect convergence and divergence of the horizontal components of magnetic fields in the facular cells. These findings support the models suggesting the existence of flux tube bundles in faculae. With this model and multi spectral line observations, we could infer the relative formation heights of those spectral lines. Title: Fast inversion of Zeeman line profiles using central moments Authors: Mein, P.; Uitenbroek, H.; Mein, N.; Bommier, V.; Faurobert, M. Bibcode: 2011A&A...535A..45M Altcode: Context. Many inversion techniques derive vector magnetic fields and other parameters of the solar atmosphere from Stokes profiles with an iterative process.
Aims: We propose a new inversion method, using functions derived from central moments (ICM), to determine magnetic field vectors with very few iterations.
Methods: Two quantities A1 and A2 that combine moments of profiles I ± S (S = Q,U,V) are proposed. They are nearly linear functions of the longitudinal and transverse components of the magnetic field, and lead to estimates of the field components through a least-squares polynomial fit. A third quantity AD can be used to interpolate between expansions that correspond to two basic models. Exponents β1 and β2 in the moment expressions are adjusted to minimize the sensitivity to data noise.
Results: Inversion coefficients are computed for magnetic fields up to 3000 G in the case of the 630.2 Fe i line by forward modeling in two selected 1D model atmospheres (FALC and MALTM). After inversion of synthetic profiles computed with four models at disk center (FALA, FALC, FALF, MALTM), the mean standard deviations with respect to the input fields do not exceed 5 G for both components over the full range 0-3000 G. A comparison of ICM results with inversion by the UNNOFIT code of profiles observed with THEMIS/MTR shows good agreement. The typical computing time for a solar map of 100 000 points is less than 30 s.
Conclusions: The ICM inversions are almost insensitive to thermodynamic properties and solve for vector magnetic fields in a wide range of solar conditions, ranging from plage to spot, with very little computational effort. They are, therefore, extremely suitable for large data sets. Further improvements should take into account instrumental profiles and effects of limited spatial resolution by using filling factors. Extensions using more parameters and models with large departures from the Milne Eddington approximation could also be considered. Title: The Shape of the Solar Limb: Models and Observations Authors: Thuillier, G.; Claudel, J.; Djafer, D.; Haberreiter, M.; Mein, N.; Melo, S. M. L.; Schmutz, W.; Shapiro, A.; Short, C. I.; Sofia, S. Bibcode: 2011SoPh..268..125T Altcode: 2010SoPh..tmp..202T; 2010SoPh..tmp..226T In this paper we compare observed, empirical, and modelled solar limb profiles and discuss their potential use to derive physical properties of the solar atmosphere. The PHOENIX, SolMod3D, and COSI radiative transfer codes as well as VAL-C models are used to calculate the solar limb shape under different assumptions. The main properties of each model are shown. The predicted limb shape as a function of wavelength for different features on the solar disk, such as quiet Sun, sunspots, and faculae, is investigated. These models provide overall consistent limb shapes with some discrepancies that are discussed here in terms of differences in solar atmosphere models, opacities, and the algorithms used to derive the solar limb profile. Our analysis confirms that the most common property of all models is limb shapes that are much steeper than what is observed, or predicted by the available empirical models. Furthermore, we have investigated the role of the Fraunhofer lines within the spectral domain used for the solar limb measurements. Our results show that the presence of the Fraunhofer lines significantly displaces the limb inflection point from its position estimated assuming only the photospheric continuum. The PICARD satellite, launched on 15 June 2010, will provide measurements of the limb shape at several wavelengths. This work shows that the precision of these measurements allows for discrimination among the available models. Title: New generation multichannel subtractive double pass for EST imaging spectropolarimetry Authors: Sayède, Frédéric; Mein, Pierre; Amans, Jean-Philippe; Moity, Jacques Bibcode: 2010SPIE.7735E..7NS Altcode: 2010SPIE.7735E.248S Any future solar telescope project should incorporate an imaging spectrometer. For the future EST (European Solar Telescope) the Observatoire de Paris offers an imaging spectro-porarimetry instrument: a new generation of MSDP. To validate this new generation, we develop a beam slicer prototype that will be tested and validated on optical bench and on existing telescopes. The study assesses the performance gain of such an instrument on a solar 4m class telescope. We present opto-mechanical solutions of a new beam splitter and its implementation in EST. Title: Spectrograph capabilities of the European Solar Telescope Authors: Calcines, A.; Collados, M.; Feller, A.; Grauf, B.; Grivel-Gelly, C.; Hirzberger, J.; López Ariste, A.; López López, R.; Mein, P.; Sayède, F. Bibcode: 2010SPIE.7735E..20C Altcode: 2010SPIE.7735E..68C EST is a project for a 4-meter class telescope to be located in the Canary Islands. EST will be optimized for studies of the magnetic coupling between the photosphere and the chromosphere. This requires high spatial and temporal resolution diagnostics tools of properties of the plasma, by using multiple wavelength spectropolarimetry. To achieve these goals, visible and near-IR multi-purpose spectrographs are being designed to be compatible with different modes of use: LsSS (Long-slit Standard Spectrograph), multi-slit multi-wavelength spectrograph with an integral field unit, TUNIS (Tunable Universal Narrow-band Imaging Spectrograph), and new generation MSDP (Multi-channel Subtractive Double-pass Spectrograph). In this contribution, these different instrumental configurations are described. Title: Velocity vectors of a quiescent prominence observed by Hinode/SOT and the MSDP (Meudon) Authors: Schmieder, B.; Chandra, R.; Berlicki, A.; Mein, P. Bibcode: 2010A&A...514A..68S Altcode: 2009arXiv0911.5091S Context. The dynamics of prominence fine structures present a challenge to our understanding of the formation of cool plasma prominence embedded in the hot corona.
Aims: Observations performed by the high resolution Hinode/SOT telescope allow us to compute velocities perpendicular to the line-of-sight or transverse velocities. Combining simultaneous observations obtained in Hα with Hinode/SOT and the MSDP spectrograph operating in the Meudon solar tower, we derive the velocity vectors of a quiescent prominence.
Methods: The velocities perpendicular to the line-of-sight are measured using a time-slice technique and the Doppler shifts velocity using the bisector method.
Results: The Doppler shifts of bright threads derived from the MSDP show counterstreaming of the order of 5 km s-1 in the prominence and reaching 15 km s-1 at the edges of the prominence. Even though they are minimum values because of seeing effects, they are of the same order as the transverse velocities.
Conclusions: These measurements are very important because they suggest that the vertical structures detected by SOT may not be true vertical magnetic structures in the sky plane. The vertical structures could be a pile up of dips in more or less horizontal magnetic field lines in a 3D perspective, as proposed by many MHD modelers. In our analysis, we also calibrate the Hinode Hα data using MSDP observations obtained simultaneously.

A movie is available in electronic form at http://www.aanda.org Title: Counterstreaming in quiescent prominences observed by Hinode/SOT and Meudon/MSDP Authors: Schmieder, Brigitte; Chandra, Ramesh; Berlicki, Arkadiusz; Mein, Pierre Bibcode: 2010cosp...38.2943S Altcode: 2010cosp.meet.2943S Prominences have been successfully observed by Hinode in April 2007 exhibiting a strong dy-namics of their fine structures. The dynamics of a prominence is a challenge to understand the formation of cool prominence plasma embedded in the hot corona. Combining simultaneous observations obtained in Hα with Hinode/SOT and the MSDP spectrograph operating at the Meudon solar tower, velocity vectors have been derived. The Doppler-shifts of bright threads are of the same order as the transverse velocities measured perpendicularly to the line of sight. Counterstreamings are detected at the top of the prominence. The vertical structures of the prominence could be a pile up of dips in magnetic field lines viewed in 3D Title: Model studies of the solar limb shape variation with wavelenght within the PICARD project. Authors: Melo, Stella M. L.; Thuillier, Gerard; Claudel, Jennyfer; Haberreiter, Margit; Mein, Nicole; Schmutz, Werner; Shapiro, Alexander; Sofia, Sabatino; Short, Christopher I. Bibcode: 2010cosp...38.1756M Altcode: 2010cosp.meet.1756M Solar images in the visible wavelength range show that the disk centre is brighter than the limb region. This phenomenon, which is both known as "centre to limb variation (CLV)", or "limb darkening function", is know to depend on wavelength. Since the CLV is determined by the density and temperature stratification, as well as the chemical composition of the so-lar photosphere, its measurement is important to validate theoretical assumption made when building numerical models of the solar atmosphere. The definition of the solar diameter is nor-mally adopted as the separation between two inflection points at opposite ends of a line passing through the center of the solar disk. Therefore, in order to understand long term variability on the solar diameter, it is important to understand what drives the dependence of the position of the inflection point on wavelength. In this paper we use different available solar atmosphere models to study this dependence. The results presented here refer to quiet Sun conditions and encompass the visible and near infra-red spectral regions, which are the regions of interest for the PICARD Satellite Mission. In a first step we utilize the solar atmosphere parameters with a radiative transfer code. This allows for the study of the impact of different factors such as opacities, electron density and temperature from different models on the results. Then, we compare results obtained using each solar atmosphere model. Our results are compared with existent ground based measurements performed by the Pic du Midi telescope, the balloon board measurements with the Solar Disk Sextant experiment, and with the measurements by the Michelson Doppler Imager on board SoHO satellite. The model simulations show that the position of the inflection point is sensitive to the different parameters and model assumptions. Furthermore, our study shows, for the first time, that the position of the inflection point changes dramatically with and outside of Fraunhofer lines. Title: Fast imaging spectroscopy with MSDP spectrometers. Vector magnetic maps with THEMIS/MSDP Authors: Mein, P.; Mein, N.; Bommier, V. Bibcode: 2009A&A...507..531M Altcode: Context: Multichannel subtractive double pass (MSDP) spectrometers produce 3D data cubes (x, y, λ) simultaneously across several line profiles. They do not suffer from image convolution by any slit width, and synchronous observations across all wavelengths avoid differential seeing effects. They are very suitable for fast 2D spectroscopy.
Aims: (1) We review specifications and capabilities of some existing MSDP spectrometers with respect to high-cadence observations. (2) THEMIS/MSDP is designed for the spectropolarimetry of strong lines. We propose new data reductions also suitable for the spectropolarimetry of photospheric lines.
Methods: An off-line algorithm is described as a way to increase the spectral resolution. Taking the opportunity of 3D data, spatial interpolations are used around each solar point by only assuming that intensity gradients partial I(x, y, λ)/partial x are constant in the range (x± ɛ_x,λ ± ɛ_λ). The UNNOFIT inversion is used to compare vector magnetic maps deduced from THEMIS/MSDP and slit-spectropolarimetry THEMIS/MTR data.
Results: Both results are in good agreement. In active regions, the rms of the MSDP noise, calculated over 1 arcsec^2, is less than 24 G for the LOS magnetic field and less than 52 G for Bx and 32 G for B_y. The MSDP scanning speed is 10 times the speed of slit-spectropolarimetry.
Conclusions: THEMIS/MSDP can provide vector magnetic maps with typical temporal resolutions that are less than 1 min for small fields-of-view and 10 min for active regions. This allows addressing a number of fast events. In the future, MSDP instruments should efficiently complement single-slit spectroscopy and tunable filters. Their main capabilities should be the multiline aspect and the high temporal and spatial resolutions. New optical devices, such as image slicers, should substantially increase the signal-to-noise ratio. For polarimetric measurements, various compromises are possible between speed, spatial resolution, and SNR. A-posteriori image restorations, either using wide band proxies or bursts of multi-wavelength short exposures, should help improving signal-to-noise ratio and spatial resolution.

Based on observations made with the French-Italian telescope THEMIS operated by the CNRS and CNR on the island of Tenerife in the Spanish Observatorio del Teide of the Instituto de Astrofísica de Canarias. Title: Spectro-imagery at the solar tower of meudon. Authors: Mein, P. Bibcode: 2008LAstr.122f..16M Altcode: No abstract at ADS Title: Spectrophotometric analysis of Ellerman bombs in the Ca II, Hα, and UV range Authors: Pariat, E.; Schmieder, B.; Berlicki, A.; Deng, Y.; Mein, N.; López Ariste, A.; Wang, S. Bibcode: 2007A&A...473..279P Altcode: Context: Even if Ellerman bombs have been observed in the Hα line within emerging magnetic flux regions since the early 20th century, their origin and the mechanisms that lead to their formation have been strongly debated. Recently, new arguments in favor of chromospheric magnetic reconnection have been advanced. Ellerman bombs seem to be the signature of reconnections that take place during the emergence of the magnetic field.
Aims: We have observed an active region presenting emergence of magnetic flux. We detected and studied Ellerman bombs in two chromospheric lines: Ca ii 8542 Å and Hα. We investigated the link between Ellerman bombs and other structures and phenomena appearing in an emerging active region: UV bright points, arch filament systems, and magnetic topology.
Methods: On August 3, 2004, we performed multi-wavelength observations of the active region NOAA 10655. This active region was the target of SoHO Joint Observation Program 157. Both SoHO/MDI and TRACE (195 Å and 1600 Å) were used. Simultaneously, we observed in the Ca ii and Na D1 lines with the spectro-imager MSDP mode of THEMIS. Alternately to the MSDP, we used the MTR spectropolarimeter on THEMIS to observe in Hα and in the Fe i doublet at 6302 Å. We derived the magnetic field vectors around some Ellerman bombs.
Results: We present the first images of EBs in the Ca ii line and confirm that Ellerman bombs can indeed be observed in the Ca ii line, presenting the same “moustache” geometry profiles as in the Hα line, but with a narrower central absorption in the Ca ii line, in which the peaks of emission are around ±0.35 Å. We noticed that the Ellerman bombs observed in the wings of Ca ii line have an elongated shape - the length about 50% greater than the width. We derived mean semi-axis lengths of 1.4'' × 2.0''. In the UV time profiles of the Ellerman bombs, we noticed successive enhanced emissions. The distribution of lifetimes of these individual impulses presents a strong mode around 210 s. Study of the magnetic topology shows that 9 out of the 13 EBs are located on the inversion line of the longitudinal field and that some typical examples might be associated with a bald patch topology.
Conclusions: We provide new arguments in favor of the reconnection origin of Ellerman bombs. The different individual impulses observed in UV may be related to a bursty mode of reconnection. We also show that this Ca ii 8542 Å chromospheric line is a good indicator of Ellerman bombs and can bring new information about these phenomena. Title: Fast vector magnetographs: THEMIS/MSDP and EST project Authors: Mein, P.; Bommier, V.; Mein, N. Bibcode: 2007sf2a.conf..601M Altcode: Imaging spectro-polarimetry with Multichannel Subtractive Double Pass (MSDP) is able to provide vector magnetic fields with high temporal resolution. We present some results obtained with THEMIS and reduced with the UNNOFIT code, as well as a new method to achieve off-line the required spectral resolution. Performances of slit- and imaging-spectroscopy are briefly compared, together with the high capabilities expected from the EST project. Title: Dual-line spectral and phase analysis of sunspot oscillations Authors: Tziotziou, K.; Tsiropoula, G.; Mein, N.; Mein, P. Bibcode: 2007A&A...463.1153T Altcode: Context: Sunspots exhibit a wide range of oscillatory phenomena within their umbrae and penumbrae.
Aims: We investigate the behavior of intensity and Doppler velocity oscillations in the umbra and the penumbra to study sunspot oscillations and their associations.
Methods: Simultaneous, high-cadence (8 s), two-dimensional, Ca II 8542 Å and Hα 6563 Å observations are used. Doppler velocity and intensity variations are studied with a wavelet spectral, phase difference and coherence analysis, both at distinct positions and within the whole umbra and the penumbra.
Results: The analysis reveals the presence of several umbral flashes (UFs) that seem to fill the whole umbra. The spectral analysis indicates oscillating elements of size 2.5'' to 5'' within the umbra with periods around the 3-min band and oscillation periods around the 5-min band within the penumbra. Two remarkable jumps of the oscillation period and the intensity-velocity phase difference are present at both umbra-penumbra and penumbra-superpenumbra boundaries reflecting a drastic change in physical and/or magnetic conditions. The intensity-velocity phase analysis shows a delay of the intensity response to the velocity variations in accordance with the physics of the observed sawtooth velocity behavior. Most of the UFs oscillate incoherently, while the calmest umbral area seems to be associated with velocity spreading from neighboring UFs. The derived incoherency among UFs in conjunction with the existence of coherently oscillating elements within the umbra suggests the presence of umbral areas with slightly different physical and/or magnetic field conditions.
Conclusions: .The presented analysis provides further important constraints for realistic models and theoretical interpretations describing sunspot oscillations. Title: Magnetic flux tubes observed with THEMIS/MSDP Authors: Mein, P.; Mein, N.; Faurobert, M.; Aulanier, G.; Malherbe, J. -M. Bibcode: 2007A&A...463..727M Altcode: Aims:We use spectro-polarimetric THEMIS/MSDP data to investigate the 3D structure of solar magnetic-flux tubes across the upper photosphere.
Methods: Profiles of the sodium D1 line 589.6 nm are analysed by the bisector method at different wavelengths from the core to the wings, for several bright features. They are compared to synthetic profiles derived from 2D magnetic models of flux tubes and from the MULTI code for NLTE line profiles. Three different magnetic models of flux tubes are investigated. Model (I) consists of a single flux tube that compensates for the horizontal Lorentz forces exactly, while model (II) uses a compromise between horizontal and vertical components. Model (III), a conglomerate of thinner flux tubes, leads to the best agreement with observations.
Results: (1) The combination of seeing effects (small filling factor) with slopes of line profiles, which are different in the flux tubes and the neighbouring quiet sun, account for the decrease in observed magnetic field from line core to line wings in central parts of magnetic features, as well as the decrease in magnetic fluxes integrated over the whole magnetic features. (2) The expansion with height of single magnetic flux tubes (models I and II) accounts for the increase in the size of magnetic features from line wings to line core. (3) Pure thermodynamical criteria characterising Dopplershifts and line-intensity fluctuations of magnetic and non-magnetic features have been proven by observations.
Conclusions: . We could account for differential Zeeman effects along the D1 line profile by combining expansion of flux tubes with height, low gas pressure inside flux tubes, and small filling factor due to seeing effects. Better agreement with observations, in particular with respect to magnetic field amplitudes, will probably need 3D models that take velocity fields and horizontal gradients of temperature into account. Title: Fast vector magnetic maps with imaging spectroscopy Authors: Mein, P.; Mein, N.; Bommier, V. Bibcode: 2007MmSAI..78..160M Altcode: We present a new observing mode of THEMIS / MSDP which can provide fast vector magnetic maps of the solar photosphere in the 610.27 Ca line. Title: Magnetic flux tubes observed with THEMIS/MSDP . Authors: Mein, P.; Mein, N.; Faurobert, M.; Aulanier, G.; Malherbe, J. -M. Bibcode: 2007MmSAI..78...92M Altcode: We use 2D spectro-polarimetric data of the NaD1 line to investigate magnetic flux tubes at several levels of the solar photosphere:

- magnetic and non-magnetic bright features can be discriminated by simple criteria of intensities and dopplershifts.

- 2D magnetic models and NLTE line profiles are compared to observations : combination of seeing effects and departures between slopes of line profiles in flux tubes and neighbouring photosphere account for vertical gradients of line-of-sight (LOS) magnetic field measurements.

