Author name code: dame
ADS astronomy entries on 2022-09-14
author:"Dame, Luc"
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Title: SoSWEET solar activity and space weather mission for extreme
events prediction, solar flares and CMEs, and solar ultraviolet
variability influence on climate
Authors: Damé, Luc; Meftah, Mustapha
Bibcode: 2022cosp...44.3214D
Altcode:
SoSWEET (Solar ultraviolet variability & Space Weather Extreme
EvenTs Microsatellite Mission) is an innovative small satellite mission
proposed in response to the ESA Call for an F mission that aims to
address, on one part, Space Weather extreme events prediction, solar
flares and coronal mass ejections (CMEs) onset and, on the other,
the solar ultraviolet variability influence on climate. Space Weather
extreme events early detection/prediction is better observed in Lyman
Alpha with 3 orders more sensitivity than in H Alpha and a resolution
and contrast on eruptions largely superior to the commonly used He II
line at 30.4 nm. Previsions are possible hours in advance by following
flux ropes rising and deforming in the solar atmosphere. However, Lyman
Alpha is a delicate spectral line to observe due to contamination
and degradation of the transmission of instruments, as observed
in the past. A disruptive telescope is developed to address this
issue. Concerning climate and solar variability, it is worth recalling
that UV is the only wavelength band with energy absorbed in the
high atmosphere (stratosphere), creating ozone (Herzberg continuum,
200-242 nm), and that high variability is most probably at the origin
of a climate influence. A simultaneous observation of the incoming UV
and of the ozone production, would bring an invaluable information on
this process of solar-climate forcing (we recommend the simultaneous
observation, by a constellation of cubesats, of ozone and of the Earth
radiation budget: the GAIA-y78 constellation mission). To address these
objectives and flares and CMEs observations, a small satellite of less
than 150 kg on a PROBA or similar platform (OneWeb Arrow, etc.), and
on a polar orbit for an almost continuous solar following, is chosen
(a polar orbit is also essential to understand the relation between
solar UV variability and stratospheric ozone on arctic and Antarctic
regions); alternately, having the satellite at L1 Lagrange point would
be a definitive advantage. The SoSWEET polar satellite model payload
definition includes the disruptive SUAVE telescope (Solar Ultraviolet
Advanced Variability Experiment), an optimized heavy-duty thermally
stable off-axis SiC telescope for FUV (Lyman-Alpha) and MUV (200-242
nm Herzberg continuum) imaging (sources of variability, extreme events
detection), and the SOLSIM spectrometer (SOLar Spectral Irradiance
Monitor), a newly designed double-monochromator instrument covering
the 170-340 nm ultraviolet spectral range (absolute measurements)
and providing 0.65 nm resolution still in within a limited mass-power
budget. The payload is completed by a small but performing coronagraph,
new UVC detectors (optimized for Herzberg continuum), Electron-Proton
detectors and a vector magnetometer. Science objectives, mission
profile and model payload will be presented.
Title: HiRISE - High-Resolution Imaging and Spectroscopy Explorer
- Ultrahigh resolution, interferometric and external occulting
coronagraphic science
Authors: Erdélyi, Robertus; Damé, Luc; Fludra, Andrzej; Mathioudakis,
Mihalis; Amari, T.; Belucz, B.; Berrilli, F.; Bogachev, S.; Bolsée,
D.; Bothmer, V.; Brun, S.; Dewitte, S.; de Wit, T. Dudok; Faurobert,
M.; Gizon, L.; Gyenge, N.; Korsós, M. B.; Labrosse, N.; Matthews,
S.; Meftah, M.; Morgan, H.; Pallé, P.; Rochus, P.; Rozanov, E.;
Schmieder, B.; Tsinganos, K.; Verwichte, E.; Zharkov, S.; Zuccarello,
F.; Wimmer-Schweingruber, R.
Bibcode: 2022ExA...tmp...21E
Altcode:
Recent solar physics missions have shown the definite role of waves and
magnetic fields deep in the inner corona, at the chromosphere-corona
interface, where dramatic and physically dominant changes occur. HiRISE
(High Resolution Imaging and Spectroscopy Explorer), the ambitious new
generation ultra-high resolution, interferometric, and coronagraphic,
solar physics mission, proposed in response to the ESA Voyage 2050
Call, would address these issues and provide the best-ever and most
complete solar observatory, capable of ultra-high spatial, spectral,
and temporal resolution observations of the solar atmosphere, from the
photosphere to the corona, and of new insights of the solar interior
from the core to the photosphere. HiRISE, at the L1 Lagrangian
point, would provide meter class FUV imaging and spectro-imaging,
EUV and XUV imaging and spectroscopy, magnetic fields measurements,
and ambitious and comprehensive coronagraphy by a remote external
occulter (two satellites formation flying 375 m apart, with a
coronagraph on a chaser satellite). This major and state-of-the-art
payload would allow us to characterize temperatures, densities, and
velocities in the solar upper chromosphere, transition zone, and inner
corona with, in particular, 2D very high resolution multi-spectral
imaging-spectroscopy, and, direct coronal magnetic field measurement,
thus providing a unique set of tools to understand the structure and
onset of coronal heating. HiRISE's objectives are natural complements
to the Parker Solar Probe and Solar Orbiter-type missions. We present
the science case for HiRISE which will address: i) the fine structure
of the chromosphere-corona interface by 2D spectroscopy in FUV at
very high resolution; ii) coronal heating roots in the inner corona by
ambitious externally-occulted coronagraphy; iii) resolved and global
helioseismology thanks to continuity and stability of observing at the
L1 Lagrange point; and iv) solar variability and space climate with,
in addition, a global comprehensive view of UV variability.
Title: Origin of the Solar Rotation Harmonics Seen in the EUV and
UV Irradiance
Authors: Giono, G.; Zender, J. J.; Kariyappa, R.; Damé, L.
Bibcode: 2021SoPh..296..172G
Altcode:
Long-term periodicities in the solar irradiance are often observed
with periods proportional to the solar rotational period of 27
days. These periods are linked either to some internal mechanism
in the Sun or said to be higher harmonics of the rotation without
further discussion of their origin. In this article, the origin of
the peaks in periodicities seen in the solar extreme ultraviolet (EUV)
and ultraviolet (UV) irradiance around the 7, 9, and 14 days periods is
discussed. Maps of the active regions and coronal holes are produced
from six images per day using the Spatial Possibilistic Clustering
Algorithm (SPoCA), a segmentation algorithm. Spectral irradiance at
coronal, transition-region/chromospheric, and photospheric levels are
extracted for each feature as well as for the full disk by applying
the maps to full-disk images (at 19.3, 30.4, and 170 nm sampling in
the corona/hot flare plasma, the chromosphere/transition region, and
the photosphere, respectively) from the Atmospheric Imaging Assembly
(AIA) on board the Solar Dynamics Observatory (SDO) from January 2011
to December 2018. The peaks in periodicities at 7, 9, and 14 days as
well as the solar rotation around 27 days can be seen in almost all
of the solar irradiance time series. The segmentation also provided
time series of the active regions and coronal holes visible area
(i.e. in the area observed in the AIA images, not corrected for the
line-of-sight effect with respect to the solar surface), which also show
similar peaks in periodicities, indicating that the periodicities are
due to the change in area of the features on the solar disk rather than
to their absolute irradiance. A simple model was created to reproduce
the power spectral density of the area covered by active regions also
showing the same peaks in periodicities. Segmentation of solar images
allows us to determine that the peaks in periodicities seen in solar
EUV/UV irradiance from a few days to a month are due to the change in
area of the solar features, in particular, active regions, as they are
the main contributors to the total full-disk irradiance variability. The
higher harmonics of the solar rotation are caused by the clipping of
the area signal as the regions rotate behind the solar limb.
Title: Segmentation of Coronal Features to Understand the Solar
EUV and UV Irradiance Variability III. Inclusion and Analysis of
Bright Points
Authors: van der Zwaard, Rens; Bergmann, Matthias; Zender, Joe;
Kariyappa, Rangaiah; Giono, Gabriel; Damé, Luc
Bibcode: 2021SoPh..296..138V
Altcode:
The study of solar irradiance variability is of great importance in
heliophysics, Earth's climate, and space weather applications. These
studies require careful identifying, tracking and monitoring of features
in the solar photosphere, chromosphere, and corona. Do coronal bright
points contribute to the solar irradiance or its variability as input
to the Earth atmosphere? We studied the variability of solar irradiance
for a period of 10 years (May 2010 - June 2020) using the Large Yield
Radiometer (LYRA), the Sun Watcher using APS and image Processing
(SWAP) on board PROBA2, and the Atmospheric Imaging Assembly (AIA),
and applied a linear model between the segmented features identified
in the EUV images and the solar irradiance measured by LYRA. Based
on EUV images from AIA, a spatial possibilistic clustering algorithm
(SPoCA) is applied to identify coronal holes (CHs), and a morphological
feature detection algorithm is applied to identify active regions
(ARs), coronal bright points (BPs), and the quiet Sun (QS). The
resulting segmentation maps were then applied on SWAP images,
images of all AIA wavelengths, and parameters such as the intensity,
fractional area, and contribution of ARs/CHs/BPs/QS features were
computed and compared with LYRA irradiance measurements as a proxy for
ultraviolet irradiation incident to the Earth atmosphere. We modeled
the relation between the solar disk features (ARs, CHs, BPs, and QS)
applied to EUV images against the solar irradiance as measured by
LYRA and the F10.7 radio flux. A straightforward linear model was
used and corresponding coefficients computed using a Bayesian method,
indicating a strong influence of active regions to the EUV irradiance
as measured at Earth's atmosphere. It is concluded that the long- and
short-term fluctuations of the active regions drive the EUV signal as
measured at Earth's atmosphere. A significant contribution from the
bright points to the LYRA irradiance could not be found.
Title: The UVSQ-SAT/INSPIRESat-5 CubeSat Mission: First In-Orbit
Measurements of the Earth's Outgoing Radiation
Authors: Meftah, Mustapha; Boutéraon, Thomas; Dufour, Christophe;
Hauchecorne, Alain; Keckhut, Philippe; Finance, Adrien; Bekki, Slimane;
Abbaki, Sadok; Bertran, Emmanuel; Damé, Luc; Engler, Jean-Luc;
Galopeau, Patrick; Gilbert, Pierre; Lapauw, Laurent; Sarkissian, Alain;
Vieau, André-Jean; Lacroix, Patrick; Caignard, Nicolas; Arrateig,
Xavier; Hembise Fanton d'Andon, Odile Hembise Fanton; Mangin, Antoine;
Carta, Jean-Paul; Boust, Fabrice; Mahé, Michel; Mercier, Christophe
Bibcode: 2021RemS...13.1449M
Altcode:
No abstract at ADS
Title: Solar Soft X-ray Irradiance Variability, I: Segmentation
of Hinode/XRT Full-Disk Images and Comparison with GOES (1 - 8 Å)
X-Ray Flux
Authors: Adithya, H. N.; Kariyappa, Rangaiah; Shinsuke, Imada; Kanya,
Kusano; Zender, Joe; Damé, Luc; Gabriel, Giono; DeLuca, Edward;
Weber, Mark
Bibcode: 2021SoPh..296...71A
Altcode:
It is of great interest and importance to study the variabilities of
solar EUV, UV and X-ray irradiance in heliophysics, in Earth's climate,
and space weather applications. A careful study is required to identify,
track, monitor and segment the different coronal features such as active
regions (ARs), coronal holes (CHs), the background regions (BGs) and
the X-ray bright points (XBPs) from spatially resolved full-disk images
of the Sun. Variability of solar soft X-ray irradiance is studied for a
period of 13 years (February 2007-March 2020, covers Solar Cycle 24),
using the X-Ray Telescope on board the Hinode (Hinode/XRT) and GOES
(1 - 8 Å). The full-disk X-ray images observed in Al_mesh filter
from XRT are used, for the first time, to understand the solar X-ray
irradiance variability measured, Sun as a star, by GOES instrument. An
algorithm in Python has been developed and applied to identify and
segment coronal X-ray features (ARs, CHs, BGs, and XBPs) from the
full-disk soft X-ray observations of Hinode/XRT. The segmentation
process has been carried out automatically based on the intensity
level, morphology and sizes of the X-ray features. The total intensity,
area, and contribution of ARs/CHs/BGs/XBPs features were estimated and
compared with the full-disk integrated intensity (FDI) and GOES (1 -
8 Å) X-ray irradiance measurements. The XBPs have been identified and
counted automatically over the full disk to investigate their relation
to solar magnetic cycle. The total intensity of ARs/CHs/BGs/XBPs/FD
regions are compared with the GOES (1 - 8 Å) X-ray irradiance
variations. We present the results obtained from Hinode/XRT full-disk
images (in Al_mesh filter) and compare the resulting integrated
full-disk intensity (FDI) with GOES X-ray irradiance. The X-ray
intensity measured over ARs/CHs/BGs/XBPs/FD is well correlated with
GOES X-ray flux. The contributions of the segmented X-ray features
to FDI and X-ray irradiance variations are determined. It is found
that the background and active regions have a greater impact on the
X-ray irradiance fluctuations. The mean contribution estimated for the
whole observed period of the background regions (BGs) will be around 65
±10.97 % , whereas the ARs, XBPs and CHs are 30 ±11.82 % , 4 ±1.18 %
and 1 ±0.52 % , respectively, to total solar X-ray flux. We observed
that the area and contribution of ARs and CHs varies with the phase of
the solar cycle, whereas the BGs and XBPs show an anti-correlation. We
find that the area of the coronal features is highly variable suggesting
that their area has to be taken into account in irradiance models,
in addition to their intensity variations. The time series results of
XBPs suggest for an existence of anti-correlation between the number
of XBPs and the sunspot numbers. It is also important to consider both
the number variation and the contribution of XBPs in the reconstruction
of total solar X-ray irradiance variability.
Title: SoSWEET-SOUP: an enhanced constellation mission concept for
Space Weather, extreme events, radiation budget and ozone
Authors: Damé, Luc; Bolsee, David; Sarkissian, Alain; Philippe,
Duvel Jean; Keckhut, Philippe; Hauchecorne, Alain; Meftah, Mustapha;
Bekki, Slimane; Pereira, Nuno; Thiéblemont, Rémi; Marchand, Marion;
Cessateur, Gäel
Bibcode: 2021cosp...43E1505D
Altcode:
SoSWEET-SOUP is an innovative small satellites constellation which aims
to measure on complementary platforms the solar influence on climate,
namely on one part solar activity and spectral variability and, on
the other, the different components of the Earth radiation budget,
energy input and energy re-emitted at the top of the Earth atmosphere,
with a particular focus on the UV part of the spectrum and on the
ozone layer, which are most sensitive to solar variability. The
UV is the only wavelength band with energy absorbed in the high
atmosphere (stratosphere), in the ozone (Herzberg continuum, 200-242
nm) and oxygen bands, and its high variability is most probably
at the origin of a climate influence. A simultaneous observation
of the incoming UV and of the ozone (O3) production, would bring an
invaluable information on this process of solar-climate forcing. Space
instruments have already measured the different components of the
Earth radiation budget but this is, to our knowledge, the first time
that all instruments could be operated simultaneously on coordinated
platforms. This characteristic guarantees by itself obtaining new
significant original scientific results. Another major scientific and
operational objective is Space Weather extreme events detection that
is better expressed in Lyman Alpha with 3 orders more sensitivity than
in H Alpha and a resolution and contrast of eruptions largely superior
to the commonly used He II line at 30.4 nm. Previsions are possible
hours in advance by following flux ropes deformation and rising in the
atmosphere. SoSWEET-SOUP is an evolution of the SUITS/SWUSV and SUMO
earlier proposed missions, acknowledging the scientific advantages
of associating a constellation of 12 small satellites of some 20 to
30 kg (12 to 24 "U" or so nanosatellites) on equatorial orbits (+/-
20° in latitude) to a small polar satellite of less than 150 kg on
a OneWeb Arrow like platform for an almost continuous solar following
(a polar orbit is also essential to understanding the relation between
solar UV variability and stratospheric ozone on arctic and antarctic
regions). SoSWEET polar satellite model payload definition's options
are still under assessment but will include, on the polar satellite,
SUAVE (Solar Ultraviolet Advanced Variability Experiment), an optimized
heavy-duty thermally stable SiC telescope for FUV (Lyman-Alpha) and
MUV (200-242 nm Herzberg continuum) imaging (sources of variability,
extreme events detection), and SOLSIM (SOLar Spectral Irradiance
Monitor), a newly designed double-monochromator instrument covering
the 170-340 nm ultraviolet spectral range and in within a limited
mass-power budget. Other instruments include a small coronagraph,
new UVC detectors (optimized for Herzberg continuum) and ozone
radiometers, an Earth radiation budget assembly, Electron-Proton
detectors and a vector magnetometer. The constellation of small
satellites includes, on its side, precise ozone profiles measurements
("miniGOMOS" experiment, derived from GOMOS ENVISAT, with dual Sun
and stars occultations), including middle atmosphere temperature
measurements (observing, during the diurnal part of the orbit, the
vertical profile of the sunlight scattering at limb), and enhanced
energy radiation budget monitors ("miniScaRaB" instrumental evolution
of ScaRaB on Megha-Tropiques). Science objectives, mission profiles
and model payloads will be presented and opportunities of missions
and potential collaborations discussed.
Title: SOLAR-v: A new solar spectral irradiance dataset based on
SOLAR/SOLSPEC observations during solar cycle 24
Authors: Meftah, M.; Snow, M.; Damé, L.; Bolseé, D.; Pereira, N.;
Cessateur, G.; Bekki, S.; Keckhut, P.; Sarkissian, A.; Hauchecorne, A.
Bibcode: 2021A&A...645A...2M
Altcode:
Context. Solar spectral irradiance (SSI) is the wavelength-dependent
energy input to the top of the Earth's atmosphere. Solar ultraviolet
(UV) irradiance represents the primary forcing mechanism for the
photochemistry, heating, and dynamics of the Earth's atmosphere. Hence,
both temporal and spectral variations in solar UV irradiance represent
crucial inputs to the modeling and understanding of the behavior
of the Earth's atmosphere. Therefore, measuring the long-term solar
UV irradiance variations over the 11-year solar activity cycle (and
over longer timescales) is fundamental. Thus, each new solar spectral
irradiance dataset based on long-term observations represents a major
interest and can be used for further investigations of the long-term
trend of solar activity and the construction of a homogeneous solar
spectral irradiance record.
Aims: The main objective of this
article is to present a new solar spectral irradiance database (SOLAR-v)
with the associated uncertainties. This dataset is based on solar UV
irradiance observations (165-300 nm) of the SOLAR/SOLSPEC space-based
instrument, which provides measurements of the full-disk SSI during
solar cycle 24.
Methods: SOLAR/SOLSPEC made solar acquisitions
between April 5, 2008 and February 10, 2017. During this period, the
instrument was affected by the harsh space environment that introduces
instrumental trends (degradation) in the SSI measurements. A new method
based on an adaptation of the Multiple Same-Irradiance-Level (MuSIL)
technique was used to separate solar variability and any uncorrected
instrumental trends in the SOLAR/SOLSPEC UV irradiance measurements.
Results: A new method for correcting degradation has been applied
to the SOLAR/SOLSPEC UV irradiance records to provide new solar cycle
variability results during solar cycle 24. Irradiances are reported at
a mean solar distance of 1 astronomical unit (AU). In the 165-242 nm
spectral region, the SOLAR/SOLSPEC data agrees with the observations
(SORCE/SOLSTICE) and models (SATIRE-S, NRLSSI 2) to within the 1-sigma
error envelope. Between 242 and 300 nm, SOLAR/SOLSPEC agrees only with
the models.
Title: VizieR Online Data Catalog: Solar spectral irradiance during
Solar Cycle 24 (Meftah+, 2021)
Authors: Meftah, M.; Snow, M.; Dame, L.; Bolsee, D.; Pereira, N.;
Cessateur, G.; Bekki, S.; Keckhut, P.; Sarkissian, A.; Hauchecorne, A.
Bibcode: 2020yCat..36450002M
Altcode:
The SOLAR/SOLSPEC Solar Spectral Irradiance (SSI) data product is
constructed using measurements from the SOLAR/SOLSPEC instrument
(low time resolution) and the SATIRE-S model (data reconstruction
to fill the gaps of SOLAR/SOLSPEC observations), which are combined
into merged daily solar spectra over the spectral intervals shown
in the table below. Irradiances are reported at a mean solar
distance of 1AU. SELECTION CRITERIA: date range: 20080405 to
20170210 cadence: 24 hours (daily) spectral range: 165.0 to 3000.0
nm number of data: 2396394 identifierproductdoi (CDS):
XXXX.XXXX.XX identifierproductdoi_authority (CDS):
http://dx.doi.org/ DATA DEFINITIONS: number = 6 (name, type,
format) nominaldateyyyy-mm-dd nominal_time wavelength bin
lower bound, f12.2 (nm) wavelength bin upper bound, f12.2 (nm) spectral
solar irradiance, e12.6 (W/m2/nm^) irradiance_uncertainty,
f12.8 (unitless, 1 sigma) (1 data file).
Title: Segmentation of coronal features to understand the solar EIV
and UV irradiance variability
Authors: Zender, Joe; van der Zwaart, Rens; Kariyappa, Rangaiah;
Damé, Luc; Giono, Gabriel
Bibcode: 2020EGUGA..2219496Z
Altcode:
The study of solar irradiance variability is of great importance in
heliophysics, the Earth's climate, and space weather applications. These
studies require careful identifying, tracking and monitoring of
features in the solar magnetosphere, chromosphere, and corona. We
studied the variability of solar irradiance for a period of 10 years
(May 2010-January 2020) using the Large Yield Radiometer (LYRA), the
Sun Watcher using APS and image Processing (SWAP) on board PROBA2, the
Atmospheric Imaging Assembly (AIA), and the Helioseismic and Magnetic
Imager (HMI) of on board the Solar Dynamics Observatory (SDO), and
applied a linear model between the identified features and the measured
solar irradiance by LYRA.We used the spatial possibilistic clustering
algorithm (SPoCA) to identify coronal holes, and a morphological feature
detection algorithm to identify active regions (AR), coronal bright
points (BPS), and the quite sun (QS) and segment coronal features from
the EUV observations of AIA. The AIA segmentation maps were then applied
on SWAP images, images of all AIA wavelengths, HMI line-of-sight (LOS)
magnetograms, and parameters such as the intensity, fractional area,
and contribution of ARs/CHs/BPs/QS features were computed and compared
with LYRA irradiance measurements as a proxy for ultraviolet irradiation
incident to the Earth atmosphere.We modelled the relation between the
solar disk features (ARs, CHs, BPs, and QS) applied to magnetrogram
and EUV images against the solar irradiance as measured by LYRA and the
F10.7 radio flux. To avoid correlation between different the segmented
features, a principal component analysis (PCM) was done. Using the
independent component, a straightforward linear model was used and
corresponding coefficients computed using the Bayesian framework. The
model selected is stable and coefficients converge well.The application
of the model to data from 2010 to 2020 indicates that both at solar
cycle timeframes as well as shorter timeframes, the active region
influence the EUV irradiance as measured at Earth. Our model replicates
the LYRA measured irradiance well.
Title: VizieR Online Data Catalog: SOLAR-ISS Spectrum covering
165-3000nm (Meftah+, 2020)
Authors: Meftah, M.; Dame, L.; Bolsee, D.; Pereira, N.; Snow, M.;
Weber, M.; Bramstedt, K.; Hilbig, T.; Cessateur, G.; Boudjella,
M. -Y.; Marchand, M.; Lefevre, F.; Thieblemont, R.; Sarkissian, A.;
Hauchecorne, A.; Keckhut, P.; Bekki, S.
Bibcode: 2020yCatp058029501M
Altcode:
A new solar reference spectrum (SOLAR-ISS - V1.1) representative of
the 2008 solar minimum was obtained from the measurements made by the
SOLAR/SOLSPEC instrument and its calibrations. (1 data file).
Title: A New Version of the SOLAR-ISS Spectrum Covering the 165 -
3000 nm Spectral Region
Authors: Meftah, M.; Damé, L.; Bolsée, D.; Pereira, N.; Snow,
M.; Weber, M.; Bramstedt, K.; Hilbig, T.; Cessateur, G.; Boudjella,
M. -Y.; Marchand, M.; Lefèvre, F.; Thiéblemont, R.; Sarkissian,
A.; Hauchecorne, A.; Keckhut, P.; Bekki, S.
Bibcode: 2020SoPh..295...14M
Altcode:
The accurate measurement of the solar spectrum at the top of the
atmosphere and its variability are fundamental inputs for solar physics
(Sun modeling), terrestrial atmospheric photochemistry, and Earth's
climate (climate's modeling). These inputs were the prime objective
set in 1996 for the SOLAR International Space Station (ISS). The SOLAR
package represents a set of three solar instruments measuring the
total and spectral absolute irradiance from 16 nm to 3088 nm. SOLAR was
launched with the European Columbus space laboratory in February 2008
aboard the NASA Space Shuttle Atlantis. SOLAR on the ISS tracked the
Sun until it was decommissioned in February 2017. The SOLar SPECtrum
(SOLSPEC) instrument of the SOLAR payload allowed the measurement
of solar spectra in the 165 - 3000 nm wavelength range for almost
a decade. Until the end of its mission, SOLAR/SOLSPEC was pushed to
its limits to test how it was affected by space environmental effects
(external thermal factors) and to better calibrate the space-based
spectrometer. To that end, a new solar reference spectrum (SOLAR-ISS -
V1.1) representative of the 2008 solar minimum was obtained from
the measurements made by the SOLAR/SOLSPEC instrument and its
calibrations. The main purpose of this article is to improve the
SOLAR-ISS reference spectrum (between 165 and 180 nm in the far
ultraviolet, between 216.9 and 226.8 nm in the middle ultraviolet,
and between 2400 and 3000 nm in the near-infrared). SOLAR-ISS has a
resolution better than 0.1 nm between 165 and 1000 nm, and 1 nm in the
1000 - 3000 nm wavelength range. Finally, a first comparison is made
between the new SOLAR-ISS spectrum (V2.0) and the Total and Spectral
solar Irradiance Sensor (TSIS-1) spectrum obtained from its first
observations from the ISS. Indeed, the launch of TSIS in December
2017 provides a new light on the absolute determination of the solar
spectrum and especially in the infrared region of the spectrum.
Title: Solar oblateness variations in phase with the 22 year-magnetic
cycle
Authors: Damé, L.; Irbah, A.
Bibcode: 2019AGUFMSH11D3392D
Altcode:
The solar oblateness results from distortion processes due to several
phenomena inside the Sun but also induced by the centrifugal potential
of the surface rotation. This fundamental parameter is therefore of
great scientific interest, but its measurements for more than a century
are still very controversial, whether for its average value and/or its
variations observed or not over time. Images acquired for almost the
whole Cycle 24 during the roll calibration mode by the Helioseismic and
Magnetic Imager (HMI) onboard the Solar Dynamic Observatory (SDO) are
used for calculating solar oblateness. The average oblateness obtained
is 8.8+/-0.8 milli-arcseconds in good agreement with measurements of
the last two decades. Variations are observed in anti-phase with the
solar activity during cycle 24 whereas they were in phase with activity
of Cycle 23. More generally, the trend of both in phase variation
during odd cycles and anti-phase variation during even cycles is also
confirmed when revisiting past measurements. We give an overview of
the main issues raised by solar oblateness, present the data used and
processing method, and discuss the major results of this study.
Title: Variations of Solar Oblateness with the 22 yr Magnetic Cycle
Explain Apparently Inconsistent Measurements
Authors: Irbah, Abdanour; Mecheri, Redouane; Damé, Luc; Djafer,
Djelloul
Bibcode: 2019ApJ...875L..26I
Altcode:
Solar oblateness results from distortion processes due to several
phenomena inside of the Sun, but it can also be induced by the
centrifugal potential of surface rotation. This fundamental parameter
is of great scientific interest, yet for more than a century its
measurements have remained a controversial topic, whether because of its
average value or its variations observed (or not) over time. Special
images acquired for almost the whole of Cycle 24 by the Helioseismic
and Magnetic Imager on board the Solar Dynamic Observatory are used
for calculating solar oblateness. The average oblateness obtained is
8.8 ± 0.8 mas, in good agreement with measurements over the last two
decades. Variations are observed in anti-phase with the solar activity
during Cycle 24, whereas they were in phase with activity during Cycle
23. More generally, the trend of both in-phase variation during odd
cycles and anti-phase variation during even cycles is confirmed when
revisiting past measurements. Therefore, it is possible that the Sun
initiates a physical process resulting in a pulsation with the 22 yr
magnetic cycle; it has extreme values during the polarity reversals,
with a maximum swelling during odd cycles and the opposite for even
ones. This oscillation could resolve the controversy surrounding
past measurements.
Title: AntarctiCor: Solar Coronagraph in Antarctica for the ESCAPE
Project
Authors: Fineschi, S.; Capobianco, G.; Massone, G.; Susino, R.;
Zangrilli, L.; Bemporad, A.; Liberatore, A.; Landini, F.; Romoli,
M.; Damé, L.; Christille, J. M.; Sandri, P.; Marmonti, M.; Galy, C.
Bibcode: 2019NCimC..42...26F
Altcode:
The Antarctica solar coronagraph - AntarctiCor- for the "Extreme
Solar Coronagraphy Antarctic Program Experiment" -ESCAPE- comprises
an internally-occulted coronagraph based on the externally-occulted
ASPIICS coronagraph for the ESA formation-flying PROBA-3 mission. This
paper describes the AntarctiCor design for ground-based observations
from the DomeC Antarctica plateau of the polarized broad-band (591 nm
± 5 nm) K-corona and of the narrow-band (FWHM = 0.5 nm), polarized
emission of the coronal green-line at 530.3 nm. The science goal of
these observations is to map the topology and dynamics of the coronal
magnetic field, addressing coronal heating and space weather questions.
Title: Solar radius determined from PICARD/SODISM observations
and extremely weak wavelength dependence in the visible and the
near-infrared
Authors: Meftah, M.; Corbard, T.; Hauchecorne, A.; Morand, F.; Ikhlef,
R.; Chauvineau, B.; Renaud, C.; Sarkissian, A.; Damé, L.
Bibcode: 2018A&A...616A..64M
Altcode:
Context. In 2015, the International Astronomical Union (IAU) passed
Resolution B3, which defined a set of nominal conversion constants for
stellar and planetary astronomy. Resolution B3 defined a new value of
the nominal solar radius (R⊙N = 695 700 km
km) that is different from the canonical value used until now (695
990 km). The nominal solar radius is consistent with helioseismic
estimates. Recent results obtained from ground-based instruments,
balloon flights, or space-based instruments highlight solar radius
values that are significantly different. These results are related to
the direct measurements of the photospheric solar radius, which are
mainly based on the inflection point position methods. The discrepancy
between the seismic radius and the photospheric solar radius can be
explained by the difference between the height at disk center and the
inflection point of the intensity profile on the solar limb. At 535.7
nm (photosphere), there may be a difference of ∼330 km between the
two definitions of the solar radius.
Aims: The main objective
of this work is to present new results of the solar radius in the
near-ultraviolet, the visible, and the near-infrared from PICARD
space-based and ground-based observations. Simulations show the
strong influence of atmosphere effects (refraction and turbulence) on
ground-based solar radius determinations and highlight the interest of
space-based solar radius determinations, particularly during planet
transits (Venus or Mercury), in order to obtain more realistic and
accurate measurements.
Methods: Solar radius observations
during the 2012 Venus transit have been made with the SOlar Diameter
Imager and Surface Mapper (SODISM) telescope on board the PICARD
spacecraft. We used the transit of Venus as an absolute calibration
to determine the solar radius accurately at several wavelengths. Our
results are based on the determination of the inflection point position
of the solar limb-darkening function (the most common solar radius
definition). A realistic uncertainty budget is provided for each solar
radius obtained with the PICARD space-based telescope during the 2012
Venus transit. The uncertainty budget considers several sources of
error (detection of the centers of Venus and Sun in PICARD images,
positions of Sun and Venus from ephemeris (planetary theory), PICARD
on-board timing, PICARD spacecraft position, and optical distortion
correction from PICARD images).
Results: We obtain new values
of the solar radius from the PICARD mission at several wavelengths and
in different solar atmosphere regions. The PICARD spacecraft with its
SODISM telescope was used to measure the radius of the Sun during the
Venus transit in 2012. At 535.7 nm, the solar radius is equal to 696 134
± 261 km (combined standard uncertainty based (ξ) on the uncertainty
budget). At 607.1 nm, the solar radius is equal to 696 156 ± 145 km
(ξ), and the standard deviation of the solar radius mean value is
±22 km. At 782.2 nm, the solar radius is equal to 696 192 ± 247 km
(ξ). The PICARD space-based results as well as PICARD ground-based
results show that the solar radius wavelength dependence in the visible
and the near-infrared is extremely weak. The differences in inflection
point position of the solar radius at 607.1 nm, 782.2 nm, and 1025.0
nm from a reference at 535.7 nm are less than 60 km for the different
PICARD measurements.
Title: The New SCIAMACHY Reference Solar Spectral Irradiance and
Its Validation
Authors: Hilbig, T.; Weber, M.; Bramstedt, K.; Noël, S.; Burrows,
J. P.; Krijger, J. M.; Snel, R.; Meftah, M.; Damé, L.; Bekki, S.;
Bolsée, D.; Pereira, N.; Sluse, D.
Bibcode: 2018SoPh..293..121H
Altcode:
This paper describes a new reference solar spectrum retrieved from
measurements of the satellite instrument SCIAMACHY in the wavelength
region from 0.24 μ m to 2.4 μ m and its comparison with several
other established solar reference spectra. The SCIAMACHY reference
spectrum was recorded early in the mission before substantial optical
degradation due to the harsh space environment sets in. The radiometric
calibration of SCIAMACHY, applied in this study, includes a physical
model of the scanner unit. Furthermore, SCIAMACHY's internal white
light source (WLS) is used to correct for on-ground to in-flight
changes. The resultant calibrated solar spectrum from SCIAMACHY is
in good agreement with several available solar spectral irradiance
(SSI) references in the visible spectral range. Strong throughput
losses due to detector icing in the near infrared (NIR) are now
adequately accounted for. Nevertheless, a deficit with respect to the
ATLAS-3 composite and SORCE/SIM SSI is observed in the NIR. However,
the SCIAMACHY solar reference spectrum agrees well with the recently
re-evaluated SOLAR/SOLSPEC-ISS and recent ground measurements taken
at Mauna Loa in the NIR.
Title: SoSWEET-SOUP (SOlar, Space Weather Extreme EvenTs and
Stratospheric Ozone Ultimate Profiles) dual constellation mission
Authors: Damé, Luc; Meftah, Mustapha
Bibcode: 2018cosp...42E.753D
Altcode:
SoSWEET-SOUP is an innovative small satellites constellation which aims
to measure on complementary platforms the solar influence on climate,
namely on one part solar activity and spectral variability and, on
the other, the different components of the Earth radiation budget,
energy input and energy re-emitted at the top of the Earth atmosphere,
with a particular focus on the UV part of the spectrum and on the ozone
layer, which are most sensitive to solar variability. The far UV (FUV)
is the only wavelength band with energy absorbed in the high atmosphere
(stratosphere), in the ozone (Herzberg continuum, 200-220 nm) and oxygen
bands, and its high variability is most probably at the origin of a
climate influence. A simultaneous observation of the incoming FUV and
of the ozone (O3) production, would bring an invaluable information on
this process of solar-climate forcing. Space instruments have already
measured the different components of the Earth radiative budget but
this is, to our knowledge, the first time that all instruments will be
operated simultaneously on coordinated platforms. This characteristic
guarantees by itself obtaining new significant original scientific
results. SoSWEET-SOUP is an evolution of the SUITS/SWUSV and SUMO
proposed missions, acknowledging the scientific advantages of
associating a constellation of 10 to 12 small satellites of some
20 to 30 kg (12 "U" or so nanosatellites) on equatorial orbits (+/-
20° in latitude) to a small polar satellite of 100 to 120 kg on a
OneWeb like platform for an almost continuous solar following (a polar
orbit is also essential to the understanding of the relation between
solar UV variability and stratospheric ozone on arctic and antarctic
regions).SoSWEET-SOUP definition's options are still under assessment
but will include, on the polar satellite, SUAVE (Solar Ultraviolet
Advanced Variability Experiment), an optimized heavy-duty thermally
stable SiC telescope for FUV (Lyman-Alpha) and MUV (200-220 nm Herzberg
continuum) imaging (sources of variability, extreme events detection),
and SOLSIM (SOLar Spectral Irradiance Monitor), a newly designed
double-monochromator instrument covering the 170-340 nm ultraviolet
spectral range and in within a limited mass-power budget. Other
instruments include a small coronagraph, UV and ozone radiometers,
Earth radiative budget assembly, Electron-Proton detectors and a vector
magnetometer. The constellation of small satellites includes, on its
side, precise ozone profiles measurements (miniGOMOS experiment with
dual Sun and stars occultations) and detailed energy radiative budget
monitors. Science objectives, mission profiles and model payloads will
be presented and opportunities of missions and potential collaborations
discussed.
Title: Eight years of solar observations with PICARD
Authors: Meftah, M.; Corbard, T.; Morand, F.; Renaud, C.; Ikhlef,
R.; Fodil, M.; Vieau, A. -J.; Damé, L.
Bibcode: 2018SPIE10704E..1FM
Altcode:
PICARD is a mission devoted to solar variability observation, which
aims at perpetuating valuable historical time-series of the solar
radius. PICARD contains a double program with in-space and on-ground
measurements using Ritchey-Chrétien telescopes. The PICARD spacecraft
was launched on June 15, 2010, commissioned in-flight in October of
the same year, and was retired in April 2014. PICARD ground-based
observatory is functional since May 2011 in the Plateau de Calern
(France), and is still operational today. We shall give an overview
of the PICARD instrumentation and the performances of the existing
ground-based telescope. We will also present our current results about
solar radius variations after eight years of solar observations.
Title: SERB, a first innovative proof-of-concept nano-satellite of
a constellation to measure the Earth Radiation Budget
Authors: Meftah, Mustapha; Sarkissian, Alain; Damé, Luc; Keckhut,
Philippe; Irbah, Abdanour; Bekki, Slimane; Thiéblemont, Rémi
Bibcode: 2018cosp...42E2242M
Altcode:
The only way to measure the imbalance with sufficient accuracy is to
measure both the incoming solar radiations (total solar irradiance)
and the outgoing terrestrial radiations (top of atmosphere outgoing
longwave radiations and shortwave radiations) onboard the same
satellite, and ideally, with the same instrument. The incoming solar
radiations and the outgoing terrestrial radiations are of nearly equal
magnitude of the order of 340.5 W/m2. The objective is to measure these
quantities over time by using differential Sun-Earth measurements (to
counter calibration errors) with an accuracy better than 0.05 W/m2. It
is necessary to observe during a decade and to measure the global
diurnal cycle with a dozen satellites. Solar irradiance and Earth
Radiation Budget (SERB) is a potential first in orbit demonstration
satellite. The SERB nano-satellite aims to measure on the same platform
the different components of the Earth radiation budget and the total
solar irradiance. Instrumental payloads (solar radiometer and Earth
radiometers) can acquire the technical maturity for the future large
missions (constellation that insure global measurement cover) by
flying in a CubeSat. This presentation is intended to demonstrate the
ability to build a low-cost satellite with a high accuracy measurement
in order to have constant flow of data from space.
Title: Cycle 24 variability of the ultraviolet solar spectral
irradiance with the SOLAR/SOLSPEC 9 years of data from the
International Space Station
Authors: Damé, Luc; Bolsee, David; Hauchecorne, Alain; Meftah,
Mustapha; Irbah, Abdanour; Bekki, Slimane; Pereira, Nuno; Sluse,
Dominique; Cessateur, Gäel
Bibcode: 2018cosp...42E.754D
Altcode:
Accurate measurements of solar spectral irradiance (SSI) and its
temporal variation are of primary interest to better understand
solar mechanisms and the links between solar variability and Earth's
atmosphere and climate. We present recent Ultra Violet (UV) SSI
observations performed by the SOLAR/SOLSPEC spectrometer on board
the International Space Station. SOLAR/SOLSPEC observations cover the
essential of the solar cycle 24, from April 5, 2008 to February 15,
2017.We provide an evolution of the solar spectral irradiance during
Cycle 24 using the SOLAR/SOLSPEC data thanks to revised engineering
corrections, improved calibrations, and advanced procedures to account
for thermal and aging corrections of the instrument. The SOLAR/SOLSPEC
observations are compared with other measurements (SORCE/SOLSTICE,
SORCE/SIM, SCIAMACHY) and models (SATIRE-S, NRLSSI).
Title: Think the way to measure the Earth Radiation Budget and the
Total Solar Irradiance with a small satellites constellation
Authors: Meftah, M.; Keckhut, P.; Damé, L.; Bekki, S.; Sarkissian,
A.; Hauchecorne, A.
Bibcode: 2018SPIE10641E..0SM
Altcode:
Within the past decade, satellites constellations have become possible
and practical. One of the interest to use a satellites constellation
is to measure the true Earth Radiation Imbalance, which is a crucial
quantity for testing climate models and for predicting the future course
of global warming. This measurement presents a high interest because the
2001-2010 decade has not shown the accelerating pace of global warming
that most models predict, despite the fact that the greenhouse-gas
radiative forcing continues to rise. All estimates (ocean heat content
and top of atmosphere) show that over the past decade the Earth
radiation imbalance ranges between 0.5 to 1W-2. Up to now,
the Earth radiation imbalance has not been measured directly. The only
way to measure the imbalance with sufficient accuracy is to measure both
the incoming solar radiations (total solar irradiance) and the outgoing
terrestrial radiations (top of atmosphere outgoing longwave radiations
and shortwave radiations) onboard the same satellite, and ideally, with
the same instrument. The incoming solar radiations and the outgoing
terrestrial radiations are of nearly equal magnitude of the order of
340.5W-2. The objective is to measure these quantities
over time by using differential Sun-Earth measurements (to counter
calibration errors) with an accuracy better than 0.05Wm-2
at 1σ. It is also necessary to have redundant instruments to track
aging in space in order to measure during a decade and to measure the
global diurnal cycle with a dozen satellites. Solar irradiance and Earth
Radiation Budget (SERB) is a potential first in orbit demonstration
satellite. The SERB nano-satellite aims to measure on the same platform
the different components of the Earth radiation budget and the total
solar irradiance. Instrumental payloads (solar radiometer and Earth
radiometers) can acquire the technical maturity for the future large
missions (constellation that insure global measurement cover) by flying
in a CubeSat. This paper is intended to demonstrate the ability to
build a low-cost satellite with a high accuracy measurement in order
to have constant flow of data from space.
Title: The Measurement of the Solar Spectral Irradiance during the
Solar Cycle 24 using SOLAR/SOLSPEC on ISS
Authors: Bolsée, David; Pereira, Nuno; Sluse, Dominique; Cessateur,
Gaël; Meftah, Mustapha; Damé, Luc; Hauchecorne, Alain; Bekki,
Slimane; Marchand, Marion
Bibcode: 2018EGUGA..2013041B
Altcode:
Between April 2008 and February 2017, the Solar Spectral Irradiance
(SSI) was measured by the SOLAR/SOLSPEC from 166 nm to 3088 nm. The
instrument was a part of the Solar Monitoring Observatory (SOLAR)
payload, externally mounted on the Columbus module of the International
Space Station. As the SSI is a key input for the validation of solar
physics models, together with playing a role in the climate system
and photochemistry of the Earth atmosphere, SOLAR/SOLSPEC spectral
measurements becomes important. In this study, the in-flight operations
and performances of the instrument -including the engineering
corrections- will be presented for the nine years of the SOLAR
mission. Using an accurate absolute calibration, the SSI as measured
by SOLAR/SOLSPEC in the course of the solar cycle 24 will be presented
and compared to other instruments and ground-based measurements. The
accuracy of these measurements will be also discussed here.
Title: Recent variability of the solar spectral irradiance by using
SOLAR/SOLSPEC data
Authors: Meftah, Mustapha; Damé, Luc; Hauchecorne, Alain; Irbah,
Abdanour; Bekki, Slimane; Bolsée, David; Pereira, Nuno; Sluse,
Dominique; Cessateur, Gael
Bibcode: 2018EGUGA..20.3498M
Altcode:
Accurate measurements of the solar spectral irradiance (SSI) and
its temporal variation are of primary interest to better understand
solar mechanisms and the links between solar variability and Earth's
atmosphere and climate. We will present recent Ultra Violet (UV) SSI
observations performed by the SOLAR/SOLSPEC spectrometer on board the
International Space Station. SOLAR/SOLSPEC observations covered the
essential of the solar cycle 24 from April 5, 2008 to February 15,
2017. We wish to provide evolution of solar spectral irradiance during
Cycle 24 using the SOLAR/SOLSPEC data thanks to revised engineering
corrections, improved calibrations, and advanced procedures to account
for thermal and aging corrections of the instrument. The SOLAR/SOLSPEC
observations will be directly compared with other measurements
(SORCE/SOLSTICE, SORCE/SIM) and models (SATIRE-S, NRLSSI).
Title: Investigation of the low flux servo-controlled limit of a
co-phased interferometer
Authors: Damé, Luc; Derrien, Marc; Kozlowski, Mathias; Merdjane,
Mohamed
Bibcode: 2018SPIE10570E..0UD
Altcode:
This paper, "Investigation of the low flux servo-controlled limit of
a co-phased interferometer," was presented as part of International
Conference on Space Optics—ICSO 1997, held in Toulouse, France.