- Best qualitative agreements are obtained with clusters of magnetic flux tubes. Title: Dual-line analysis of sunspot oscillations Authors: Tziotziou, K.; Tsiropoula, G.; Mein, N.; Mein, P. Bibcode: 2007MmSAI..78...98T Altcode: Umbral oscillations and running penumbral (RP) waves are studied with simultaneous, two-dimensional, high cadence (8 sec), dual-line sunspot observations in Ca II 8542 Å and Halpha , obtained with the MSDP spectrograph on the German VTT in Tenerife. Doppler velocity and intensity images are used to investigate the physical characteristics of umbral flashes (UFs) and RP waves while a wavelet spectral and phase analysis shows their temporal behaviour and permits us to elaborate on their nature and possible association. Title: Spectro polarimetry with liquid crystals . Authors: Malherbe, J. -M.; Roudier, Th.; Moity, J.; Mein, P.; Arnaud, J.; Muller, R. Bibcode: 2007MmSAI..78..203M Altcode: We report spectro polarimetric observations made with the spectrograph of the Lunette Jean Rösch at Pic du Midi, France. We have tested Ferroelectric (FLC) and Nematic (NLC) Liquid Crystals. The instrument setup is briefly decribed, together with first observations of magnetic fields obtained with the Multichannel Subtractive Double Pass (MSDP). Polarization analysis of various spectral lines performed with the single pass (SP) spectrograph in active regions or at the limb is also presented. Title: Evolving Photospheric Flux Concentrations and Filament Dynamic Changes Authors: Schmieder, B.; Aulanier, G.; Mein, P.; Ariste, A. López Bibcode: 2006SoPh..238..245S Altcode: 2006SoPh..tmp...64S We analyze the role of weak photospheric flux concentrations that evolve in a filament channel, in the triggering of dynamic changes in the shape of a filament. The high polarimetric sensitivity of THEMIS allowed us to detect weak flux concentrations (few Gauss) associated with the filament development. The synoptic instruments (MDI, SOLIS) even if their sensitivity is much less than THEMIS were useful to follow any subsequent strengthening of these flux concentrations after their identification in the THEMIS magnetograms. We found that (1) the northern part of the filament develops an Hα barb at the same time that weak minority polarity elements develop near a plage; (2) a section in the southern part of the Hα filament gradually disappears and later reforms at the same time that several mixed-polarity magnetic elements appear, then subsequently cancel or spread away from each other. These changes correspond to increases in EUV emission, as observed by TRACE, EIT, and CDS. This suggests that the plasma is temporarily heated along the filament spine. An idealized sequence of force-free models of this filament channel, based on plasma-supporting magnetic dips occurring in the windings of a very weakly twisted flux tube, naturally explains the evolution of its southern part as being due to changes in the topology of the coronal magnetic field as the photospheric flux concentrations evolve. Title: Long-period astronomical forcing of mammal turnover Authors: van Dam, Jan A.; Abdul Aziz, Hayfaa; Ángeles Álvarez Sierra, M.; Hilgen, Frederik J.; van den Hoek Ostende, Lars W.; Lourens, Lucas J.; Mein, Pierre; van der Meulen, Albert J.; Pelaez-Campomanes, Pablo Bibcode: 2006Natur.443..687V Altcode: Mammals are among the fastest-radiating groups, being characterized by a mean species lifespan of the order of 2.5millionyears (Myr). The basis for this characteristic timescale of origination, extinction and turnover is not well understood. Various studies have invoked climate change to explain mammalian species turnover, but other studies have either challenged or only partly confirmed the climate-turnover hypothesis. Here we use an exceptionally long (24.5-2.5Myr ago), dense, and well-dated terrestrial record of rodent lineages from central Spain, and show the existence of turnover cycles with periods of 2.4-2.5 and 1.0Myr. We link these cycles to low-frequency modulations of Milankovitch oscillations, and show that pulses of turnover occur at minima of the 2.37-Myr eccentricity cycle and nodes of the 1.2-Myr obliquity cycle. Because obliquity nodes and eccentricity minima are associated with ice sheet expansion and cooling and affect regional precipitation, we infer that long-period astronomical climate forcing is a major determinant of species turnover in small mammals and probably other groups as well. Title: Observational characteristics and association of umbral oscillations and running penumbral waves Authors: Tziotziou, K.; Tsiropoula, G.; Mein, N.; Mein, P. Bibcode: 2006A&A...456..689T Altcode: Context: .Umbral flashes (UFs) and running penumbral (RP) waves are believed to be closely related oscillatory phenomena of sunspots.
Aims: .We investigate the association of UFs and RP waves to see whether the latter are a visual pattern created by a common source with UFs or a trans-sunspot wave driven by UFs.
Methods: .Simultaneous, two-dimensional, dual-line observations in Ca II 8542 Å and Hα 6563 Å, obtained with the Multichannel Subtractive Double Pass (MSDP) spectrograph mounted on the German VTT at Teide Observatory on Tenerife, are used for this study. High-cadence 8 s Doppler velocity images, spectrograms, and spectral-analysis results are used to study the characteristics and the relationship of UFs and RP waves.
Results: .Several UFs were observed that seem to fill the whole umbra. Doppler velocity variations with time indicate a shock behaviour for UFs, as well as for umbral and RP waves and a smooth continuous propagation of the latter from the umbra through the umbra-penumbra boundary out to the edge of the penumbra. Furthermore, the spectral analysis shows a decreasing oscillatory frequency as we move from the umbra outwards and a jump at the umbra-penumbra boundary that could possibly reflect, apart from a change in physical conditions, a drastic change of the magnetic field inclination with respect to the vertical.
Conclusions: .The results do not permit us to convincingly support one scenario over the other (i.e. visual pattern vs. trans-sunspot wave) for RP waves; however, they do provide important constraints for future models of sunspot oscillations and RP waves. Title: Sub arcsec evolution of solar magnetic fields Authors: Roudier, Th.; Malherbe, J. M.; Moity, J.; Rondi, S.; Mein, P.; Coutard, Ch. Bibcode: 2006A&A...455.1091R Altcode: Context: .The evolution of the concentrated magnetic field in flux tubes is one challenge of the nowadays Solar physics which requires time sequence with high spatial resolution.
Aims: .Our objective is to follow the properties of the magnetic concentrations during their life, in intensity (continuum and line core), magnetic field and Doppler velocity.
Methods: .We have observed solar region NOAA 0644 on 2004 July 15 at Pic du Midi observatory with the Multichannel Subtractive Double Pass (MSDP) operating mode and analysed the circular polarization of the Na D1 589.6 nm spectral line in terms of longitudinal magnetic field in 2D field of view (5.6 arcsec× 80 arcsec), during 41 mn at two altitudes 327 km and 170 km in the photosphere.
Results: .Our data analysis reveals that all the concentrated magnetic features are associated with downward motions and the magnetic field remains very stable during the 41 mn. At different height 327 and 170 km, a clear depth effect is visible on Doppler velocity but not in the magnetic field strength.
Title: THEMIS/MSDP magnetic field measurements Authors: Berlicki, A.; Mein, P.; Schmieder, B. Bibcode: 2006A&A...445.1127B Altcode: We present an analysis of longitudinal magnetic field measurements using the spectral data obtained with the French - Italian polarisation free telescope THEMIS working in Multichannel Subtractive Double Pass (MSDP) mode. We also used SOHO/MDI data to extend our analysis. THEMIS observations in the MSDP mode allows us to perform imaging spectropolarimetry characterized by high spatial and time resolution. In our analysis we used the observations of solar active region NOAA 10484 performed on October 20, 2003. From THEMIS 2D spectral images recorded in Na D1 5896 Å line we obtained the longitudinal magnetic field in the active region. The value of the magnetic field was calculated at different distances from the Na D1 line centre. We determine the LOS magnetic field at different heights in the solar atmosphere. SOHO/MDI observations provide the longitudinal magnetic field in Ni I (6768 Å) line. THEMIS/MSDP measurements at Δλ= 0.30 Å are similar to SOHO/MDI results. Gradients of longitudinal magnetic fields derived from MSDP measurements at Δλ= 0.08 and Δλ=0.24 Å exhibit different behaviours according to solar targets. A decrease with height is seen in spot umbrae and penumbrae, while the gradient in facular and network areas suggests a slight increase of the longitudinal magnetic field, which might be explained by the 3D-structure of canopies. Title: Active Region Magnetic Field Observed with Themis/msdp and Soho/mdi Instruments Authors: Berlicki, A.; Mein, P.; Schmieder, B. Bibcode: 2005ESASP.600E..57B Altcode: 2005ESPM...11...57B; 2005dysu.confE..57B No abstract at ADS Title: Sunspot Umbral Oscillations and Running Waves Authors: Tziotziou, K.; Tsiropoula, G.; Mein, N.; Mein, P. Bibcode: 2005ESASP.600E..15T Altcode: 2005dysu.confE..15T; 2005ESPM...11...15T No abstract at ADS Title: Non-LTE diagnostics of velocity fields during the gradual phase of a solar flare Authors: Berlicki, A.; Heinzel, P.; Schmieder, B.; Mein, P.; Mein, N. Bibcode: 2005A&A...430..679B Altcode: We perform an analysis of the velocity field within the Hα ribbons during the gradual phase of an M 1.0 solar flare observed on October 22, 2002. We use spectroscopic observations performed with the German VTT (Vacuum Tower Telescope) working in the MSDP (Multichannel Subtractive Double Pass spectrograph) observing mode. From these observations the Hα line profiles in chosen areas of the flare ribbons were reconstructed and these observational profiles were compared with a grid of synthetic Hα line profiles calculated by the non-LTE radiative-transfer code. This code allows us to calculate different models of the chromosphere with a prescribed velocity field. By optimising the best fit between the observed and synthetic profiles we find the most appropriate models of the chromosphere and vertical structure of the velocity field in the analysed areas of the flare ribbons. By means of the non-LTE radiative-transfer calculations we show that in most analysed areas of the Hα flare ribbons the chromospheric plasma exhibited upward motion with a mean velocity of a few km;s-1. These results are consistent with previous estimates and support the scenario of a gentle evaporation during the gradual phase. Title: High resolution solar magnetometry with the spectrograph of the Pic du Midi Turret Dome Authors: Malherbe, J. -M.; Roudier, Th.; Mein, P.; Moity, J.; Muller, R. Bibcode: 2004A&A...427..745M Altcode: 2000astro.ph..3094R We present the first results obtained with a new Ferroelectric Liquid Crystal (FLC) polarimeter operating with the spectrograph of the Pic du Midi Turret Dome, since September 2003. We observed the solar granulation around active region NOAA 0459 with the Multichannel Subtractive Double Pass (MSDP) operating mode and analysed the circular polarization of the Na D1 589.6 nm spectral line in terms of longitudinal magnetic fields in a 2D field of view (16× 142 arcsec). Image quality was fairly good and limited to 0.4 arcsec due to the pixel sampling. This observation reveals the presence of magnetic concentrations of several hundred Gauss which are mainly located in the intergranular lanes. Data analysis performed at two different optical depths (line core and line wings) also suggests that magnetic lines are curved and diverge with increasing altitude. Title: On the nature of the chromospheric fine structure. II. Intensity and velocity oscillations of dark mottles and grains Authors: Tziotziou, K.; Tsiropoula, G.; Mein, P. Bibcode: 2004A&A...423.1133T Altcode: We study periodicities of dark mottles and grains observed in high spatial and temporal resolution Hα 2-D intensity and velocity images, obtained with the Multichannel Subtractive Double Pass (MSDP) spectrograph at THEMIS in Tenerife, Canary Islands. Intensity and velocity variations of individual mottles and grains, as well as of large regions containing a substantial number of these structures are examined with a wavelet analysis which provides the temporal distribution of periods and with a randomization method that gives the respective probabilities associated with them. The wavelet analysis, which shows that velocity variations are the dominant ones, results in a wide range of periods, from 100 to 500 s, with variable probabilities. However, it strongly indicates the presence of a predominant period of ∼5 min seen in both dark mottle and grain oscillations. We suggest that differences in periods found in individual mottles as well as in averages of regions containing these structures are due to the topology of the local magnetic field which can affect oscillatory processes. We report for the first time oscillations of dark grains which are more likely vertical structures ``anchored" in the photosphere. The analysis supports further the suggestion that dark mottles and grains are the same structures, the only difference between them being their respective inclinations to the line-of-sight. Title: Magnetic changes observed in the formation of two filaments in a complex active region: TRACE and MSDP observations Authors: Schmieder, Brigitte; Mein, Nicole; Deng, Yuanyong; Dumitrache, Cristiana; Malherbe, Jean-Marie; Staiger, Joachim; Deluca, E. E. Bibcode: 2004SoPh..223..119S Altcode: This paper is focused on the formation of two filaments in a complex center of decaying active regions (AR 8329 and AR 8326), located in the northern hemisphere. The observations were obtained in Hα by the Multi-channel Subtractive Double Pass spectrograph (MSDP mounted on the German telescope VTT in Tenerife) and EUV lines with TRACE (Transition Region And Corona Explorer). High Doppler shifts are found to be related to the ends of filament segments where canceling magnetic fields are also located (as seen on magnetograms from Big Bear Solar Observatory). At these locations, velocities along the line of sight, derived by using a cloud model method reach −20 km s−1, the segments of filaments merge and frequently a time-related sub-flare is observed by TRACE. The chirality of the filament segments has been determined by different methods: the segments of dextral chirality join together and form a long dextral filament, and a single filament of sinistral chirality forms end to end with the dextral filament but does not merge with it. Assuming a model of twisted flux tube for filament material, we suggest that the dextral filament has negative helicity and a relationship between its formation and the close by sunspot with the same sign of helicity. Title: Multi-wavelength flare study and magnetic configuration Authors: Schmieder, Brigitte; Berlicki, A.; Vilmer, N.; Aulanier, G.; Démoulin, P.; Mein, P.; Mandrini, C.; Deluca, E. Bibcode: 2004IAUS..223..397S Altcode: 2005IAUS..223..397S Recent results of two observation campaigns (October 2002 and October 2003) are presented with the objective of understanding the onset of flares and CMEs. The magnetic field was observed with THEMIS and MDI, the chromosphere with the MSDP operating on the German telescope VTT and on THEMIS, the EUV images with SOHO/CDS and TRACE, the X-ray with RHESSI. We show how important is the magnetic configuration of the active region to produce CMEs using two examples: the October 28 2003 X 17 flare and the October 22 2002 M 1.1 flare. The X 17 flare gave a halo CME while the M 1.1 flare has no corresponding CME. The magnetic topology analysis of the active regions is processed with a linear-force-free field configuration. Title: On the Nature of Chromospheric Umbral Flashes And Running Penumbral Waves (Abstract) Authors: Tziotziou, K.; Tsiropoula, G.; Mein, N.; Mein, P. Bibcode: 2004hell.conf...50T Altcode: No abstract at ADS Title: Multi-Wavelength Observations of an M1.0 Flare on 22 October 2002 Authors: Berlicki, A.; Schmieder, B.; Vilmer, N.; Mein, P.; Mein, N.; Heinzel, P.; Staiger, J.; Deluca, E. E. Bibcode: 2004IAUS..219..669B Altcode: No abstract at ADS Title: Magnetic configuration reorganisation before the X 17 flare of October28 2003 Authors: Schmieder, B.; Mandrini, C.; Demoulin, P.; Mein, P. Bibcode: 2004cosp...35.1528S Altcode: 2004cosp.meet.1528S The active region NOAA 0486 was observed during a multi-wavelength campaign with ground based and space instruments. We analyse the magnetic configuration of the region during a pre-event, which reorganizes the magnetic connectivities of the field lines before the occurence of a X17 flare of October 28 2003. The magnetic field was observed with THEMIS and MDI, the chromosphere with the MSDP operating on on THEMIS and with the Meudon heliograph, the EUV images with SOHO/CDS and TRACE. The X17 flare gave a halo CME while the M1.9 flare has no corresponding CME. The magnetic field analysis of the active regions is performed by using a linear-force-free field code. The pre-flare event before the X17 flare change the connectivities in a first phase and allows the stressed field to relax in a second phase producing the X17 flare. Title: Spectro-polarimetric observation of the fine structure of a quiescent filament Authors: Zong, W. G.; Tang, Y. H.; Fang, C.; Mein, P.; Mein, N.; Xu, A. A. Bibcode: 2003A&A...412..267Z Altcode: This paper presents the spectro-polarimetric measurements of a big quiescent filament observed by the MSDP mode of the THEMIS on August 24, 2000. The Hα , CaII 8542 and NaI D2 line profiles of a segment of the filament were obtained. By use of the Hα images with high spatial resolution, the two barb endpoints were identified. The parameters at the barbs' endpoints, including intensity, velocity and longitudinal magnetic field were measured. Using the data with high spatial resolution (0.16'' per pixel), we have found the following results. 1) There was mass motion at the barb endpoints in the chromosphere, the values and the directions of the mass motion at the barb endpoints change in several minutes. 2) The two barb endpoints are located between the majority polarities and the minority polarities. Title: High spatial resolution capabilities of Doppler measurements with the Pic du Midi MSDP spectrograph Authors: Roudier, Th.; Malherbe, J. M.; Mein, P.; Muller, R.; Coutard, C.; Lafon, M.; Grimaud, F. Bibcode: 2003A&A...409..793R Altcode: We analyse observations in the NaD1 line (lambda 5896 Å) obtained with the MSDP spectrograph of the Turret Dome of the Pic du Midi Observatory. Individual images reveal high spatial resolution and the data reduction shows the high capabilities of the spectrograph to get doppler measurements up to the limit of the resolution of the refractor (0\farcs3). Dopplershifts are obtained in the middle and high photosphere. The smallest granules 0\farcs4 show upward motions in the middle photosphere. Title: On the nature of the chromospheric fine structure. I. Dynamics of dark mottles and grains Authors: Tziotziou, K.; Tsiropoula, G.; Mein, P. Bibcode: 2003A&A...402..361T Altcode: We analyze a time series of forty high spatial and temporal resolution two-dimensional intensity and Doppler velocity images at different wavelengths within the Hα line. The observations were obtained with the Multichannel Subtractive Double Pass (MSDP) spectrograph at THEMIS. We study the morphology of dark mottles and grains as seen in different wavelengths and examine their relation to the MDI magnetic field topology. We determine some physical properties of dark mottles with an inversion technique based on an iterative cloud model method with constant source function, giving the optical thickness tau0, the Doppler width Delta lambdaD , the velocity v and the source function S distribution along a structure. The obtained global properties of mottles as well as the spatial and temporal evolution of several physical parameters along the axes of individual mottles are discussed. The derived velocities in mottles as a function of space and time (time slice images) exhibit a quasi-periodic, bi-directional pattern. It is suggested that magnetic reconnection is the mechanism responsible for their formation and dynamics. Furthermore, a similar quasi-periodic behaviour of the Doppler velocity variations in dark grains and their morphological characteristics both suggest the similarity of dark mottles and grains. Title: Na I D1 Stokes V Asymmetries and Velocity Structure Around Sunspots Authors: Eibe, M. T.; Sánchez Almeida, J.; Mein, P.; Aulanier, G.; Malherbe, J. M. Bibcode: 2003ASPC..307..374E Altcode: No abstract at ADS Title: Osiris, HD 209458b, une exoplanete a l'allure de comete. Authors: Ferlet, R.; Vidal-Madjar, A.; Lecavelier Des Etangs, A.; Desert, J. -M.; Hebrard, G.; Mein, N. Bibcode: 2003LAstr.117..194F Altcode: No abstract at ADS Title: Spectral diagnostics of the magnetic field orientation in a round-shaped filament Authors: Schmieder, B.; Mein, N.; Heinzel, P.; Anzer, U. Bibcode: 2002ESASP.506..469S Altcode: 2002ESPM...10..469S; 2002svco.conf..469S During several campaigns focused on prominences we have obtained coordinated spectral observations from the ground and from space. The SOHO/SUMER spectrometer allows us to observe, among others, the whole Lyman series of hydrogen, while the Hα line was observed by the MSDP spectrograph at the VTT. For Lyman lines, the non-LTE radiative-transfer computations have shown the importance of the prominence-corona transition region (PCTR) and its relation to the magnetic field orientation for the explanation of the observed line profiles (Schmieder et al. 1998, Heinzel et al. 2001). Moreover, Heinzel and Anzer (2001) developed new 2D models which demonstrate how the shapes of Lyman lines vary depending on the orientation of the magnetic field with respect to the line of sight. To confirm this result observationally, we focus here on a round-shaped filament observed during three days as it was crossing the limb. The Lyman profiles observed on the limb are different from day to day and we interpret these differences by the change of orientation of the prominence axis (and therefore the magnetic field direction) with respect to the line-of-sight. Title: MHD waves in active region filament from SOHO-THEMIS joint observations Authors: Régnier, S.; Solomon, J.; Vial, J. C.; Mein, P. Bibcode: 2002ESASP.505..647R Altcode: 2002IAUCo.188..647R; 2002solm.conf..647R The stability of solar filaments and their implications for eruptive events can be revealed by the existence of magnetohydrodynamic (MHD) waves. During the MEDOC campaign on May 2000, we performed joint observations involving SOHO and THEMIS instruments (CDS and MSDP respectively). We analyse the modes of oscillations for several spectral lines (Hα at 6563 Å, He I at 584 Å and Mg X at 609 Å): intermediate (6-40 min) and short (< 5 min) periods are found and are discusssed in terms of MHD waves. The Hα time series (MSDP) in both line center intensity and line-of-sight Doppler shifts provide constraints on models of filament oscillations. Title: Magnetic cancellation and small-scale activity in an AR filament Authors: Schmieder, B.; Engvold, O.; Yong, Lin; Deng, Y. Y.; Mein, N. Bibcode: 2002ESASP.505..223S Altcode: 2002solm.conf..223S; 2002IAUCo.188..223S A long set of observations obtained with the VTT/MSDP spectrograph in September 1998 (8 to 11) allows us to follow the formation of a complex filament in and around a nest of active regions during its disk passage. Continuous shear of magnetic field in this region can explain the formation and the relative stability of the filament structure before the occurrence of a flare which leads to important changes in the magnetic configuration. The corona overlying the region and the flare, as well, is observed by TRACE. The studied filament is stable on long term time scale. However, high spatial and temporal observations obtained in La Palma (SVST) show high Doppler shifts and strong transverse motions of absorbing blobs along the filament. These velocities are directly related to magnetic activity as observed with the SVST. A small scale magnetic analysis shows emergence of MMFs (Moving Magnetic Features) around a decaying sunspot and canceling flux with the neighbor network. Magnetic reconnection could occur and explain the ejection of blobs along the new magnetic field lines. Formation of the transient blobs is discussed. Title: Chromospheric fine structure dynamics Authors: Tziotziou, K.; Tsiropoula, G.; Mein, P. Bibcode: 2002ESASP.505..163T Altcode: 2002solm.conf..163T; 2002IAUCo.188..163T We investigate the dynamics of chromospheric mottles observed with THEMIS. We study a half an hour time series of 2-D intensity and Doppler velocity images at different wavelengths within the Hα line, obtained with the Multichannel Subtractive Double Pass (MSDP) spectrograph with a cadence of 40.5 sec. We determine the physical parameters in dark mottles with an inversion technique which is based on an iterative cloud model method with constant source function. With this method we calculate the optical thickness τmax, the Doppler width ΔλD, the velocity v and the source function S describing the structure. We discuss the results of the inversion technique and show the spatial and temporal evolution of several physical parameters along the axes of individual mottles. The pattern of the derived velocities as a function of space and time (time slice images) suggests the presence of magnetic reconnection as the driving mechanism of their formation. Title: Theoretical hydrogen population relations for horizontal cloud-like solar structures Authors: Tziotziou, K.; Mein, N.; Mein, P.; Heinzel, P. Bibcode: 2002ESASP.477..183T Altcode: 2002scsw.conf..183T A large set of parameterized NLTE models has been computed for a 1D horizontal cloud-like structure standing above the solar surface. The used input model parameters are temperature, velocity, microturbulence, electronic density and geometrical thickness of the structure. From the output of our computations which is the hydrogen level populations as a function of the line center optical depth, we calculate several relations between the hydrogen population levels and the considered electron density. These relations are important for the study of prominence-like structures from observations. Title: The 3D Spectroscopy for Adaptive Optics (Invited Talk) Authors: Le Coarer, E.; Mein, P. Bibcode: 2002ASPC..282..447L Altcode: 2002gtd..conf..447L According to our experience of GRAF, GRIF we try to survey the art in matter of 3D Spectrocopy behind Adaptive Optic systems for large telescopes. The Fabry Perot Interferometer can continue to play a role in future but some important factors as instrument must be taken into account in order to offers the best service. We also examine other optical mounts with slicers. Title: The MSDP of THEMIS: Capabilities, first results and prospects Authors: Mein, P. Bibcode: 2002A&A...381..271M Altcode: We present some capabilities and results of the Multi Channel Subtractive Double Pass instrument of THEMIS. More details and references can be found at http://www.themis.iac.es. MSDP imaging spectropolarimetry is characterized by high space and time resolution. The spatial resolution is close to seeing limitations, and large areas of the Sun can be scanned within short time intervals. In the case of THEMIS, polarization measurements are possible. 2 Stokes parameters and 16 wavelengths of a line profile can be observed simultaneously in a 2D field of view. The scattered light is reduced by the use of the long predisperser as a first-pass spectrograph. Some results are presented for fine structures of the chromosphere and stratification of magnetic fields. The MSDP of THEMIS is very efficient to observe fast extended events, such as eruptive phenomena and mass ejections, in particular during coordinated campaigns with space instruments. General outlines of the data-processing are given. All codes are available at http://BASS2000.bagn.obs-mip.fr. In conclusion, we mention future prospects with respect to spatial and spectral resolution, large field-of-view, multi-line observations, and compatibility with other THEMIS observing modes. Title: Vertical structure of sunspots from THEMIS observations Authors: Eibe, M. T.; Aulanier, G.; Faurobert, M.; Mein, P.; Malherbe, J. M. Bibcode: 2002A&A...381..290E Altcode: We have analysed two-dimensional spectro-polarimetric data taken with the MSDP observing mode of THEMIS in the Na I D1 line to investigate the height variation of the magnetic field in sunspot umbrae. From the Zeeman-induced circular polarization measured at individual MSDP channels within the line profile, maps of the longitudinal magnetic field have been computed. A method based on Response Functions has been developed to estimate the depth in the atmosphere at which the Zeeman measurements are originated, thus providing the line-of-sight field at different altitudes in the photosphere. The magnetogram corresponding to the deepest level has served as a boundary condition to perform the potential field extrapolation into the corona. We have found that the spatial distribution of vertical field gradient contours predicted from extrapolation is in qualitatively good agreement with that inferred from observations. Quantitatively, however, the longitudinal field gradients obtained with both methods differ about one order of magnitude, being larger for observations. The origin of this discrepancy has been discussed with respect to possible observation biases, as well as to idealizations used for field extrapolation. This is a crucial problem to be addressed in future work, and may have important implications for the physics of how the magnetic field evolves through sunspots and how the flux is distributed in the corona. Title: Ca II 8542 Å sunspot oscillations observed with THEMIS Authors: Tziotziou, K.; Tsiropoula, G.; Mein, P. Bibcode: 2002A&A...381..279T Altcode: Oscillations in the umbra and the penumbra of an isolated sunspot located near the solar disk centre were investigated. The observations were obtained with the Multichannel Subtractive Double Pass (MSDP) spectrograph operating in the Ca Ii 8542 Å line and installed at the focus of THEMIS (Tenerife). From the MSDP data, two-dimensional intensity and Doppler shift images were computed at different wavelengths within the line. Intensity and Doppler shift oscillations in the umbra and the penumbra of the sunspot showing up as umbral flashes and penumbral waves were analyzed using a 23 min time series with a cadence of 46 s. The Ca Ii umbral flash intensity profile shows an emission core in its blue wing. We investigate the relation between umbral flashes and running penumbral waves by a power spectrum analysis which shows a 6 mHz frequency for the standing umbral oscillations (flashes) which are observed only on the upper half part of the umbra. The running penumbral waves propagate with an average phase velocity of 16 km s-1 and their frequency is constant in the penumbra and equal to 3 mHz. Although the time slice images suggest that umbral flashes and running penumbral waves are probably due to the same resonator, the power analysis shows no direct relationship between the two phenomena. Based on observations made with the THEMIS telescope operated on the island of Tenerife by CNRS-CNR in the Spanish Observatorio del Teide of the Instituto de Astrof{ísica de Canarias. Title: Recent results from THEMIS/MSDP campaigns Authors: Tziotziou, K.; Mein, P. Bibcode: 2002joso.book..129T Altcode: We present recent results based on observations of the 2000 campaign with the Multichannel Subtractive Double Pass (MSDP) spectrograph of the solar telescope THEMIS. The MSDP spectrograph permits the simultaneous recording of line profiles at every pixel of a two-dimensional solar image. We show results based on inversion methods developed for the study of THEMIS observations, either with the use of a non-LTE grid of line profiles or with the use of response functions. We also discuss results concerning sunspot observations and in particular a study of magnetic field gradients in the umbra of sunspots and a study of oscillatory phenomena like umbral flashes and running penumbral waves. Title: JOSO national report 2000-2001 - France Authors: Schmieder, B.; Mein, P.; Lemaire, P.; Pick, M.; Vilmer, N. Bibcode: 2002joso.book...56S Altcode: We report on the scientific advances in solar physics in France. The French Solar community is large split in different laboratories and observatories. We report on specific groups (THEMIS, SOHO, Nançay). Title: 2D spectroscopy and science with THEMIS Authors: Tziotziou, K.; Mein, P.; Tsiropoula, G.; Eibe, T. Bibcode: 2001hell.confE..25T Altcode: No abstract at ADS Title: A Study of Hydrogen Density in Emerging Flux Loops from a Coordinated Transition Region and Coronal Explorer and Canary Islands Observation Campaign Authors: Mein, N.; Schmieder, B.; DeLuca, E. E.; Heinzel, P.; Mein, P.; Malherbe, J. M.; Staiger, J. Bibcode: 2001ApJ...556..438M Altcode: During an international ground-based campaign in the Canary Islands coordinated with space instruments (i.e., Transition Region and Coronal Explorer [TRACE]), we observed an active region on 1998 September 10 with high spatial and temporal resolution. New emerging flux in the central part of the active region was observed in magnetograms of the Swedish Vacuum Solar Telescope, La Palma. Emerging loops (arch-filament systems [AFSs]) are well developed in Hα and Ca II according to the observations made at the Vacuum Tower Telescope (VTT) and THEMIS telescope in Tenerife with the Multichannel Subtractive Double Pass (MSDP) spectrographs. The TRACE images obtained at 171 and 195 Å show low-emission regions that are easily identified as the individual AFS. They are due to absorption by hydrogen and helium continua in the cool filament plasma. We compare two techniques of measuring the hydrogen density in the cool dense fibrils of AFSs. The first method based on TRACE observations derived the neutral hydrogen column density of the plasma absorbing coronal lines. The second one using Hα line profiles provided by the MSDP spectrographs is based on the cloud model. The results are consistent. We derive also electron density values using Hα lines that are in good agreement with those derived from the 8542 Å Ca II line observed with THEMIS (Mein et al.). The three types of observations (TRACE, VTT, THEMIS) are well complementary: absorption of coronal lines giving a good approximation for the maximum value of the neutral hydrogen column density, the Hα line giving a good determination of ne, and the 8542 Å Ca II line a good determination of the electronic temperature. Title: Investigation of temperature and velocity fluctuations through the solar photosphere with the Na I D lines Authors: Eibe, M. T.; Mein, P.; Roudier, Th.; Faurobert, M. Bibcode: 2001A&A...371.1128E Altcode: In this work we explore the diagnostic properties of the Na I D resonance lines by calculating the response functions of their line profiles to temperature and velocity perturbations in the atmosphere. We propose a method to transform spectral line intensity fluctuations measured at several wavelengths into temperature and velocity disturbances at different height levels. Results from tests done with several theoretical models of perturbations are discussed. Perturbations that vary as linear functions of depth are efficiently reproduced. The method also provides good estimations for exponential models. As an example we present an application to solar granulation data obtained with Multichannel Subtractive Double Pass (MSDP) spectroscopy. Title: Temporal height properties of the exploding granules Authors: Roudier, Th.; Eibe, M. T.; Malherbe, J. M.; Rieutord, M.; Mein, P.; Mein, N.; Faurobert, M. Bibcode: 2001A&A...368..652R Altcode: Based on time series of 2D MSDP spectrograms, taken at the Turret Dome in Pic du Midi, we present the temporal evolution of exploding granules in intensity and Doppler velocity through the solar photosphere. We describe the penetration of exploding granules in the solar photosphere during their lifes and the related phenomena like the ``Bright Plumes'' located in the downflowing plasma just on the edge of the granule. We suggest a possible scenario of the exploding granule evolution in the solar photosphere. Title: Non-LTE inversion of chromospheric {\Ca Ii} cloud-like features Authors: Tziotziou, K.; Heinzel, P.; Mein, P.; Mein, N. Bibcode: 2001A&A...366..686T Altcode: A chromospheric cloud-like feature observed in the 8542 Å {{Ca Ii} line is studied by a two step inversion procedure which provides estimates of its temperature, electronic density, microturbulence, geometrical thickness and bulk velocity. The first step involves the computation of a large grid of models by a multi-level non-LTE transfer code which gives the {{Ca Ii} line depth-dependent mean intensity inside an isolated, isothermal cloud lying above the chromosphere. The second step involves the inversion of the observed profiles with the grid of computed synthetic {{Ca Ii} profiles. A searching and matching chi 2 algorithm is implemented followed by an interpolation algorithm which permits a more accurate determination of the parameters on which the profiles depend. The five grid parameters are reduced to four by defining the emission measure from the geometrical thickness and electronic density. We show that this inversion procedure gives accurate results for some of our inversion parameters when dealing with solar filaments and is complementary to a previous study of the same object in the {{Hα }} line. The main advantages, problems and future extension of the inversion approach are also discussed. Title: First hominid from the Miocene (Lukeino Formation, Kenya) Authors: Senut, Brigitte; Pickford, Martin; Gommery, Dominique; Mein, Pierre; Cheboi, Kiptalam; Coppens, Yves Bibcode: 2001CRASE.332..137S Altcode: Remains of an early hominid have been recovered from four localities in the Lukeino Formation, Tugen Hills, Kenya, in sediments aged ca 6 Ma. 13 fossils are known, belonging to at least five individuals. The femora indicate that the Lukeino hominid was a biped when on the ground, whilst its humerus and manual phalanx show that it possessed some arboreal adaptations. The upper central incisor is large and robust, the upper canine is large for a hominid and retains a narrow and shallow anterior groove, the lower fourth premolar is ape-like, with offset roots and oblique crown, and the molars are relatively small, with thick enamel. A new genus and species is erected for the remains. Title: Using the Na I D resonance lines to probe the solar photosphere Authors: Eibe, M. T.; Mein, P.; Faurobert, M.; Roudier, Th. Bibcode: 2001ESASP.464..199E Altcode: 2001soho...10..199E Observational techniques in helioseismology are often based on measurements made in the Na I D resonance lines. A good knowledge of their spectral profiles is crucial for the purposes of calibration and interpretation of data. Here we explore their diagnostic properties by calculating response functions of the D1 and D2 line profiles to temperature and velocity perturbations in the atmosphere. We propose a method to transform spectral line intensity fluctuations measured at several wavelenths into temperature and velocity disturbances at different height levels. The possibilities of such a procedure to trace the vertical structure of the photosphere are discussed. Title: Solar arch filaments observed with THEMIS Authors: Mein, P.; Briand, C.; Heinzel, P.; Mein, N. Bibcode: 2000A&A...355.1146M Altcode: Arch Filaments (AF) have been observed in the Ca Ii 8542 Å line with the THEMIS telescope in September 1998. We present a preliminary analysis of MSDP spectro-imaging data. A cloud-model fit provides line-of-sight velocities and a set of plausible values for the model parameters. The high sensitivity of the filament opacity to temperature, coupled with the rough linearity versus electronic density, shows that this Ca Ii line should be very efficient to complement usual Hα data for a more rigorous diagnostics. Based on observations made with the THEMIS telescope operated on the island of Tenerife by CNRS-CNR in the spanish Observatorio del Teide of the Instituto de Astrofisica de Canarias Title: Association of chromospheric sunspot umbral oscillations and running penumbral waves. I. Morphological study Authors: Tsiropoula, G.; Alissandrakis, C. E.; Mein, P. Bibcode: 2000A&A...355..375T Altcode: Observations of a sunspot region located near the center of the solar disk were obtained on October 3, 1994, with the Multichannel Subtractive Double Pass Spectrograph (MSDP). This instrument, operating in Hα , was installed at the focus of the VTT at Tenerife (Canary Islands) and provided Hα intensity profiles at every pixel of the field of view. Reconstruction of the Hα profile allowed the computation of two dimensional intensity and Doppler velocity images at different wavelengths within the line. We analyse a time series of 1 hour and 8 min, obtained with a cadence of 36 sec and investigate the relation between umbral oscillations and running penumbral waves. The Doppler velocity as a function of time, along radial cuts through the center of the spot, shows several clear cases where waves that originate inside the umbra continue to propagate in the penumbra. In one case we were able to follow the evolution of an oscillating element for 216 sec, from the inner part of the umbra to the penumbra and we describe the propagation characteristics. We confirm the close association between sunspot oscillations and running penumbral waves and suggest that they are probably due to the same resonator. Title: Study of Chromospheric Ca II Cloud-like Structures Authors: Tziotziou, K.; Heinzel, P.; Mein, P.; Mein, N. Bibcode: 2000ESASP.463..443T Altcode: 2000sctc.proc..443T No abstract at ADS Title: Investigating the Vertical Structure of the Solar Granulation with the Sodium D2 Line Authors: Eibe, M. T.; Roudier, Th.; Mein, P.; Faurobert, M. Bibcode: 2000ESASP.463..309E Altcode: 2000sctc.proc..309E No abstract at ADS Title: Inversion of line profiles and solar fine structures Authors: Mein, P. Bibcode: 2000ASIC..558..221M Altcode: 2000asre.conf..221M We present some methods to analyse data cubes produced by large solar telescopes. Applications to fine structures observed at the disc or at the limb are briefly reviewed. Title: 3-D Magnetic Configurations for Filaments and Flares: The Role of ``Magnetic Dips'' and ``Bald Patches'' Authors: Aulanier, G.; Schmieder, B.; van Driel-Gesztelyi, L.; Kucera, T.; Démoulin, P.; Fang, C.; Mein, N.; Vial, J. -C.; Mein, P.; Tang, Y. H.; Deforest, C. Bibcode: 2000AdSpR..26..485A Altcode: The 3-D magnetic configuration of a filament and of a low energy flare is reconstructed, using linear mag- netohydrostatic (lmhs) extrapolations. In both cases, we find observational signatures of energy release at the locations of computed ``bald patches'' separatrices, characterised by field lines which are tangent to the photosphere.The filament was observed on Sept. 25, 1996, in Hα with the MSDP on the German VTT, Tenerife, as well as in Si IV with SOHO/SUMER. It is modeled as a twisted flux-tube deformed by the magnetic polarities observed with SOHO/MDI. The shape and location of the computed dipped field lines are in good agreement with the shape of the filament and its feet observed in Hα. Some ``bald patches'' (BPs) are present where the distribution of dips reaches the photosphere. We show that some of the large scale field lines rooted in BPs can be related to bright fine structures in Si IV. We propose that the plasma there is heated by ohmic dissipation from the currents expected to be present along the BP separatrices.The flare was observed on May 18, 1994, in soft X-rays with Yohkoh/SXT, and in Hα at Mitaka (Japan). The magnetic