Title: SOLAR/SOLSPEC: a new solar reference spectrum, SOLAR-ISS
165-3000 nm and 9 years observations of solar spectral irradiance
from space from the ISS
Authors: Damé, Luc; Meftah, Mustapha; Hauchecorne, Alain; Irbah,
Abdenour; Bekki, Slimane; Bolsée, David; Pereira, Nuno; Sluse,
Dominique; Cessateur, Gael
Bibcode: 2018EGUGA..2016445D
Altcode:
For 9 years since April 5, 2008 and until February 15, 2017, the SOLSPEC
(SOLar SPECtrometer) spectro-radiometer of the SOLAR facility on the
International Space Station (ISS) performed accurate measurements
of Solar Spectral Irradiance (SSI) from the far ultraviolet to the
infrared (165 nm to 3000 nm). These measurements, unique by their large
spectral coverage and long time range, are of primary importance for
a better understanding of solar physics and of the impact of solar
variability on climate (via Earth's atmospheric photochemistry),
noticeably through the "top-down" mechanism amplifying ultraviolet
solar forcing effects on the climate (UV affects stratospheric dynamics
and temperatures, altering interplanetary waves and weather patterns
both poleward and downward to the lower stratosphere and troposphere
regions). SOLAR/SOLSPEC, with almost 9 years of observations covering
the essential of the unusual solar cycle 24, followed UV temporal
variability and established a new reference solar spectra from UV
to IR (165-3000 nm). A complete reanalysis of data was possible
thanks to revised engineering corrections, improved calibrations
and advanced procedures to account for thermal influence, aging
(degradation) and pointing corrections. These intensive ground and
space calibrations allowed a proper evaluation of uncertainties on these
measurements. Results, UV variability and absolute reference spectrum
(SOLAR-ISS), are displayed and compared with other measurements (WHI,
ATLAS-3, SCIAMACHY, SORCE/SOLSTICE, SORCE/SIM) and models (SATIRE-S,
NRLSSI2).
Title: SOLAR-ISS: A new reference spectrum based on SOLAR/SOLSPEC
observations
Authors: Meftah, M.; Damé, L.; Bolsée, D.; Hauchecorne, A.; Pereira,
N.; Sluse, D.; Cessateur, G.; Irbah, A.; Bureau, J.; Weber, M.;
Bramstedt, K.; Hilbig, T.; Thiéblemont, R.; Marchand, M.; Lefèvre,
F.; Sarkissian, A.; Bekki, S.
Bibcode: 2018A&A...611A...1M
Altcode:
Context. Since April 5, 2008 and up to February 15, 2017, the SOLar
SPECtrometer (SOLSPEC) instrument of the SOLAR payload on board the
International Space Station (ISS) has performed accurate measurements
of solar spectral irradiance (SSI) from the middle ultraviolet to
the infrared (165 to 3088 nm). These measurements are of primary
importance for a better understanding of solar physics and the impact
of solar variability on climate. In particular, a new reference solar
spectrum (SOLAR-ISS) is established in April 2008 during the solar
minima of cycles 23-24 thanks to revised engineering corrections,
improved calibrations, and advanced procedures to account for thermal
and aging corrections of the SOLAR/SOLSPEC instrument.
Aims:
The main objective of this article is to present a new high-resolution
solar spectrum with a mean absolute uncertainty of 1.26% at 1σ from 165
to 3000 nm. This solar spectrum is based on solar observations of the
SOLAR/SOLSPEC space-based instrument.
Methods: The SOLAR/SOLSPEC
instrument consists of three separate double monochromators that use
concave holographic gratings to cover the middle ultraviolet (UV),
visible (VIS), and infrared (IR) domains. Our best ultraviolet, visible,
and infrared spectra are merged into a single absolute solar spectrum
covering the 165-3000 nm domain. The resulting solar spectrum has a
spectral resolution varying between 0.6 and 9.5 nm in the 165-3000 nm
wavelength range. We build a new solar reference spectrum (SOLAR-ISS)
by constraining existing high-resolution spectra to SOLAR/SOLSPEC
observed spectrum. For that purpose, we account for the difference of
resolution between the two spectra using the SOLAR/SOLSPEC instrumental
slit functions.
Results: Using SOLAR/SOLSPEC data, a new solar
spectrum covering the 165-3000 nm wavelength range is built and is
representative of the 2008 solar minimum. It has a resolution better
than 0.1 nm below 1000 nm and 1 nm in the 1000-3000 nm wavelength
range. The new solar spectrum (SOLAR-ISS) highlights significant
differences with previous solar reference spectra and with solar
spectra based on models. The integral of the SOLAR-ISS solar spectrum
yields a total solar irradiance of 1372.3 ± 16.9 Wm-2
at 1σ, that is yet 11 Wm-2 over the value recommended
by the International Astronomical Union in 2015. The spectrum
shown in Fig. B.1 is available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/611/A1
Title: Solar-Iss a New Solar Reference Spectrum Covering the Far UV
to the Infrared (165 to 3088 Nm) Based on Reanalyzed Solar/solspec
Cycle 24 Observations
Authors: Damé, L.; Meftah, M.; Irbah, A.; Hauchecorne, A.; Bekki,
S.; Bolsée, D.; Pereira, N.; Sluse, D.; Cessateur, G.
Bibcode: 2017AGUFMSH42A..07D
Altcode:
Since April 5, 2008 and until February 15, 2017, the SOLSPEC
(SOLar SPECtrometer) spectro-radiometer of the SOLAR facility on the
International Space Station performed accurate measurements of Solar
Spectral Irradiance (SSI) from the far ultraviolet to the infrared
(165 nm to 3088 nm). These measurements, unique by their large spectral
coverage and long time range, are of primary importance for a better
understanding of solar physics and of the impact of solar variability
on climate (via Earth's atmospheric photochemistry), noticeably
through the "top-down" mechanism amplifying ultraviolet (UV) solar
forcing effects on the climate (UV affects stratospheric dynamics
and temperatures, altering interplanetary waves and weather patterns
both poleward and downward to the lower stratosphere and troposphere
regions). SOLAR/SOLSPEC, with almost 9 years of observations covering
the essential of the unusual solar cycle 24 from minimum in 2008
to maximum, allowed to establish new reference solar spectra from
UV to IR (165 to 3088 nm) at minimum (beginning of mission) and
maximum of activity. The complete reanalysis was possible thanks to
revised engineering corrections, improved calibrations and advanced
procedures to account for thermal, aging and pointing corrections. The
high quality and sensitivity of SOLSPEC data allow to follow temporal
variability in UV but also in visible along the cycle. Uncertainties
on these measurements are evaluated and results, absolute reference
spectra and variability, are compared with other measurements (WHI,
ATLAS-3, SCIAMACHY, SORCE/SOLSTICE, SORCE/SIM) and models (SATIRE-S,
NRLSSI, NESSY)
Title: SSI Variations in the visible as observed with SOLAR/SOLSPEC
during cycle 24 - Comparison with SORCE/SIM.
Authors: Irbah, A.; Damé, L.; Meftah, M.; Bekki, S.; Bolsée, D.
Bibcode: 2017AGUFMSH43B2808I
Altcode:
The solar spectral irradiance (SSI) and its temporal variations
are of prime importance to apprehend the physics of the Sun and to
understand its effects on Earth climate through changes of atmospheric
properties. Ground based measurements of SSI are indeed affected by
the Earth atmosphere and space observations are therefore required
to perform adequate observations. Only a few long series of SSI space
measurements were obtained these last decades. The SOLSPEC instrument
of the SOLAR payload on the International Space Station (ISS) has
recorded one of them from April 2008 to February 2017 covering almost
the whole solar cycle 24. The instrument is a spectro-radiometer
recording data of the Sun from 166 to 3088 nm. Operated from the ISS
in a harsh environment it needed appropriate processing methods to
extract significant scientific results from noise and instrumental
effects. We present the methods used to process the data to evidence
visible SSI variations during cycle 24. We discuss the results obtained
showing SSI variations in phase with solar activity. We compare them
with SORCE/SIM measurements.
Title: ASPIICS: a giant, white light and emission line coronagraph
for the ESA proba-3 formation flight mission
Authors: Lamy, P. L.; Vivès, S.; Curdt, W.; Damé, L.; Davila, J.;
Defise, J. -M.; Fineschi, S.; Heinzel, P.; Howard, Russel; Kuzin,
S.; Schmutz, W.; Tsinganos, K.; Zhukov, A.
Bibcode: 2017SPIE10565E..0TL
Altcode:
Classical externally-occulted coronagraphs are presently limited in
their performances by the distance between the external occulter and
the front objective. The diffraction fringe from the occulter and
the vignetted pupil which degrades the spatial resolution prevent
useful observations of the white light corona inside typically 2-2.5
solar radii (Rsun). Formation flying offers and elegant solution to
these limitations and allows conceiving giant, externally-occulted
coronagraphs using a two-component space system with the external
occulter on one spacecraft and the optical instrument on the
other spacecraft at a distance of hundred meters [1, 2]. Such
an instrument ASPIICS (Association de Satellites Pour l'Imagerie
et l'Interférométrie de la Couronne Solaire) has been selected
by the European Space Agency (ESA) to fly on its PROBA-3 mission
of formation flying demonstration which is presently in phase B
(Fig. 1). The classical design of an externally-occulted coronagraph is
adapted to the formation flying configuration allowing the detection
of the very inner corona as close as 0.04 solar radii from the solar
limb. By tuning the position of the occulter spacecraft, it may even be
possible to reach the chromosphere and the upper part of the spicules
[3]. ASPIICS will perform (i) high spatial resolution imaging of the
continuum K+F corona in photometric and polarimetric modes, (ii) high
spatial resolution imaging of the E-corona in two coronal emission lines
(CEL): Fe XIV and He I D3, and (iii) two-dimensional spectrophotometry
of the Fe XIV emission line. ASPIICS will address the question of the
coronal heating and the role of waves by characterizing propagating
fluctuations (waves and turbulence) in the solar wind acceleration
region and by looking for oscillations in the intensity and Doppler
shift of spectral lines. The combined imaging and spectral diagnostics
capabilities available with ASPIICS will allow mapping the velocity
field of the corona both in the sky plane (directly on the images)
and along the line-of-sight by measuring the Doppler shifts of
emission lines in an effort to determine how the different components
of the solar wind, slow and fast are accelerated. With a possible
launch in 2014, ASPIICS will observe the corona during the maximum of
solar activity, insuring the detection of many Coronal Mass Ejections
(CMEs). By rapidly alternating high-resolution imaging and spectroscopy,
CMEs will be thoroughly characterized.
Title: High resolution solar physics by aperture synthesis: the
SOLARNET program
Authors: Derrien, Marc; Damé, Luc; Perrot, Sylvain; Kozlowski, Mathias
Bibcode: 2017SPIE10569E..2GD
Altcode:
We present the 3 telescopes breadboards used to demonstrate the
cophasing and imaging capabilities of the Solar Imaging Interferometer
(SOLARNET).
Title: A solar diameter metrology measurement: the Picard
microsatellite program
Authors: Damé, Luc; Brun, Jean-Francis; Cugnet, David; Derrien, Marc;
Leroy, Claude; Meftah, Mustapha; Meissonnier, Mireille; Porteneuve,
Jacques
Bibcode: 2017SPIE10569E..14D
Altcode:
The PICARD microsatellite mission will provide 3 to 4 years
simultaneous measurements of the solar diameter, differential rotation
and solar constant to investigate the nature of their relations and
variabilities. The major instrument, SODISM, is a whole Sun imaging
telescope of Ø110 mm which will deliver an absolute measure (better
than 4 mas) of the solar diameter and solar shape. Now in Phase B,
PICARD is expected to be launched by 2005. We recall the scientific
goals linked to the diameter measurement with interest for Earth
Climate, Space Weather and Helioseismology, present the instrument
optical concept and design, and give a brief overview of the program
aspects.
Title: Mathematical modelling of the complete metrology of the
PROBA-3/ASPIICS formation flying solar coronagraph
Authors: Stathopoulos, F.; Vives, S.; Damé, L.; Tsinganos, K.
Bibcode: 2017SPIE10565E..2SS
Altcode:
Formation flying, with ESA's mission PROBA-3, is providing the chance of
creating a giant solar coronagraph in Space. The scientific payload,
the solar coronagraph ASPIICS, has been selected in January 2009
[1]. The advantages of formation flying are: 1) larger dimensions
for the coronagraph, which leads to better spatial resolution and
lower straylight level and 2) possibility of continuous observations
of the inner corona. The PROBA-3/ASPIICS mission is composed of two
spacecrafts (S/Cs) at 150 meters distance, the Occulter-S/C (O-S/C)
which holds the external occulter, and the Coronagraph-S/C (C-S/C)
which holds the main instrument, i.e. the telescope. In addition of
the scientific capabilities of the instrument, it will continuously
monitor the exact position and pointing of both S/Cs in 3D space, via
two additional metrology units: the Shadow Position Sensor (SPS) and
the Occulter Position Sensor (OPS). In this paper we are presenting the
metrology of this formation flying mission combining the outputs of the
above mentioned sensors, SPS and OPS. This study has been conducted in
the framework of an ESA "STARTIGER" initiative, a novel approach aimed
at demonstrating the feasibility of a new and promising technology
concept (in our case formation flying applied to solar coronagraphy,
cf. [2, 3]) on a short time scale (six months study).
Title: VizieR Online Data Catalog: SOLAR/SOLSPEC Spectral Irradiance -
0.5-3000nm (Meftah+, 2018)
Authors: Meftah, M.; Dame, L.; Bolsee, D.; Hauchecorne, A.; Pereira,
N.; Sluse, D.; Cessateur, G.; Irbah, A.; Bureau, J.; Weber, M.;
Bramstedt, K.; Hilbig, T.; Thieblemont, R.; Marchand, M.; Lefevre,
F.; Sarkissian, A.; Bekki, S.
Bibcode: 2017yCat..36110001M
Altcode:
The SOLAR/SOLSPEC space-based instrument has measured the solar spectral
irradiance from 165 to 3000nm at 0.6 to 9.5nm spectral resolution during
the almost nine years of the SO- LAR/ISS mission. The instrument was
calibrated using the PTB standard blackbody developed for temperatures
up to 3200K. The absolute accuracy, based on a detailed analysis of
error sources, indicates a mean absolute uncertainty of 1.26% of the
total solar irradiance in the 165-3000nm range. Using SOLAR/SOLSPEC
data, a new solar spectrum (SOLAR-ISS) covering the 165-3000nm
wavelength range is built with added high spectral resolution. This
SOLAR-ISS spectrum is developed by combining high spectral resolution
from reference solar spectra with the resulting SOLAR/SOLSPEC spectrum
through the knowledge of the slit functions of the SOLAR/SOLSPEC
instrument. (1 data file).
Title: Segmentation of photospheric magnetic elements corresponding to
coronal features to understand the EUV and UV irradiance variability
Authors: Zender, J. J.; Kariyappa, R.; Giono, G.; Bergmann, M.;
Delouille, V.; Damé, L.; Hochedez, J. -F.; Kumara, S. T.
Bibcode: 2017A&A...605A..41Z
Altcode:
Context. The magnetic field plays a dominant role in the solar
irradiance variability. Determining the contribution of various magnetic
features to this variability is important in the context of heliospheric
studies and Sun-Earth connection.
Aims: We studied the solar
irradiance variability and its association with the underlying magnetic
field for a period of five years (January 2011-January 2016). We used
observations from the Large Yield Radiometer (LYRA), the Sun Watcher
with Active Pixel System detector and Image Processing (SWAP) on board
PROBA2, the Atmospheric Imaging Assembly (AIA), and the Helioseismic
and Magnetic Imager (HMI) on board the Solar Dynamics Observatory
(SDO).
Methods: The Spatial Possibilistic Clustering Algorithm
(SPoCA) is applied to the extreme ultraviolet (EUV) observations
obtained from the AIA to segregate coronal features by creating
segmentation maps of active regions (ARs), coronal holes (CHs) and
the quiet sun (QS). Further, these maps are applied to the full-disk
SWAP intensity images and the full-disk (FD) HMI line-of-sight (LOS)
magnetograms to isolate the SWAP coronal features and photospheric
magnetic counterparts, respectively. We then computed full-disk
and feature-wise averages of EUV intensity and line of sight (LOS)
magnetic flux density over ARs/CHs/QS/FD. The variability in these
quantities is compared with that of LYRA irradiance values.
Results: Variations in the quantities resulting from the segmentation,
namely the integrated intensity and the total magnetic flux density
of ARs/CHs/QS/FD regions, are compared with the LYRA irradiance
variations. We find that the EUV intensity over ARs/CHs/QS/FD is well
correlated with the underlying magnetic field. In addition, variations
in the full-disk integrated intensity and magnetic flux density values
are correlated with the LYRA irradiance variations.
Conclusions:
Using the segmented coronal features observed in the EUV wavelengths as
proxies to isolate the underlying magnetic structures is demonstrated
in this study. Sophisticated feature identification and segmentation
tools are important in providing more insights into the role of various
magnetic features in both the short- and long-term changes in the solar
irradiance. The movie associated to Fig. 2 is available at http://www.aanda.org
Title: A New Solar Spectrum from 656 to 3088 nm
Authors: Meftah, M.; Damé, L.; Bolsée, D.; Pereira, N.; Sluse, D.;
Cessateur, G.; Irbah, A.; Sarkissian, A.; Djafer, D.; Hauchecorne,
A.; Bekki, S.
Bibcode: 2017SoPh..292..101M
Altcode:
The solar spectrum is a key parameter for different scientific
disciplines such as solar physics, climate research, and atmospheric
physics. The SOLar SPECtrometer (SOLSPEC) instrument of the Solar
Monitoring Observatory (SOLAR) payload onboard the International Space
Station (ISS) has been built to measure the solar spectral irradiance
(SSI) from 165 to 3088 nm with high accuracy. To cover the full
wavelength range, three double-monochromators with concave gratings are
used. We present here a thorough analysis of the data from the third
channel/double-monochromator, which covers the spectral range between
656 and 3088 nm. A new reference solar spectrum is therefore obtained
in this mainly infrared wavelength range (656 to 3088 nm); it uses
an absolute preflight calibration performed with the blackbody of the
Physikalisch-Technische Bundesanstalt (PTB). An improved correction of
temperature effects is also applied to the measurements using in-flight
housekeeping temperature data of the instrument. The new solar spectrum
(SOLAR-IR) is in good agreement with the ATmospheric Laboratory for
Applications and Science (ATLAS 3) reference solar spectrum from 656
nm to about 1600 nm. However, above 1600 nm, it agrees better with
solar reconstruction models than with spacecraft measurements. The new
SOLAR/SOLSPEC measurement of solar spectral irradiance at about 1600
nm, corresponding to the minimum opacity of the solar photosphere,
is 248.08 ± 4.98 mW m−2 nm−1 (1 σ ),
which is higher than recent ground-based evaluations.
Title: On-orbit degradation of recent space-based solar instruments
and understanding of the degradation processes
Authors: Meftah, M.; Dominique, M.; BenMoussa, A.; Dammasch, I. E.;
Bolsée, D.; Pereira, N.; Damé, L.; Bekki, S.; Hauchecorne, A.
Bibcode: 2017SPIE10196E..06M
Altcode:
The space environment is considered hazardous to spacecraft, resulting
in materials degradation. Understanding the degradation of space-based
instruments is crucial in order to achieve the scientific objectives,
which are derived from these instruments. This paper discusses
the on-orbit performance degradation of recent spacebased solar
instruments. We will focus on the instruments of three space-based
missions such as the Project for On-Board Autonomy 2 (PROBA2)
spacecraft, the Solar Monitoring Observatory (SOLAR) payload onboard the
Columbus science Laboratory of the International Space Station (ISS)
and the PICARD spacecraft. Finally, this paper intends to understand
the degradation processes of these space-based solar instruments.
Title: VizieR Online Data Catalog: SOLAR/SOLSPEC UV SSI from 2008-2015
(Meftah+, 2016)
Authors: Meftah, M.; Bolsee, D.; Dame, L.; Hauchecorne, A.; Pereira,
N.; Irbah, A.; Bekki, S.; Cessateur, G.; Foujols, T.; Thieblemont, R.
Bibcode: 2017yCatp058029101M
Altcode:
The SOLar SPECtrum (SOLSPEC) instrument of the Solar Monitoring
Observatory (SOLAR) was exposed to sunlight for the first time on
April 5, 2008. The duration to record a solar spectrum (165-3088nm)
is less than 17 minutes. Between April 2008 and May 2016, more
than 700 solar spectra were acquired. The present article is
dedicated to the UV portion (165-400nm) of the solar spectrum and
its temporal variations during Solar Cycle 24. Measurements from two
separated double-spectrometers of SOLAR/SOLSPEC ('UV' and 'VIS') are
combined. From these data, we obtained the UV solar spectrum above
Earth's atmosphere at a distance of one astronomical unit (initial
values for studying the UV solar variability). (1 data file).
Title: SOLAR/SOLSPEC mission on ISS: In-flight performance for SSI
measurements in the UV
Authors: Bolsée, D.; Pereira, N.; Gillotay, D.; Pandey, P.; Cessateur,
G.; Foujols, T.; Bekki, S.; Hauchecorne, A.; Meftah, M.; Damé, L.;
Hersé, M.; Michel, A.; Jacobs, C.; Sela, A.
Bibcode: 2017A&A...600A..21B
Altcode:
Context. The SOLar SPECtrum (SOLSPEC) experiment is part of the
Solar Monitoring Observatory (SOLAR) payload, and has been externally
mounted on the Columbus module of the International Space Station (ISS)
since 2008. SOLAR/SOLSPEC combines three absolutely calibrated double
monochromators with concave gratings for measuring the solar spectral
irradiance (SSI) from 166 nm to 3088 nm. This physical quantity is a
key input for studies of climatology, planetary atmospheres, and solar
physics.
Aims: A general description of the instrument is given,
including in-flight operations and performance of the ultraviolet
(UV) channel from 175 nm to 340 nm.
Methods: We developed a
range of processing and correction methods, which are described in
detail. For example, methods for correcting thermal behavior effects,
instrument linearity, and especially the accuracy of the wavelength
and absolute radiometric scales have been validated by modeling the
standard uncertainties.