field is directly extrapolated from a photospheric magnetogram from Kitt Peak Observatory. The intersections with the photosphere of the computed separatrices match well the bright Hα ribbons. The later are associated to three BPs, with overlaying dipped field lines. We show that enhanced densities are present in these dips, which can be correlated with dark Hα fibrils.Both cases show the importance of dipped field lines and BPs in the solar atmosphere. Energy release via ohmic dissipation as well as reconnection along BP separatrices is proposed to provide heating observed as UV brightenings in filament channels and even as small flares Title: Bright Rims of Solar Prominences Authors: Hansen, I.; Engvold, O.; Schmieder, B.; Mein, N.; Mein, P. Bibcode: 1999ESASP.448..491H Altcode: 1999mfsp.conf..491H; 1999ESPM....9..491H No abstract at ADS Title: Association between Umbral Oscillations and Running Penumbral Waves Authors: Alissandrakis, C. E.; Tsiropoula, G.; Mein, P. Bibcode: 1999ESASP.448..217A Altcode: 1999ESPM....9..217A; 1999mfsp.conf..217A No abstract at ADS Title: A Study of Hydrogen Density in Emerging Flux Loops from a Coordinated TRACE and Canary Islands Observation Campaign Authors: Schmieder, B.; Deluca, E.; Mein, N.; Mein, P.; Malherbe, J. M.; Wilken, V.; Staiger, J.; Engvold, O.; Hanssen, I. Bibcode: 1999ESASP.448..653S Altcode: 1999mfsp.conf..653S; 1999ESPM....9..653S No abstract at ADS Title: Analysis of evolution of NOAA 7912 active region on 19 October 1995 Authors: Rudawy, P.; van Driel-Gesztelyi, L.; Cader-Sroka, B.; Mein, P.; Mein, N.; Schmieder, B.; Malherbe, J. -M.; Rompolt, B. Bibcode: 1999A&AS..139...89R Altcode: An analysis of a minor (B3.2) flare related to an X-ray jet in the reversed polarity NOAA 7912 active region is presented, focusing on various kinds of activity observed in the Hα line with the MSDP instrument. Using complementary Yohkoh soft X-ray observations and a Kitt Peak magnetic field map we study the influence of a rather low and graduate energy release on filaments, fibrils and chromospheric brightenings and their relevant coronal features. We find that this small flare affected the entire AR and was associated with strong up- and downflows along remote fibrils and filaments, which appear to be connected by large-scale loops. It is shown that at least one of the observed brightenings was caused by downflow of the matter, thus, by the kinematic heating of the material. The filament in the vicinity of the flare footpoints changed the most: it broke into two parts, temporarily rose to higher altitudes inside the AR and even erupted outside of the AR, re-forming only three hours later. We show that even a minor flare can lead to important morphological and dynamical changes in an active region. Title: The Role of "Magnetic Dips" and "Bald Patches" for a Filament Observed by SOHO and GBO Authors: Aulanier, G.; Schmieder, B.; Kucera, T.; van Driel-Gesztelyi, L.; Démoulin, P.; Mein, N.; Vial, J. -C.; Mein, P. Bibcode: 1999ASPC..184..291A Altcode: The studied filament was observed on Sept. 25, 1996, in Hα with the MSDP on the German VTT, Tenerife, as well as in Si IV with SOHO/SUMER. The 3-D magnetic configuration of the filament channel is reconstructed, using linear magnetohydrostatic (lmhs) extrapolations from a SOHO/MDI magnetogram, which is modified by a background magnetic component constraining a twisted flux-tube. This flux-tube is deformed by the magnetic polarities observed with SOHO/MDI. The shape and location of the computed "dipped field lines" are in good agreement with the shape of the filament and its feet observed in Hα. Some "bald patches" (BPs) are present where the distribution of dips reaches the photosphere. We find observational signatures in Si IV brightenings of energy release at the locations of computed "bald patch separatrices", defined by field lines which are tangent to the photosphere. We propose that the plasma is there heated by ohmic dissipation from the expected currents in the BP separatrices. The results show the importance of "dipped field lines" and "bald patches" in filament channels. Title: Coordinated Prominence Observations by SOHO and Ground-Based Observatories Authors: Schmieder, B.; Heinzel, P.; Vial, J. -C.; Malherbe, J. M.; Mein, P.; Rudawy, P.; Ceppatelli, G. Bibcode: 1999ASPC..184..296S Altcode: Coordinated observations obtained during the JOP12 (Joint Observing Programme between SOHO and ground-based instruments) allow us to analyse the physical conditions in a prominence of 5 June 1997 and its environment in the solar corona. The arch-shaped prominence shows either vertical or horizontal structures according to the observed lines (Hα with the coronagraph of the Wroclaw University Observatory at Bialków and lines in a broad temperature range by the Coronal Diagnostic Spectrometer CDS). The less dynamic behaviour of this prominence was shown by the persistence of bubbles in the prominence and confirmed by the Dopplershifts measured in CDS lines and in Hα by the Italian Panoramic Monochromator (IPM) filter on the THEMIS telescope in Tenerife. We explain the complex morphology of this prominence by recent 3D MHD models. Finally, we present prominence spectra in higher lines of the hydrogen Lyman series (from Lδ to L-9), together with some other UV lines. These data have been obtained by the Solar Ultraviolet Measurements of Emitted Radiation (SUMER). We demonstrate the basic characteristics of the calibrated line profiles of Lyman lines and compare them with the theoretical profiles computed from isothermal-isobaric models. This leads to some constraints on the environment of the prominence. Title: Cloud model with variable source function for solar Hα structures. II. Dynamical models Authors: Heinzel, P.; Mein, N.; Mein, P. Bibcode: 1999A&A...346..322H Altcode: It was demonstrated in the previous paper (Paper I)that the cloud model technique can be largely improved if one considers realistic boundary conditions in evaluating the true form of the line source function. For structures seen against the solar disk, the Hα line source function is decreasing from bottom towards the top. In the present paper we investigate the effect of Doppler brightening on Hα source function. In frame of 1D non-LTE models it is demonstrated how the Hα line source function is increased depending on the velocity of the moving cloud and direction of the motion. For the same set of cloud models as used in Paper I, we have reevaluated the variations of the source function with optical depth including the effect of cloud motion. The resulting curves have been approximated by a second-degree polynomial and the respective coefficients have been subsequently used in a modified iterative method in order to derive the cloud model parameters. As expected, dynamical models lead to more precise specification of these parameters, namely the optical thickness, as compared to the static case investigated in Paper I. We have applied this new method to MSDP observations of a dark chromospheric feature (loop) with considerable flows. Title: Filament channel structures in a SI IV line related to a 3d magnetic model Authors: Kucera, T. A.; Aulanier, G.; Schmieder, B.; Mein, N.; Vial, J. -C. Bibcode: 1999SoPh..186..259K Altcode: A recent 3D magnetic model of filament support (Aulanier and Démoulin, 1998) has shown that specific morphologies derived from the model, based on SOHO/MDI magnetograms, match quite well with the observations of a filament observed in Hα and Ca ii lines with the German telescope VTT in Tenerife on 25 September 1996 (Aulanier et al., 1998, 1999a). Some predictions of this model concern the filament channel. To continue the comparison of model and data, we have investigated the same filament region observed in ultraviolet by the SOHO spectrometers SUMER and CDS. The elongated EUV fine structures in the filament channel observed in the Si iv 1393.76 Å line by SUMER have similar orientations and locations to features predicted by the model of Aulanier et al. (1999a). These regions are near the bases of field lines which tangentially join to the photosphere in so called 'bald patches' and are parts of large arcades above the filament channel. In addition, we consider the Si iv Doppler shifts in these structures and compare them to what might be expected from the model field structure. Our study also suggests that the filament has a very low opacity in Si iv, lower than that of the O v line observed by CDS. Title: A non-LTE inversion procedure for chromospheric cloud-like features Authors: Molowny-Horas, R.; Heinzel, P.; Mein, P.; Mein, N. Bibcode: 1999A&A...345..618M Altcode: A fast inversion procedure which provides estimates of the temperature, electronic density, microturbulence, geometrical thickness and bulk velocity of chromospheric features, so-called ``clouds'', has been implemented. The procedure has been divided into two steps: 1) the construction of a large grid of models by means of a multi-level non-LTE transfer code, which solves in a fast and reliable way the radiative transfer problem of the formation of the Hα line inside an isolated, isothermal cloud laying above the photosphere, and 2) the implementation of searching, matching and interpolating algorithms which yield an inversion of the observed line profile in terms of the grid's computed profiles. The aforementioned 5 parameters, on which the profiles depend, can be reduced to 4 if one defines the so-called emission measure from the geometrical thickness and electronic density parameters. We show that this strategy yields excellent results when dealing with solar filaments. The main advantages of this approach are also discussed. Title: 3-D magnetic configurations supporting prominences. III. Evolution of fine structures observed in a filament channel Authors: Aulanier, G.; Démoulin, P.; Mein, N.; van Driel-Gesztelyi, L.; Mein, P.; Schmieder, B. Bibcode: 1999A&A...342..867A Altcode: On September 25() th 1996, a quiescent filament located near the center disc (S2, E5) was observed on the German VTT (Tenerife) with the MSDP instrument, in the Hα line center and wings. SOHO/MDI line-of-sight magnetograms were co-aligned with the MSDP images, showing the position and evolution of the lateral feet of the filament in the vicinity of the parasitic magnetic polarities observed in the filament channel. Using the assumptions developed in the previous papers of this series related to the reconstruction of the 3-D magnetic configuration of filaments, we perform ``linear magnetohydrostatic'' extrapolations (taking into account the effects of plasma pressure and gravity) on the SOHO/MDI magnetograms. The main hypothesis is the presence of a twisted flux-tube located above the photospheric inversion line. Assuming that the parameters of the model do not need to be significantly modified during the evolution of the configuration for a duration of 1 day, we have shown that the 3-D distribution of dipped field lines is well correlated with Hα dark absorbing features in the filament channel: the filament itself, its lateral feet and some of the surrounding dark fibrils. In this way we confirm what was suggested in our earlier papers, i.e. that the feet are composed of the dipped portions of some field lines, which form a continuous pattern from the corona to the photosphere. We propose the same explanation for the magnetic configuration of some of the dark Hα fibrils in the channel. We show that the plasma effects are not responsible for the existence of most of the magnetic dips, however their inclusion helps to get a better correspondence between the model and the observations. We find that the average Hα Doppler velocities associated with the filament and with the chromospheric fibrils is of the order of a few hundred m s(-1) (though it can go locally up to 3 km s(-1) in the filament). These upward velocities are consistent with a quasi-static evolution of the magnetic configuration and with the support of dense plasma in magnetic dips. Title: Gradient of the line-of-sight velocities in the dark superpenumbral fibrils. Authors: Tsiropoula, G.; Alissandrakis, C. E.; Mein, P.; Mein, N. Bibcode: 1999joso.proc..116T Altcode: An isolated sunspot located near the centre of the solar disk was observed on October 3, 1994. The present high resolution observations were obtained with the Multichannel Subtractive Double Pass Spectrograph (MSDP) operating in Hα. Two dimensional intensity and Doppler velocity maps at several depths in the Hα line were computed. The monochromatic intensities at two wavelengths on either side of the line are used in terms of the photographic subtraction method expressing the "Doppler signal" to give, under some assumptions, the velocities at different depths in the Hα line. The values of the velocities obtained by this method are compared to those given by the bisector method while comparison of the velocities at different depths can give a picture of the gradient of the velocity in the dark superpenumbral fibrils. Title: Non-LTE inversions of solar filament in Hα profiles. Authors: Molowny-Horas, R.; Mein, P.; Mein, N.; Heinzel, P. Bibcode: 1999joso.proc..209M Altcode: Results are shown of a new grid-based, non-LTE inversion procedure which can carry out fast and accurate spectral inversions of Hα line profiles. The code has been applied to a set of observed MSDP Hα line profiles of a solar filament. The results of this inversion are shown as 2-D maps of temperature, microturbulence and emission measure. Title: 3-D magnetic configurations supporting prominences. II. The lateral feet as a perturbation of a twisted flux-tube Authors: Aulanier, G.; Demoulin, P.; van Driel-Gesztelyi, L.; Mein, P.; Deforest, C. Bibcode: 1998A&A...335..309A Altcode: In a previous paper we have shown that a twisted flux-tube is the most probable magnetic configuration supporting prominences. The model interprets many observations in a natural way (in particular the magnetic measurements in prominences and the chirality properties). Moreover, prominence feet appear as a direct consequence of the parasitic polarities present in the filament channel. Here we investigate further the link between feet and parasitic polarities by modelling explicitly these polarities. We show that the prominence lateral feet appear naturally, above secondary photospheric inversion lines and we describe the morphological change of feet as parasitic polarities evolve. This approach is applied to an observed filament in Hα with the MSDP on the German VTT (Tenerife) where SOHO/MDI magnetograms are available. We show that the shape of the prominence is defined by the distribution of the dips in the computed magnetic configuration. Then we analyse the topology of the magnetic field using the quasi-separatrix layers (QSLs) method. We describe the basic changes in the topology as the parasitic polarities evolve, in particular how the configuration pass from an OX to an OF topology. We find a correspondance between the computed QSLs and some of the chromospheric brightenings, observed around the feet of filaments in the y line (Ca II, 8542 Angstroms). It confirms the deduced magnetic configuration and shows that energy release is present at a low level in the complex topology of the filament configuration. Title: Arch Filament Systems Associated with X-Ray Loops Authors: Malherbe, J. M.; Schmieder, B.; Mein, P.; Mein, N.; Van Drielgesztelyi, L.; Von Uexküll, M. Bibcode: 1998SoPh..180..265M Altcode: Using multi-wavelength observations obtained with the Tenerife telescopes (VTT and GCT) and with the Yohkoh satellite, we observed new emerging flux with an associated arch filament system (AFS) in the chromosphere and bright X-ray loops in the corona. We observed the change of connectivity of the X-ray loop footpoints which may be at the origin of the occurrence of a subflare. Densities, gas and magnetic pressures of cold AFS and hot loops were derived and discussed. The extrapolation of the photospheric magnetic field observed with the GCT in a linear force-free field assumption (constant α) shows that this region, in spite of having roughly a global potential configuration, consists of two systems of arch filaments. We found these two systems best fitted with two sheared magnetic topologies of opposite α values of ± 0.1 Mm-1 Title: First Observations with THEMIS Authors: Rayrole, J.; Mein, P.; Schmieder, B. Bibcode: 1998ASPC..155..260R Altcode: 1998sasp.conf..260R No abstract at ADS Title: The Solar Telescope THEMIS Authors: Arnaud, J.; Mein, P.; Rayrole, J. Bibcode: 1998ESASP.417..213A Altcode: 1998cesh.conf..213A No abstract at ADS Title: Evolution of the Magnetic Field and Chromospheric Fine Structure in a Filament Channel Authors: van Driel-Gesztelyi, L.; Mein, P.; Mein, N.; Schmieder, B.; Malherbe, J. -M.; Aulanier, G.; Démoulin, P.; Deforest, C.; Staiger, J. Bibcode: 1998ASPC..155..321V Altcode: 1998sasp.conf..321V No abstract at ADS Title: Umbral and Penumbral Waves in a Chromospheric Sunspot Authors: Alissandrakis, C. E.; Tsiropoula, G.; Mein, P. Bibcode: 1998ASPC..155...49A Altcode: 1998sasp.conf...49A No abstract at ADS Title: 3-D Modelling of a Filament Observed in Hα and with SOHO Authors: Aulanier, G.; Schmieder, B.; Démoulin, P.; Mein, N.; van Driel-Gesztelyi, L.; Mein, P.; Vial, J. C.; Deforest, C. Bibcode: 1998ESASP.417..217A Altcode: 1998cesh.conf..217A No abstract at ADS Title: X-ray jets in a reversed polarity region and interplanetary effects Authors: Schmieder, B.; van Driel, L.; Mein, N.; Mein, P.; Willson, R.; Raoult, A. Bibcode: 1998ESASP.421..157S Altcode: 1998sjcp.conf..157S No abstract at ADS Title: Velocity Fields of a Filament Region Observed with Ground-Based Telescopes and from SOHO Authors: Mein, P.; Schmieder, B.; Malherbe, J. -M.; Wiik, J. E.; Engvold, O.; Brekke, P.; Zirker, J. B.; Poland, A. I.; Delaboudiniere, J. -P.; Staiger, J. Bibcode: 1998ASPC..150..135M Altcode: 1998npsp.conf..135M; 1998IAUCo.167..135M No abstract at ADS Title: 3-D Modelling of a Filament Observed in Hα and with SOHO/MDI Authors: Aulanier, G.; Démoulin, P.; van Driel-Gesztelyi, L.; Mein, P.; Deforest, C. Bibcode: 1998ASPC..155..326A Altcode: 1998sasp.conf..326A No abstract at ADS Title: Evolution of a reversed polarity active region NOAA 7912 in the photosphere, the chromosphere and the corona. Authors: van Driel-Gesztelyi, L.; Baranyi, T.; Mein, N.; Cader-Sroka, B.; Rudawy, P.; Mein, P.; Rompolt, B.; Schmieder, B.; Malherbe, J. -M.; Willson, R.; Kile, J. N.; Raoult, A. Bibcode: 1998joso.proc..103V Altcode: The authors follow the evolution and activity of NOAA 7912, a reversed polarity region, in the photosphere (Kitt Peak magnetograms and Debrecen white-light photoheliograms), chromosphere (MSDP instrument mounted on the German VTT at Tenerife), and the corona (Yohkoh/SXT, Nançay radioheliograph and the VLA) between October 12-20, 1995. They find that in spite of the high shear and creation of several mixed-polarity regions through flux emergence, the flares in the group did not exceed the M-class level. This might be due to the fact that the highly inclined bipolar fields emerging in the following part of the primary reversed dipole were relatively small and quickly "consumed" by cancellation enhanced by sunspot motions. On the other hand, the presence of high shear and minor fast-moving parasitic polarities in NOAA 7912 was sufficient to produce eruptive events like X-ray jets with important coronal and interplanetary effects. Title: X-Ray Jets and Their Radio Signatures at Metric and Centimeter Wavelenths Authors: van Driel-Gesztelyi, L.; Willson, R. F.; Kile, J. N.; Raoult, A.; Klein, L.; Mein, N.; Rudawy, P.; Cader, B.; Rompolt, B.; Schmieder, B.; Mein, P.; Malherbe, J. M. Bibcode: 1998ASPC..154..707V Altcode: 1998csss...10..707V On October 19, 1995 at 10:30 UT and 17:00 UT, two semi-homologous X-ray jets were observed with the Yohkoh/SXT from AR 7912, a region having a reversed polarity group with vortex-like Hα fibril pattern and X-ray loops. The jets appeared over a mixed magnetic polarity region in the vicinity of the leading spot. The first event was also observed with the Nancay radio heliograph at 167, 236, and 327 MHz. Type III activity, indicating the presence of electron beams, superimposed on a noise-storm was clearly visible. Type III activity first appeared at 10:25 UT, coincident with the onset of the X-ray jet, at 164 MHz and 236 MHz close to the storm position, and in the direction of the X-ray jet. At 10:28:40 UT a new group of sources appeared eastward of the former activity, which may correspond to another jet branch along a more easterly path seen in the ohkoh} images. The second X-ray jet event was also observed with the Very Large Array (VLA) at 6.2, 20.7, and 91.6 cm. For this event, VLA snapshot maps at 6.2 and 20.7 cm reveal low-brightness temperature changes in source structure at the site of the X-ray jet during the preburst, impulsive, and decay phases. The VLA 91.6 cm observations also show noise storm emission above the active region but there is no clear temporal correlation between this later X-ray jet and the impulsive decimetric bursts that were observed during this period. Although the X-ray observations show that the two jets had similar temperatures, emission measures, speeds and trajectories they appear to have had dissimilar metric responses to these events. This surprising result may question our understanding of the process of electron beam acceleration in jets. Title: Nouvelles découvertes de Vertébrés miocènes dans le synclinal de Dera Bugti (Balouchistan, Pakistan) Authors: Welcomme, Jean-Loup; Antoine, Pierre-Olivier; Duranthon, Francis; Mein, Pierre; Ginsburg, Léonard Bibcode: 1997CRASE.325..531W Altcode: Since Forster-Cooper in 1910, no paleontologist bas visited the area of Dera Bugti in Baluchistan (Pakistan). In 1995 and 1996, two small French expeditions prospected the syncline of Dera Bugti. They established stratigraphical sections ana discovered many fossils, mainly reptiles, and mammals. On top of the Eocene marine limestone of the Kirthar there lies a Burdigalian marine falun. Above, about 250 m of continental marls, sands and sandstones are deposited. The first 100 m have yielded five fossiliferous levels of MN3 b in age, and one of MN4, surrounded by a more sandy series. The top of the series has yielded Hipparion of the Upper Miocene. Title: Flare Multi-Line 2D-SPECTROSCOPY Authors: Mein, P.; Mein, N.; Malherbe, J. -M.; Heinzel, P.; Kneer, F.; von Uexkull, M.; Staiger, J. Bibcode: 1997SoPh..172..161M Altcode: 1997ESPM....8..161M A small flare was observed at the Teide Observatory on October 5, 1994. Simultaneous data were obtained at the German Vacuum Tower Telescope (VTT) with the MSDP spectrograph providing high-resolution imaging spectroscopy in two chromospheric lines, and the Gregory Coudé Telescope (GCT) providing information about the magnetic field. Basic flare characteristics are: Title: Evolution in Space and Time of Superpenumbral Chromospheric Fibrils Authors: Tsiropoula, G.; Dialetis, D.; Alissandrakis, C. E.; Mein, P.; Mein, N. Bibcode: 1997SoPh..172..139T Altcode: 1997ESPM....8..139T We have studied the spatial structure and temporal evolution of the intensity and Doppler velocity of dark fibrils forming the superpenumbra of an isolated regular sunspot. The observations were obtained with the Multichannel Subtractive Double Pass (MSDP) spectrograph which operates in Hα and is installed at the focus of the Vacuum Tower Telescope (VTT) at Tenerife (Canary Islands). The fibril pattern shows a remarkable stability during the period of our observations (64 min). Moreover, almost all individual fibrils are identifiable in all frames, but they undergo continual changes in contrast, shape and size. Investigating the temporal evolution of intensity and velocity of individual fibrils, fluctuations were found which have a quasi periodic behavior. As mechanisms for these changes we may suggest (a) change of the Doppler shift due to a wave, (b) periodic changes of the density of the Hα absorbing material, (c) disappearance and reappearance of fibrils, in more or less the same magnetic flux tube, at regular intervals. Title: THEMIS: Latest News Authors: Mein, P.; Rayrole, J. Bibcode: 1997ASPC..118..334M Altcode: 1997fasp.conf..334M No abstract at ADS Title: Comparison of line-of-sight velocities of chromospheric structures derived by three different methods Authors: Tsiropoula, G.; Christopoulou, E.; Madi, C.; Dialetis, D.; Mein, P.; Mein, N. Bibcode: 1997jena.confE..61T Altcode: We have used three different methods to derive line-of-sight velocities in dark fibrils forming the superpenumbra of an isolated regular sunspot located near the centre of the solar disk (NOOA/AR 7783). The present observations were obtained on October 3, 1994. They were performed with the Multichannel Subtractive Double Pass (MSDP) spectrograph which operates in H-alpha and it is installed at the focus of the Vacuum Tower Telescope (VTT) at Tenerife (Canary Islands). This instrument records a two dimensional field of view on the solar surface with good spatial and temporal resolution. The observations were made simultaneously in 9 wavelengts, 0.3AA apart in the H-alpha profile. At every pixel of the 2D field of view the line profile can be restored from the measured values of the intensity in the 9 channels and a third degree spline interpolation. These profiles were used for the computation of the line-of-sight velocity by three different methods: (a) the Doppler shift method, (b) the photographic subtraction method expressing the ``Doppler signal'' and (c) the classical Beckers' cloud model. 2D maps of the velocity are computed, comparison of the values derived by the 3 different methods is performed and the conditions governing the validity of the 3 methods are stated. Title: New Ground-Based Solar Instrumentation Authors: Mein, P. Bibcode: 1997LNP...489..241M Altcode: 1997shpp.conf..241M Solar physics requires more and more multiwavelength observations, not only with high spatial and time resolution, but also with wide coverage in space and time. We review briefly instruments dedicated to the solar interior, visible layers and the corona. In addition to the accuracy of spectroscopy and polarization measurements, we emphasize the coverage of data sets in the k - ω diagram. New image restoration methods are reviewed, in the context of the best compromise between spatial resolution and isoplanetic field of view. Ambitious projects do exist, as well as new generation telescopes under construction. Progress in the establishment of data bases and easier data exchange between observatories using complementary facilities look very promising for the future. Title: THEMIS: Expected Capabilities for Coordinated Observations Authors: Mein, P. Bibcode: 1997ASPC..118..320M Altcode: 1997fasp.conf..320M Several spectroscopic modes will be available in THEMIS for coordinated observations. They should provide high accuracy vector magnetic fields (Multi-line Spectroscopy), fast imaging spectro-polarimetry (MSDP) and fast magnetograms (Full Disc). Title: Spatial relation between the 5-minute oscillations and granulation patterns. Authors: Espagnet, O.; Muller, R.; Roudier, T.; Mein, P.; Mein, N.; Malherbe, J. M. Bibcode: 1996A&A...313..297E Altcode: A white light, high resolution movie of the quiet photosphere has been used to study the spatial relation between the solar granulation and the 5-min oscillations of high degree mode (small spatial scale). The granular and oscillatory brightness components have been separated with the help of a specific filter, in the k-ω diagram. The surface of the Sun appears to be covered with adjacent oscillating cells of apparent size 2" (1500km) to 3" (2000km). Some cells are noticeable by their amplitude which is much larger than average. These strong oscillations usually appear in expanding intergranular spaces. Our observations suggest that the 5-min oscillations are stochastically generated by turbulent convection. However, the most energetic oscillations occur in downflows only, well separated of each other in time and space. Title: Periodic and Non-Periodic Phenomena in a Sunspot Region Authors: Tsiropoula, G.; Alissandrakis, C. E.; Dialetis, D.; Mein, P. Bibcode: 1996SoPh..167...79T Altcode: We have studied running penumbral waves, the homogeneous Evershed effect, and the spatial relation between intensity and Doppler velocity penumbral features of a chromospheric sunspot. The observations were obtained with the multichannel subtractive double-pass spectrograph (MSDP) operating in Hα at the Vacuum Tower Telescope (VTT) installed at Tenerife (Canary Islands). We derived intensity and Doppler velocity maps at Hα ± 0.3 Å over a two-dimensional field of view. We have computed the components of the velocity vector (radial, azimuthal, vertical) as a function of distance from the center of the spot under the assumption of axial symmetry. The results show the well-known, from previous observations, general large-scale characteristics of the chromospheric Evershed flow. Our measurements show that the axes along the discrete structures, where the Evershed flow is confined, are not spatially related to the axes along Hα ± 0.3 Å intensity features, and we suggest that either the flow is confined in flow channels or that it takes place along sheared magnetic field lines. We also detected, for the first time in velocity images, running penumbral waves, which started in the outer 0.3 of the umbral radius and propagated through the penumbra with propagation velocities 13-24 km s−1. The propagation velocity, as well as the velocity amplitude, is greater for the waves closer to the center of the spot and diminishes as one moves outward. Title: Cloud model with variable source function for solar Hα structures. Authors: Mein, N.; Mein, P.; Heinzel, P.; Vial, J. -C.; Malherbe, J. M.; Staiger, J. Bibcode: 1996A&A...309..275M Altcode: The "cloud model" used to derive the physical parameters of solar chromospheric features is extended to the cases of non-constant source function and of velocity gradients. This model assumes a given relationship between the source function and the opacity of the cloud which is derived from non-LTE modelling. An algorithm using 4 points of the Halpha_ profile is proposed to derive the optical thickness, the line-of-sight velocity and the dopplerwidth. The results are compared with a 5-points inversion which does not use the given relationship between source function and opacity. Effects of the uncertainty about the radiation coming from the underlying chromosphere, as well as effects of data noise, are discussed. The inversion method is illustrated by some examples of observed profiles obtained with the MSDP spectrograph of the VTT telescope (Teide Observatory). Title: Chromospheric ejections and their signatures in X-ray observed by YOHKOH Authors: Schmieder, B.; Mein, N.; Shibata, K.; van Driel-Gesztelyi, L.; Kurokawa, H. Bibcode: 1996AdSpR..17d.193S Altcode: 1996AdSpR..17..193S Surges, or condensations of chromospheric material, are commonly observed in active regions when new emerging magnetic flux (EMF) occurs. In order to study EMF-related phenomena in the corona, observing campaigns were organized with the Yohkoh X-ray satellite and ground based observatories. EMFs could be detected in magnetograms made in Potsdam and Hawaii, surge and arch filament system (AFS) events (on Oct 7 1991, May 1 1993, respectively) with the Multichannel Subtractive Double Pass instruments operating at Meudon and on the Canary Islands and with the Hida telescope at Kyoto University. Bright X-ray loops coincident with chromospheric surge activity were detected in the high resolution Yohkoh SXT images. We also found coincident brightness variations between an X-ray bright point (XBP) and the underlying chromospheric plage related to EMF. We interpret the appearance of AFS as condensation of material among magnetic field lines, the X-ray bright points as the result of a magnetic reconnection process, and surges as ejection of cold plasma bubbles squeezed between field lines as a result of reconnection. Title: X-Ray Bright Point Flares Due to Magnetic Reconnection Authors: Van Driel-Gesztelyi, L.; Schmieder, B.; Cauzzi, G.; Mein, N.; Hofmann, A.; Nitta, N.; Kurokawa, H.; Mein, P.; Staiger, J. Bibcode: 1996SoPh..163..145V Altcode: Ground-based optical observations coordinated with Yohkoh/SXT X-ray observations of an old, disintegrating bipolar active region AR NOAA 7493 (May 1, 1993) provided a multiwavelength data base to study a flaring `active region' X-ray bright point (XBP) of about 16 hr lifetime, and the activity related to it in different layers of the solar atmosphere. The XBP appeared to be related to a new minor bipole of about 1020 Mx. Superposed on a global evolution of soft X-ray brightness, the XBP displayed changes of brightness, lasting for 1-10 min. During the brightenings the XBP apparently had a spatial structure, which was (tiny) loop-like rather than point-like. The X-ray brightenings were correlated with chromospheric activity: (i) brightenings of underlying chromospheric faculae, and (ii) appearance of strong turbulent velocities in the arch filament system. We propose that the XBP brightenings were due to reconnection of the magnetic field lines (sketched in 3D) between the new bipole and a pre-existing plage field induced by the motion of one of the new pores (v = 0.2 km s−1) towards the plage, and that the XBP itself was a reconnected hot loop between them. Title: Dynamics of solar magnetic arches in the photosphere and the chromosphere. Authors: Mein, P.; Demoulin, P.; Mein, N.; Engvold, O.; Molowny-Horas, R.; Heinzel, P.; Gontikakis, C. Bibcode: 1996A&A...305..343M Altcode: Mass motions in chromospheric arch filaments have been observed with imaging spectroscopy (MSDP) at the VTT telescope of the Teide Observatory. Coordinated observations of time sequences of continuum images were carried out at the SVST telescope of the Observatorio del Roque de los Muchachos, which provided transverse velocities of photospheric tracers, by "local correlation tracking." Hα profiles along 3 arch filaments are analysed in terms of "differential cloud MODel", to discuss the Doppler velocities of chromospheric material. Models of ascending arches with downflows in both legs are investigated. The gas pressure is neglected, but the free-fall equations are integrated versus time (non-stationary case). We first assume circular lines of force with constant radius. We can account for chromospheric velocities, but we cannot fit the slow motion of footpoints derived from photospheric tracers. A better agreement is obtained by assuming lines of force with fixed footpoints and variable radius. Typical values are: half distance between footpoints of 10 to 15Mm, upward velocity at the top of loops of 4km/s after an integration time of 800s. The obtained values are consistent with the sizes and the lifetime of arch filaments. Title: Signatures of New Emerging Flux in the Solar Atmosphere Authors: Schmieder, B.; Malherbe, J. M.; Mein, P.; Mein, N.; van Driel-Gesztelyi, L.; Roudier, T.; Nitta, N.; Harra-Murnion, L. K. Bibcode: 1996ASPC..111...43S Altcode: 1997ASPC..111...43S The emergence of new flux in the low atmosphere leads to magnetic reconnection of field lines. In a stable phase the phenomenon is observed in the chromosphere by the formation of dark filaments (arch filament system, AFS). The authors show how bright loops visible in soft X-rays are co-aligned with the AFS. Different types of events appear as the released energy increases. With less energetic phenomena than flares one observes surges, jets or X-ray bright points, according to the configuration of the field lines (open/closed). A low-level reconnection process is detectable as an X-ray bright point. If the energy is ≡1028ergs cm-3, one observes subflares. The authors document their statement by showing examples observed in coordinated observations obtained with the MSDP (Pic du Midi and Tenerife) and Yohkoh/SXT and BCS for the events occurring on Oct 5, 1994, Oct 27, 1993, and May 1, 1993. Title: High resolution flare observations with multi-line imaging spectroscopy. Authors: Mein, P.; Heinzel, P.; Malherbe, J. -M.; Staiger, J. Bibcode: 1996joso.proc...68M Altcode: No abstract at ADS Title: Running Penumbral Waves in a chromospheric Sunspot Authors: Tsiropoula, G.; Dialetis, D.; Alissandrakis, C. E.; Mein, P. Bibcode: 1996hell.conf...37T Altcode: No abstract at ADS Title: Emerging Flux, Reconnection, and XBP Authors: van Driel-Gesztelyi, L.; Schmieder, B.; Demoulin, P.; Mandrini, C.; Cauzzi, G.; Hofmann, A.; Nitta, N.; Kurokawa, H.; Mein, N.; Mein, P. Bibcode: 1996mpsa.conf..459V Altcode: 1996IAUCo.153..459V No abstract at ADS Title: The fine scale Structure of the velocity Field in the chromospheric Penumbra of a solar Sunspot Authors: Tsiropoula, G.; Alissandrakis, C. E.; Dialetis, D.; Mein, P. Bibcode: 1996hell.conf...32T Altcode: No abstract at ADS Title: Emerging flux seen by Yohkoh. Authors: van Driel-Gesztelyi, L.; Schmieder, B.; Mandrini, C.; Démoulin, P.; Cauzzi, G.; Hofmann, A.; Nitta, N.; Kurokawa, H.; Mein, N.; Mein, P. Bibcode: 1996joso.proc..124V Altcode: No abstract at ADS Title: Penetration of the solar granulation into the photosphere: height dependence of intensity and velocity fluctuations. Authors: Espagnet, O.; Muller, R.; Roudier, T.; Mein, N.; Mein, P. Bibcode: 1995A&AS..109...79E Altcode: A 16-min time series of two-dimensional "Multichanel Subtractive Double Pass" spectrograms, recorded in the NaD_2_ 5690 line, has been used to study the vertical structure of the photosphere and, in particular, the penetration of granules. A statistical and a morphological investigations have been made. The 5-min oscillations have been carefully filtered in the k-ω space. Intensity fluctuations associated to granules disappear in a very short distance, about 60 to 90km above the continuum level. The intensity features in the upper photosphere are not related to the granules. The velocity fluctuations associated to the granulation, cross the whole thickness of the photosphere. The photosphere can thus be separated into two distinct layers, but only for the intensity features, not for the velocity features which are the same from the bottom to the top of the stable atmosphere. In the lower photosphere, below 90km, only granules are detected. In the upper photosphere, our observations suggest that the weak pattern visible there, is turbulent in origin. In addition to this weak pattern, bright sinking plumes have been discovered; they are associated with strong downflows, often adjacent to strong upflows. The size of most plumes is 1" to 2"; however the most outstanding of them may be as large as 4". Their origin, which may be photospheric or chromospheric, is still unknown. Title: Solar Imaging Spectroscopy: Multichannel Subtractive Double Pass Instruments Authors: Mein, P. Bibcode: 1995ASPC...71..350M Altcode: 1995IAUCo.149..350M; 1995tosm.conf..350M No abstract at ADS Title: THEMIS IR Capabilities Authors: Roudier, T.; Mein, P.; Rayrole, J. Bibcode: 1995itsa.conf..195R Altcode: No abstract at ADS Title: THEMIS: its capabilities and key programs Authors: Schmieder, B.; Mein, P. Bibcode: 1994ESASP.373..393S Altcode: 1994soho....3..393S No abstract at ADS Title: Dynamical Fine Structure of a Quiescent Filament Authors: Mein, N.; Mein, P.; Wiik, J. E. Bibcode: 1994SoPh..151...75M Altcode: A quiescent filament was observed near the center of the disk (N5, W5) with the MSDP spectrograph of the 50 cm refractor of the Pic-du-Midi Observatory on June 17, 1986. We focus our study on the statistical moments of the Dopplershift,V1, and the intensity,I1, at the center of a chord of the Hα profile (±0.256 å), versus the minimum intensityI0. We use a statistical model simulating a numbernmax of threads (of optical thicknessτ0 and source functionS0), seen over the chromosphere. The threadsj along the same line-of-sighti are identical except for the velocityvj (gaussian distributionv0,σv). We search for the best fit between the observed and simulated quantities:V1,σ (V1),I1,σ(I1), and the histogram of theI0 values over the field of view. A good fit is obtained with: (a) threads characterized byτ0 = 0.2,S0 = 0.06 (unit of the continuum at disk center), mean upward velocityv0 = 1.7 km s−1 and gaussian-type velocity distributionσv = 3.5 km s−1. Other possible values ofτ0 andσv are discussed; (b) underlying chromosphere deduced from observed quiet Sun (outside the filament) by modifying the chromospheric velocities: additional mean upward velocity 0.7 km s−1, standard deviation reduced by a factorFc ∼ 0.7. The results are discussed in connection with the values deduced from prominence observations. Title: Fine Structure of Prominences and Filaments (Invited) Authors: Mein, P. Bibcode: 1994scs..conf..289M Altcode: 1994IAUCo.144..289M The author concentrates on quiescent prominences, and reviews some recent results about resolved structures, statistical properties of "threads", and detailed analysis of average line profiles. He mentions magnetic field measurements and thermal problems. New magnetostatic models are very promising. The author discusses briefly the problem of the scale of fine structures, and suggests some directions for further works. Title: Imaging spectro-polarimetry with THEMIS. Authors: Mein, P.; Rayrole, J. Bibcode: 1994imfm.conf..116M Altcode: No abstract at ADS Title: High resolution solar observations: Spectropolarimetry with THEMIS Authors: Landi Degl'Innocenti, E.; Rayrole, J.; Mein, P. Bibcode: 1994LNP...432..315L Altcode: 1994LNPM...11..315L Solar observations now require many capabilities: high resolution to detect fine flux tubes, polarization-free optics to measure the vector magnetic field, spectral range including many lines to disentangle thermodynamic from magnetic signatures. The site of Canary Islands, the active optics, the Cassegrain telescope, the long spectrographs and the universal filter of THEMIS fulfill many conditions for major advances in the near future of solar physics. Title: The THEMIS telescope Authors: Rayrole, J.; Mein, P.; Cavallini, F. Bibcode: 1994ASIC..433..507R Altcode: No abstract at ADS Title: Dynamical Fine Structure of a Quiescent Filament Authors: Mein, N.; Mein, P.; Wiik, J. E. Bibcode: 1994scs..conf..385M Altcode: 1994IAUCo.144..385M A quiescent filament was observed in Hα by the MSDP spectrograph of the Pic-du-Midi Observatory. The fitting by a numerical simulation provides the velocity distribution of the "threads", and the dynamical characteristics of the underlying chromospheric fine structures. Title: Dynamics of solar magnetic arches in photosphere and chromosphere Authors: Mein, P.; Mein, N.; Démoulin, P.; Gontikakis, C.; Engvold, O.; Molowby, R. Bibcode: 1994smf..conf..366M Altcode: No abstract at ADS Title: Solar dynamics over solar cycle 21 using sunspots as tracers. I. Sunspot rotation. Authors: Nesme-Ribes, E.; Ferreira, E. N.; Mein, P. Bibcode: 1993A&A...274..563N Altcode: Sunspots observed on spectroheliograms have been used as tracers to derive the rotation of the convective layers. Image-processing and pattern recognition technique were developed to infer the position of the tracer, thereby its motions, with a good accuracy. Some new properties of sunspot rotation have been detected, concerning the amplitude of the differential rotation and its variability through the solar cycle. Comparison is made with similar studies which do not offer the same accuracy. The results presented here give a hint of the depth where the magnetic field of sunspots is anchored. This is of importance for a better understanding of the origin of the differential rotation and of the solar dynamo. Title: Turbulent power spectra of solar granulation. Authors: Espagnet, O.; Muller, R.; Roudier, T.; Mein, N. Bibcode: 1993A&A...271..589E Altcode: High resolution "Multichannel Subtractive Double Pass" spectrograms and white light photographs have been used to compute power spectra of the solar granulation. The 5 min oscillations have been carefully filtered, and the influence of the variation of the mean size of granules at the mesogranulation scale has been taken into account.

It results that both the power spectra of velocity and intensity fluctuations, displayed in a log P - log k scale, are characteristic of a turbulent atmosphere: they present a discontinuity at 3" = 2000 km (which corresponds to the size of a large granules) and an energy which decreases according to the Kolmogorov -5/3 power law in the granulation range; another discontinuity, at 1".4 = 1000 km (which corresponds approximately to a Peclet number Pe = 1, for which thermal diffusion and advection are of equal importance) is present in the intensity power spectrum, which decreases with a -17/3 power law, in the range of sizes smaller than 1".4.

These results indicate that granules are turbulent eddies. They have some convective characters (like the correlation between velocities and brightness) because they are formed in a strongly superadiabatic atmosphere. Title: Imaging Spectroscopy of Flows in Active Regions Authors: Mein, P.; Mein, N. Bibcode: 1993ASPC...46..542M Altcode: 1993mvfs.conf..542M; 1993IAUCo.141..542M No abstract at ADS Title: THIEMIS Telescope: Prospects in High Resolution Magnetic Field Observations Authors: Rayrole, J.; Mein, P. Bibcode: 1993ASPC...46..170R Altcode: 1993IAUCo.141..170R; 1993mvfs.conf..170R No abstract at ADS Title: Dynamical Fine Structure of Filaments and Prominences Authors: Mein, N.; Mein, P.; Wiik, J. E. Bibcode: 1993ASPC...46..391M Altcode: 1993IAUCo.141..391M; 1993mvfs.conf..391M No abstract at ADS Title: Active Region Evolution Through Coordinated Observations Authors: Mein, N.; Mein, P.; Schmieder, B.; Engvold, O.; Molowny, R.; Ai, G. X. Bibcode: 1993ASPC...46...63M Altcode: 1993mvfs.conf...63M; 1993IAUCo.141...63M No abstract at ADS Title: Underneath coronal loops: MSDP observations coordinated with SERTS 4 and NIXT flights. Authors: Schmieder, B.; Mein, N.; Golub, L.; Davila, J. M.; Thomas, R.; Brosius, J. Bibcode: 1992ESASP.348..257S Altcode: 1992cscl.work..257S Ground-based coordinated observations with the multichannel subtractive double pass spectrograph (MSDP) allowed to portray the chromospheric intensity and velocity fields below coronal structures during recent launchs of sounding rockets. During SERTS 4 observations (May 7, 1991), two different active regions presenting flare and filament have been coaligned with UV structures. In July 11, 1991 (eclipse day) large Hα ejection material in AR 6713 was detected during the NIXT flight. Preliminary results are displayed. Title: Dynamique de la photosphère solaire: granulation, mésogranulation, oscillations. Authors: Espagnet, O.; Muller, R.; Roudier, T.; Mein, N.; Mein, P. Bibcode: 1992JAF....43...36E Altcode: No abstract at ADS Title: Time evolution of arch filaments Authors: Tsiropoula, G.; Georgakilas, A. A.; Alissandrakis, C. E.; Mein, P. Bibcode: 1992A&A...262..587T Altcode: We have studied the spatial structure and the temporal evolution of the velocity in active region arch filaments. The observations were obtained with the Multichannel Double Pass Spectrograph operating in H-alpha at the Pic du Midi Observatory. Line profiles were reconstructed and monochromatic images and Doppler shift velocities were derived over a 2D FOV. Using Beckers' (1964) cloud model we derived physical parameters, in particular the line of sight velocity. The arches showed the 'classical' type of motion, with material moving towards the observer near the apex and away from the observer near the footpoints. Assuming a symmetric loop, we reconstructed the velocity vector along the arch filaments. The results are consistent with the picture where material is draining out of the filament, while the whole structure is ascending. In one case we observed changes in the geometry and the velocity vector; however, other arch filaments did not change appreciably in a time period of about 13.5 min. Title: MSDP imaging spectroscopy for high resolution solar physics. Authors: Mein, P. Bibcode: 1992ESASP.344..153M Altcode: 1992spai.rept..153M Three facilities using Multichannel Subtractive Double Pass spectrographs are presently operated at Meudon, Pic du Midi, Tenerife (VTT telescope). A fourth one is expected at Tenerife (THEMIS telescope). The imaging spectroscopy with MSDP spectrographs allows very high spatial resolution and fast time sequences over 2D solar targets. The author recalls some capabilities, showing that the MSDP are very suitable for coordinated experiments between ground-based and space observations. Title: Structure and Dynamics of Cool Flare Loops Authors: Heinzel, P.; Schmieder, B.; Mein, P. Bibcode: 1992SoPh..139...81H Altcode: MSDP observations of the 16 May, 1981 two-ribbon flare are used to study the physical structure and the dynamical behaviour of cool flare loops. The loops have been detected in the Hα line just after the flare maximum and they appeared in absorption against the disk. Using the first-order differential cloud model (DCM1) technique, we derive empirically some basic plasma parameters at 15 points along one loop leg. The flow velocities and the true heights have been reconstructed with respect to a geometrical projection. Subsequently, detailed non-LTE models of cool loops have been constructed in order to fit Hα source function values previously derived from DCM1 analysis. It is demonstrated that this source function is rather sensitive to the radial component of the flow velocity (the so-called Doppler brightening) and to enhanced irradiation of the loops from the underlying flare ribbons. In this way, we have been able to estimate quantitatively all plasma parameters which determine the physical structure of cool loops (i.e., the temperature, pressure, density), as well as the momentum-balance condition within the loops. For these dark loops we have arrived at relatively low gas pressures of the order of 0.1-0.5 dyne cm-2 with corresponding electron densities around 1011 cm-3. Pressure-gradient forces have been found to be of small importance in the momentum-balance equation, and thus they cannot explain departures from a free-fall motion found in our MSDP data analysis. We propose three possible solutions to this problem. Title: Dynamics of the solar atmosphere. Authors: Mein, Pierre Bibcode: 1992soti.book..179M Altcode: Contents: (1) Introduction. (2) Outline of the solar structure: internal sun; solar atmosphere; solar activity. (3) One-dimension non-magnetic model atmosphere continuum and spectral line formation: model atmosphere; spectral intensity and source function; formation of the continuous spectrum; formation of spectral lines. (4) Diagnostic methods for velocity measurements: in situ measurements; indirect measurements; intensity measurements (continuum and lines); Dopplershifts of line profiles; averaging effects in line Doppler-shifts; instrumental aspects: velocity measurements. (5) Rotation and convection: solar rotation from Doppler measurements; solar rotation from tracers; large-scale meridional circulation; convection (intermediate and small scales). (6) Waves in the non-magnetic atmosphere: the five minutes oscillations; the k-ω diagram; power spectrum in the k-ω diagram; phase-lags between two lines or between intensity and Dopplershift; mechanical energy flux; coronal heating. (7) Motions in magnetic flux tubes and spots. (8) Velocity fields in prominences and filaments: classification, structure; velocity measurements; steady flows; oscillations; instabilities ("disparitions brusques", eruptions). (9) Mass ejections - instabilities. Title: Plasma Parameters Derived from MSDP Observations of Cool Flare Loops Authors: Heinzel, P.; Schmieder, B.; Mein, P. Bibcode: 1992LNP...399..134H Altcode: 1992IAUCo.133..134H; 1992esf..coll..134H MSDP observations of 16 May 1981 two-ribbon flare are used to study the physical structure and dynamical behaviour of cool flare loops. The loops have been detected in the H line just after the flare maximum and they appeared in absorption against the disk. Using the first-order differential cloud model (DCM1) technique, we derive empirically some basic plasma parameters at 15 points along one loop leg. The flow velocities and true heights have been reconstructed with respect to a geometrical projection. Subsequently, detailed non-LTE models of cool loops have been constructed in order to fit H source-function values previously derived from DCM1 analysis. It is demonstrated that this source function is rather sensitive to the radial component of the flow velocity (the so-called Doppler brightening) and to the enhanced irradiation of the loops from the underlying flare ribbons. In this way, we have been able to estimate quantitatively all plasma parameters which determine the physical structure of cool loops (i. e. the temperature, pressure, density, etc.), as well as the momentum-balance condition within the loops. For these dark loops we have arrived at relatively low gas pressures of the order of 0.1 - 0.5 dyn cm-2 , with corresponding electron densities around 1011 cm-3. Pressure-gradient forces have been found to be of small importance in the momentum-balance equation. However, the classical momentum equation is not capable of explaining significant departures from a free-fall motion under the gravity force, found from our MSDP data. We propose three possible explanations to this problem. Title: Dynamical Fine Structure of a Quiescent Prominence Authors: Mein, P.; Mein, N. Bibcode: 1991SoPh..136..317M Altcode: A quiescent prominence has been observed with the MSDP spectrograph at the Pic du Midi Observatory. Hα profiles are obtained simultaneously in a 2D field, allowing a statistical analysis. The standard deviations of Doppler shifts and line widths are investigated as functions of the line intensity. The observations are compared with numerical simulations assuming that the prominence is made of identical `threads', the velocity of which is distributed according to gaussian functions. The processing of simulations is very close to the processing of observations. The mixing by seeing effects and the transfer of radiation across several threads along the line of sight are considered. The results are consistent with the values derived by Engvold et al. (1989) and Zirker and Koutchmy (1989, 1990, 1991). Title: Solar 2D spectroscopy - A new MSDP instrument Authors: Mein, P. Bibcode: 1991A&A...248..669M Altcode: The present study describes a new instrument that uses the multichannel subtractive double pass (MSDP) technique. Its main capabilities are: simultaneous spectro-imaging in two line profiles (medium and strong lines), high spatial resolution in all the 2D fields, no differential seeing effects at all wavelengths, best compromises between exposure time and spectral resolution for lines, fast change of wavelength, and the possibility of spectro-imaging with high spectral resolution by successive exposures (weak lines). Either 9 or 11 channels are recorded simultaneously in each line profile. The field size is typically 120 x 1000 or 60 x 1000 diffraction widths of the telescope image. The spectral resolving power is 100,000 in one exposure. The optical design and the codes for data processing are reviewed. The performances of the MSDP and the other 2D spectroscopy techniques are briefly compared and possible improvements with regard to the spectral resolution are discussed. Title: Dynamics of the solar granulation. II - Statistical analysis: Power spectra, coherence, phase Authors: Roudier, T.; Vigneau, J.; Espagnet, O.; Muller, R.; Mein, P.; Malherbe, J. M. Bibcode: 1991A&A...248..245R Altcode: The solar granulation is analyzed statistically by the computation of coherence, phase, and power spectra using data provided by the Multichannel Subtractive Double Pass spectrograph of the Pic du Midi Observatory. The main result of the analysis is that the velocity power spectrum of the granulation changes in shape at 3 arcsec: the raw spectrum features a slope discontinuity; the corrected spectra have a power maximum at 3 arcsec. Between 3 arcsec and the resolution limit (0.8 arcsec), the power decreases almost linearly, with a slope close to -5/3, consistent with the Kolmogorov power law for a turbulent energy cascade. Title: Dynamics of solar granulation. I - Processing of MSDP spectra Authors: Roudier, T.; Vigneau, J.; Mein, P.; Malherbe, J. M.; Coutard, C.; Hellier, R.; Muller, R. Bibcode: 1991A&A...248..237R Altcode: High resolution (about 0.5 arcsec) 2D spectra have been obtained with the Multichannel Subtractive Double Pass spectrograph of the Pic du Midi Observatory in a quiet region at the solar disk center. The adapted image processing which provides 2D intensity and velocity maps of the solar granulation, at two intensity levels of the line NaD2, is described. A quantitative evaluation of the spatial resolution is determined both for the intensity and velocity granulation fields. Title: Projet THEMIS. Authors: Mein, P.; Rayrole, J. Bibcode: 1991sed..conf..291M Altcode: Contents: (1) Introduciton. (2) Performances atendues: (2.1) Le télescope sans polariseur et son analyseur. (2.2) La haute résolution spatiale. (2.3) Spectrographe échelle et long prédisperseur. (2.4) Caméras CCD et informatique. (3) Programmes et groupes de travail. (4) Etat du projet. Title: Results from high resolution solar images and spectra obtained at the Pic du Midi Observatory (1986-1990) Authors: Roudier, Th.; Muller, R.; Vigneau, J.; Auffret, H.; Espagnet, O.; Simon, G. W.; Title, A. M.; Frank, Z.; Shine, R. A.; Tarbell, T. D.; Mein, P.; Malherbe, J. M. Bibcode: 1991AdSpR..11e.205R Altcode: 1991AdSpR..11..205R We present an overview of our recent results about solar granulation and mesogranulation, obtained with Pic du Midi observations. These results were obtained during 1986-1990 using image and spectrographic analysis of high spatial resolution data. The study of the solar granulation, with 2 Dim. ``Multichannel Subtractive Double Pass'' (M.S.D.P.) spectra, shows a clear change of the dynamical regime at 3'' (⋍ 2200 km) of the photospheric velocity field when oscillatory components are filtered out.