Results: The deliverable is a quiet Sun
UV reference solar spectrum as measured by SOLAR/SOLSPEC during the
minimum of solar activity prior to cycle 24. Comparisons with other
instruments measuring SSI are also presented. The quiet Sun UV
spectrum (FITS file) is only available at the CDS via anonymous ftp to
http://cdsarc.u-strasbg.fr
(http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/600/A21
Title: A new solar reference spectrum from 165 to 3088 nm
Authors: Damé, Luc; Meftah, Mustapha; Bolsée, David; Pereira, Nuno;
Bekki, Slimane; Hauchecorne, Alain; Irbah, Abdenour; Cessateur, Gaël;
Sluse, Dominique
Bibcode: 2017EGUGA..1913906D
Altcode:
Since April 5, 2008 and until February 15, 2017 the SOLAR/SOLSPEC
spectro-radiometer on the International Space Station performed
accurate measurements of Solar Spectral Irradiance (SSI) from the far
ultraviolet to the infrared (165 nm to 3088 nm). These measurements
are of primary importance for a better understanding of solar physics
and of the impact of solar variability on climate (via Earth's
atmospheric photochemistry). In particular, a new reference solar
spectrum is established covering most of the unusual solar cycle
24 from minimum in 2008 to maximum. Temporal variability in the UV
(165 to 400 nm) is presented in several wavelengths bands. These
results are possible thanks to revised engineering corrections,
improved calibrations and new procedures to account for thermal and
aging advanced corrections. Uncertainties on these measurements are
evaluated and compare favorably with other instruments.
Title: 8 years of Solar Spectral Irradiance Observations from the
ISS with the SOLAR/SOLSPEC Instrument
Authors: Damé, L.; Bolsée, D.; Meftah, M.; Irbah, A.; Hauchecorne,
A.; Bekki, S.; Pereira, N.; Cessateur, G.; Marchand, M.; Thiéblemont,
R.; Foujols, T.
Bibcode: 2016AGUFMSA51B2426D
Altcode:
Accurate measurements of Solar Spectral Irradiance (SSI) are of
primary importance for a better understanding of solar physics
and of the impact of solar variability on climate (via Earth's
atmospheric photochemistry). The acquisition of a top of atmosphere
reference solar spectrum and of its temporal and spectral variability
during the unusual solar cycle 24 is of prime interest for these
studies. These measurements are performed since April 2008 with the
SOLSPEC spectro-radiometer from the far ultraviolet to the infrared
(166 nm to 3088 nm). This instrument, developed under a fruitful
LATMOS/BIRA-IASB collaboration, is part of the Solar Monitoring
Observatory (SOLAR) payload, externally mounted on the Columbus module
of the International Space Station (ISS). The SOLAR mission, with its
actual 8 years duration, will cover almost the entire solar cycle 24. We
present here the in-flight operations and performances of the SOLSPEC
instrument, including the engineering corrections, calibrations and
improved know-how procedure for aging corrections. Accordingly, a SSI
reference spectrum from the UV to the NIR will be presented, together
with its UV variability, as measured by SOLAR/SOLSPEC. Uncertainties
on these measurements and comparisons with other instruments will be
briefly discussed.
Title: A new solar reference spectrum obtained with the SOLAR/SOLSPEC
space-based spectro-radiometer
Authors: Meftah, M.; Bolsée, D.; Hauchecorne, A.; Damé, L.; Bekki,
S.; Pereira, N.
Bibcode: 2016AGUFMSH31B2554M
Altcode:
The solar spectrum is a key input for different disciplines such as
Solar Physics and Climate Physics. Based on SOLAR/SOLSPEC data, we
will present a new solar irradiance spectrum from 165 to 3088 nm. The
methodology for obtaining these results will be described. Finally,
this new solar reference spectrum will be compared with other solar
irradiance reference spectra (ATLAS 3 and WHI 2008).
Title: Solar Irradiance from 165 to 400 nm in 2008 and UV Variations
in Three Spectral Bands During Solar Cycle 24
Authors: Meftah, M.; Bolsée, D.; Damé, L.; Hauchecorne, A.; Pereira,
N.; Irbah, A.; Bekki, S.; Cessateur, G.; Foujols, T.; Thiéblemont, R.
Bibcode: 2016SoPh..291.3527M
Altcode: 2016SoPh..tmp..162M
Accurate measurements of the solar spectral irradiance (SSI) and
its temporal variations are of primary interest to better understand
solar mechanisms, and the links between solar variability and Earth's
atmosphere and climate. The SOLar SPECtrum (SOLSPEC) instrument of the
Solar Monitoring Observatory (SOLAR) payload onboard the International
Space Station (ISS) has been built to carry out SSI measurements from
165 to 3088 nm. We focus here on the ultraviolet (UV) part of the
measured solar spectrum (wavelengths less than 400 nm) because the
UV part is potentially important for understanding the solar forcing
of Earth's atmosphere and climate. We present here SOLAR/SOLSPEC UV
data obtained since 2008, and their variations in three spectral bands
during Solar Cycle 24. They are compared with previously reported UV
measurements and model reconstructions, and differences are discussed.
Title: VizieR Online Data Catalog: Sun UV spectrum
(06/06/2008-26/04/2009) (Bolsee+, 2017)
Authors: Bolsee, D.; Pereira, N.; Gillotay, D.; Pandey, P.; Cessateur,
G.; Foujols, T.; Bekki, S.; Hauchecorne, A.; Meftah, M.; Dame, L.;
Herse, M.; Michel, A.; Jacobs, C.; Sela, A.
Bibcode: 2016yCat..36000021B
Altcode:
This file provides the data of the Figure 12 of the paper. It is
the average spectral irradiance of the Sun as measured by the space
instrument SOLAR/SOLSPEC on ISS during the minimum of solar activity
prior to cycle 24. Spectral range: 175nm-340nm by step of 0.5nm. Time
interval for averaging: 6th June 2008 - 26th April 2009. (1
data file).
Title: Variations in the Geometry of the Sun Observed with HMI/SDO
during Cycle 24
Authors: Irbah, Abdenour; Damé, Luc
Bibcode: 2016usc..confE.128I
Altcode:
Geometry of the Sun and its temporal variations observed with
ground-based instruments are still subject to questioning. The geometry,
which inform us on the interior of the Sun, is achieved by high
resolution measurements of the radius, oblateness and gravitational
moments c2 and c4. Several space missions were developed these last
decades to validate or refute its observed variations with ground
experiments and the link with solar activity. High angular resolution
of solar radius measurements and its long term trend is however a
challenge in Space. The first attempts with MDI (Soho) then SODISM
(PICARD) and HMI (SDO) revealed the difficulties of such measures
due to hostile environment which introduces thermal variations of
the instruments along the satellite orbit. These variations have
non negligible impacts on optical properties of onboard telescopes
and therefore on images and parameters extracted, such as the solar
radius. We need to take into account the thermal behavior (housekeeping
data) recorded together with the science data to correct them. Solar
oblateness and gravitational moments ask for both special spacecraft
operations and appropriate processing methods to obtain the needed
accuracy for their measurements. We present here some results on the
solar radius and oblateness obtained with HMI data. Images analysed
cover six years since May 1, 2010 (beginning of Cycle 24), until
now. Results show that the geometry of the Sun presents some temporal
variations related to solar activity. In particular we evidence a
Quasi-Biennale Oscillation (QBO) correlated with the solar cycle,
as was observed with ground observations.
Title: 8 years of Solar Spectral Irradiance Variability Observed
from the ISS with the SOLAR/SOLSPEC Instrument
Authors: Damé, Luc; Bolsée, David; Meftah, Mustapha; Irbah, Abdenour;
Hauchecorne, Alain; Bekki, Slimane; Pereira, Nuno; Cessateur, Marchand;
Gäel; , Marion; et al.
Bibcode: 2016usc..confE.129D
Altcode:
Accurate measurements of Solar Spectral Irradiance (SSI) are of
primary importance for a better understanding of solar physics
and of the impact of solar variability on climate (via Earth's
atmospheric photochemistry). The acquisition of a top of atmosphere
reference solar spectrum and of its temporal and spectral variability
during the unusual solar cycle 24 is of prime interest for these
studies. These measurements are performed since April 2008 with the
SOLSPEC spectro-radiometer from the far ultraviolet to the infrared
(166 nm to 3088 nm). This instrument, developed under a fruitful
LATMOS/BIRA-IASB collaboration, is part of the Solar Monitoring
Observatory (SOLAR) payload, externally mounted on the Columbus module
of the International Space Station (ISS). The SOLAR mission, with
its actual 8 years duration, will cover almost the entire solar cycle
24. We present here the in-flight operations and performances of the
SOLSPEC instrument, including the engineering corrections, calibrations
and improved know-how procedure for aging corrections. Accordingly,
a SSI reference spectrum from the UV to the NIR will be presented,
together with its variability in the UV, as measured by SOLAR/SOLSPEC
for 8 years. Uncertainties on these measurements and comparisons with
other instruments will be briefly discussed.
Title: Future space missions and ground observatory for measurements
of coronal magnetic fields
Authors: Fineschi, Silvano; Gibson, Sarah; Bemporad, Alessandro;
Zhukov, Andrei; Damé, Luc; Susino, Roberto; Larruquert, Juan
Bibcode: 2016cosp...41E.602F
Altcode:
This presentation gives an overview of the near-future perspectives for
probing coronal magnetism from space missions (i.e., SCORE and ASPIICS)
and ground-based observatory (ESCAPE). Spectro-polarimetric imaging of
coronal emission-lines in the visible-light wavelength-band provides an
important diagnostics tool of the coronal magnetism. The interpretation
in terms of Hanle and Zeeman effect of the line-polarization
in forbidden emission-lines yields information on the direction
and strength of the coronal magnetic field. As study case, this
presentation will describe the Torino Coronal Magnetograph (CorMag)
for the spectro-polarimetric observation of the FeXIV, 530.3 nm,
forbidden emission-line. CorMag - consisting of a Liquid Crystal (LC)
Lyot filter and a LC linear polarimeter. The CorMag filter is part
of the ESCAPE experiment to be based at the French-Italian Concordia
base in Antarctica. The linear polarization by resonance scattering
of coronal permitted line-emission in the ultraviolet (UV)can be
modified by magnetic fields through the Hanle effect. Space-based
UV spectro-polarimeters would provide an additional tool for the
disgnostics of coronal magnetism. As a case study of space-borne UV
spectro-polarimeters, this presentation will describe the future upgrade
of the Sounding-rocket Coronagraphic Experiment (SCORE) to include new
generation, high-efficiency UV polarizer with the capability of imaging
polarimetry of the HI Lyman-α, 121.6 nm. SCORE is a multi-wavelength
imager for the emission-lines, HeII 30.4 nm and HI 121.6 nm, and
visible-light broad-band emission of the polarized K-corona. SCORE
has flown successfully in 2009. The second lauch is scheduled in
2016. Proba-3 is the other future solar mission that would provide
the opportunity of diagnosing the coronal magnetic field. Proba-3 is
the first precision formation-flying mission to launched in 2019). A
pair of satellites will fly together maintaining a fixed configuration
as a 'large rigid structure' in space. The paired satellites will
together form a 150-m long solar coronagraph (ASPIICS) to study the
Sun's faint corona closer to the solar limb than has ever before been
achieved. High-resolution imaging in polarized visible-light of shock
waves generated by Coronal Mass Ejections would provide a diagnostics
of the magnetic field in the pre-shock ambient corona.
Title: SOLAR/SOLSPEC ultraviolet solar spectral irradiance variability
since 2008
Authors: Damé, Luc; Bolsee, David; Hauchecorne, Alain; Meftah,
Mustapha; Bekki, Slimane; Pereira, Nuno
Bibcode: 2016cosp...41E.398D
Altcode:
The SOLAR/SOLSPEC experiment measures the Solar Spectral Irradiance
(SSI) from the Space Station since April 2008. Measurements are carried
between 166 nm and 3088 nm by three double-monochromators. SSI,
particularly in the ultraviolet, is a key input to determine the
dynamics and coupling of Earth's atmosphere in response to solar
and terrestrial inputs. In-flight operations and performances of the
instrument, including corrections, will be presented for the 8 years
of the mission. After an accurate calibration following recent special
on-orbit new operations, we present the variability measured in the UV
by SOLAR/SOLSPEC. The accuracy of these measurements will be discussed.
Title: Main results of the PICARD mission
Authors: Meftah, M.; Corbard, T.; Hauchecorne, A.; Irbah, A.; Boumier,
P.; Chevalier, A.; Schmutz, W.; Ikhlef, R.; Morand, F.; Renaud, C.;
Hochedez, J. -F.; Cessateur, G.; Turck-Chièze, S.; Salabert, D.;
Rouzé, M.; van Ruymbeke, M.; Zhu, P.; Kholikov, S.; Koller, S.;
Conscience, C.; Dewitte, S.; Damé, L.; Djafer, D.
Bibcode: 2016SPIE.9904E..0ZM
Altcode:
PICARD is a mission devoted to solar variability observations through
imagery and radiometric measurements. The main goal is to provide data
for scientific investigation first in the area of solar physics, and
second in the assessment of the influence of the solar variability on
the Earth climate variability. PICARD contains a double program with
in-space and on-ground measurements. The PICARD spacecraft was launched
on June 15, 2010, commissioned in-flight in October of the same year
and was retired in April 2014. The PICARD ground-based observatory is
operational since May 2011. We shall give a short overview of the PICARD
instrumentation. New estimates of the absolute values of the total solar
irradiance, of the solar spectral irradiance at typical wavelengths,
and of the solar oblateness will be given. We will also report about
helioseismic studies. Finally, we will present our current results
about solar radius variations after six years of solar observation.
Title: How mission requirements affect observations: case of the
PICARD mission
Authors: Irbah, A.; Meftah, M.; Hauchecorne, A.; Damé, L.; Djafer, D.
Bibcode: 2016SPIE.9904E..4GI
Altcode:
The scientific objectives of a space mission result into instrumental
developments and specific satellite operations to observe astronomical
objects of interest. The payload in its space environment is however
subject to important thermal variations that affect observations. This
is well observed when images of the Sun are recorded with the constraint
of keeping the solar rotational axis in a constant direction relatively
to the camera reference frame. Consequences are clearly observed
on image positions that follow the thermal variations induced by
the satellite orbit. This is, in particular, the case for the space
mission PICARD. This phenomenon is similar to defocus and motions of
images recorded with ground-based telescopes. We first present some
simulations showing these effects. We then compare our results with
real data obtained from the space mission PICARD.
Title: Solar seeing monitor MISOLFA: A new method for estimating
atmospheric turbulence parameters
Authors: Irbah, A.; Borgnino, J.; Djafer, D.; Damé, L.; Keckhut, P.
Bibcode: 2016A&A...591A.150I
Altcode:
Aims: Daily observation conditions are needed when observing the
Sun at high angular resolution. MISOLFA is a daytime seeing monitor
developed for this purpose that allows the estimation of the spatial
and temporal parameters of atmospheric turbulence. This information
is necessary, for instance, for astrometric measurements of the
solar radius performed at Calern Observatory (France) with SODISM
II, the ground-based version of the SODISM instrument of the PICARD
mission.
Methods: We present a new way to estimate the spatial
parameters of atmospheric turbulence for daily observations. This
method is less sensitive to vibrations and guiding defaults of the
telescope since it uses short-exposure images. It is based on the
comparison of the optical transfer function obtained from solar data
and the theoretical values deduced from the Kolmogorov and Von Kàrmàn
models. This method, previously tested on simulated solar images, is
applied to real data recorded at Calern Observatory in July 2013 with
the MISOLFA monitor.
Results: First, we use data recorded in the
pupil plane mode of MISOLFA and evaluate the turbulence characteristic
times of angle-of-arrival fluctuations: between 5 and 16 ms. Second,
we use the focal plane mode of MISOLFA to simultaneously record solar
images to obtain isoplanatic angles: ranging from 1 to 5 arcsec (in
agreement with previously published values). These images and our
new method allow Fried's parameter to be measured; it ranges from 0.5
cm to 4.7 cm with a mean value of 1.5 cm when Kolmogorov's model is
considered, and from less than 0.5 to 2.6 cm with a mean value of 1.3
cm for the Von Kàrmàn model. Measurements of the spatial coherence
outer scale parameter are also obtained when using the Von Kàrmàn
model; it ranges from 0.25 to 13 m with a mean value of 3.4 m for the
four days of observation that we analyzed. We found that its value
can undergo large variations in only a few hours and that more data
analysis is needed to better define its statistics.
Title: HiRISE/NEOCE: an ESA M5 formation flying proposed mission
combining high resolution and coronagraphy for ultimate observations
of the chromosphere, corona and interface
Authors: Damé, Luc; Von Fay-Siebenburgen Erdélyi, Robert
Bibcode: 2016cosp...41E.397D
Altcode:
The global understanding of the solar environment through the magnetic
field emergence and dissipation, and its influence on Earth, is at
the centre of the four major thematics addressed by HiRISE/NEOCE (High
Resolution Imaging and Spectroscopy Explorer/New Externally Occulted
Coronagraph Experiment). They are interlinked and also complementary:
the internal structure of the Sun determines the surface activity
and dynamics that trigger magnetic field structuring which evolution,
variation and dissipation will, in turn, explain the coronal heating
onset and the major energy releases that feed the influence of the Sun
on Earth. The 4 major themes of HiRISE/NEOCE are: - fine structure of
the chromosphere-corona interface by 2D spectroscopy in FUV at very
high resolution; - coronal heating roots in inner corona by ultimate
externally-occulted coronagraphy; - resolved and global helioseismology
thanks to continuity and stability of observing at L1 Lagrange point;
- solar variability and space climate with a global comprehensive view
of UV variability as well. Recent missions have shown the definite
role of waves and of the magnetic field deep in the inner corona, at
the chromosphere-corona interface, where dramatic changes occur. The
dynamics of the chromosphere and corona is controlled by the emerging
magnetic field, guided by the coronal magnetic field. Accordingly,
the direct measurement of the chromospheric and coronal magnetic
fields is of prime importance. This is implemented in HiRISE/NEOCE,
to be proposed for ESA M5 ideally placed at the L1 Lagrangian point,
providing FUV imaging and spectro-imaging, EUV and XUV imaging and
spectroscopy, and ultimate coronagraphy by a remote external occulter
(two satellites in formation flying 375 m apart minimizing scattered
light) allowing to characterize temperature, densities and velocities
up to the solar upper chromosphere, transition zone and inner
corona with, in particular, 2D very high resolution multi-spectral
imaging-spectroscopy and direct coronal magnetic field measurement:
a unique set of tools to understand the structuration and onset of
coronal heating. We give a detailed account of the major scientific
objectives, and present the ESA M5 proposed mission profile and model
payload (in particular of the SuperASPIICS package of visible, NIR
and UV, Lyman-Alpha and OVI, coronagraphs).
Title: SUITS/SWUSV: a small-size mission to address solar spectral
variability, space weather and solar-climate relations
Authors: Damé, Luc; Keckhut, Philippe; Hauchecorne, Alain; Meftah,
Mustapha; Bekki, Slimane
Bibcode: 2016cosp...41E.396D
Altcode:
We present the SUITS/SWUSV microsatellite mission investigation:
"Solar Ultraviolet Influence on Troposphere/Stratosphere, a Space
Weather & Ultraviolet Solar Variability" mission. SUITS/SWUSV was
developed to determine the origins of the Sun's activity, understand the
flaring process (high energy flare characterization) and onset of CMEs
(forecasting). Another major objective is to determine the dynamics and
coupling of Earth's atmosphere and its response to solar variability
(in particular UV) and terrestrial inputs. It therefore includes the
prediction and detection of major eruptions and coronal mass ejections
(Lyman-Alpha and Herzberg continuum imaging) the solar forcing on
the climate through radiation and their interactions with the local
stratosphere (UV spectral irradiance measures from 170 to 400 nm). The
mission is proposed on a sun-synchronous polar orbit 18h-6h (for
almost constant observing) and proposes a 7 instruments model payload
of 65 kg - 65 W with: SUAVE (Solar Ultraviolet Advanced Variability
Experiment), an optimized telescope for FUV (Lyman-Alpha) and MUV
(200-220 nm Herzberg continuum) imaging (sources of variability);
SOLSIM (Solar Spectral Irradiance Monitor), a spectrometer with 0.65
nm spectral resolution from 170 to 340 nm; SUPR (Solar Ultraviolet
Passband Radiometers), with UV filter radiometers at Lyman-Alpha,
Herzberg, MgII index, CN bandhead and UV bands coverage up to 400 nm;
HEBS (High Energy Burst Spectrometers), a large energy coverage (a few
tens of keV to a few hundreds of MeV) instrument to characterize large
flares; EPT-HET (Electron-Proton Telescope - High Energy Telescope),
measuring electrons, protons, and heavy ions over a large energy
range; ERBO (Earth Radiative Budget and Ozone) NADIR oriented; and a
vector magnetometer. Complete accommodation of the payload has been
performed on a PROBA type platform very nicely. Heritage is important
both for instruments (SODISM and PREMOS on PICARD, LYRA on PROBA-2,
SOLSPEC on ISS,...) and platform (PROBA-2, PROBA-V,...), leading to
high TRL levels (>7). SUITS/SWUSV was initially designed in view of
the ESA/CAS AO for a Small Mission; it is now envisaged for a joint
CNES/NASA opportunity with Europeans and Americans partners for a
possible flight in 2021.
Title: The future of solar spectral irradiance in the ultraviolet
with the SOLSIM double-monochromator
Authors: Damé, Luc; Bolsee, David; Rouanet, Nicolas; Gilbert, Pierre
Bibcode: 2016cosp...41E.399D
Altcode:
Solar Spectral Irradiance (SSI) in the UV, and its variability, are of
prime importance to quantify the solar forcing on the climate through
radiation and their interactions with the local stratosphere, noticeably
through the "top-down" mechanism amplifying UV solar forcing on the
climate (UV affects stratospheric dynamics and temperatures, altering
interplanetary waves and weather patterns both poleward and downward to
the lower stratosphere and tropopause regions). SOLSIM (Solar Spectral
Irradiance Monitor) is a newly designed double-monochromator instrument
covering the 170 - 340 nm ultraviolet spectral range. It is an enhanced
and optimized version of the previously flown SOLSPEC instrument
externally mounted on the Columbus module of the International Space
Station. While SOLSPEC had 3 double-monochromators to cover the UV to
the IR, the SOLSIM spectrometer is covering only the UV but with an
almost constant 0.65 nm spectral resolution from 170 to 340 nm. To
avoid thermal issues with the instrument, a sun-synchronous polar
orbit 18h-6h (for almost constant observing) is preferred to the Space
Station (SOLSIM is part of the model payload of the SUITS/SWUSV proposed
mission). Characteristics, performances and calibrations foreseen for
this new generation SSI instrument will be presented.
Title: The Measurement of the Solar Spectral Irradiance Variability
during the Solar Cycle 24 using SOLAR/SOLSPEC on ISS
Authors: Bolsée, David; Pereira, Nuno; Pandey, Praveen; Cessateur,
Gaël; Gillotay, Didier; Foujols, Thomas; Hauchecorne, Alain; Bekki,
Slimane; Marchand, Marion; Damé, Luc; Meftah, Mustapha; Bureau,
Jerôme
Bibcode: 2016EGUGA..18.8103B
Altcode:
Since April 2008, SOLAR/SOLSPEC measures the Solar Spectral Irradiance
(SSI) from 166 nm to 3088 nm. The instrument is a part of the Solar
Monitoring Observatory (SOLAR) payload, externally mounted on the
Columbus module of the International Space Station. As the SSI is a key
input for the validation of solar physics models, together with playing
a role in the climate system and photochemistry of the Earth atmosphere,
SOLAR/SOLSPEC spectral measurements becomes important. In this study,
the in-flight operations and performances of the instrument -including
the engineering corrections- will be presented for seven years of the
SOLAR mission. Following an accurate absolute calibration, the SSI
variability in the UV as measured by SOLAR/SOLSPEC in the course of the
solar cycle 24 will be presented and compared to other instruments. The
accuracy of these measurements will be also discussed here.