A three hour movie obtained on film at Pic du Midi Observatory and analyzed at the Lockheed Research Laboratory and the National Solar Observatory (Sacramento Peak) was used to calculate the horizontal flow pattern. The mean lifetime of the diverging areas related to mesogranulation is estimated at 3 hours; these diverging areas are swept by the supergranulation flow towards the supergranule boundary with a mean speed of 0.4 km/s. Title: Oscillations detected in C IV and Hα lines in magnetic structures Authors: Schmieder, B.; Thompson, W. T.; Mein, P. Bibcode: 1991AdSpR..11d.195S Altcode: 1991AdSpR..11..195S Different processes involving the magnetic field and its fine structures in the atmosphere have been proposed to explain the heating of the corona. To help explore phenomena related to these different processes, we will report some new observations of oscillations in fine chromospheric structures using the MSDP spectrograph operating at Meudon and the UVSP spectrograph aboard SMM. The temporal analysis of radial velocities measured in the C IV line shows that no oscillations are detectable in the transition zone. It is in good agreement with the wave reflection model generally admitted. In the Hα line the 2 D analysis points out that the energy observed in an unresolved frequency range around 250 s in the chromospheric power spectrum is in fact concentrated in structures parallel to chromospheric fibrils along which the phase extends coherently. The oscillations appear to be transverse and might be interpreted either by Alfvén waves generated in the chromosphere and propagating through magnetic filamentary structures or by eigenmodes of filamentary structures excited by chromospheric p-modes. Title: Solar Rotation Over SOLAR-CYCLE-21 Authors: Ribes, Elisabeth; Vince, Istvan; Mein, Pierre; Neto Ferreira, Eduardo Bibcode: 1991LNP...380..241R Altcode: 1991sacs.coll..241R; 1991IAUCo.130..241R Having measured the rotation rate of sunspots through solar cycle 21, from 1977 to 1983, we have found that the mean differential rotation averaged over this seven year record is similar to the grand average differential rotation determined by Howard et al. (1984) over the period 1921-1982. However, the rotation rate does change from year to year. These changes are evidenced by a steepening or a flattening of the mean differential rotation profile, as well as significant changes in the equatorial rate. The presence of a time-dependent pattern of azimuthal roils inferred from the meridional circulation pattern of the sunspots offers a qualitative explanation of the observed rotation rates. The amplitude of the changes is almost one order of magnitude larger than that of the torsional oscillations found by Howard and LaBonte (1981). Title: Dynamique de l'atmosphère solaire. Authors: Mein, P. Bibcode: 1991sed..conf..263M Altcode: Contents: (1) Introduction. (2) Conditions physiques dans l'atmosphère solaire. (3) Diagnostic des vitesses de matière. (4) Mouvements hydrodynamiques: rotation et convection, ondes: (4.1) Rotation différentielle. (4.2) Circulation méridienne. (4.3) Supergranulation, Mésogranulation, Granulation. (4.4) Ondes en l'absence de champ magnétique. (5) Mouvements et champ magnétique: (5.1) Dynamique des tubes de flux photosphériques. (5.2) Dynamique des taches. (5.3) Protubérances et filaments. (5.4) Ejections de matière. Title: Chromospheric structures and prominences: dynamics and magnetic support. Authors: Mein, P. Bibcode: 1991joso.proc.....M Altcode: The author reports on some examples of investigations concerning chromospheric structures and prominences. Two examples refer to flows in the vicinity of sunspots. Two other ones concern prominences, from theoretical and observational points of view. Some instrumental capabilities, presently available at the Canary Island Observatory, and well suitable for the study of such objects are mentioned. Title: Current and planned facilities, Canary Islands-France Authors: Mein, P.; Rayrole, J. Bibcode: 1991AdSpR..11e.151M Altcode: 1991AdSpR..11..151M In the field of high resolution solar physics, the french telescope THEMIS is designed to be operated at the Teide Observatory. It is a 90cm polarization-free telescope, with two 7.5m spectrographs, devoted to magnetic field measurements, in a number of simultaneous spectral line profiles. The instrument is under construction. The time schedule aims at operation during the SOHO observations.