Title: Solar Spectral Irradiance at 782 nm as Measured by the SES
Sensor Onboard Picard
Authors: Meftah, M.; Hauchecorne, A.; Irbah, A.; Cessateur, G.; Bekki,
S.; Damé, L.; Bolsée, D.; Pereira, N.
Bibcode: 2016SoPh..291.1043M
Altcode: 2016SoPh..tmp...53M
Picard is a satellite dedicated to the simultaneous measurement
of the total and solar spectral irradiance, the solar diameter,
the solar shape, and to the Sun's interior through the methods of
helioseismology. The satellite was launched on June 15, 2010, and
pursued its data acquisitions until March 2014. A Sun Ecartometry Sensor
(SES) was developed to provide the stringent pointing requirements
of the satellite. The SES sensor produced an image of the Sun at
782 ±2.5 nm. From the SES data, we obtained a new time series of
the solar spectral irradiance at 782 nm from 2010 to 2014. During
this period of Solar Cycle 24, the amplitude of the changes has
been of the order of ± 0.08 %, corresponding to a range of about 2
×10−3Wm−2nm−1. SES observations
provided a qualitatively consistent evolution of the solar spectral
irradiance variability at 782 nm. SES data show similar amplitude
variations with the semi-empirical model Spectral And Total Irradiance
REconstruction for the Satellite era (SATIRE-S), whereas the Spectral
Irradiance Monitor instrument (SIM) onboard the SOlar Radiation and
Climate Experiment satellite (SORCE) highlights higher amplitudes.
Title: Solar radius measurements with the space instrument HMI (SDO)
Authors: Irbah, Abdanour; Hauchecorne, Alain; Meftah, Mustapha; Damé,
Luc; Keckhut, Philippe
Bibcode: 2016EGUGA..18.6886I
Altcode:
The solar radius variations and its effects on the Earth climate are
still a long scientific debate. The observed variations from ground
experiments were not totally admitted and several space missions
have had these measures as a goal. The high angular resolution of
radius measurements and its long-term trend is however a challenge in
space. The first attempts with MDI (Soho) then SODISM (PICARD) and HMI
(SDO) revealed the difficulties of such measures due to the hostile
environment which introduces thermal variations on the instruments all
along the satellite orbit. These variations have non-negligible impacts
on the optical properties of the onboard telescopes and therefore on
the images and the parameters which are extracted such as the solar
radius. We need then to make a posteriori corrections using the thermal
housekeeping's recorded together with the data science. We present here
how we make such correction on the solar radius obtained from the HMI
images. We will then compare and discuss the results with the solar
radius recorded at 607 nm with the ground-based instrument of PICARD.
Title: SUITS/SWUSV: a Solar-Terrestrial Space Weather & Climate
Mission
Authors: Damé, Luc; Hauchecorne, Alain
Bibcode: 2016EGUGA..1816581D
Altcode:
The SUITS/SWUSV (Solar Ultraviolet Influence on
Troposphere/Stratosphere, a Space Weather & Ultraviolet Solar
Variability mission) microsatellite mission is developed on one hand
to determine the origins of the Sun's activity, understand the flaring
process (high energy flare characterization) and onset (forecasting) of
Coronal Mass Ejections (CMEs) and, on the other hand, to determine the
dynamics and coupling of Earth's atmosphere and its response to solar
variability (in particular UV) and terrestrial inputs. It therefore
includes the prediction and detection of major eruptions and CMEs
(Lyman-Alpha and Herzberg continuum imaging 200-220 nm), the solar
forcing on the climate through radiation, and their interactions
with the local stratosphere (UV spectral irradiance 170-400 nm and
ozone measurements). SUITS/SWUSV includes a 8 instruments model
payload with, in particular for Space Weather and Climate, SUAVE
(Solar Ultraviolet Advanced Variability Experiment), an optimized
telescope for FUV (Lyman-Alpha) and MUV (Herzberg continuum) imaging
(sources of variability), SOLSIM (Solar Spectral Irradiance Monitor),
a spectrometer with 0.65 nm spectral resolution from 170 to 340 nm, SUPR
(Solar Ultraviolet Passband Radiometers), with UV filter radiometers
at Lyman-Alpha, Herzberg, MgII, CN bandhead and UV bands coverage up to
400 nm, and ERBO (Earth Radiative Budget and Ozone), NADIR oriented to
measure ozone (6 bands) and 0.1-100 μm ERB. Example of accommodation
of the payload has been performed on a new PROBA type platform very
nicely by Qinetic. Heritage is important both for instruments and
platform leading to high TRL levels. SUITS/SWUSV is designed in view
of ESA Small Mission Calls and other possible CNES/NASA opportunities
in the near future (Heliophysics, Earth Observation, etc.).
Title: Ground-based measurements of the solar diameter during the
rising phase of solar cycle 24
Authors: Meftah, M.; Corbard, T.; Irbah, A.; Ikhlef, R.; Morand, F.;
Renaud, C.; Hauchecorne, A.; Assus, P.; Borgnino, J.; Chauvineau, B.;
Crepel, M.; Dalaudier, F.; Damé, L.; Djafer, D.; Fodil, M.; Lesueur,
P.; Poiet, G.; Rouzé, M.; Sarkissian, A.; Ziad, A.; Laclare, F.
Bibcode: 2014A&A...569A..60M
Altcode:
Context. For the past thirty years, modern ground-based time-series of
the solar radius have shown different apparent variations according to
different instruments. The origins of these variations may result from
the observer, the instrument, the atmosphere, or the Sun. Solar radius
measurements have been made for a very long time and in different
ways. Yet we see inconsistencies in the measurements. Numerous
studies of solar radius variation appear in the literature, but
with conflicting results. These measurement differences are certainly
related to instrumental effects or atmospheric effects. Use of different
methods (determination of the solar radius), instruments, and effects
of Earth's atmosphere could explain the lack of consistency on the
past measurements. A survey of the solar radius has been initiated
in 1975 by Francis Laclare, at the Calern site of the Observatoire
de la Côte d'Azur (OCA). Several efforts are currently made from
space missions to obtain accurate solar astrometric measurements,
for example, to probe the long-term variations of solar radius, their
link with solar irradiance variations, and their influence on the
Earth climate.
Aims: The Picard program includes a ground-based
observatory consisting of different instruments based at the Calern site
(OCA, France). This set of instruments has been named "Picard Sol" and
consists of a Ritchey-Chrétien telescope providing full-disk images
of the Sun in five narrow-wavelength bandpasses (centered on 393.37,
535.7, 607.1, 782.2, and 1025.0 nm), a Sun-photometer that measures the
properties of atmospheric aerosol, a pyranometer for estimating a global
sky-quality index, a wide-field camera that detects the location of
clouds, and a generalized daytime seeing monitor allowing us to measure
the spatio-temporal parameters of the local turbulence. Picard Sol is
meant to perpetuate valuable historical series of the solar radius and
to initiate new time-series, in particular during solar cycle 24.
Methods: We defined the solar radius by the inflection-point position
of the solar-limb profiles taken at different angular positions of the
image. Our results were corrected for the effects of refraction and
turbulence by numerical methods.
Results: From a dataset of more
than 20 000 observations carried out between 2011 and 2013, we find a
solar radius of 959.78 ± 0.19 arcsec (696 113 ± 138 km) at 535.7 nm
after making all necessary corrections. For the other wavelengths in
the solar continuum, we derive very similar results. The solar radius
observed with the Solar Diameter Imager and Surface Mapper II during
the period 2011-2013 shows variations shorter than 50 milli-arcsec
that are out of phase with solar activity.
Title: Thermal effects on solar images recorded in space
Authors: Irbah, A.; Meftah, M.; Hauchecorne, A.; Damé, L.; Bocquier,
M.; Cissé, M.
Bibcode: 2014SPIE.9143E..42I
Altcode:
The Earth's atmosphere introduces a spatial frequency filtering in
the object images recorded with ground-based instruments. A solution
is to observe with telescopes onboard satellites to avoid atmospheric
effects and to obtain diffraction limited images. However, similar
atmosphere problems encountered with ground-based instruments may
subsist in space when we observe the Sun since thermal gradients at
the front of the instrument affect the observations. We present in
this paper some simulations showing how solar images recorded in a
telescope focal plane are directly impacted by thermal gradients in
its pupil plane. We then compare the results with real solar images
recorded with the PICARD mission in space.
Title: SUAVE: a UV telescope for space weather and solar variability
studies
Authors: Damé, L.; Meftah, M.; Irbah, A.; Hauchecorne, A.; Keckhut,
P.; Quémerais, E.
Bibcode: 2014SPIE.9144E..31D
Altcode:
SUAVE (Solar Ultraviolet Advanced Variability Experiment) is a far
ultraviolet (FUV) imaging solar telescope of novel design for ultimate
thermal stability and long lasting performances. SUAVE is a 90 mm
Ritchey- Chrétien telescope with SiC (Silicon Carbide) mirrors
and no entrance window for long and uncompromised observations
in the UV (no coatings of mirrors, flux limited to less than
a solar constant on filters to avoid degradation), associated
with an ultimate thermal control (heat evacuation, focus control,
stabilization). Design of the telescope and early thermal modeling
leading to a representative breadboard (a R and T program supported
by CNES) will be presented. SUAVE is the main instrument of the SUITS
(Solar Ultraviolet Influence on Troposphere/Stratosphere) microsatellite
mission, a small-size mission proposed to CNES and ESA.
Title: A nano-satellite to study the Sun and the Earth
Authors: Meftah, M.; Irbah, A.; Hauchecorne, A.; Damé, L.; Sarkissian,
A.; Keckhut, P.; Lagage, P. -O.; Dewitte, S.; Chevalier, A.
Bibcode: 2014SPIE.9085E..0YM
Altcode:
Since the launch of the first artificial satellite in 1957, more than
6,000 satellites have been sent into space. Despite technological
advances, the space domain remains little accessible. However, with
the miniaturization of electronic components, it has recently become
possible to develop small satellites with which scientific goals can
be addressed. Micro-satellites have demonstrated that these goals are
achievable. However, completion times remain long. Today, we hope
through the use of nano-satellites to reduce size, costs, time of
development and accordingly to increase accessibility to space for
scientific objectives. Nano-satellites have become important tools
for space development and utilization, which may lead to new ways of
space exploration. This paper is intended to present a future space
mission enabled by the development of nano-satellites and the underlying
technologies they employ. Our future mission expands observations of the
Sun (total solar irradiance and solar spectral irradiance measurements)
and of the Earth (outgoing long-wave radiation, short-wave radiation
measurements and stratospheric ozone measurements). Constellations of
nano-satellites providing simultaneous collection of data over a wide
area of geo-space may be built later and present a great interest for
Sun-Earth relationships.
Title: Picard SODISM, a Space Telescope to Study the Sun from the
Middle Ultraviolet to the Near Infrared
Authors: Meftah, M.; Hochedez, J. -F.; Irbah, A.; Hauchecorne, A.;
Boumier, P.; Corbard, T.; Turck-Chièze, S.; Abbaki, S.; Assus,
P.; Bertran, E.; Bourget, P.; Buisson, F.; Chaigneau, M.; Damé,
L.; Djafer, D.; Dufour, C.; Etcheto, P.; Ferrero, P.; Hersé, M.;
Marcovici, J. -P.; Meissonnier, M.; Morand, F.; Poiet, G.; Prado,
J. -Y.; Renaud, C.; Rouanet, N.; Rouzé, M.; Salabert, D.; Vieau,
A. -J.
Bibcode: 2014SoPh..289.1043M
Altcode: 2013arXiv1303.0731M
The Solar Diameter Imager and Surface Mapper (SODISM) onboard the
Picard space mission provides wide-field images of the photosphere
and chromosphere of the Sun in five narrow bandpasses centered at
215.0, 393.37, 535.7, 607.1, and 782.2 nm. The Picard spacecraft
was successfully launched on 15 June 2010 into a Sun-synchronous
dawn-dusk orbit. The Picard space mission represents a European asset
in collecting solar observations useful to improve Earth climatic
models. The scientific payload consists of the SODISM imager and
of two radiometers, SOlar VAriability Picard (SOVAP) and PREcision
MOnitor Sensor (PREMOS), which measure the Total Solar Irradiance
(TSI) and part of the Solar Spectral Irradiance (SSI).
Title: NEOCE: a new external occulting coronagraph experiment for
ultimate observations of the chromosphere, corona and interface
Authors: Damé, Luc; Fineschi, Silvano; Kuzin, Sergey; Von
Fay-Siebenburgen, Erdélyi Robert
Bibcode: 2014cosp...40E.617D
Altcode:
Several ground facilities and space missions are currently dedicated
to the study of the Sun at high resolution and of the solar corona
in particular. However, and despite significant progress with the
advent of space missions and UV, EUV and XUV direct observations
of the hot chromosphere and million-degrees coronal plasma, much is
yet to be achieved in the understanding of these high temperatures,
fine dynamic dissipative structures and of the coronal heating in
general. Recent missions have shown the definite role of a wide
range of waves and of the magnetic field deep in the inner corona,
at the chromosphere-corona interface, where dramatic and physically
fundamental changes occur. The dynamics of the chromosphere and corona
is controlled and governed by the emerging magnetic field. Accordingly,
the direct measurement of the chromospheric and coronal magnetic fields
is of prime importance. The solar corona consists of many localised
loop-like structures or threads with the plasmas brightening and
fading independently. The plasma evolution in each thread is believed
to be related to the formation of filaments, each one being dynamic,
in a non-equilibrium state. The mechanism sustaining this dynamics,
oscillations or waves (Alfvén or other magneto-plasma waves),
requires both very high-cadence, multi-spectral observations, and high
resolution and coronal magnetometry. This is foreseen in the future
Space Mission NEOCE (New External Occulting Coronagraph Experiment),
the ultimate new generation high-resolution coronagraphic heliospheric
mission, to be proposed for ESA M4. NEOCE, an evolution of the HiRISE
mission, is ideally placed at the L5 Lagrangian point (for a better
follow-up of CMEs), and provides FUV imaging and spectro-imaging,
EUV and XUV imaging and spectroscopy, and ultimate coronagraphy by
a remote external occulter (two satellites in formation flying 375 m
apart minimizing scattered light) allowing to characterize temperature,
densities and velocities up to the solar upper chromosphere, transition
zone and inner corona with, in particular, 2D very high resolution
multi-spectral imaging-spectroscopy and direct coronal magnetic field
measurement: a unique set of tools to understand the structuration and
onset of coronal heating. We give a detailed account of the proposed
mission profile, and its major scientific objectives and model payload
(in particular of the SuperASPIICS package of visible, NIR and UV,
Lyman-Alpha and OVI, coronagraphs).
Title: SWUSV: a microsatellite mission for space weather early
forecasting of major flares and CMEs and the complete monitoring of
the ultraviolet solar variability influence on climate
Authors: Damé, Luc
Bibcode: 2014cosp...40E.614D
Altcode:
The SWUSV (Space Weather & Ultraviolet Solar Variability) proposed
microsatellite mission encompasses three major scientific objectives:
(1) Space Weather including the prediction and detection of major
eruptions and coronal mass ejections (using Lyman-Alpha and Herzberg
continuum imaging and H-Alpha ground support); (2) solar forcing on
the climate through radiation and their interactions with the local
stratosphere (UV spectral irradiance from 180 to 400 nm by bands of
10 to 20 nm, including ozone, plus Lyman-Alpha and the CN bandhead);
(3) simultaneous local radiative budget of the Earth, UV to IR,
with an accuracy better than 1% in differential. The mission is on a
sun-synchronous polar orbit and proposes 5 instruments to the model
payload: SUAVE (Solar Ultraviolet Advanced Variability Experiment), an
optimized telescope for FUV (Lyman-Alpha) and MUV (200-220 nm Herzberg
continuum) imaging (sources of variability); UPR (Ultraviolet Passband
Radiometers), with 64 UV filter radiometers; a vector magnetometer;
thermal plasma measurements and Langmuir probes; and a total and
spectral solar irradiance and Earth radiative budget ensemble (SERB,
Solar irradiance & Earth Radiative Budget). SWUSV is proposed as
a small mission to CNES and to ESA for a possible flight as early
as 2020-2021. With opening to Chinese collaboration (ESA-CAS Small
Mission) a further instrument could be added (HEBS, High Energy Burst
Spectrometers) to reinforced Space Weather flares prediction objectives.
Title: SUMO: solar ultraviolet monitor and ozone nanosatellite for
spectral irradiance, ozone and Earth radiative budget simultaneous
evaluation
Authors: Damé, Luc
Bibcode: 2014cosp...40E.615D
Altcode:
SUMO is an innovative proof-of-concept nano-satellite which aims to
measure on the same platform the different components of the Earth
radiation budget, the solar energy input and the energy reemitted at the
top of the Earth atmosphere, with a particular focus on the UV part of
the spectrum and on the ozone layer, which are the most sensitive to
the solar variability. The far UV (FUV) is the only wavelength band
with energy absorbed in the high atmosphere (stratosphere), in the
ozone (Herzberg continuum, 200-220 nm) and oxygen bands, and its high
variability is most probably at the origin of a climate influence (UV
affects stratospheric dynamics and temperatures, altering interplanetary
waves and weather patterns both poleward and downward to the lower
stratosphere and tropopause regions). Recent measurements at the time of
the last solar minimum suggest that variations in the UV may be larger
than previously assumed what implies a very different response in both
stratospheric ozone and temperature. A simultaneous observation of
the incoming FUV and of the ozone (O _{3}) production, would bring an
invaluable information on this process of solar-climat forcing. Space
instruments have already measured the different components of the Earth
radiative budget but this is, to our knowledge, the first time that
all instruments are operated on the same platform. This characteristic
guarantees by itself obtaining original scientific results. SUMO is a
10x10x30 cm (3) nanosatellite (``3U"), the payload occupying ``1U",
i.e. a cube of 10x10x10 cm (3) for 1 kg and 1 W of power. Orbit is
polar since a further challenge in understanding the relation between
solar UV variability and stratospheric ozone on arctic and antarctic
regions. SUMO definition has been completed (platform and payload
assembly integration and tests are possible in 24 months) and it is
now intended to be proposed to CNES for a flight in 2017. Mission
is expected to last up to 1 year. Follow-up is 2 fold: on one part
a more complete set of measurements is possible by integrating SUMO
miniaturized instruments on a larger satellite (e.g. on the SWUSV
microsatellite mission for instance, the SERB package); on the other
part it is particularly advantageous to increase the coverage in local
time and latitude using a constellation of SUMO nanosatellites around
the Earth.
Title: The Space Weather & Ultraviolet Solar Variability
Microsatellite Mission (SWUSV)
Authors: Damé, Luc; Damé
Bibcode: 2014IAUS..300..525D
Altcode:
We present a summary of the scientific objectives, payload and mission
profile of the Space Weather & Ultraviolet Solar Variability
Microsatellite Mission (SWUSV) proposed to CNES and ESA (small mission).
Title: Segmentation of coronal features to understand the solar EUV
and UV irradiance variability
Authors: Kumara, S. T.; Kariyappa, R.; Zender, J. J.; Giono, G.;
Delouille, V.; Chitta, L. P.; Damé, L.; Hochedez, J. -F.; Verbeeck,
C.; Mampaey, B.; Doddamani, V. H.
Bibcode: 2014A&A...561A...9K
Altcode:
Context. The study of solar irradiance variability is of great
importance in heliophysics, the Earth's climate, and space weather
applications. These studies require careful identifying, tracking
and monitoring of active regions (ARs), coronal holes (CHs), and the
quiet Sun (QS).
Aims: We studied the variability of solar
irradiance for a period of two years (January 2011-December 2012)
using the Large Yield Radiometer (LYRA), the Sun Watcher using APS and
image Processing (SWAP) on board PROBA2, and the Atmospheric Imaging
Assembly (AIA) on board the Solar Dynamics Observatory (SDO).
Methods: We used the spatial possibilistic clustering algorithm (SPoCA)
to identify and segment coronal features from the EUV observations of
AIA. The AIA segmentation maps were then applied on SWAP images, and
parameters such as the intensity, fractional area, and contribution
of ARs/CHs/QS features were computed and compared with the full-disk
integrated intensity and LYRA irradiance measurements.
Results:
We report the results obtained from SDO/AIA and PROBA2/SWAP images
taken from January 2011 to December 2012 and compare the resulting
integrated full-disk intensity with PROBA2/LYRA irradiance. We
determine the contributions of the segmented features to EUV and UV
irradiance variations. The variations of the parameters resulting
from the segmentation, namely the area, integrated intensity, and
relative contribution to the solar irradiance, are compared with LYRA
irradiance. We find that the active regions have a great impact on the
irradiance fluctuations. In the EUV passbands considered in this study,
the QS is the greatest contributor to the solar irradiance, with up
to 63% of total intensity values. Active regions, on the other hand,
contribute to about 10%, and off-limb structures to about 24%. We
also find that the area of the features is highly variable suggesting
that their area has to be taken into account in irradiance models,
in addition to their intensity variations.
Conclusions:
We successfully show that the feature extraction allows us to use
EUV telescopes to measure irradiance fluctuations and to quantify
the contribution of each part to the EUV spectral solar irradiance
observed with a calibrated radiometer. This study also shows that
SPoCA is viable, and that the segmentation of images can be a useful
tool. We also provide the measurement correlation between SWAP and
AIA during this analysis.