In addition to this great project, a french spectro-imaging instrument is presently working at the german VTT telescope. Using a Multichannel Subtractive Double Pass (MSDP), it provides simultaneous images in many wavelengths (typically 20), covering two line profiles. The 2D-character is very valuable for coordinated observations with space probes. Title: Physical parameters of solar H-alpha absorption features derived with the cloud model Authors: Alissandrakis, C. E.; Tsiropoula, G.; Mein, P. Bibcode: 1990A&A...230..200A Altcode: Observations of a fibril region and of an arch filament region obtained by the Multichannel Subtractive Double Pass Spectrograph (MSDP) operating in H-alpha at the Pic du Midi Observatory are presented. Intensity fluctuations and Doppler shift velocities were derived over two dimensional fields of view. The observed contrast profiles have been matched with theoretical contrast profiles based on the cloud model which has four parameters: the line-of-sight velocity, the source function, the optical depth, and the Doppler width. Contour maps and histograms of the 4 parameters were made for these regions, and a comparison of the velocities given by 3 different methods (cloud model, Doppler shift, and the '3-optical depths' method of Mein and Mein, 1988) is made. Title: Oscillations detected in Hα filaments. Authors: Schmieder, B.; Thompson, W. T.; Mein, P. Bibcode: 1990PDHO....7..296S Altcode: The authors report some new observations of oscillations in filaments observed at different positions on the disk using the MSDP spectrograph operating at Meudon. The velocity power spectra made over whole filament regions show a smooth maximum around 200 s period. Oscillations are detected principally in discrete areas in the filaments and in chromospheric fibrils, with well defined periods around 250 s and 150 s. The oscillations could be interpreted by Alfvén waves generated in the chromosphere and propagating through magnetic filamentary structures or by eigenmodes of filamentary structures excited by chromospheric p-modes. Title: Spectroheliograms and motions of magnetic tracers Authors: Mein, P.; Ribes, E. Bibcode: 1990A&A...227..577M Altcode: The series of spectroheliograms of the Paris-Meudon Observatory, starting in 1919, is a powerful tool for studies of the solar cycle and the solar dynamo. This paper describes a method of data processing which corrects most of the predictable distortions by the use of Fourier expansions of the shape of the limb. The drifts of magnetic tracers (spots and faculae in the case of K1v spectroheliograms) are computed automatically. The accuracy is checked by some comparisons with results published by the Debrecen Observatory. In most cases, the departures are 0.1 or 0.2 heliographic degree, and comparable to the spatial resolution of the spectroheliograms. Title: Dynamical Structure of a Quiescent Prominence Authors: Mein, P.; Mein, N.; Schmieder, B.; Noëns, J. C. Bibcode: 1990LNP...363..252M Altcode: 1990doqp.coll..252M; 1990IAUCo.117..252M A statistic analysis of H profiles in a quiescent prominence is consistent with the superposition of individual velocity structures (typically 10), with standard deviation ~ 15 km s-1. Title: Hα diagnostics of 16 May 1981 flare loops. Authors: Heinzel, P.; Mein, P.; Schmieder, B. Bibcode: 1990PDHO....7..272H Altcode: MSDP observations (Meudon) of 16 May 1981 post-flare loops are used to derive the hydrogen plasma parameters in flare loops. The authors compare two recently developed methods: a differential cloud model and a probabilistic transfer technique. Title: Evolution of Fine Structures in a Filament Authors: Schmieder, B.; Mein, P. Bibcode: 1990LNP...363..235S Altcode: 1990doqp.coll..235S; 1990IAUCo.117..235S A quiescent filament observed in June 1986 underwent a slow Disparition Brusque which lasted 4 days. Here, we focus our study on the dynamical behaviour of the fine structures ( Full-Width Half-Max ~ 350 km) in this filament which were observed at Pic du Midi with the Multi-Channel Subtractive Double Pass (MSDP) spectrograph during a period of 30 minutes. We observed no changes in intensity during this period, but we did observe changes in the velocity field with no correlation from one minute to the next. High velocities were detected at the footpoints where the filament is anchored in the photosphere , of the same order than those observed at the boundaries of the supergranules (between ±10 km s-1). To explain these observations we suggest a spicule-like model which supplies material to the prominence. Title: Granulation velocity field: latest results from Pic-du-Midi - processing of MSDP data Authors: Mein, P.; Roudier, Th.; Vigneau, J.; Muller, R.; Malherbe, J. M.; Contard, C.; Hellier, R. Bibcode: 1989hsrs.conf..521M Altcode: No abstract at ADS Title: Prospects of MSDP observations: high spatial resolution and adaptive optics Authors: Mein, P. Bibcode: 1989hsrs.conf..195M Altcode: No abstract at ADS Title: High resolution observations with THEMIS: prospects in magnetic field observations Authors: Mein, P. Bibcode: 1989hsrs.conf...12M Altcode: No abstract at ADS Title: Oscillations of the sun's chromosphere. V - Importance of network dynamics for chromospheric heating Authors: von Uexkuell, M.; Kneer, F.; Malherbe, J. M.; Mein, P. Bibcode: 1989A&A...208..290V Altcode: A 64-min time sequence of disk center H-alpha spectrograms taken with the MSDP spectrograph at the Observatoire du Pic du Midi is analyzed. This type of spectrograph allows spectroscopy of a two-dimensional field of view. From the H-alpha line profiles at each pixel, line-shift and minimum intensity fluctuation are determined as functions of spatial and temporal coordinates. A frequency analysis with standard Fourier techniques is performed. It is confirmed that in the interior of the chromospheric network cells the oscillatory behavior dominates, whereas at the boundaries one generally finds random motions on scales of 2-10 arcsec. The random behavior of the H-alpha structures outlines the permanent rearrangement of the magnetic field lines pushed around by the subphotospheric granular flow. Title: Evolution of Fine Structures in a Filament Authors: Schmieder, B.; Mein, P. Bibcode: 1989HvaOB..13...31S Altcode: No abstract at ADS Title: Echelle grating spectrograph for LEST. Constraints and tentative scheme. Authors: Mein, P. Bibcode: 1989egsl.book.....M Altcode: The large aperture of LEST combined with adaptive optics should lead to a great number of new results in solar physics. The author reviews briefly the requirements in the case of the echelle grating spectrometer. Then he analyses the capabilities and limitations of some special designs and observing modes, proposes a tentative optics and lists some available operating modes. Title: A surge in the chromosphere and the transition region: velocities and microturbulence. Authors: Mein, P.; Schmieder, B.; Tandberg-Hanssen, E. Bibcode: 1989sasf.confP.223M Altcode: 1989IAUCo.104P.223M; 1988sasf.conf..223M Simultaneous observations of a surge in Hα and C IV are analysed in terms of Doppler velocities and "microturbulence". The behaviour of both quantities suggests strong velocity shears with small spatial scales. Title: Chromospheric eruptions, Jan - Dec 1989. Authors: Cailloce, E.; Mein, N.; Lantos, P. Bibcode: 1989QBSA...31....1C Altcode: This report shows, in a chronological order, a list of all reported flare events whatever their importance. Title: Dynamical Structure of a Quiescent Prominence Authors: Mein, P.; Mein, N.; Schmieder, B.; Noens, J. C. Bibcode: 1989HvaOB..13..113M Altcode: No abstract at ADS Title: Chromospheric ejections associated with type III radio-bursts. Authors: Mein, N.; Mein, P. Bibcode: 1989sasf.confP.181M Altcode: 1988sasf.conf..181M; 1989IAUCo.104P.181M The authors study the dynamics of an Hα absorbing structure associated with a type III radioburst. They use a "Differential Cloud Model" to analyse the observed line profiles, in order to determine radial velocity and microturbulence (or shear) as functions of time. The authors assume that the material is flowing inside magnetic flux tubes, with a given velocity distribution. They analyse the motions in a phase-diagram (position x, velocity V). The evolution of velocity and microturbulence is compared to the observations. The model accounts qualitatively for the evolution of velocity, and qualitatively for the decrease of microturbulence. Title: Differential cloud models for solar velocity field measurements Authors: Mein, P.; Mein, N. Bibcode: 1988A&A...203..162M Altcode: The analysis of velocity fields in solar ejecta is an important step in understanding mechanisms of acceleration and energy transfer. Unfortunately, Beckers' cloud model is not quite valid in the case of fast mass flows observed on the disk, because of the fluctuations of the chromospheric background in active regions, and because of strong velocity gradients along the line of sight. The authors propose two kinds of differential cloud models (first order and second order) to determine some parameters characterizing the velocity field, in spite of these difficulties. They discuss an example of a solar ejection observed at Meudon observatory. Title: An example of the association of X-ray and UV emission with H-alpha surges Authors: Schmieder, B.; Mein, P.; Simnett, G. M.; Tandberg-Hanssen, E. Bibcode: 1988A&A...201..327S Altcode: From H-alpha UV, and X-ray data, the nature of a well-observed surge on November 12, 1980 has been studied to try to understand the relationships between the mechanical motions and the high-temperature emissions. The cool (H-alpha) and the hot (O v) parts of the surge plasma both show velocities in the range of 100-120 km/s. The kinetic and potential energies of the surge are two orders of magnitude higher than the radiative energy. The observations suggest that the surge occurs in open structures parallel to one leg of a large scale coronal magnetic loop. The energy is released principally in the open structure (surge) and only a small amount heats the coronal loop (X-ray signature). This energy division should probably not be treated as a general characteristic of surge events. Different events are expected to exhibit a different energy balance, and this can account for the lack of a consensus in the previous literature regarding surge/X-ray associations. Title: The Evershed flow in the solar photosphere, chromosphere and chromosphere-corona transition region Authors: Alissandrakis, C. E.; Dialetis, D.; Mein, P.; Schmieder, B.; Simon, G. Bibcode: 1988A&A...201..339A Altcode: The authors have studied the height dependence of the characteristics of the Evershed flow in the photosphere, chromosphere and chromosphere-corona transition region. The Multichannel Subtractive Double Pass Spectrograph was used to obtain line of sight velocity maps in Hα, the Meudon magnetograph for mapping the photospheric velocity and magnetic field and the Ultraviolet Spectrometer and Polarimeter on the Solar Maximum Mission spacecraft for line-of-sight velocities in C IV, in sunspot regions. The observations are practically simultaneous in the three atmospheric levels and cover three consecutive days (Sep 28, 29 and 30, 1980). The emphasis was on the large scale, quasi-stationary characteristics of the flow. Title: Photospheric-induced destabilization and ejection of prominence material Authors: Raadu, M. A.; Schmieder, B.; Mein, N.; Gesztelyi, L. Bibcode: 1988A&A...197..289R Altcode: The sequence of events leading up to prominence activation in two different cases is studied. In one case, observed on September 3, 1980, strong velocity shears were produced indicating filament twisting. In the other case, observed on June 22, 1980, activation results in the ejection of prominence material. The paper presents new evidence for a common initial triggering mechanism, the birth or motion of pores at one end of the activated filament sections. This is taken as an indication of emerging magnetic flux and current induction in the filaments. The difference in the final results is partly due to the different ambient magnetic field structures. In particular in the case leading to material ejection there is a subsequent associated flare occurred indicating the storage of magnetic energy in the region. Models are proposed for the two sequences of events, clarifying the underlying similarities and interpreting the distinct features of the two sets of observations. Title: Two-dimensional spectroscopy of the Sun in Hα. Authors: von Uexküll, M.; Kneer, F.; Mein, P. Bibcode: 1988AGAb....1...11V Altcode: No abstract at ADS Title: Variations of the Solar Limb Brightness with the Oscillations Authors: Schmieder, B.; Mein, P. Bibcode: 1988IAUS..123..429S Altcode: The aim of this work is to compute the amplitude of the limb darkening fluctuations due to oscillations in order to compare it with the observations made with the heliometer at the Pic du Midi (Rösch and Yerle 1983 - 1984). It is shown that 5 min oscillations lead to variation in the brightness gradient of less than 2%. Title: Environment and dynamics of a prominence observed at Pic du Midi. Authors: Noëns, J. C.; Schmieder, B.; Mein, P. Bibcode: 1988dssp.conf..177N Altcode: Simultaneous observations were made at Pic du Midi using the 20 cm Coronograph and the Multichannel Subtractive Double Pass spectrograph operating in the "Coupole Tourelle". The prominence observed on June 17, 1987 is composed of three principal vertical structures 50000 km high with faint material connecting then. A coronal cavity is visible above the prominence. The dynamics of this prominence in Hα is large, horizontal circulation is observed. Images in Hα versus time show a slow evolution in the general shape with an exchange of material between the vertical structures. Title: Mass ejections in the low corona: microturbulence and type III associations. Authors: Mein, Pierre; Mein, Nicole Bibcode: 1988sscd.conf..514M Altcode: Mass ejections visible in Hα have often been correlated with type III radio bursts. Among the possible mechanisms which can account for the radio emission, energy transfer from turbulence or velocity shears have been suggested. The authors analyse velocity fields inside the ejecta by using two "Differential Cloud Models" derived from the well-known Beckers model. They apply these models to a sample of ejection observed with the MSDP of the Meudon Solar Tower. They derive the time evolution of radial velocities and microturbulence at the edges of the structure as well as the range of radial velocities along the line of sight in the middle part. Title: Velocity shear and microturbulence in solar filaments a differential cloud model. Authors: Mein, P.; Schmieder, B. Bibcode: 1988dssp.conf...17M Altcode: The authors analyse the time sequence of an active region filament observed at the MSDP of the Meudon Solar Tower. They use a "differential cloud model" which is well suited to the interpretation of Hα profiles with an inhomogeneous chromospheric background. A previous model (Schmieder et al. 1985) suggesting twisting motions of magnetic ropes is confirmed. Title: Chromospheric eruptions, Jan - Dec 1988. Authors: Cailloce, E.; Mein, N.; Lantos, P. Bibcode: 1988QBSA...30....1C Altcode: This report shows, in a chronological order, a list of all reported flare events whatever their importance. Title: Post-flare loops: formation and velocity Authors: Schmieder, B.; Mein, P.; Malherbe, J. -M.; Forbes, T. G. Bibcode: 1988AdSpR...8k.145S Altcode: 1988AdSpR...8..145S Post-flare loops are generally observed between two ribbon flares. The formation of post flare loops and active region or plage filaments has been explained in a model based on magnetic reconnection and chromospheric ablation /1,2/. This model uses a magnetic topology which is relevant to solar flares /3/ : a large flare or an instability opens the magnetic lines of a coronal arcade (or arch) and a vertical current sheet forms. Then the reconnection of the magnetic field follows according to the scenario of Kopp and Pneuman /4/. In this magnetic configuration, we show that the formation of condensations or dense loops is induced by reconnection shocks.