Title: Extreme solar coronagraphy in Antarctica (ESCAPE) to support
ASPIICS/PROBA-3 ESA program
Authors: Damé, Luc
Bibcode: 2014cosp...40E.616D
Altcode:
The coronal heating problem is still one of the most debated questions
in solar physics. ESCAPE (the Extreme Solar Coronagraphy Antarctic
Program Experiment) is designed to measure wave properties in corona
and their possible contribution to the coronal heating and solar wind
acceleration. It measures the polarization of coronal line emission,
allowing to map the topology and dynamics of the magnetic field
in corona. Furthermore, ESCAPE will be able of up to 3 months of
continuous monitoring of the coronal activity, such as CMEs that are
relevant for space weather studies. The Dome C high plateau is unique
for coronagraphic observations: sky brightness is reduced, water vapour
is low, seeing is excellent and continuity of observations on several
weeks is possible. ESCAPE will perform 2-dimensional spectroscopy of
the forbidden line of FeXIV at 530.285 nm, of FeXIII at 1074.7 nm
and of the Sodium D3 line at 587 nm (precise line profile analysis
will allow the diagnostic of the nature of waves by simultaneous
measurements of velocities and intensities in the corona). ESCAPE is
approved by CNRS/INSU with a test this summer at Pic du Midi and a first
campaign planned at Dome C/Concordia in 2015/2016. Most subsystems
are available thanks to the ESA STARTIGER R&D program ``Toward
a New Generation of Formation Flying Coronagraph" performed in 2010
in support of the ASPIICS ESA/PROBA-3 formation flying coronagraph
mission. A Three Mirrors Anastigmat telescope and a 4 stages Liquid
Crystal Tunable-filter Polarimeter have been developed and allow us
to propose an automated Coronal Green Line full-field Polarimeter for
unique observations (waves nature and intensity to address coronal
heating) and with the best possible performances on Earth. No other
ground site would allow such coronagraphic performances (the sky
brightness is a factor 2 to 4 better than in Hawaii) and with high
spatial resolution (better than an arcsec). ESCAPE will also help in
validating the experimental approach of critical sub-systems of future
space coronagraphy missions (e.g. the 587 nm filters of ASPIICS), bring
ground simultaneous/complementary observations, and will open the way
to future and more ambitious projects in Antarctica (e.g. AFSIIC)
and in Space (e.g. HiRISE, NEOCE). ESCAPE is part of the SCAR/AAA
research working group international effort.
Title: Solar Activity Monitoring of Flares and CMEs Precursors
through Lyman-Alpha Imaging and Tracking of Filaments and Prominences
Authors: Damé, Luc; Khaled, Safinaz A.
Bibcode: 2014IAUS..300..523D
Altcode:
We investigate the advantages of imaging solar filaments and prominences
in Lyman-Alpha, coupled to H-Alpha on ground, to develop more reliable
precursors indicators for large flares, several hours before their
occurrence.
Title: Special Issue on "Heliospheric Physics during and after a
deep solar minimum"
Authors: Damé, Luc; Hady, A.
Bibcode: 2013JAdR....4..205D
Altcode:
No abstract at ADS
Title: The Space Weather and Ultraviolet Solar Variability (SWUSV)
Microsatellite Mission
Authors: Damé, Luc
Bibcode: 2013JAdR....4..235D
Altcode:
We present the ambitions of the SWUSV (Space Weather and Ultraviolet
Solar Variability) Microsatellite Mission that encompasses three major
scientific objectives: (1) Space Weather including the prediction and
detection of major eruptions and coronal mass ejections (Lyman-Alpha
and Herzberg continuum imaging); (2) solar forcing on the climate
through radiation and their interactions with the local stratosphere
(UV spectral irradiance from 180 to 400 nm by bands of 20 nm,
plus Lyman-Alpha and the CN bandhead); (3) simultaneous radiative
budget of the Earth, UV to IR, with an accuracy better than 1% in
differential. The paper briefly outlines the mission and describes
the five proposed instruments of the model payload: SUAVE (Solar
Ultraviolet Advanced Variability Experiment), an optimized telescope
for FUV (Lyman-Alpha) and MUV (200-220 nm Herzberg continuum) imaging
(sources of variability); UPR (Ultraviolet Passband Radiometers),
with 64 UV filter radiometers; a vector magnetometer; thermal plasma
measurements and Langmuir probes; and a total and spectral solar
irradiance and Earth radiative budget ensemble (SERB, Solar irradiance
& Earth Radiative Budget). SWUSV is proposed as a small mission
to CNES and to ESA for a possible flight as early as 2017-2018.
Title: Cooler and Hotter X-ray Bright Points from Hinode/XRT
Observations
Authors: Kariyappa, R.; DeLuca, E. E.; Saar, S. H.; Golub, L.; Damé,
L.; Varghese, B. A.
Bibcode: 2012ASPC..454..149K
Altcode:
We use a 7-hour (17:00 UT - 24:00 UT) time sequence of soft X-ray images
observed almost simultaneously in two filters (Ti_poly and Al_mesh) on
April 14, 2007 with X-Ray Telescope (XRT) on-board the Hinode mission
to determine the temperature of X-ray bright points (XBPs). A sample
of 14 XBPs and 2 background coronal regions have been identified and
selected on both the images for detailed analysis. The temperature of
XBPs is determined by filter ratio method. We find that the XBPs show
temperature fluctuations and that the average temperature ranges from
1.1 MK to 3.4 MK which may correspond to different X-ray fluxes. These
results suggest the existence of cooler and hotter XBPs and that the
heating rate of XBPs is highly variable on short time scales.
Title: SWUSV: a Space Weather Microsatellite Program to Investigate
CMEs Precursors and the Influence of Solar UV Variability on Climate
Authors: Damé, Luc; Dudok De Wit, Thierry; Abdel Hady, Ahmed; Mahrous,
Ayman; Quemerais, Eric; Keckhut, Philippe; Hauchecorne, Alain; Meftah,
Mustapha; Zaki, Amal; Khaled, Safinaz; Ghitas, Ahmed; Marzouk, Besheir
Bibcode: 2012cosp...39..394D
Altcode: 2012cosp.meet..394D
No abstract at ADS
Title: Solar Activity Monitoring of Flares and CMEs Precursors:
the Importance of Lyman-Alpha
Authors: Damé, Luc; Kretzschmar, Matthieu; Dammasch, Ingolf; Kumara,
S. T.; Kariyappa, R.; Dominique, Marie; Ueno, Satoru; Khaled, Safinaz
Bibcode: 2012cosp...39..395D
Altcode: 2012cosp.meet..395D
No abstract at ADS
Title: Segmentation of Coronal Features to Understand the UV and
EUV Irradiance Variations
Authors: Kumara, S. T.; Hochedez, Jean-François; Damé, Luc;
Doddamani, Vijayakumar H.; Kariyappa, R.
Bibcode: 2012cosp...39.1641K
Altcode: 2012cosp.meet.1641K
No abstract at ADS
Title: ESCAPE : a first step to high resolution solar coronagraphy
in Antarctica
Authors: Damé, L.; Abe, L.; Faurobert, M.; Fineschi, S.; Kuzin, S.;
Lamy, P.; Meftah, M.; Vives, S.
Bibcode: 2012EAS....55..359D
Altcode:
The Dome C high plateau is unique for coronagraphic observations: sky
brightness is reduced, water vapour is low, seeing is excellent and
continuity of observations on several weeks is possible. ESCAPE (the
Extreme Solar Coronagraphy Antarctic Program Experiment) will perform
2-dimensional spectroscopy of the forbidden line of FeXIV at 530.285 nm:
precise line profile analysis will allow the diagnostic of the nature
of waves by simultaneous measurements of velocities and intensities in
the corona. ESCAPE is proposed to Institut Paul-Emile Victor (IPEV)
for a campaign in 2012-2013 at Dome C/Concordia since all subsystems
are available in particular thanks to an ESA STARTIGER 2010 R&D
"Toward a New Generation of Formation Flying Coronagraph". Using
state-of-the-art technologies developed for Space missions (a
Three Mirrors Anastigmat telescope, the TMA, a 4 stages Liquid
Crystal Tunable-filter Polarimeter, the LCTP) allows us to propose
an automated Coronal Green Line full-field Polarimeter for unique
observations (waves nature and intensity to address coronal heating)
with the best possible performances on Earth and for preparing and
testing the technologies for the next steps in Space. No other site
would allow such coronagraphic performances (the sky brightness is a
factor 2 to 4 better than in Hawaï) and with high spatial resolution
(better than an arcsec is possible).
Title: New Technology Solar Coronagraphs
Authors: Koutchmy, S.; Bazin, C.; Damé, L.; Rochain, S.; Tavabi, E.
Bibcode: 2012EAS....55..375K
Altcode:
We present the Mirror Advanced technology Coronagraph (MAC) as a
new generation solar telescope to be put at suitable high altitude
coronal sites in order to resolve modern problems of solar physics,
like the origin of the heating of the chromosphere and of the corona,
the analysis of the mesospheric layers of the solar atmosphere and the
effects of shearing the photospheric magnetic fields on the dynamics
of the upper coronal layers.
Title: Preliminary Results on Irradiance Measurements from Lyra
and Swap
Authors: Kumara, S. T.; Kariyappa, R.; Dominique, M.; Berghmans, D.;
Damé, L.; Hochedez, J. F.; Doddamani, V. H.; Chitta, Lakshmi Pradeep
Bibcode: 2012AdAst2012E...5K
Altcode: 2012AdAst2012E..10K
No abstract at ADS
Title: Temperature variability in X-ray bright points observed
with Hinode/XRT
Authors: Kariyappa, R.; Deluca, E. E.; Saar, S. H.; Golub, L.; Damé,
L.; Pevtsov, A. A.; Varghese, B. A.
Bibcode: 2011A&A...526A..78K
Altcode:
Aims: We investigate the variability in temperature as
a function of time among a sample of coronal X-ray bright points
(XBPs).
Methods: We analysed a 7-h (17:00-24:00 UT) long time
sequence of soft X-ray images observed almost simultaneously in two
filters (Ti_poly and Al_mesh) on April 14, 2007 with X-ray telescope
(XRT) onboard the Hinode mission. We identified and selected 14 XBPs
for a detailed analysis. The light curves of XBPs were derived using
the SolarSoft library in IDL. The temperature of XBPs was determined
using the calibrated temperature response curves of the two filters
by means of the intensity ratio method.
Results: We find that
the XBPs show a high variability in their temperature and that the
average temperature ranges from 1.1 MK to 3.4 MK. The variations
in temperature are often correlated with changes in average X-ray
emission. It is evident from the results of time series that the XBP
heating rate can be highly variable on short timescales, suggesting
that it has a reconnection origin.
Title: Demonstrator of the formation flying solar coronagraph
ASPIICS/PROBA-3
Authors: Vives, Sébastien; Damé, Luc; Lamy, Philippe; Antonopoulos,
A.; Bon, W.; Capobianco, G.; Crescenzio, G.; da Deppo, V.; Ellouzi,
M.; Garcia, J.; Guillon, C.; Mazzoli, A.; Soilly, T.; Stathopoulos,
F.; Tsiganos, C.
Bibcode: 2010SPIE.7731E..47V
Altcode: 2010SPIE.7731E.136V
Formation Flying opens the possibility to conceive and deploy giant
solar coronagraphs in space permanently reproducing the optimum
conditions of a total eclipse of the Sun ("artificial" eclipse) thus
giving access to the inner corona with unprecedented spatial resolution
and contrast (low stray light). The first opportunity to implement such
a coronagraph "ASPIICS" will be offered by the European Space Agency
(ESA) PROBA-3 technology mission devoted to the in-orbit demonstration
of formation flying technologies. Two spacecrafts separated by about 150
m form a giant externally-occulted coronagraph: the optical part hosted
by one spacecraft remains entirely protected from direct sunlight
by remaining in the shadow of an external occulter hosted by the
other spacecraft. We developed and tested a scale-model 'breadboard'
(i.e., 30m) of the PROBA-3/ASPIICS Formation Flying coronagraph. The
investigations focused on two metrology systems capable of measuring
both the absolute pointing of the coronagraph (by sensing the projected
shadow and penumbra produced by the external occulting disk) and
the alignment of the formation (by re-imaging light sources located
on the rear-side of the occulting disk with the optical part of the
coronagraph). In this contribution, we will describe the demonstrator
and report on our results on the crucial question of the alignment and
pointing in space of long instruments (> 100 m) with an accuracy of
a few arcsec. This study has been conducted in the framework of an ESA
"STARTIGER" Initiative, a novel approach aimed at demonstrating the
feasibility of a new and promising technology on a very short time scale
(six months).
Title: ASPIICS: a giant coronagraph for the ESA/PROBA-3 Formation
Flying Mission
Authors: Lamy, Philippe; Damé, Luc; Vivès, Sébastien; Zhukov, Andrei
Bibcode: 2010SPIE.7731E..18L
Altcode: 2010SPIE.7731E..31L
Classical externally-occulted coronagraphs are presently limited in
their performances by the distance between the external occulter and
the front objective. The diffraction fringe from the occulter and the
vignetted pupil which degrades the spatial resolution prevent useful
observations of the white light corona inside typically 2-2.5 solar
radii. Formation flying offers an elegant solution to these limitations
and allows conceiving giant, externally-occulted coronagraphs using a
two-component space system with the external occulter on one spacecraft
and the optical instrument on the other spacecraft at a distance of
hundred meters. Such an instrument, ASPIICS (Association de Satellites
Pour l'Imagerie et l'Interférométrie de la Couronne Solaire), has
just been selected by the European Space Agency (ESA) to fly (launch
expected in 2014) on its third PROBA (Project for On-Board Autonomy)
mission of formation flying demonstration which is presently in phase
B. It will perform both high spatial resolution imaging of the solar
corona as well as 2- dimensional spectroscopy of several emission
lines (in particular the forbidden line of FeXIV at 530.285 nm) from
the coronal base out to 3 solar radii. For this, it will use filters,
polarisers and a solid Fabry-Perot interferometer ("étalon"). The
classical design of an externally-occulted coronagraph is adapted to the
formation flying configuration allowing the detection of the very inner
corona as close as 0.04-0.05 solar radii (40-50 arcsec) from the solar
limb. By tuning the position of the occulter spacecraft, it may even be
possible to reach the chromosphere and the upper part of the spicules.
Title: Simulation of the metrology of the PROBA-3/ASPIICS formation
flying solar coronagraph
Authors: Stathopoulos, F.; Antonopoulos, A.; Vives, S.; Damé, L.
Bibcode: 2010SPIE.7731E..44S
Altcode: 2010SPIE.7731E.133S
Formation Flying is now considered to be the most promising and
effective approach to deploy the forthcoming generation of very
large instruments in space. PROBA-3 is a technology mission devoted
to the in-orbit demonstration of formation flying techniques and
technologies. PROBA-3 will implement a giant coronagraph (called
ASPIICS) that will both demonstrate and exploit the capabilities
and performances of formation flying. ASPIICS is distributed on two
spacecrafts separated by 150m, one hosting the external occulting
disk and the other the optical part of the coronagraph. ASPIICS
will incorporate metrology units which will allow determining
both the absolute pointing and the relative alignment of the
formation. Photosensors located around the entrance pupil of the
coronagraph will determine the absolute positioning of the instrument
by sensing the penumbra behind the occulting disk. Light sources
located on the rear-side of the occulting disk will allow verifying
the alignment of the formation. We carried out a complete numerical
simulation of the metrology system and showed how corrections are
derived from the measurements to be applied to each spacecraft in
case of misalignments. This simulation was validated by a scaled
model of the coronagraph developed at Laboratoire d'Astrophysique de
Marseille. This study has been conducted in the framework of an ESA
"STARTIGER" Initiative, a novel approach aimed at demonstrating the
feasibility of a new and promising technology on a very short time scale
(six months).
Title: Towards a New Formation Flying Solar Coronagraph
Authors: Lamy, P.; Vives, S.; Curdt, W.; Dame, L.; Davila, J.; Defise,
J. M.; Fineschi, S.; Heinzel, P.; Kuzin, S.; Schmutz, W.; Tsinganos,
K.; Turck-Chieze, S.; Zhukov, A.
Bibcode: 2010ASPC..424...15L
Altcode:
We briefly describe an investigation aiming at the development of a
giant solar coronagraph instrument onboard of two satellites, separated
by about 150 m in formation flight for the detailed observation of the
solar coronal plasma. The European Space Agency (ESA) has selected this
instrument as the only payload onboard the Proba 3 satellites which
will be launched in 2013. The Greek team is developing the command
control board of the coronagraph.
Title: Calibration and alignment of the demonstrator of the
PROBA-3/ASPIICS formation flying coronagraph
Authors: Crescenzio, Giuseppe; Capobianco, Gerardo; da Deppo, Vania;
Damé, Luc; Vivès, Sébastien; Garcia, Josè; Guillon, Christophe
Bibcode: 2010SPIE.7731E..48C
Altcode: 2010SPIE.7731E.137C
This article describes the calibration and alignment procedures of a
demonstrator for the ASPIICS coronagraph proposed for the ESA technology
mission PROBA-3 aimed at demonstrating the feasibility of a Formation
Flying coronagraph. ASPIICS is distributed on two spacecrafts separated
by 150 m, one hosting the external occulting disk and the other the
optical part of the coronagraph. The purpose of the demonstrator
is to reproduce on ground the metrology systems that will equip the
coronagraph in order to realize the alignment of the two spacecrafts
and the absolute pointing to the center of the Sun. The demonstrator is
composed of a device that reproduces the solar umbra/penumbra created
by the solar occulter[1] and of a Three Mirror Anastigmatic (TMA)
telescope mounted on a hexapod, a new-generation platform that allows 6
degrees of freedom. A large plane folding mirror is used on ground to
obtain a distance between the occulter and the TMA up to 30 m. Photo
sensors located around the entrance pupil of the TMA determine the
absolute positioning of the instrument by sensing the penumbra behind
the occulting disk. Light sources (LEDs) located on the rear-side of the
occulting disk allow verifying the alignment of the formation. The paper
describes the whole demonstrator, its integration, its calibration, and
the performance of the metrology systems of the coronagraph. This study
has been conducted in the framework of an ESA "STARTIGER" Initiative,
a novel approach aimed at demonstrating the feasibility of a new and
promising technology on a very short time scale (six months).
Title: HiRISE Mission to Address the Dynamical Chromosphere-Corona
Interface
Authors: Damé, Luc; Lamy, Philippe; von Fay-Siebenburgen Erdélyi,
Robert
Bibcode: 2010cosp...38.2844D
Altcode: 2010cosp.meet.2844D
Several ground facilities and space missions are currently dedicated
to the study of the Sun at high resolution and of the solar corona
in particular. However, and despite significant progress with the
advent of space missions and UV, EUV and XUV direct observations of
the hot chro-mosphere and million degrees coronal plasma, much is yet
to be achieved in the understanding of these high temperatures, fine
dissipative structures and of the coronal heating in general. Recent
missions have shown the definite role of waves and of the magnetic
field deep in the inner corona, at the chromosphere-corona interface,
where dramatic changes occur. The dynamics of the chromosphere and
corona is controlled by the emerging magnetic field, guided by the
coronal magnetic field. Accordingly, the direct measurement of the
chromospheric and coronal magnetic fields is of prime importance. The
solar corona consists of many thin loops or threads with the plasmas
brightening and fading independently. The dynamics in each thread is
believed to be related to the formation of filaments, each one being
dynamic, in a non-equilibrium state. The mechanism sustaining that
dynamics, oscillations or waves (Alfvén or MHD?), require both very
high-cadence, multi-spectral observations, and high resolution. This
is foreseen in the future Space Mission HiRISE, the ultimate new
generation ultrahigh resolution, interferomet-ric and coronagraphic,
Solar Physics Mission, proposed for ESA Cosmic Vision (pre-selected
in 2007, and under preparation for 2012 second call). HiRISE (High
Resolution Imaging and Spectroscopy Explorer), at the L1 Lagrangian
point, provides meter class FUV imaging and spectro-imaging, EUV and
XUV imaging and spectroscopy, and ultimate coronagraphy by a remote
external occulter (satellites in formation flying 280 m apart) allowing
to characterize temperature, densities and velocities in the solar upper
chromosphere, transition zone and inner corona with, in particular, 2D
very high resolution multi-spectral imaging-spectroscopy, direct coronal
magnetic field measurement: a unique set of tools to understand the
structuration and onset of coronal heating. We give a detail account
of the proposed mission profile, major scien-tific objectives and
model payload of HiRISE, a natural complement to the Solar Probe type
missions lacking duty cycle, high resolution, spatial, spectral and
temporal multi-temperature diagnostics and full coronal magnetometry.
Title: ASPIICS / PROBA-3 formation flying externally-occulted giant
coronagraph mission
Authors: Lamy, Philippe; Damé, Luc
Bibcode: 2010cosp...38.1882L
Altcode: 2010cosp.meet.1882L
During the time operation of the Helios mission, from 1974 to
metricconverterProductID1986, a1986, a large number of magnetic clouds
was identified by the magnetic field and solar wind sensors onboard
the probes. Among these magnetic clouds, some of them were identified
by at least two probes, provided that IMP-8 and ISEE-3 were monitoring
the dayside magnetosphere. The magnetic cloud observed on from DOY 029
to DOY 030/1977 by Helios 1, Helios 2, and IMP-8 represents a potential
multi-spacecraft observed magnetic cloud. Despite the interaction with
the high-speed stream that compressed the magnetic cloud, the minimum
variance analysis technique showed the same direction of rotation of
the magnetic field inside the magnetic cloud. This helped to associate
the observation of the magnetic cloud at multi-spacecraft.
Title: Long-period intensity oscillations of the quiet solar
atmosphere from TRACE 1600 Åcontinuum observations.
Authors: Kariyappa, R.; Damé, L.
Bibcode: 2010MmSAI..81..786K
Altcode:
We have analysed a 6-hour long time sequence of ultraviolet (uv) images
obtained on May 24, 2003 in 1600 Å continuum under high spatial
and temporal resolutions from the Transition Region and Coronal
Explorer (TRACE). We have selected 15 isolated bright points, 15
network elements and 15 quiet background regions from these images for
detailed analysis. We derived the cumulative intensity values and the
light curves of these features for the total duration of observations,
and performed also a power spectrum analysis using the complete time
series data. We found that the uv bright points, the uv network and
the uv background regions exhibit long-period intensity oscillations
namely, 5.5 hours, 4.6 hours and 3.4 hours respectively, in addition
to the more familiar small scale intensity fluctuations. We suggest
that these longer periods of oscillation might be related to solar
atmospheric g-modes.
Title: ARENA Solar Astrophysics Working Group Reporting on Dome C
Exceptional Potential for Solar Observations
Authors: Damé, L.; Andretta, V.; Arena Solar Astrophysics Working
Group Members
Bibcode: 2010EAS....40..451D
Altcode:
The ARENA Solar Astrophysics Working Group (WG6) is reviewing the
exceptional site conditions prevailing at Dome C/Concordia making it
a unique place on Earth for solar observations: excellent seeing, low
sky brightness, low water vapour and high duty cycle. These qualities
open science programmes which can combine very high resolution,
coronagraphy, infrared access, and long time series (continuity). Major
objectives accessible are the chromosphere-corona interface at very
high resolution, direct magnetic field measurements in the chromosphere
(prominences) and in the corona, 2D imaging spectroscopy and waves. A
first mid-size facility is proposed and described, AFSIIC (Antarctica
Facility for Solar Interferometric Imaging and Coronagraphy),
using 3×Ø50 cm off-axis telescopes (1.4 m equivalent telescope)
to access these objectives with the proper flux, angular resolution
and coronagraphic potential. Support infrastructure and logistics have
been studied and are discussed, noticeably a 30 m tower to place the
observatory over the very thin surface turbulent layer of Dome C.