We give in this communication a new method of diagnostic to derive from Hα profiles physical parameters, i.e. source function, optical depth and velocity. This method called ``differential cloud method'' is very promising for future observations. Title: Closed Magnetic Structures in the Chromosphere and in the Transition Region Authors: Malherbe, J. M.; Schmieder, B.; Simon, G.; Mein, P.; Tandberg-Hanssen, E. Bibcode: 1987SoPh..112..233M Altcode: Using simultaneous observations of the same solar regions in the lines Hα and CIV 1548 Å, we have derived schematic models of closed magnetic lines from dynamical constraints. We conclude that the magnetic loops are closed at higher levels above facular than above non-facular regions. This result remains valid whatever are the assumed density models and even if we take into account the 3 min oscillations. The center-to-limb behaviour is well predicted by taking into account the relative opacity in chromosphere and transition region. Title: Inversion of line profile disturbances - A nonlinear method applied to solar CaII lines Authors: Mein, P.; Mein, N.; Malherbe, J. M.; Dame, L. Bibcode: 1987A&A...177..283M Altcode: Thermodynamical disturbances in the solar atmosphere can be deduced from observations of line profiles. The authors propose a non-linear method based on Fourier analysis: each profile is converted into a "double profile" for a fast convergence of Fourier expansions. Disturbances of Fourier coefficients are connected theoretically with physical disturbances by second order developments. Temperature and velocity fluctuations are derived from a least square inversion of these developments. The authors apply this method to a time sequence of high resolution profiles of the Ca II 3968 Å line. The accuracy of the results is discussed. The enhanced blue peaks occurring in the asymmetric profiles are interpreted as downward velocity gradients, associated with temperature excesses. Title: Material Ejecta in a Disturbed Solar Filament Authors: Raadu, M. A.; Malherbe, J. M.; Schmieder, B.; Mein, P. Bibcode: 1987SoPh..109...59R Altcode: Hα observations, using the Multichannel Subtractive Double Pass (MSDP) spectrograph operating on the Meudon Solar Tower, have been made of an active region filament which undergoes a `disparition brusque'. The period of observation was from 10 ∶ 45 to 13 ∶ 30 UT on 22 June, 1981. Velocity and intensity fluctuations in Hα were measured. The proper motions of ejecta were followed allowing their trajectories and vector velocities to be determined. To model the dynamics of ejecta several models using thermal or magnetic driving forces are compared. The most promising model explains the motion as the consequence of magnetic stresses acting on an isolated magnetized plasmoïd in a diverging flux tube. Title: Dynamics of the solar granulation. Authors: Muller, R.; Roudier, Th.; Malherbe, J. M.; Mein, P. Bibcode: 1987PAICz..66..175M Altcode: 1987eram....1..175M In order to understand the origin of the solar granulation, convective or turbulent, in this paper the authors report results about the intensity-velocity correlation and the energy power spectrum derived from the Doppler shifts measurement on two-dimensional high resolution spectrograms. Title: The Evershed flow in the solar photosphere, chromosphere and chromosphere-corona transition region. Authors: Alissandrakis, C. E.; Dialetis, D.; Mein, P.; Schmieder, B.; Simon, G. Bibcode: 1987PAICz..66..147A Altcode: The authors have studied the height dependent characteristics of the Evershed flow in the photosphere, chromosphere and chromosphere-corona transition region. Title: Photospheric Induced Destabilization and Ejection of Prominence Material Authors: Raadu, M. A.; Schmieder, B.; Mein, N.; Gesztelyi, L. Bibcode: 1987HvaOB..11..105R Altcode: The cause of the sudden activation of solar prominences is not clear. The authors present observations of two cases which were preceded by the emergence and motion of pores (new flux) in the near vicinity of the filaments, which seem to be closely related to the process which triggered the filament destabilization. These observations may be well described by a theoretical model in which the new flux interacts with the older "stable" magnetic field. Title: Dynamics of solar filaments. V - Oscillations in the H-alpha and 1548 A C IV lines Authors: Malherbe, J. M.; Schmieder, B.; Mein, P.; Tandberg-Hanssen, E. Bibcode: 1987A&A...172..316M Altcode: Using the Multichannel Subtractive Double Pass Spectrograph operating in the Meudon solar tower and the Ultraviolet Spectrometer and Polarimeter aboard the Solar Maximum Mission satellite, the authors analyze by Fourier transform technique time sequence observations of filaments in both the Hα line and in the 1548 Å C IV line. The Hα data confirm previous findings that there are no oscillations at the location of the filament in the observed range 1 - 10 mHz. In the C IV line the authors observe power in some parts of the filament where a steady velocity gradient is present, e.g. in the footpoints. The energy is probably due to convective motions rather than pressure oscillations. Title: Environment and Dynamics of a Prominence Observed at Pic-Du Authors: Noens, J. C.; Schmieder, B.; Mein, P. Bibcode: 1987dssp.work..177N Altcode: 1987ASSL..150..177N No abstract at ADS Title: Joint Discussion on Topics of Sessions 9 and 10 Authors: Mein, P.; Roberts, B. Bibcode: 1987rfsm.conf..292M Altcode: No abstract at ADS Title: La physique solaire et les performances de THÉMIS. Authors: Mein, P. Bibcode: 1987JAF....29...14M Altcode: No abstract at ADS Title: Chromospheric eruption, Jan - Dec 1987. Authors: Cailloce, E.; Mein, N.; Lantos, P. Bibcode: 1987QBSA...29....1C Altcode: This report shows, in a chronological order, a list of all reported events whatever their importance. Title: On the onset of eruptive prominences and coronal transients. Authors: Simon, G.; Mein, N.; Schmieder, B.; Tandberg-Hanssen, E.; Wu, S. T. Bibcode: 1987PAICz..66..211S Altcode: 1987eram....1..211S During the Maximum Year, preflare and preeruptive phenomena have been observed which give a new idea on the association of eruptive prominences and coronal transients. Title: Surges as tracers of magnetic lines. Authors: Schmieder, B.; Mein, P.; Martres, M. J.; Simnett, G.; Tandberg-Hanssen, E. Bibcode: 1987PAICz..66..109S Altcode: 1987eram....1..109S The authors focus their study to chromospheric mass ejecta of cool material visible in Hα and occurring, with or without any flare. Associated with the events are either X ray emission or type III bursts. Title: Velocity Shear and Microturbulence in Solar Filaments Authors: Mein, P.; Schmieder, B. Bibcode: 1987dssp.work...17M Altcode: 1987ASSL..150...17M No abstract at ADS Title: On the existence of oscillations in solar filaments observed in H&alpha; and C IV lines. Authors: Schmieder, B.; Malherbe, J. M.; Mein, P.; Tandberg-Hanssen, E. Bibcode: 1986NASCP2442..197S Altcode: Time sequence observations of filaments in both the H&alpha; line and the 1548 Å C IV line were analyzed with the Fourier transform technique in the frequency range (1 - 10 mHz). No oscillation is detected in filaments except at the footpoints where a steady velocity gradient is large. The energy is probably due to convective motions rather than pressure oscillations. Title: Filament eruption connected to photospheric activity. Authors: Simon, G.; Gesztelyi, L.; Schmieder, B.; Mein, N. Bibcode: 1986NASCP2442..229S Altcode: 1986copp.nasa..229S Two cases of activation of filaments that occured in regions of intense magnetic activity was studied. The simultaneous observations from Debrecen Observatory (white light and H alpha filtergram), and from Meudon Observatory (magnetogram, MSDP dopplergram and intensity maps in H alpha) gave a complementary set of data from which can be produced evidence of the influence of the photospheric magnetic field on the destabilization process of the filaments. On June 22, 1980, the eruption of the filament is associated with the motion of pores, which are manifestations of emerging flux knots. On September 3, 1980, the twisting motions in the filament are associated to the birth of a pore in its neighborhood. These observations are discussed. Title: Material ejecta in a disturbed solar filament Authors: Raadu, Michael A.; Malherbe, Jean-Marie; Schmieder, Brigitte; Mein, Pierre Bibcode: 1986STIN...8722594R Altcode: H alpha observations, using a multichannel subtractive double pass spectrograph were made of an active region filament which undergoes a sudden disappearance. The period of observation was from 10:45 UT to 13:30 UT on 22 June, 1981. Velocity and intensity fluctuations in H alpha were measured. The proper motions of ejecta were followed allowing their trajectories and vector velocities to be determined. To model the dynamics of ejecta, models using thermal or magnetic driving forces are compared. The most promising model explains the motion as the consequence of magnetic stresses acting on an isolated magnetized plasmoid in a diverging flux tube. Title: The effect of solar oscillations on the brightness of the limb Authors: Schmieder, B.; Mein, P. Bibcode: 1986A&A...161....7S Altcode: Using the realistic atmosphere model VALC, and assuming a spherical geometry, the intensity of the solar limb is calculated, and measured amplitude fluctuations are compared with those expected due to oscillations. In the model, the atmosphere is perturbed successively by density and temperature fluctuations of amplitude smaller than the 6 percent limiting value, and the perturbations are defined by exponential laws corresponding to propagating or evanscent waves. It is shown that 5-minute oscillations lead to variations in the brightness gradient of less than 2 percent. Limb brightness fluctuation amplitudes observed with the Pic du Midi heliometer (Yerle, 1981) show peaks of 10 percent which have too high a value to be explained by solar wave theory. Title: Unstable Chromospheric Dark Features and Type-Iii Bursts Association Authors: Chiuderi-Drago, F.; Mein, N.; Pick, M. Bibcode: 1986SoPh..103..235C Altcode: The temporal association between the kinematic parameters of chromospheric dark features (DF) and the production of radio type-III bursts is investigated during a period of five months. The Doppler shifts inside six different DF are measured by means of the Meudon Multichannel Subtracting Double Pass Spectrograph (MSDP) during periods of some minutes around 24 type-III bursts. The position of the radio bursts has been checked to be associated with the same active region observed by MSDP, by using the Nançay Radioheliograph. Title: Chromospheric eruption, Jan - Dec 1986. Authors: Cailloce, E.; Mein, N.; Lantos, P. Bibcode: 1986QBSA...28....1C Altcode: This report shows, in a chronological order, a list of all reported events whatever their importance. Title: First evidence of a large-scale circulation in the solar convection zone Authors: Ribes, E.; Mein, P. Bibcode: 1986ASIC..169..103R Altcode: 1986ssds.proc..103R No abstract at ADS Title: THEMIS: un projet solaire national pour une recherche internationale. Authors: Rayrolle, J.; Mein, P.; Malherbe, J. -M. Bibcode: 1986JAF....28....6R Altcode: No abstract at ADS Title: A large-scale meridional circulation in the convective zone Authors: Ribes, E.; Mein, P.; Mangeney, A. Bibcode: 1985Natur.318..170R Altcode: Many attempts have been made to detect, at the solar photospheric level, large-scale motions related to the Sun's global convection and dynamo (see ref. 1). Because these motions are likely to be influenced by solar rotation, one might expect that they would take the form of `bananas' aligned with the solar rotation axis2, as a result of the Taylor-Proudman constraint. The Paris observatory has one of the longest series of spectroheliograms, dating back to 1919. In view of the current interest in the history of solar activity, we have started to digitize the collection3. This allows us to measure rotational rate and meridional drift for individual sunspots with an accuracy of a few ni s-1 for the best seeing conditions at Meudon. A new phenomenon, which may lead us drastically to revise our ideas on the large-scale convection of the Sun, can immediately be seen. Newly-born sunspots trace a roughly axisymmetric meridional circulation, in the form of four zonal bands, with relatively large velocity amplitude. If these drifts are assumed to trace fluid motions at some level in the solar envelope, the resulting circulation pattern cannot be associated with the `banana' cells mentioned above. We report here results based on two sets of data; one involves a detailed analysis of two periods, each covering five solar rotations while the other is essentially qualitative and results from eye-estimates of the spot meridional drifts over much longer time sequences. Title: Inversion of Chromospheric Line Profiles Authors: Mein, P.; Mein, N.; Malherbe, J. M. Bibcode: 1985tphr.conf..303M Altcode: No abstract at ADS Title: Mass Motions in Hα Absorbing Structures of the Solar Chromosphere Authors: Mein, P.; Malherbe, J. M.; Mein, N.; Mouradian, Z.; Schmeider, B. Bibcode: 1985tphr.conf..316M Altcode: No abstract at ADS Title: The Evershed flow as a steady-state homogeneous phenomenon Authors: Dialetis, D.; Mein, P.; Alissandrakis, C. E. Bibcode: 1985A&A...147...93D Altcode: The present observations of photospheric and chromospheric line-of-sight velocity, as well as the photospheric magnetic field, facilitate the comprehensive study of the Evershed (1909) flow, with emphasis on large scale, quasi-stationary characteristics of the flow and its association with the topology of the magnetic field. A multichannel subtractive double pass spectrograph was used to obtain line-of-sight velocity maps in H-alpha, together with the Meudon magnetograph. Computations are made for the components of the velocity vector as a function of distance from the center of the spot, under the assumption of axial symmetry. The radial component is the dominant one in both chromosphere and magnetosphere. The present analysis of the magnetograms, using current-free and force-free models, indicates that the velocity maximum occurs in regions where the magnetic field is almost horizontal in both layers; the results are judged to appear consistent with subsonic flow in magnetic flux tubes. Title: Ejection of Chromospheric Material Associated with Injection of Electrons in the Solar Corona Authors: Mein, N.; Avignon, Y. Bibcode: 1985SoPh...95..331M Altcode: Observations of a type III radio event and of concurrent Hα absorbing features are related. They were obtained with the Nançay Radioheliograph and the Multichannel Subtractive Double Pass spectrograph operating in Hα at Meudon. We are looking for the signature at chromosphere levels of the acceleration of the elctron beams triggering the type III bursts. Some promising results are pointed out: the relationship between velocities in Hα and the occurrence of the type III bursts, the shape of Hα line which reveals turbulent motions, the presence of parasitic magnetic polarity and the probable existence of a shock wave. A schematic scenario of the phenomenon is proposed, taking into account the observational constraints. Title: Mass motions in Hα absorbing structures of the solar chromosphere. Authors: Mein, P.; Malherbe, J. M.; Mein, N.; Mouradian, Z.; Schmieder, B. Bibcode: 1985MPARp.212..316M Altcode: Two examples of Hα absorbing structures have been observed with the Multichannel Subtractive Double Pass spectrograph at the turret dome (Pic du Midi) and at the solar tower (Meudon). In both cases, 9 points of the line profile are measured simultaneously in a 2D-field of view. Title: Inversion of chromospheric line profiles. Authors: Mein, P.; Mein, N.; Malherbe, J. M. Bibcode: 1985MPARp.212..303M Altcode: Because of the large amount of high resolution data which becomes available now from solar observations, fast codes are urgently needed in order to interpret disturbed line profiles. The authors present briefly two kinds of algorithms usable in the case of chromospheric lines. Title: Spectrographie des structures fines solaires. Un grand pas réalisé au Pic-du-Midi. Authors: Mein, P. Bibcode: 1985LAstr..99..167M Altcode: No abstract at ADS Title: Search for Giant Convective Cells from the Analysis of Meudon Spectroheliograms Authors: Ribes, E.; Mein, P. Bibcode: 1985LNP...233..282R Altcode: 1985hrsp.proc..282R The results of digitizing the K IV spectroheliograms (violet wing of the Ca II line) of the Meudon Collection are discussed. Sunspots are found to rotate faster than old facula by two percent, and it is concluded that they can be tracers of angular momentum transport at the very beginning of their emergence. Afterwards, they become detached from the depth of anchorage and float with the photospheric plasma. A complex meridional circulation, analogous to zonal belts observed on the major planets, has been detected which changes throughout the solar cycle. The existence of two active longitudes together with the meridional circulation pattern suggests that the solar dynamo works as a nonlinear oscillator. Title: Themis solar telescope Authors: Mein, P.; Rayrole, J. Bibcode: 1985VA.....28..567M Altcode: Thémis is a 90cm solar telescope expected to be constructed at the Teide Observatory by 1990 for polarisation analysis simultaneously over a broad spectral range. Title: Differential Rotation and Large Scale Convection Authors: Ribes, E.; Mein, P. Bibcode: 1985spit.conf..212R Altcode: No abstract at ADS Title: Chromospheric eruption, Jan - Dec 1985. Authors: Cailloce, E.; Mein, N.; Lantos, P. Bibcode: 1985QBSA...27....1C Altcode: This report shows, in a chronological order, a list of all reported events whatever their importance. Title: New instrumentation for diagnostics of chromospheric fine structure and dynamics: MSDP spectrographs; capabilities and latest results. Authors: Mein, P. Bibcode: 1985cdm..proc..297M Altcode: High spatial resolution can be achieved in bidimensional spectroscopy by "Multichannel Subtractive Double Pass" spectrographs. The capabilities of such instruments are briefly reviewed, as well as the processing of data, the latest results and the plans for the future. Title: Atmospheric structure deduced from disturbed line profiles - application to Ca II lines. Authors: Mein, N.; Mein, P.; Malherbe, J. -M.; Dame, L.; Dumont, S. Bibcode: 1985cdm..proc..167M Altcode: A new method is described in order to derive physical quantities (temperature, pressure, radial velocities) from the observation of disturbed line profiles. The authors suggest a method of Fourier analysis with double profiles and a non linear expansion of the coefficient of the Fourier terms. An application to a sequence of H - Ca II line is attempted. The method seems a powerful tool allowing the determination of at least 4 physical quantities simultaneously. Title: Bright Points in H Wings and Mass Flows in the Solar Chromosphere Authors: Mein, P.; Malherbe, J. -M.; Mouradian, Z.; Mein, N.; Schmieder, B.; Muller, R. Bibcode: 1985LNP...233..203M Altcode: 1985hrsp.proc..203M Many mass flows in the chromosphere are physically connected with bright photospheric points. Bidimensional spectroscopy with high spatial resolution is very well suited for the study of both kinds of structures. The authors give some preliminary results derived from recent observations of the MSDP at the Pic-du-Midi. Title: Mass fluxes and magnetic structures in the chromosphere and the transition region; canopies. Authors: Mein, P.; Malherbe, J. -M.; Schmieder, B.; Simon, G.; Tandberg-Hanssen, E. Bibcode: 1985cdm..proc..206M Altcode: Preliminary results of applying a model of canopy-type magnetic lines to account for observed mass fluxes in the chromosphere and transiton region are presented. A set of center-to-limb data obtained in H-alpha and C IV, and to which the model is applied, is reported. The C IV line is assumed to form everywhere at the same height, and the H-alpha formation height is derived by assuming that the absorption coefficient is proportional to the local density. The density ratio between H-alpha and C IV levels is taken to be 100. From the results, it is concluded that the model accounts for the low ratio of radial velocities C IV/H-alpha at r = 0, the increase of H-alpha velocity near the limb, and the general center-to-limb behavior in both lines. Title: Recent Progress in the Physics of Solar Prominences Authors: Ribes, E.; Mein, P.; Malherbe, J. M.; Schmieder, B. Bibcode: 1985spit.conf..467R Altcode: No abstract at ADS Title: Dynamic evolution of recurrent mass ejections observed in Hα and C iv lines Authors: Schmieder, B.; Mein, P.; Martres, M. J.; Tandberg-Hanssen, E. Bibcode: 1984SoPh...94..133S Altcode: During a coordinated SMY program, the consecutive formation of two new active centers merging together within AR 2646 was observed from 28 August, to 5 September, 1980. The two preceding spots compressed an inverse polarity spot on 1 September 1980, causing recurrent ejecta of matter with time intervals around 10 min. The observations of the MSDP spectrograph operating in Hα at the Meudon Solar tower and of the UVSP spectrometer on SMM in the CIV 1548 Å line show that cold and hot material had the same projection, although the upward CIV velocity structure was more extended than the Hα one. We present evidence that observed contrasts of the Hα absorbing structure can be interpreted in terms of a dynamic `cloud model' overlying the chromosphere. Hα matter follows a magnetic channel with upward velocity around 20-30 km s−1 in the first phase of the event and with downward velocity (∼ - 40 km s−1) in the second phase. The stored energy is not sufficient to trigger a flare, nor even to propulse matter along the full length of an arch, because of the periodic reorganisation of the magnetic field. Title: Dynamics of solar filaments. III - Analysis of steady flows in H-alpha and C IV lines Authors: Schmieder, B.; Malherbe, J. M.; Mein, P.; Tandberg-Hanssen, E. Bibcode: 1984A&A...136...81S Altcode: A statistical analysis of intensities and radial velocities of several solar plage filaments (i.e. prominences seen on the solar disk) observed at disk center is presented. Intensity and radial (= vertical) velocity maps were derived from simultaneous 2D measurements of the H-alpha chromospheric line with the Multichannel Subtractive Double Pass spectrograph operating on the Meudon solar tower, and also obtained from 2D recordings of the C IV transition-zone line (1548 A) with the UV Spectrometer and Polarimeter aboard the Solar Maximum Mission satellite. A good correlation (around 0.5) is found between intensities in both lines, as well as between velocities. Persistent upflows are measured in both lines at the filament location. The mean vertical velocities are respectively 0.5 km/s in H-alpha and 5.6 km/s in C IV. The analysis of mass fluxes suggests that C IV upflows occur in the transition region around prominences rather than below, in the chromosphere-corona transition zone. Title: Preflare Activity of Solar Prominences Authors: Simon, G.; Mein, N.; Mein, P.; Gesztelyi, L. Bibcode: 1984SoPh...93..325S Altcode: The preflare activity of a plage filament is analysed from Hα observations made with the Multichannel Subtractive Double Pass Spectrograph (MSDP) of the Meudon Solar Tower. The June 22, 1980 event is studied and interpreted in terms of preflare heating of a filament, connected to the rise of emerging flux, and the relative approach of pores of different magnetic polarity, prior to the onset of a two-ribbon flare. Title: Oscillations and stationary motions in filaments Authors: Schmieder, B.; Malherbe, J. M.; Mein, P.; Tandberg-Hanssen, E. Bibcode: 1984MmSAI..55..325S Altcode: Observation of oscillations in filaments, which are cold magnetic structures suspended in the corona, are used to test theories of coronal heating by acoustic waves high in the atmosphere. Long lived stationary motions observed in filaments suggest exchanges of material between them and the surrounding corona. A coupling between upflows in filaments and subphotospheric convective motions, dragging the field lines of the prominence magnetic support, is possible. Title: Dynamical behaviour of the corona in association with radio emissions Authors: Trottet, G.; Avignon, Y.; Kerdraon, A.; Mein, N.; Pick, M. Bibcode: 1984AdSpR...4g.271T Altcode: 1984AdSpR...4..271T From a combined analysis of radioheliographic observations and white light images of the Corona, it is shown that metric continua onsets or enhancements are associated with a great variety of dynamical changes of the Corona. It is found that if the most spectacular radio bursts (type IV) are associated with mass ejection transients, the more common noise storm onsets or enhancements are systematically associated with coronal changes which are not necessarly mass ejections.

Simultaneous observations of Radio type III bursts and Hα mass ejecta are related. We are looking to the signature at low levels in the corona of the electron beam acceleration triggering type III bursts. The results deal with the relationship between the type III occurrence and optical features : the presence of velocities in Hα, the shape of Hα line which reveals trubulent motions and the probable existence of a shock wave. Title: Etude de la rotation des traceurs magnétiques observés sur les spectroheliogrammes K IV (Collection de Meudon) - Résultats préliminaires. Authors: Ribes, E.; Mein, P. Bibcode: 1984cms..conf..369R Altcode: No abstract at ADS Title: Flare build-up study - Homologous flares group - Part I Authors: Martres, M. -J.; Woodgate, B. E.; Mein, N.; Mouradian, Z.; Rayrole, J.; Schmieder, B.; Simon, G.; Soru-Escaut, I. Bibcode: 1984AdSpR...4g...5M Altcode: 1984AdSpR...4....5M According to the definition of the homology (optical) kept in reference, the homologous flares (HFl) may be observed wherever flares occur. The supposed supplementary preflaring conditions to have HFl may be either that the preflaring conditions have not been destroyed by the first flare (and then what mechanism has stopped the first and triggered the second ?) or that the preflaring conditions have been destroyed and rebuilt (and then, how ?). The analysis of data related to some selected active regions AR by the members of the working group, and the earlier works on HFl, may be used simultaneously to investigate the differences between one set of HFl and the others, the location of their sites and the evolution of HFl productive AR. This study brings the appearance of new footpoints from one flare to the following, the behaviour of cool arches (surging arches) leading to information on the changes of the magnetic configuration, and to peculiar characteristics of HFl, oif 2nd, 3rd in the time order concerning the chromospheric transition zone or coronal regions. The time delay between two consecutive homologous flares appears very quickly as an essential parameter to study homology. It was found that every set of flares (same type of site) is able to produce ``rafales'' of homologous flares, i.e. two, three, four, oir more flares with Δt in the range of one hour or less. The observations show no great chantes in macroscopic photospheric patterns (B, V) during this H flaring period. They lead to compare their temporal variation curves of flare brightness. A quantitative brightness parameter of homology relation has been defined. Some scale changes have also been detected in the dynamic spectrum of the site, and it is in good agreement with a very interesting theoretical suggestion made by P. Sturrock to produce such ``rafales''. It may be shown that the closely consecutive time-homologous flares (CCHF) or ``rafales'' represent a good tool to analyse the critical conditions related to the origin and the amount of energy, mechanism of storage and release, necessary and, perhaps, sufficient conditions. New statistical results, applied to the different selected homologous flare active regions are presented and show the existence in homologous flaring areas of a ``pivot'' of previous filaments interpreted as a signature of an anomaly in the Solar rotation. Title: Les traceurs du champ magnétique en physique solaire. Authors: Mein, P. Bibcode: 1984cms..conf..341M Altcode: No abstract at ADS Title: Activity in the homologous flare site Authors: Mein, N.; Martres, M. -J.; Simon, G.; Mein, P.; Soru-Escaut, I. Bibcode: 1984AdSpR...4g..33M Altcode: 1984AdSpR...4...33M The evolution of a site where homologous flares occured on June 8, 1980 is analysed by using observations both in the photosphere and in the chromosphere. The homology is discussed through space, energy and dynamical aspects. The criteria are used in order to propose the definition of a coefficient of homology. Title: Analysis of the Homology Criteria of Two Closely Consecutive Flares Authors: Martres, M. J.; Mein, N.; Mein, P.; Rayrole, J.; Simon, G.; Soru-Escaut, I. Bibcode: 1984apoa.conf..261M Altcode: The authors study the last two events of a series of closely consecutive homologous flares ("rafale"). The main criteria of homology are present: localization, evolution, brightness, magnetic structure. Although they are among the best cases of homologous flares observed, some differences may be detected which affect the dynamics of the region. This feature must be taken into account to explain the annihilation of the homologous mechanism. Title: Recurrent mass ejections observed in Hα and CIV Authors: Schmieder, B.; Simon, G.; Martres, M. -J.; Mein, P.; Mein, N.; Tandberg-Hanssen, E. Bibcode: 1984AdSpR...4g..27S Altcode: 1984AdSpR...4...27S Time sequences of recurrent mass ejections have been observed during a coordinated SMY program (1 Sept. 1980 - 23 Sept. 1980 - 2 Oct. 1980).

Comparison of the temporal evolution of Hα and CIV brightnesses shows a weak phase lag between H α and CIV maxima, in the case of homologous flares, with CIV brightness maxima preceding H α maxima. The analysis of the variation of the ejection velocities is expected to lead to the determination of an energy balance.

Such recurrent ejections could be due to periodic energy storage and periodic reorganisation of magnetic field as envisaged to occur for flares, but at lower energy levels. Title: Recommendations on post focus instrumentation for LEST. Authors: Wöhl, H.; Huber, M. C. E.; Mein, P.; Smaldone, L. Bibcode: 1984LFTR....5.....W Altcode: No abstract at ADS Title: Chromospheric eruption, Jan - Dec 1984. Authors: Cailloce, E.; Mein, N.; Lantos, P. Bibcode: 1984QBSA...26....1C Altcode: This report shows, in a chronological order, a list of all reported events whatever their importance. Title: Dynamics of a surge observed in the C IV and H alpha lines Authors: Schmieder, B.; Mein, P.; Vial, J. -C.; Tandberg-Hanssen, E. Bibcode: 1983A&A...127..337S Altcode: Time sequences of a surge have been obtained in Active Region 2701 during a coordinated SMY program, on October 2nd, 1980, while the MSDP spectrograph operated in H-alpha at the Meudon Solar Tower and the UVSP spectrometer on SMM observed in the 1548 A C IV resonance line. The cold (H-alpha) and hot (C IV) material follow the same channel, and the event lasts about 10 min in both lines. A good correlation is found between H-alpha and C IV velocities; radial velocities along the surge are in the range 40-60 km/s in both cases. The observations are consistent with the hypothesis that a pressure gradient drives the surge. The H-alpha data seem to indicate the presence of a shock wave in the chromosphere, while the C IV quantities (velocities, accelerations) vary on a very short time scale. Their maxima occur at some locations which could be interpreted as 'pinched' zones. Title: Evidence of high chromospheric activity in Hyades dwarfs from spectroscopic observations. Authors: Cayrel, R.; de Strobel, G. Cayrel; Campbell, B.; Mein, N.; Mein, P.; Dumont, S. Bibcode: 1983A&A...123...89C Altcode: The Hα Balmer line and the infrared Ca II triplet have been observed in two solar type dwarfs of the Hyades at the Coudé Spectrograph of the Canada-France-Hawaii Telescope. Noticeable differences appear in the cores of the lines between the stellar spectra and the solar spectrum (moonlight). These differences are ascribed to a more active chromosphere in the relatively young Hyades stars. Non-LTE computations show that the average disk of one of the Hyades dwarf is similar to a very bright element of the solar chromospheric network. Title: Dynamics of solar filaments. II - Mass motions in an active region filament from H-alpha center to limb observations Authors: Malherbe, J. M.; Schmieder, B.; Ribes, E.; Mein, P. Bibcode: 1983A&A...119..197M Altcode: The authors present the observations of a solar filament obtained at Meudon with the Hα spectroheliograph over a period of 10 d. They show a morphologically stable feature. The authors perform a statistical analysis of the radial velocity field. Assuming long-lived (several days) stationary motions, they compute a 3-dimensional velocity field from center to limb observations of the radial component of velocity in the stable feature. Different pictures of stationary material circulations are suggested and compared with theoretical models of filaments. On the contrary, in the case of short-lived (a few 10 min) flows of material, the authors interpret their data in terms of velocity loops in the magnetic structure supporting the filament, and they compare the results with the MHD model proposed by Ribes and Unno (1980). Possible improvements to this model are pointed out in the conclusion. Title: Measurements of solar transition zone velocities and line broadening using the ultraviolet spectrometer and polarimeter on the Solar Maximum Mission Authors: Simon, G.; Mein, P.; Vial, J. C.; Shine, R. A.; Woodgate, B. E. Bibcode: 1982A&A...115..367S Altcode: The UVSP instrument on SMM is able to observe solar regions at two wavelengths in the same line with a band-pass of 0.3 A. Intensity and Doppler velocity maps are derived. It is shown that the numerical values are sensitive to the adopted Doppler width and the range of velocities is limited to within 30 km/sec. A method called Double Dopplergram Determination (DDD) is described for deriving both the Doppler width and the velocity (up to 80 km/sec), and the main sources of uncertainties are discussed. To illustrate the method, a set of C IV 1548 A observations is analyzed according to this procedure. The mean C IV Doppler width measured (0.15 A) is comparable to previous determinations. A relation is found between bright regions and down-flows. Large Doppler widths correspond to strong velocity gradients. Title: Dynamics of the eruptive prominence of 6 May 1980 and its relationship to the coronal transient Authors: Mein, N.; Schmieder, B.; Simon, G.; Tandberg-Hanssen, E.; Wu, S. T. Bibcode: 1982A&A...114..192M Altcode: The active prominence of the 6 May 1980 has been observed between 5.23 and 10.22 UT with the Ultraviolet Spectrometer and Polarimeter (UVSP) on board the Solar Maximum Mission (SMM) satellite. Intensities of 1548 A line of CIV and dopplershifts have been derived. A motion of the magnetic tube maintaining the prominence material is noted. This motion is followed by a coronal transient observed with the Coronagraph and Polarimeter (C/P) between 11 and 13 UT. It is suggested that the event is related to a MHD wave induced by a flare occurring behind the solar disk, and a MHD modeling of the perturbation is proposed. Title: Dynamics of POST Flare Ejections and Magnetic Loop Geometry Authors: Mein, P.; Mein, N. Bibcode: 1982SoPh...80..161M Altcode: Flare-associated mass ejections have been observed at the solar limb on June 29, 1980 in the Hα line, with the Multichannel Subtractive Double Pass spectrograph of the Meudon solar tower. Radial velocities were measured as a function of time in a two dimensional field, and kinematics investigated in one selected fine structure. A simple model of locally dipole-type magnetic field increasing with time can be fitted to the data. It can be checked from extrapolation that the model is consistent with an ejection starting roughly from the same point at the same time. Height of the loops (∼ 135 000 km) is consistent with other determinations. Magnetic field is found to be increasing locally by a factor 1.14 within 10 min. Title: Mass motions in the solar chromosphere and transition zone Authors: Mein, P.; Simon, G.; Vial, J. C.; Shine, R. A. Bibcode: 1982A&A...111..136M Altcode: A comparison is made between H-alpha and C IV observations of Active Region 2717 on October 9, 1980. On the basis of this comparison, it is found that upward velocities are present above sunspots in the chromosphere-corona transition zone (20 km/s). The downward velocities are found to be well correlated in both lines. Doppler-shift ratios between C IV and H-alpha levels (approximately 10) are seen to be much smaller than expected from density ratio estimates. The comparison is seen as suggesting that flow lines are probably far from vertical in the transition zone. It is pointed out, however, that this depends on model densities that may not be correct. A simple method for comparing matter flows is presented. The best fit between H-alpha and C IV levels is obtained when C IV Doppler shifts are multiplied by the line intensity to the power 0.5 (approximately) in order to make allowance for density fluctuations. Title: Preflare heating of filaments Authors: Malherbe, J. M.; Simon, G.; Mein, P.; Mein, N.; Schmieder, B.; Vial, J. C. Bibcode: 1982AdSpR...2k..53M Altcode: 1982AdSpR...2...53M Disappearances of preflare filaments have been observed on June 22, 1980 (S07,W13) (flare at 13.04 U.T.) and September 3, 1980 (flare at 7.52 U.T.). The analysis of MSDP data (MEUDON) leads to the followings conclusions : - Disappearances begin a few minutes before the Hα impulsive phase. - The filaments can be seen again after the flares. - Upwards motions occur in several points, without disturbing significantly preëxisting downflows.

Velocity maps suggest shears or velocity loops.

The filament disappearance seems to be due to a heating mechanism beginning before the flare maximum. Title: A surge obsrved in Hα and CIV Authors: Schmieder, B.; Mein, P.; Vial, J. C.; Tandberg-Hanssen, E. Bibcode: 1982AdSpR...2k.225S Altcode: 1982AdSpR...2..225S Simultaneous Hα (MSDP at Meudon) and C IV (UVSP aboard SMM) measurements of Active Region 2701 were made on October 2, 1980. Isodensity and velocity maps were derived for both lines and superposed. A good correlation was found between Hα and C IV velocities. A surge was observed for 10 minutes. The base was located in a bright point in CIV and Hα, and escaping matter followed the same channel (``absorbing'' in Hα, ``emitting'' in C IV). The velocity along the surge was about 80 kms.-1 in Hα and 100 km s-1 in C IV. A loop appeared in C IV. We discuss the existing models and conclude that the vertical pressure gradient was capable of driving the surge. Title: Mass motions in a quiescent filament Authors: Malherbe, J. M.; Mein, P.; Schmieder, B. Bibcode: 1982AdSpR...2k..57M Altcode: 1982AdSpR...2R..57M The ``disparition brusque'' (DB) of a filament (N20, E35) has been observed above an active region with the Multichannel Subtractive Double Pass (MSDP) spectrograph operating on the Meudon Solar Tower, from 10h45 UT to 13h30 UT on June 22, 1981.

Velocity fields and intensity fluctuations are measured in the Hα line. The DB doesn't take place simultaneously in all parts of the filament : thin threads (thickness <3 arc seconds) with upward radial velocities reaching about 50 km/s are successively observed inside the prominence from S to N regions. These motions correspond likely to the rise of material along magnetic loops closely related to the prominence structure. The dynamics inside such a magnetic loop is investigated : a high speed flow (supersonic, likely superalfvénic) strongly accelerated is evidenced and a deformation of the flux tube, probably due to the centrifugal forces exerted by the flow on the magnetic lines, is suggested.

These results are compared with some theoretical works on dynamics inside magnetic loops, especially to siphon flow models. However, as in the case of the prominence support problem, better theoretical models are still needed. Title: About the onsets of closely-consecutive homologous flares Authors: Martres, M. J.; Mein, N.; Mein, P.; Mouradian, Z.; Rayrole, J.; Schmieder, B.; Simon, G.; Soru-Escaut, I.; Woodgate, B.; Strong, K. Bibcode: 1982AdSpR...2k.109M Altcode: 1982AdSpR...2R.109M The onsets of closely consecutive homologous flares (CCHF), which are separated by less than 6 hours and most often by about 1 hour, are compared with that of isolated flares (no flare in the region half a day before). Isolated flares appear to be formed of two components, a surging arch and a flaring arch, while a set of CCHF may be composed of consecutive elementary flares or of a series of complex ones. It is shown that the onset of eruptive flare phenomena is not the same for an isolated event and for a member of CCHF (excluding the first) as found in H-alpha and EUV observations, and probably in X-ray observations also. It is suggested that a CCHF set would become a single flare with episodic enhancement of brightness by taking account of the common H-alpha behavior of surging and flaring arches as well as the EUV emission. Title: Dynamics in the filaments. I - Oscillations in a quiescent filament Authors: Malherbe, J. M.; Schmieder, B.; Mein, P. Bibcode: 1981A&A...102..124M Altcode: A quiescent filament is observed by the 9 channel MSDP spectrograph operating on the Meudon Observatory tower during 720 s with a 30 s time step. The field view of 6 x 1 arcmin permits the study of the dynamics of 50 oscillation cells which increases the freedom degree comparatively to the one slit spectrograph techniques. A Fourier analysis of the radial velocity measured in the H-alpha line shows that the steady velocities are upward in the filament, while the chromospheric oscillations are almost undetectable inside the filament. Title: Mechanical flux in the solar chromosphere. III - Variation of the mechanical flux Authors: Mein, N.; Schmieder, B. Bibcode: 1981A&A....97..310M Altcode: The mechanical flux in the photosphere and the chromosphere is inferred from observations of atmospheric oscillations made over a large range of periods (60s-400s). Observations of Doppler shifts in Ca II and Mg I lines are related to velocities by means of heights of formation and modulation transfer functions deduced from weighting functions. The flux is derived from estimates of the amplitude and phase of the velocity at different heights in the atmosphere. The results imply that the energy dissipated by waves in a plane-parallel atmospheric model is insufficient to balance the radiative losses. The short-fall can reach a factor 100 in the high chromosphere. Heating of the corona by shock wave dissipation is inconsistent with our results. Title: Structure and Evolution of Velocities in Quiescent Filaments Authors: Martres, M. -J.; Mein, P.; Schmieder, B.; Soru-Escaut, I. Bibcode: 1981SoPh...69..301M Altcode: Simultaneous observations of radial velocities in a `quiescent' prominence seen in Hα on the disk and in the underlaying photosphere have been obtained in the Meudon Observatory: Doppler shifts in photospheric lines are weaker than in the surrounding regions (<0.3 km s-1); the scale of velocity structures is smaller (<104 km). The vertical component of velocities cannot be neglected. Hα Doppler shifts show that: (a) Highest velocities are often correlated with high brightness horizontal gradients, which suggests that filament and surrounding bright regions belong to the same geometrical and dynamical structure. (b) Fast motions (7 km s-1) have short life-times (a few minutes). (c) Slow motions in dark regions (<3 km s-1) are associated with blue shifts and may last several hours. This behaviour was confirmed in many other cases by filament observations with the 3-wavelength Hα patrol. This is consistent with EUV observations of the transition zone around prominences, but disagrees with `downward motions' as seen at the limb, unless these motions do not refer to material velocities. Title: Mechanical flux in the solar chromosphere. Authors: Mein, P. Bibcode: 1981ASIC...68..265M Altcode: 1981spss.conf..265M Energy transport by pressure waves in the solar atmosphere is studied on the basis of observations of chromospheric line profiles. Mechanical fluxes are deduced as a function of frequency from Doppler shifts in the 3933 and 8542 Ca II lines; and integrated over the period range 800 to 30 sec to obtain a total flux of 6000 erg/sq cm per sec. Flux values determined as a function of height from the Doppler shifts and intensity fluctuations of one or more lines are also presented. It is pointed out that the values of mechanical flux derived are almost two orders of magnitude less than the 300,000 erg/sq cm per sec of radiant energy lost from the transition region and corona, requiring an additional mechanism to account for the heating of the upper atmosphere. Title: The sites of solar flares Authors: Mein, P. Bibcode: 1981soac.rept.....M Altcode: Observations of solar flares were studied. Results on the magnetic field structure associated with an elementary flare are discussed. Conditions which prelude the triggering of instabilities (homologous flares, disappearance of filaments) are covered. The postflare relaxation phase is also considered. Linear polarization of lines during flare events and the variable geometry of magnetic field lines (mass ejection dynamics) are treated. The importance of continuous observation over several hours in interpreting these events is shown. Title: Mechanical flux in the solar chromosphere. I - Velocity and temperature weighting functions for CA II lines Authors: Mein, N.; Mein, P. Bibcode: 1980A&A....84...96M Altcode: Weighting functions for velocity and temperature disturbances are computed in the case of Ca II 3933, 8498, and 8542 with the HSRA model atmosphere. Temperature W-functions are generally broader than velocity W-functions, due to coupling between lines. Subsequently, formation altitudes and transfer functions for doppler shifts and intensity fluctuations are very different. Results are plotted against frequency with a view to the derivation of wave mechanical flux from line observations. Title: Mechanical flux in the solar chromosphere. II - Determination of the mechanical flux Authors: Schmieder, B.; Mein, N. Bibcode: 1980A&A....84...99S Altcode: The observations of two lines of Ca II (8542-8498) made with the Sacramento Peak Tower and formation altitudes values Z(omega) for these two lines determined by weighting functions are used to evaluate, for each frequency omega, the mechanical flux F(omega) corresponding to the altitude Z(omega). Corrections taking into account the weakening of waves of wavelengths smaller than the line formation layer were applied to the flux. The corrected flux does not show a significant increase with the frequency (up to 10 mHz), which seems to indicate that nonthermal microturbulence does not correspond necessarily to progressive wave. The mechanical flux integrated over the frequency range 0-10 mHz reaches at the most 2000 erg/sq cm s in the middle chromosphere (1100 km). This is not sufficient to balance the energy losses of the transition zone and the corona. Title: Motions and Oscillations in Filaments Authors: Malherbe, J. M.; Martres, M. J.; Mein, P.; Schmieder, B.; Soru-Escaut, I. Bibcode: 1980jfss.conf..166M Altcode: No abstract at ADS Title: Multi-Channel Subtractive Double Pass Spectrograph Authors: Mein, P. Bibcode: 1980jfss.conf..285M Altcode: No abstract at ADS Title: Observational Proof of the Inefficiency of the Chromospheric Heating by Acoustic Waves Authors: Mein, P.; Mein, N.; Schmieder, B. Bibcode: 1980jfss.conf...70M Altcode: No abstract at ADS Title: Dynamics of a Quiescent Filament Authors: Schieder, B.; Martres, M.; Mein, P.; Soru-Escaut, I. Bibcode: 1980IAUS...91..213S Altcode: No abstract at ADS Title: Wave Reflections in the Solar Atmosphere Authors: Provost, J.; Mein, N. Bibcode: 1979SoPh...64...43P Altcode: The small phase-lag between velocities observed at different chromospheric levels is interpreted as being due to acoustic waves reflected by the very hot atmospheric layers of the chromosphere-corona transition zone. We consider first an isothermal slab, then a realistic solar atmospheric model and calculate weighting functions for velocities in Ca II lines. It is shown that taking into account these functions and integrating over horizontal wave numbers leads to a good agreement with previous observations (Mein, 1977) in the case of 8498 and 8542 Ca II lines. For the K line, the less good agreement shows that magnetoacoustic waves become important in the upper chromospheric layers. Title: Mechanical energy transport in the solar photosphere and chromosphere. Authors: Mein, P. Bibcode: 1979ssms.conf...15M Altcode: No abstract at ADS Title: Relation between the mode of oscillation and the velocity amplitude of chromospheric waves. Authors: Mein, N. Bibcode: 1978SoPh...59....3M Altcode: The distribution of oscillation-amplitude for Doppler shifts in chromospheric lines is computed as a function of position on the disk and time frequency. High amplitude regions are restricted to a small part of the solar surface. Propagation modes are investigated with respect to the oscillation amplitude in the K line. Waves seem to be standing or evanescent for most of the points (small amplitude in K) and progressive for some other ones, with perhaps upward and downward motions (partial reflections). Mechanical energy could only escape into corona from narrow chromospheric structures. Title: The Evolution of a transient Hα Feature probably associated with a Type III Burst Authors: Mein, P.; Martres, M. J.; Soru-Escaut, I. Bibcode: 1978pfsl.conf..233M Altcode: 1978ESPM....2..233M No abstract at ADS Title: Multi-channel subtractive spectrograph and filament observations. Authors: Mein, P. Bibcode: 1977SoPh...54...45M Altcode: A Multi-Channel Subtractive Double Pass spectrograph (MSDP) has been achieved at the Meudon solar tower. Line profiles are obtained simultaneously in a two dimensional field. Space and time resolutions are very suitable for observation of fast chromospheric phenomena. Title: Wave propagation in the quiet solar chromosphere. Authors: Mein, N. Bibcode: 1977SoPh...52..283M Altcode: In order to precise previous results about wave propagation in the quiet chromosphere (N. Mein and P. Mein, 1976), we study the behaviour of Doppler shifts and intensity fluctuations in 3 lines of Ca II. Title: Velocity waves in the quiet solar chromosphere. Authors: Mein, N.; Mein, P. Bibcode: 1976SoPh...49..231M Altcode: Propagation of velocity waves are investigated in the solar chromosphere, with a special view to high frequencies (periods ≥ 60 s). Four line profiles have been observed during 27 mn with the Sacramento Peak vacuum telescope (Hα, 3933, 8498 and 8542 Ca II). Three Fourier analysis are performed according to the location in the cells of the chromospheric network. Phase-shifts and amplitude ratios between the line Doppler shifts are computed as functions of frequency. The "pollution" of high frequency results by energetic low frequency oscillations is investigated. Title: Radiation and structure of the solar atmosphere (Radiation et structure de l'atmosphère solaire). Authors: Giovanelli, R. G.; Mein, P.; Bappu, M. K. V.; Jordan, C.; MacQueen, R. M. Bibcode: 1976IAUTA..16b..55G Altcode: No abstract at ADS Title: Propagation des ondes dans la chromosphère Authors: Mein, N.; Mein, P. Bibcode: 1976pmas.conf..269M Altcode: No abstract at ADS Title: The Photosphere Authors: Mein, P. Bibcode: 1976IAUTA..16...55M Altcode: 1976IAUT...16A..55M No abstract at ADS Title: The Hydrogen Balmer Lines and the Structure of the Quiet Solar Chromosphere. I: Observations at the Limb Authors: Mein, P.; Mein, N. Bibcode: 1975SoPh...40..317M Altcode: Spectra of Hα, Hβ and Hδ have been taken under good seeing conditions with the vacuum tower telescope of Sacramento Peak Observatory. Intensity curves are given at various wavelengths in these lines to permit further comparison with a theoretical model. Moreover, considering in each case the range of height in which the lines are almost optically thin and using a few approximations, the following results are derived: between 2000 and 6000 km above the limb the average thermal + turbulent velocity of the atoms is found to increase from 20 km s−1 to 30 km s−1 and the mean number of hydrogen atoms per cm3 in level 2 is given by log n2 = 4.5 - 0.00056(z-2000) z being the altitude above the limb in km. For line profile computations a new interpolation formula is presented; it gives good profiles with a small number of scans, saving microphotometer time. Title: A Substractive Double Pass Spectrograph for Solar Observations Authors: Mein, P.; Blondel, M. Bibcode: 1972SoPh...27..489M Altcode: Two-dimensional images in locally monochromatic light are obtained, using a subtractive double pass spectrograph. The spatial resolution is high and independent of the spectral bandwidth. The system is very suitable for fine structure observations in strong lines. Title: Inhomogeneities in the Solar Atmosphere from the Ca II Infra-Red Lines Authors: Mein, Pierre Bibcode: 1971SoPh...20....3M Altcode: From a time sequence of high dispersion spectra taken by Evans, the solar fine structures are studied in the CaII infra-red triplet. The Doppler shifts and the intensity fluctuations in different points of the profiles are converted into fluctuations of the model atmosphere. A weighting function method is worked out in that purpose. The theoretical line profiles are computed in non LTE from a program written by Dumont. The results are arranged in two parts: Low temporal frequencies. A three-column model describes the steady field of temperature, microturbulence and radial velocities fluctuations in the photosphere-chromosphere transition zone. Title: Propagation of Magneto-Acoustic Waves along the Gravitational Field in an Isothermal Atmosphere Authors: Bel, N.; Mein, P. Bibcode: 1971A&A....11..234B Altcode: We study the local dispersion equation obtained by MoLellan and Winterberg (1968) for magneto-acoustic waves propagating in an isothermal atmosphere. We restrict ourselves to wave propagation vectors along the gravitational field, for an arbitrary direction of the magnetic field. The propagation of the waves is shown to depend on two parameters, namely the ratios of the Alfve'n velocity and of the Alfv6n velocity for the vertical component of the magnetic field to the speed of sound. For typical values of these two parameters, we obtain representative curves for the phase and the amplitude of the waves as functions of the frequency. We find two modes, which are the counterparts of the usual fast and slow magneto-acoustic waves. A comparison with the case of an isothermal and compressible atmosphere without a magnetic field shows that the new mode is the slow one. We find that the magnetic field decreases the hydrodynarnic cut-off frequency and that, for large values of the magnetic field, the fast and the slow modes can intersect. The theoretical curves thus obtained make possible a direct comparison with observational data concerning the solar atmosphere. Key wor : waves - magnetic field - gravity - solar atmosphere Title: Observations du rapport Hα/[N II] par une méthode interférométrique. Application à la nébuleuse de la Rosette Authors: Mein, N. Bibcode: 1968AnAp...31..579M Altcode: No abstract at ADS Title: Étude spatio-temporelle de la granulation solaire. Amélioration des images déformées par l'agitation atmosphérique Authors: Mein, P. Bibcode: 1968AnAp...31..115M Altcode: No abstract at ADS Title: Champ macroscopique des vitesses dans l'atmosphère solaire d'après les mesures de déplacements des raies de Fraunhofer Authors: Mein, P. Bibcode: 1966AnAp...29..153M Altcode: No abstract at ADS Title: Déformation du Profil des Raies Liées aux Ondes Sonores dans le Cas Solaires Authors: Mein, P. Bibcode: 1966IAUTB..12..563M Altcode: No abstract at ADS Title: Propagation Horizontale des Oscillations de Vitesse Observées sur le Disque Solaire Authors: Mein, P. Bibcode: 1965CRASB.260.1867M Altcode: No abstract at ADS Title: Etude d'une Raie Solaire Perturbée par des Ondes Acoustiques Planes; Résultats Numériques Authors: Mein, P. Bibcode: 1964CRASB.258..819M Altcode: No abstract at ADS Title: Etude d'une Raie Solaire Perturbée par des Ondes Acoustiques Planes; Exposé d'une Méthode Authors: Mein, P. Bibcode: 1964CRASB.258..453M Altcode: No abstract at ADS Title: Spectre continu du Soleil Authors: Mein, P. Bibcode: 1959LAstr..73....5M Altcode: No abstract at ADS