Title: The solar diameter is most probably constant over the solar
cycle
Authors: Damé, Luc
Bibcode: 2010cosp...38.1701D
Altcode: 2010cosp.meet.1701D
We analyzed 7 years of filtregrams data (150000 photograms and
magnetograms) of the SOHO/MDI experiment. We used the maximum possible
sampling compatible with full frame recording, carefully avoiding any
suspicious filtregram. Going further than the previous analysis of
Emilio et al. (Ap. J. 543, 2000) and Kuhn et al. (Ap. J. 613, 2004)
we better corrected for changes in optical aberrations and, along
Turmon et al. (Ap. J., 568, 396, 2002), we reduced radius measurement
errors by identifying active regions from magnetograms and by avoiding
radius measurements herein. We found that, within the limit of our noise
level uncertainties (8 to 9 mas), the solar diameter is compatible with
constancy over the half cycle investigated. Our results confirm the
reanalysis of the 7 years of MDI data of Antia (Ap. J. 590, 2003), with
a completely different method since using the ultra-precise frequency
variation of the f-modes (fundamental modes linked to the diameter),
who found (carefully removing the yearly Earth induced variations
and avoiding the SOHO data gap of 1999) that the diameter is constant
over the half solar cycle (radius variation are less than 0.6 km, 0.8
mas -nothing over noise level). We can conclude, along Antia, that:
"If a careful analysis is performed, then it turns out that there is
no evidence for any variation in the solar radius." There were no
theoretical reasons for large solar radius variations and there is
no observational evidence for them with consistent space observations
made with 3 different approaches.
Title: ASPIICS / PROBA-3: a formation flying externally-occulted
giant coronagraph mission
Authors: Lamy, Philippe; Damé, Luc; Curdt, W.; Davila, J.; Defise,
J. M.; Fineschi, S.; Heinzel, P.; Howard, R.; Kuzin, S.; Schmutz,
W.; Tsinganos, K.; Turck-Chièze, S.; Zhukov, A.
Bibcode: 2010cosp...38.2858L
Altcode: 2010cosp.meet.2858L
Classical externally-occulted coronagraphs are presently limited in
their performances by the distance between the external occulter and
the front objective. The diffraction fringe from the occulter and
the vignetted pupil which degrades the spatial resolution prevent
useful observa-tions of the white light corona inside typically 2-2.5
Rsun. Formation flying offers an elegant solution to these limitations
and allows conceiving giant, externally-occulted coronagraphs
us-ing a two-component space system with the external occulter on
one spacecraft and the optical instrument on the other spacecraft
at distances of hundred meters. Such an instrument has just been
selected by ESA to fly (by the end of 2013) on its PROBA-3 mission,
presently in phase B, to demonstrate formation flying. It will perform
both high spatial resolution imaging of the solar corona as well as
2-dimensional spectroscopy of several emission lines (in partic-ular
the forbidden line of FeXIV at 530.285 nm) from the coronal base out
to 3 Rsun using a Fabry-Perot interferometer. The classical design of
an externally-occulted coronagraph is adapted to the formation flying
configuration allowing the detection of the very inner corona as close
as 0.05 Rsun from the solar limb. By tuning the position of the occulter
spacecraft, it may even be possible to try reaching the chromosphere
and the upper part of the spicules. ASPIICS/PROBA-3 mission, payload
and scientific objectives are detailed.
Title: Multi-spacecraft observation of a magnetic cloud
Authors: de Lucas, Aline; Dal Lago, Alisson; Schwenn, Rainer; Clúa de
Gonzalez, Alicia L.; Marsch, Eckart; Lamy, Philippe; Damé, Luc; Curdt,
W.; Davila, J.; Defise, J. M.; Fineschi, S.; Heinzel, P.; Howard, R.;
Kuzin, S.; Schmutz, W.; Tsinganos, K.; Turck-Chièze, S.; Zhukov, A.
Bibcode: 2010cosp...38.1921D
Altcode: 2010cosp.meet.1921D
Classical externally-occulted coronagraphs are presently limited in
their performances by the distance between the external occulter and
the front objective. The diffraction fringe from the occulter and
the vignetted pupil which degrades the spatial resolution prevent
useful observa-tions of the white light corona inside typically 2-2.5
Rsun. Formation flying offers an elegant solution to these limitations
and allows conceiving giant, externally-occulted coronagraphs
us-ing a two-component space system with the external occulter on
one spacecraft and the optical instrument on the other spacecraft
at distances of hundred meters. Such an instrument has just been
selected by ESA to fly (by the end of 2013) on its PROBA-3 mission,
presently in phase B, to demonstrate formation flying. It will perform
both high spatial resolution imaging of the solar corona as well as
2-dimensional spectroscopy of several emission lines (in partic-ular
the forbidden line of FeXIV at 530.285 nm) from the coronal base out
to 3 Rsun using a Fabry-Perot interferometer. The classical design of
an externally-occulted coronagraph is adapted to the formation flying
configuration allowing the detection of the very inner corona as close
as 0.05 Rsun from the solar limb. By tuning the position of the occulter
spacecraft, it may even be possible to try reaching the chromosphere
and the upper part of the spicules. ASPIICS/PROBA-3 mission, payload
and scientific objectives are presented.
Title: 30 m Stable towers for optimum astronomical observations at
dome c/concordia
Authors: Dournaux, J. -L.; Amans, J. -P.; Damé, L.; Le Moigne, J.
Bibcode: 2010EAS....40..477D
Altcode:
This paper gives an overview of conceptual studies that have been
realized since 2007 on 30 m towers for Dome C taking into account
local available infrastructures and conditions. Some 30 m tower's
concepts are presented and finite element simulations are carried to
determine their dynamic behaviour including wind-induced vibrations,
and to optimize their design.
Title: New perspectives in solar coronagraphy offered by formation
flying: from PROBA-3 to Cosmic Vision
Authors: Lamy, P.; Vivès, S.; Damé, L.; Koutchmy, S.
Bibcode: 2008SPIE.7010E..1HL
Altcode:
Formation flying opens new perspectives in solar physics, and allow to
conceive giant, externally-occulted coronagraphs using a two-component
space system with the external occulter on one spacecraft and the
optical instrument on the other spacecraft at a distance of hundred
meters. Conditions close to those of a solar total eclipse can then be
achieved offering the capability of imaging the solar corona down to the
limb at very high spatial resolution. ASPIICS (Association de Satellites
Pour l'Imagerie et l'Interférométrie de la Couronne Solaire) is a
mission proposed to ESA in the framework of its PROBA-3 demonstration
program of formation flying which is presently in phase A. ASPIICS is
a single coronagraph which will perform both high spatial resolution
imaging of the solar corona as well as 2-dimensional spectroscopy of
several emission lines from the coronal base out to 3 R\beye using
a Fabry-Pérot étalon interferometer. The classical design of an
externally-occulted coronagraph is adapted to the formation flying
configuration allowing the detection of the very inner corona as
close as 0.01 R\beye from the solar limb. Super-ASPIICS is an even
more ambitious instrument part of the scientific payload of HiRise,
the High Resolution Imaging and Spectroscopy Explorer proposed to
ESA in the framework of its Cosmic Vision program. With an increased
inter-satellite distance of 280 m, an aperture of 300 mm, a spectral
domain extending from the ultraviolet to the near-infrared, and
spectroscopic capabilities, Super-ASPIICS will offer unprecedented
diagnostic capabilities, including the measurement of coronal magnetic
fields.
Title: Observational searches for g-mode oscillations in the quiet
solar atmosphere from TRACE 1600A Continuum Observations
Authors: Kariyappa, R.; Dame, L.
Bibcode: 2008arXiv0804.3502K
Altcode:
Our aim is to search for atmospheric g-mode oscillations in UV
network, UV bright points and Uv background regions. We have analysed
a 6-hours of time sequence of ultraviolet (uv) images obtained on
May 24, 2003 in 1600A continuum under high spatial and temporal
resolution from Transition Region and Coronal Explorer (TRACE). We
have selected an isolated 15 uv bright points, 15 uv network elements
and 15 uv background regions in a quiet region from the images for
the detailed analysis. We derived the cumulative intensity values of
these features. The light curves of all the features have been derived
for the total duration of observations and done the power spectrum
analysis using the time series data. We found that the uv bright points,
the uv network and uv background regions will exhibit a longer period
of intensity oscillations namely, 5.5 hours, 4.6 hours and 3.4 hours
respectively, in addition to the more familiar small scale intensity
fluctuations. We suggest that the longer periods of oscillation may
be related to solar atmospheric g-modes.
Title: Solar Astrophysics, Interferometry, and Coronagraphy at
DomeC/Concordia
Authors: Damé, L.; Amans, J. -P.; Dournaux, J. -L.; Koutchmy, S.;
Lamy, P.; Preumont, A.
Bibcode: 2008EAS....33..105D
Altcode:
Excellent seeing, coronal conditions, and very low IR thermal
background are qualities of the Dome C/Concordia station site that
will allow unique solar astrophysics science. We review the science
case for inner corona observations (onset of the coronal heating
mechanism still poorly understood) and the promises of high angular
resolution to disentangle the possible mechanisms at work between
waves, convection, and reconnection in this particularly magnetically
structured solar atmosphere between the high chromosphere and inner
corona. For coronagraphy, IR and high resolution possibilities, Dome
C is a case by itself between classical ground-based sites and space
opportunities. Telescopes from 50 cm (coronagraphy oriented) to 4 m
(full high resolution advantage including IR access) are proposed to
benefit from these remarkable observing capabilities. Using 3×O50
cm off-axis telescopes, we first propose a medium size facility
(1.4 m equivalent telescope) for very high resolution access, ADSIIC
(Antarctica Demonstrator of Solar Interferometric Imaging &
Coronagraphy), before the ultimate 9-telescope Solar Facility
equivalent to a 4 m diameter telescope: A-FOURMI (Antarctica 4 m
Interferometer). Finally, 30 m tower designs and their logistics using
standard containers and elementary elements of 6 m maximum length,
are presented and discussed. These towers are indeed of general
interest also for the other optical and IR telescopes intended for
Dome C/Concordia, allowing to get over most of the turbulent ground
layer and to reach the best possible permanent seeing conditions
(better than half an arcsec).
Title: Telescope and instrument robotization at Dome C
Authors: Strassmeier, K. G.; Agabi, K.; Agnoletto, L.; Allan, A.;
Andersen, M. I.; Ansorge, W.; Bortoletto, F.; Briguglio, R.; Buey,
J. -T.; Castellini, S.; Coudé du Foresto, V.; Damé, L.; Deeg,
H. J.; Eiroa, C.; Durand, G.; Fappani, D.; Frezzotti, M.; Granzer, T.;
Gröschke, A.; Kärcher, H. J.; Lenzen, R.; Mancini, A.; Montanari,
C.; Mora, A.; Pierre, A.; Pirnay, O.; Roncella, F.; Schmider, F. -X.;
Steele, I.; Storey, J. W. V.; Tothill, N. F. H.; Travouillon, T.;
Vittuari, L.
Bibcode: 2007AN....328..451S
Altcode: 2004astro.ph..8233Z
This article reviews the situation for robotization of telescopes
and instruments at the Antarctic station Concordia on Dome C. A
brain-storming meeting was held in Tenerife in March 2007 from which
this review emerged. We describe and summarize the challenges for
night-time operations of various astronomical experiments at conditions
``between Earth and Space'' and conclude that robotization is likely
a prerequisite for continuous astronomical data taking during the
2000-hour night at Dome C.
Title: Solar Shape Changes and Oscillations from Space (P15)
Authors: Damé, L.
Bibcode: 2006ihy..workE.107D
Altcode:
The diameter was observed to be constant over the last solar cycles and,
as such, is not a "proper" solar-terrestrial "climate" indicator. Ground
measurements with small telescopes are spurious diffraction and seeing
affected, the Maunder Minimum ones of Picard during the XVII century
not being an exception. Large instruments (like the 45 cm Gregory's of
A. Wittmann in Locarno and Tenerife) that average seeing cells see no
variations (< 40 mas) and, as well, space instruments (MDI/SOHO)
that are naturally not affected by turbulence. We present the four
approaches, Wittmann on ground with large telescopes, Kuhn et al. (2004)
who used the six pixels limb data of MDI, Antia (2003) with a completely
different method since using the ultra-precise frequency variation of
the f-modes, and our approach (Damé and Cugnet, 2006) using seven years
of MDI filtergrams data (150 000 photograms and magnetograms). These
four careful analyses converge towards the same insignificant variations
(below 15 mas for space experiments or even less: 0.6 km, 0.8 mas for
the helioseismology approach!). Following Antia, we conclude that:
"If a careful analysis is performed, then it turns out that there is
no evidence for any variation in the solar radius." There were no
theoretical reasons for large solar radius variations and there is
no observational evidence for them with consistent ground and space
observations. This being said, the radius measurements are of interest
for the solar shape changes that might occur along the cycle (sub-
surface convective flows?). Radius oscillations (but higher in the
atmosphere, further in the UV: 220 nm) might also bring up low order
p-modes and, eventually, g-modes if ever accessible. At the level of
formation of the 220 nm continuum there is the maximum magnification
of the p-modes and intensity oscillations. 220 nm is also the Lyman
Alpha absorption region and ozone formation layer. A New Solar Shape
and Oscillation Telescope (NSSOT) is proposed and designed along the
non-degraded UV imaging concept developed earlier for SODISM/PICARD
(Damé, et al., 1999, 2000, 2001), optimized for these measures of solar
shape and oscillations at 220 nm. It has a carbon-carbon structure, SiC
mirrors, no window and no spurious optics affecting thermal behavior and
scattered light. A model of simplicity and precision. Lyman Alpha and UV
images, in selected wavelengths, will complete these measurements. We
present the design and bread-boarding activities (SiC thermally
controlled mirrors) of NSSOT, and its scientific revisited objectives.
Title: Chromosphere and Transition Zone Dynamics and Heating: Need
for Future Space Missions
Authors: Damé, L.
Bibcode: 2006ihy..workE..34D
Altcode:
SOHO and TRACE observations have clearly shown that even the very
quietest part of the solar chromosphere is very structured and
dynamic with brightenings and waves. Diagnostics from this region
are very difficult because spectral lines are neither formed in
LTE nor under optically thin conditions that prevail higher in the
Transition Zone. The gas goes from being dominated by the gas pressure
in the photosphere to being dominated by the magnetic pressure in the
upper chromosphere, involving steep gradients to obtain significant
dissipation or heating. The ionization balance of important elements
is furthermore out of equilibrium. A proper understanding thus demands
very high spatial resolution with accurate measurements of velocity and
line width, uninterrupted in Space, across a broad range of temperature
("heights"), to distinguish between wave heating and reconnection
events in the chromosphere and Transition Zone. Complex modeling, that
ideally should include non-LTE radiative transfer in 3D including the
dynamic driving in the convection zone, non- equilibrium ionization,
magnetic fields, the transition region and the corona, will be necessary
to understand these observations. We will discuss various aspects of
this very complex problem and insist on ground measures and, above all,
Future Space Missions which should better address Doppler information,
temperature coverage and discrimination and, most important, very high
spatial resolution to progress on the way to a fully comprehensive
view of chromospheric and coronal heating.
Title: Observational Searches for Chromospheric g-Mode
Oscillationsfrom CaII H-Line Observations
Authors: Kariyappa, R.; Dame, L.; Hiremath, K. M.
Bibcode: 2006JApA...27..327K
Altcode:
We have used a high spatial and temporal resolution of long time
sequence of spectra in CaII H-line obtained at the Vacuum Tower
Telescope (VTT) of the Sacramento Peak Observatory on a quiet region
at the center of the solar disk over a large number of bright points
and network elements to search for atmospheric (chromospheric) g-mode
oscillations. An important parameter of the H-line profile, intensity at
H2V(IH2V), has been derived from a large number
of line profiles. We derived the light curves of all the bright points
and network elements. The light curves represent the main pulse with
large intensity amplitude and followed by several follower pulses with
lower intensity amplitudes. The light curves of these bright points
would give an impression that one can as well draw curves towards and
away from the highest peak (main pulse) showing an exponential growth
and decay of the amplitudes. An exponential decaying function has been
fitted for all the light curves of the bright points to determine the
damping time of the modes that are more or less the same, and one
value of the coefficient of exponent can represent reasonably well
the decay for all the cases. The FFT analysis of temporal variation of
both the bright points and the network elements indicates around 10-min
periodicity. We speculate that this longer period of oscillation may
be related to chromospheric g-mode oscillations.
Title: Search For Atmospheric G-mode Oscillations from TRACE
Observations
Authors: Kariyappa, R.; Dame, L.; Varghese, B. A.
Bibcode: 2006IAUJD...3E...1K
Altcode:
An identification and clarification of different modes of oscillations
may eventually illuminate the solar neutrino problem. The internal
g-modes of the Sun are the most powerful tool for investigation of
solar core and the neutrino problem. The detection of atmospheric
g-mode oscillations are also equally important in order to know
the role of different kinds of oscillations in the heating of the
chromosphere and corona. We have analysed a 6-hours of time sequence of
ultraviolet images obtained on May 24, 2003 in 1600 Å continuum under
high spatial and temporal resolution with TRACE Space Mission. We have
chosen 15 uv bright points, 15 uv network elements and 15 uv background
regions from the time sequence images for the detailed analysis. We
derived the cumulative intensity values of all these features using
SolarSoftware (SSW) in IDL. The light curves of all the features have
been generated for the total duration of observations. We have done
the power spectrum analysis using their time series data. We find that
the uv bright points, the uv network and uv background regions will
exhibit longer period of intensity oscillations namely, 5.5 hours,
4.6 hours and 3.4 hours respectively, in addition to small scale
intensity fluctuations. We suggest that these periods may be related
to a very high order atmospheric g-modes showing a large periods at
the transition region.
Title: Contribution of Chromospheric Features to UV Irradiance
Variability
Authors: Kariyappa, R.; Dame, L.
Bibcode: 2006IAUJD...8E...1K
Altcode:
We have determined the time series data of the different parameters
like the intensity, area, the full-disk intensity (spatial K index),
and the Full Width at Half Maximum (FWHM) for the segregated features
of the chromosphere from the CaII K spectroheliograms of 1992 and 1980,
observed at the NSO at Sac Peak, using their histograms taken for the
full-disk. We established, for the first time, from the results of 1992
and 1980 images that the FWHM can be used as a good index for measuring
and describing the chromospheric activity in the K-line. Our study
shows that besides the plages, a significant portion of the variation
observed in UV irradiance is related to the changing emission of the
network and intranetwork + background regions. This indicates that in
addition to plages and network, the intranetwork + background regions
may also play a significant role in their contribution to the variation
in UV irradiance. We estimated the contribution of various chromospheric
features to the total CaII K flux from the intensity time series data
and found that about 50% of the CaII K solar cycle variability results
from plages, about 32% from network, and about 18% from intranetwork +
background features.
Title: A Very High Resolution Vision for Solar Physics: Interferometry
& Spectral-Imaging in the Far Ultraviolet
Authors: Damé, L.
Bibcode: 2006ESASP.617E..35D
Altcode: 2006soho...17E..35D
No abstract at ADS
Title: Multi-aperture Instantaneous Interferometric Imaging of
Extended and Moving Objects by Phase Optimized Spatial Filtering
Authors: Dame, L.
Bibcode: 2006ESASP.621E..74D
Altcode: 2006spop.confE..74D
No abstract at ADS
Title: Preliminary results from the March 29, 2006 total eclipse
observations in Egypt
Authors: Koutchmy, S.; Daniel, J. -Y.; Mouette., J.; Vilinga, J.;
Noëns, J. -C.; Damé, L.; Faurobert, M.; Dara, H.; Hady, A.; Semeida,
M.; Sabry, M.; Domenech, A.; Munier, J. -M.; Jimenez, R.; Legault,
Th.; Viladrich, Ch.; Kuzin, S.; Pertsov, A.; O. A. Team
Bibcode: 2006sf2a.conf..547K
Altcode:
A coordinated effort has been carried in the framework of
the French-Egyptian scientific cooperation to permit joined
simultaneous eclipse observations of the solar corona during the
total solar eclipse of March 29, 2006. Spaceborne EIT and Lasco (SoHO)
observations were also planned at the same time and were successfully
collected. Scientists from other countries collaborated on different
experiments. The synthetic image showing the magnetic coronal structure
of this quasi-minimum corona seen in W-L is given. Some preliminary
results are presented; a White Light (W.L.) movie has been also taken
during the totality.
Title: SOLARNET & LAIME: Imaging & Spectroscopy in the
Far Ultraviolet
Authors: Damé, Luc; Koutchmy, Serge
Bibcode: 2006IAUS..233..435D
Altcode:
SOLARNET is a medium size high resolution solar physics mission proposed
to CNES and ESA for a new start in 2007 and a possible launch in 2012
(CNES) or later (ESA Cosmic Vision framework: 2015-2016). Partnerships
with India and China are under discussion, and several European
contributions are considered. At the center of the SOLARNET mission is
a 3-telescope interferometer of 1 meter baseline capable to provide 40
times the best ever spatial resolution achieved in Space with previous,
current or even planned solar missions: 20 mas - 20 km on the Sun in the
FUV. The interferometer is associated to an on-axis Subtractive Double
Monochromator coupled to an Imaging Fourier Transform Spectrometer
capable of high spectral (0.01 nm) and high temporal resolutions
(50 ms) on a field of view of 40 arcsec and covering the FUV and UV
spectral domains (from 117.5 to 400 nm). This will allow to access
process scales of magnetic reconnection, dissipation, emerging flux
and much more, from the chromosphere to the low corona with emphasis
on the transition zone where the magnetic confinement is expected
to be maximum. A whole new chapter of the physics of solar magnetic
field structuring, evolution and mapping from the photosphere to the
high atmosphere will be opened. The interferometer is completed by
instruments providing larger field of view and higher temperature
(EUV-XUV coronal imaging & spectroscopy) to define the context
and extension of the solar phenomena. The 3-telescope interferometer
design results of an extensive laboratory demonstration program
of interferometric imaging of extended objects. We will review the
scientific program of SOLARNET, describe the interferometer concept
and design, present the results of the breadboard and give a short
overview of the mission aspects. In a different category, LAIME,
the Lyman Alpha Imaging-Monitor Experiment, is a remarkably simple
(no mechanisms) and compact full Sun imager to be flown with TESIS on
the CORONAS-PHOTON mission in 2008. It could be the only chromospheric
imager to be flown in the next years, supporting Solar-B, STEREO,
SDO and the Belgian LYRA Lyman Alpha flux monitor. We will give a
short description of this unique 60 mm aperture imaging telescope,
dedicated to the investigation of the UV sources of solar variability
and of the chromospheric and coronal disruptive events (Moreton waves,
prominences, CMEs, etc.).
Title: Frontier full field spectro-imaging with the SOLARNET
3-telescope interferometric breadboard
Authors: Damé, L.; Fu, X.; Kozlowski, M.; Maury, V.; Montaron, C.
Bibcode: 2006cosp...36.3517D
Altcode: 2006cosp.meet.3517D
The SOLARNET breadboard consists in 3 small objectives of diameter
60 mm on a 165 mm baseline As such fed by a large siderostat acting
as the satellite platform it mimics the SOLARNET space mission using 3
larger 35 cm telescopes on a 1 meter equivalent interferometric baseline
Because of its compact design and of an appropriate imaging spectrometer
in the focal plane instantaneous imaging in narrow spectral bands is
possible The 3-telescopes interferometer design results of an extensive
laboratory demonstration program of interferometric imaging of extended
objects started 10 years ago The principles of the interferometric
compact recombination of the SOLARNET Space Mission capable of
large field instantaneous spectro-imaging have been demonstrated
in laboratory since 2000 Over the last 5 years the breadboard was
completed with active fine pointing and spectro-imaging capabilities
to directly observe the Sun and the breadboard was moved to the Grand
Sid erostat de Foucault at Meudon Observatory Ultimate refinements in
the global three telescopes phase measure by active spatial filtering
centering of the cophasing reference field of view have recently been
implemented to guarantee cophasing even on a moving changing reference
field of view Design and concepts will be explicited and the first
interferometric images of the Sun obtained at Meudon Observatory with
the breadboard will be presented validating the concept retained for
the SOLARNET space mission
Title: SOLARNET: a UV, FUV, EUV, XUV high resolution imaging,
spectro-imaging and spectroscopy mission.
Authors: Damé, L.
Bibcode: 2006cosp...36.3513D
Altcode: 2006cosp.meet.3513D
SOLARNET is a high resolution mission which encompass extremely high
resolution in the UV and FUV to access process scales of magnetic
reconnection dissipation emerging flux onset of Flares and CME s origin
of solar wind The chromosphere to the low corona with emphasis on
the transition zone where the magnetic confinement is expected to be
maximum are at the heart of this mission which will open a whole new
chapter of the physics of solar magnetic field structuring evolution
and mapping from the photosphere to the heliosphere SOLARNET is an
inexpensive and compact medium size high resolution solar physics
mission that will bring together most of the best of SOHO and TRACE
It is proposed to CNES and ESA for a new start in 2006 and a possible
launch in 2011-2012 to fill the gap before the first results of the
Solar Orbiter or Probe results in the late 2018 at best Partnerships
with India and China are under discussion and several European
contributions are considered SOLARNET instrumentation consists in a
multiple instrument payload to achieve both the necessary global view
of extended events and the detailed high resolution understanding of
them The major instrument is a 3-telescope interferometer of 1 meter
baseline capable to provide 50 times the best ever spatial resolution
achieved in Space with previous current or even planned solar missions
20 mas -- 20 km on the Sun in the FUV The interferometer is associated
to an on-axis Subtractive Double Monochromator coupled to an Imaging
Fourier Transform Spectrometer itself capable of very high spectral
Title: An Observational Evidence for Solar Atmospheric G-Mode
Oscillations From 1600A UV Continuum Observations
Authors: Kariyappa, R.; Dame, L.
Bibcode: 2006cosp...36....6K
Altcode: 2006cosp.meet....6K
An identification and clarification of different modes of oscillations
may eventually illuminate the solar neutrino problem Particularly the
internal g-modes of the Sun are the most powerful tool for investigation
of solar core and a way to solve for instance the neutrino problem We
have used a high spatial and temporal resolution of long time sequence
of images obtained under high spatial and temporal resolution with
TRACE Space Mission in 1600A UV continuum We derived the cumulative
intensity values of the UV bright points The light curves of the UV
bright points have been generated The FFT analysis of temporal variation
of the UV bright points of the transition region indicates an evidence
of longer periods of oscillations of the order of 45-min and 10-min This
confirms the results obtained from CaII H -line observations Kariyappa
et al 2005 and suggest that the longer period of oscillations may be
related to solar atmospheric g-mode oscillations The detailed results
of this analysis will be discussed in this paper
Title: The New Solar Shape and Oscillations Telescope (NSSOT)
Experiment for SOLARNET
Authors: Damé, L.
Bibcode: 2006cosp...36.3526D
Altcode: 2006cosp.meet.3526D
The diameter was observed to be constant over the solar cycle and as
such will never be a proper solar-terrestrial climate indicator ground
measures with small telescopes are spurius the Maunder Minimum ones of
Picard during the XVII century not being an exception Large instruments
like the 45 cm Gregorys of Axel Wittmann in Locarno and Tenerife which
average seeing cells see no variations ll 40 mas as well as the space
instrument MDI SOHO naturally not affected by turbulence either We
present the 4 approaches Wittmann on ground with large telescopes
Emilio et al 2000 and Kuhn et al 2004 whom used the 6 pixels limb
data of MDI Antia 2003 with a completely different method since using
the ultra-precise frequency variation of the f-modes and our approach
Dam e and Cugnet 2006 using the complete 7 years of filtergrams data
150 000 photograms and magnetograms of the SOHO MDI experiment These
4 careful analysis converge towards the same insignificant below 15
mas variations or even less 0 6 km 0 8 mas in the helioseismology
approach Following Antia we can conclude that If a careful analysis is
performed then it turns out that there is no evidence for any variation
in the solar radius There were no theoretical reasons for large solar
radius variations and there is no observational evidence for them
with consistent ground and space observations This being stated and
admitted the radius measure keeps interest through the solar shape
that might change along the cycle sub-surface convective flows
Title: The Lyman Alpha Imaging-Monitor Experiment (LAIME) for
TESIS/CORONAS-PHOTON
Authors: Damé, L.; Koutchmy, S.; Kuzin, S.; Lamy, P.; Malherbe,
J. -M.; Noëns, J. -C.
Bibcode: 2006cosp...36.3524D
Altcode: 2006cosp.meet.3524D
LAIME the Lyman Alpha Imaging-Monitor Experiment is a remarkably
simple no mechanisms and compact 100x100x400 mm full Sun imager to be
flown with TESIS on the CORONAS-PHOTON mission launch expected before
mid-2008 As such it will be the only true chromospheric imager to be
flown in the next years supporting TESIS EUV-XUV imaging SDO and the
Belgian LYRA Lyman Alpha flux monitor on the ESA PROBA-2 microsatellite
launch expected in September 2007 We will give a short description
of this unique O60 mm aperture imaging telescope dedicated to the
investigating of the magnetic sources of solar variability in the UV and
chromospheric and coronal disruptive events rapid waves Moreton waves
disparitions brusques of prominences filaments eruptions and CMEs onset
The resolution pixel is 2 7 arcsec the field of view 1 4 solar radius
and the acquisition cadence could be as high as 1 image minute The back
thinned E2V CCD in the focal plane is using frame transfer to avoid
shutter and mechanisms Further more the double Lyman Alpha filtering
allows a 40 AA FWHM bandwidth and excellent rejection yet providing
a vacuum seal design of the telescope MgF2 entrance window Structural
stability of the telescope focal length 1 m is preserved by a 4-INVAR
bars design with Aluminium compensation in a large pm 10 o around 20 o
Title: Contribution of Solar Chromospheric Features to UV Irradiance
Variability
Authors: Kariyappa, R.; Hiremath, K. M.; Dame, L.
Bibcode: 2005BASI...33..364K
Altcode:
No abstract at ADS
Title: Period-brightness relationship in chromospheric bright points
Authors: Kariyappa, R.; Narayanan, A. Satya; Dame, L.
Bibcode: 2005BASI...33...19K
Altcode:
Chromospheric bright points are sites where intense heating takes
place by 3-min period waves. A 35-min-long time series of photographic
spectra obtained in CaII H-line on a quiet region at the center of the
solar disk under high spatial, spectral, and temporal resolution at
the Vacuum Tower Telescope (VTT) of the Sacramento Peak Observatory
has been analyzed to show that the period of intensity oscillations
associated with bright points in the interior of the supergranular
cells is independent of their intensity enhancements. We find evidence
for a constant period of oscillations in bright points, independent
of their peak brightness, and different from the period of network
oscillations. This suggests that the heating mechanism may be identical
(by 3-min period waves) in any class of bright points while in the
case of network elements it may be an entirely different mechanism (by
5-7 min period waves). In addition, it is shown that the amplitudes of
the main and the follower pulses of bright points decay exponentially
with time and the decay rate is constant with their brightness in any
class of bright points.
Title: Solar full field interferometric imaging with 3 telescopes
Authors: Damé, Luc; Cladé, S.; Zhao, B.
Bibcode: 2004ESASP.554..373D
Altcode: 2004icso.conf..373D
For the last 7 years we have been developing a 3-telescopes breadboard
of the SOLARNET imaging interferometer proposed to CNES (French
National Space Agency) for a possible Space Mission as early as 2010
(new start expected in 2006). After having been successfully tested in
laboratory for phase control (up to λ/300) and interferometric direct
imaging performances, the setup was moved to Meudon Observatory at
the "Grand Sidérostat de Foucault" in 2000 for direct testing on
the Sun. Following the implementation of an automatic guiding and
dedicated fine pointing for each telescope (capable of one twentieth
of an arcsec), the complete interferometric setup is now nearly ready
to observe properly in a coordinated cophased and copointed mode and to
acquire its first images. We report the progress achieved in developing
the breadboard and its spectro-imaging capabilities (a subtractive
double monochromator), and indicate what are the next possible steps
and prospects of the SOLARNET program both on ground and in Space.
Title: SOLARNET: the solution to the high resolution needs of
solar physics
Authors: Dame, L.; Clade, S.; Malherbe, J. M.
Bibcode: 2004cosp...35.3583D
Altcode: 2004cosp.meet.3583D
Encounter missions like the Solar Orbiter have high resolution
imaging goals in addition to the plasma measurements. If context,
arcsec imaging, might be possible and useful to interpret the plasma
observation, we will demonstrate that the thermal conditions near the
Sun will prevent to achieve any of the higher resolution goals even
by taking the most state-of-the-art solar telescope (carbon-carbon
structure, SiC mirrors, etc.). A far better solution to fulfill the
high resolution needs is the SOLARNET mission. SOLARNET is a medium
size high resolution solar physics mission proposed to CNES for a new
start in 2006 and a possible launch in 2010. Partnerships with Germany,
Belgium, China and India are under discussion. At the center of the
SOLARNET mission is a 3-telescopes interferometer of 1 meter baseline
capable to provide 50 times the best ever spatial resolution achieved
in Space with previous, current or even planned solar missions: 20
mas - 20 km on the Sun in the FUV. The interferometer is associated
to an on-axis subtractive double monochromator (imaging spectrograph)
capable of high spectral (0.01 nm) and high temporal resolutions (50
ms) on a field of view of 40 arcsec and over the FUV and UV spectral
domains (from 117.5 to 400 nm). This will allow to access process
scales of magnetic reconnection, dissipation, emerging flux and much
more, from the high chromosphere to the low corona with emphasis on
the transition zone where the magnetic confinement is expected to be
maximum. A whole new chapter of the physics of solar magnetic field
structuring and evolution will be opened. Launched by an Eurockot on a
high altitude sun-synchronous non-eclipsing orbit, SOLARNET will also
provide continuous observations at a sustained rate for Helioseismology
and solar cycle studies. We review the scientific program of SOLARNET
and its advantages (and complementarities) with an encounter type
mission (probe or orbiter), describe the interferometer concept and
design, present the first imaging results of the SOLARNET breadboard
obtained at Meudon Observatory this spring and give a short overview
of the mission aspects.
Title: No link between the solar activity cycle and the diameter
Authors: Dame, L.; Cugnet, D.
Bibcode: 2004cosp...35.3358D
Altcode: 2004cosp.meet.3358D
We do not understand the physical mechanisms responsible for the solar
irradiance cycle. Measurements of small variations in the solar diameter
could have been a critical probe of the Sun 's interior stratification,
telling us how and where the solar luminosity is gated or stored. We
have reanalyzed the 7 years of filtregrams data (150 000 photograms
and magnetograms) of the SOHO/MDI experiment. We used the maximum
possible sampling compatible with full frame recording, carefully
avoiding any suspicious filtregram. Going further than the previous
analysis of 2 years of data by Emilio et al. (Ap. J. 543,1007, 2000),
we better corrected for changes in optical aberrations and, along
Turmon et al. (Ap. J., 568, 396, 2002), we reduced radius measurement
errors by identifying active regions and avoiding radius measurements
herein. We found that, within the limit of our noise level uncertainties
(2 mas), the solar diameter could be constant over the half cycle
investigated. Our results confirm the recent reanalysis of the 7 years
of MDI data made by Antia (Ap. J. 590, 567, 2003), with a completely
different method since using the ultra-precise frequency variation
of the f-modes (fundamental modes linked to the diameter). He found
(carefully removing the yearly Earth induced variations and avoiding
the SOHO data gap of 1999) that the diameter is constant over the half
solar cycle (radius variation are less than 0.6 km, 0.8 mas - nothing
over noise level). Along Antia, we can conclude that: "If a careful
analysis is performed, then it turns out that there is no evidence
for any variation in the solar radius." There were no theoretical
reasons for large solar radius variations and there is no observational
evidence for them with consistent space observations. If changes exit,
they are to be very small.
Title: Non-variation of the solar diameter with the cycle: the end
of a possible link between activity and diameter
Authors: Dame, L.; Cugnet, D.
Bibcode: 2004cosp...35.3352D
Altcode: 2004cosp.meet.3352D
We have reanalyzed the 7 years of filtregrams data (150 000 photograms
and magnetograms) of the SOHO/MDI experiment. We used the maximum
possible sampling compatible with full frame recording, carefully
avoiding any suspicious filtregram. Going further than the previous
analysis of 2 years of data by Emilio et al. (Ap. J. 543,1007, 2000),
we better corrected for changes in optical aberrations and, along
Turmon et al. (Ap. J., 568, 396, 2002), we reduced radius measurement
errors by identifying active regions and avoiding radius measurements
herein. We found that, within the limit of our noise level uncertainties
(2 mas), the solar diameter could be constant over the half cycle
investigated. Our results confirm the recent reanalysis of the 7 years
of MDI data made by Antia (Ap. J. 590, 567, 2003), with a completely
different method since using the ultra-precise frequency variation
of the f-modes (fundamental modes linked to the diameter). He found
(carefully removing the yearly Earth induced variations and avoiding
the SOHO data gap of 1999) that the diameter is constant over the
half solar cycle (radius variation are less than 0.6 km, 0.8 mas
- nothing over noise level). Along Antia, we can conclude that:
"If a careful analysis is performed, then it turns out that there
is no evidence for any variation in the solar radius." There were no
theoretical reasons for large solar radius variations and there is no
observational evidence for them with consistent space observations.
Title: SOLARNET: a high resolution mission to complement the ILWS
programme
Authors: Dame, L.; Clade, S.; Malherbe, J. M.
Bibcode: 2004cosp...35.3579D
Altcode: 2004cosp.meet.3579D
SOLARNET is a medium size high resolution solar physics mission
proposed to CNES for a new start in 2006 and a possible launch in
2010. Partnerships with Germany, Belgium, China and India are under
discussion. At the center of the SOLARNET mission is a 3-telescopes
interferometer of 1 meter baseline capable to provide 50 times
the best ever spatial resolution achieved in Space with previous,
current or even planned solar missions: 20 mas - 20 km on the Sun in
the FUV. The interferometer is associated to an on-axis subtractive
double monochromator (imaging spectrograph) capable of high spectral
(0.01 nm) and high temporal resolutions (50 ms) on a field of view of
40 arcsec and over the FUV and UV spectral domains (from 117.5 to 400
nm). This will allow to access process scales of magnetic reconnection,
dissipation, emerging flux and much more, from the high chromosphere
to the low corona with emphasis on the transition zone where the
magnetic confinement is expected to be maximum. A whole new chapter
of the physics of solar magnetic field structuring and evolution
will be opened. The interferometer is complemented by several other
instruments providing larger field of view and higher temperature
(EUV-XUV coronal imaging) to define the context and extension of
the solar phenomena. Helioseismology, a strong asset of SOHO, is
also intended with both velocity and diameter measures, allowed by
a non-eclipsing Sun synchronous orbit. The SOLARNET interferometer
design results of an extensive laboratory demonstration program of
interferometric imaging of extended objects. It started 10 years ago
and culminates this year with the first interferometric observations
(images) of the Sun at Meudon Observatory at the "Grand Siderostat
de Foucault" with a complete 3 telescopes cophased interferometer
representative of SOLARNET. We will review the scientific program of
SOLARNET, describe the interferometer concept and design, present the
first solar imaging results of the breadboard and give a short overview
of the mission aspects.
Title: Solar physics and interferometry mission (SPI)
Authors: Damé, L.; Derrien, M.
Bibcode: 2002AdSpR..29.2061D
Altcode:
This paper presents the scientific objectives of the Solar Physics and
Interferometry Mission (SPI), describes succinctly the model payload and
summarizes mission's issues. Novel instrumentation (interferometry) and
clever mission design (small platform on low orbit with high telemetry
and dedicated smaller platform on hexapod for permanently Sun-centered
instruments) allow both spectral imaging and Helioseismology at very
high spatial and temporal resolutions. Although not retained by ESA,
this mission could become reality through NASA MIDEX and/or CNES
PROTEUS opportunities as soon as 2007-2008.
Title: Technologies for solar interferometry in space
Authors: Damé, L.; Derrien, M.; Kozlowski, M.; Perrot, S.; Preumont,
A.
Bibcode: 2002AdSpR..29.2075D
Altcode:
This paper summarizes, on one part, the results of a 3-telescope
breadboard used to demonstrate the cophasing and imaging capabilities
of the Solar Imaging Interferometer, SOLARNET, of the Solar Physics
and Interferometry Mission (SPI) and, on the other, possibilities for
state-of-the-art recombination optics (molecular binding) and novel
delay lines using magnetic bearing to achieve unprecedented cophasing
quality and ease of interferometric recombination and imaging.
Title: Preface
Authors: Damé, Luc; Marsch, Eckart
Bibcode: 2002AdSpR..29.1997D
Altcode:
No abstract at ADS
Title: PICARD: solar diameter measure and g-mode search
Authors: Damé, L.; Appourchaux, T.; Berthomieu, G.; Boumier, P.;
Cugnet, D.; Gelly, B.; Provost, J.; Toutain, T.
Bibcode: 2001ESASP.464..321D
Altcode: 2001soho...10..321D
The PICARD microsatellite mission will provide 3 to 4 years simultaneous
measurements of the solar diameter, differential rotation and
solar constant to investigate the nature of their relations and
variabilities. The major instrument, SODISM, is a whole Sun imaging
telescope of Ø 110 mm which will deliver an absolute measure
(better than 4 mas) of the solar diameter and solar shape. Now in
Phase B, PICARD is expected to be launched by 2005. We recall the
scientific goals linked to the diameter measurement with emphasis on the
helioseismology g-mode interest, present the instrument optical concept
and present design, and give a brief overview of the program aspects.
Title: Results from a revisit to the K2V bright points
Authors: Sivaraman, K. R.; Gupta, S. S.; Livingston, W. C.; Damé,
L.; Kalkofen, W.; Keller, C. U.; Smartt, R.; Hasan, S. S.
Bibcode: 2000A&A...363..279S
Altcode:
We have used pairs of temporally simultaneous CaII K-line
spectroheliograms and magnetic area scans to search for spatial
correlation between the CaII K2V bright points in the
interior of the network and corresponding magnetic elements. We find
that about 60% of the K2V bright points spatially coincide
with magnetic elements of flux density > 4 Mx cm-2. About
25% of the K2V bright points with equally enhanced emission
lie over bipole elements where the fields are > 4 Mx cm-2
for both polarity elements which merge and presumably cancel and
result in low fields. The rest, 15%, of the bright points coincide
with areas of fields < 4 Mx cm-2 which is the noise
level set by us for the magnetic scans. When magnetic elements of
opposite polarity merge and form bipoles, the associated K2V
bright points show excess emission. Although such excess emission is a
magnetic-field-driven phenomenon, the measured value of the field at the
site of the bipole is typically low, and these cases would therefore be
excluded in the count of coincidences of excess emission with excess
magnetic fields. In our opinion, these cases of excess emission at
the sites of the bipoles, as well as at the sites of fields >
4 Mx cm-2, are both instances of magnetic-field-related
emissions. If the former are not taken into account as coincidences,
the correlation will drop down and this might be interpreted as not an
obvious correlation. Our present results, taking into account the low
fields of merging bipoles, establish the association of K2V
bright points with magnetic elements.
Title: New High Resolution Observations of the Solar Diameter from
Space and Ground with the Microsatellite Program PICARD
Authors: Damé, L.
Bibcode: 2000JApA...21..135D
Altcode:
No abstract at ADS
Title: PICARD: Solar Diameter, Irradiance and Climate
Authors: Damé, L.; Cugnet, David; Herse, Michel; Crommelynck,
Dominique; Dewitte, Stevens; Joukoff, Alexandre; Ruedi, Isabelle;
Schmutz, Werner; Wehrli, Christoph; Delmas, Christian; Laclare,
Francis; Rozelot, Jean-Pierre
Bibcode: 2000ESASP.463..223D
Altcode: 2000sctc.proc..223D
No abstract at ADS
Title: PICARD: simultaneous measurements of the solar diameter,
differential rotation, solar constant and their variations
Authors: Damé, Luc; Hersé, Michel; Thuillier, Gérard; Appourchaux,
Thierry; Crommelynck, Dominique; Dewitte, Steven; Joukoff, Alexandre;
Fröhlich, Claus; Laclare, Francis; Delmas, Christian; Boumier, Patrick
Bibcode: 1999AdSpR..24..205D
Altcode:
PICARD is a CNES micro-satellite mission due for flight by the end
of 2002, named after the name of a French astronomer who first
observed with consistency the solar diameter changes during the
Maunder minimum in the 16th century. It consists of two instruments
measuring (i) the solar diameter and differential rotation, and (ii)
the total solar irradiance. These quantities are fundamental for the
understanding of the solar-Terrestrial relations, e.g. the influence
of the Sun on the Earth's climate, and of the internal structure
of the Sun. The continuous - or nearly continuous - viewing of the
Sun from an appropriate orbit, the 5 minutes sampling rate and the
very low noise measurements, will allow g-modes detection and precise
diameter measurements besides accurately establishing the relationship
between irradiance and diameter changes. Providing an absolute measure
of the solar diameter to 1 milliarcsecond, PICARD is the first step
towards instruments capable of accurate and perennial measurements,
for the centuries to come, of the solar-terrestrial influence. The
objectives of the mission, instrument capabilities, observing modes
and performances are described.
Title: High Resolution Solar Physics by Interferometry: SOLARNET
Authors: Damé, L.; Derrien, M.; Kozlowski, M.; Merdjane, M.
Bibcode: 1998ESASP.417..109D
Altcode: 1998cesh.conf..109D
No abstract at ADS
Title: Laboratory and Sky Demonstrations of Solar Interferometry
Possibilities
Authors: Damé, L.; Derrien, M.; Kozlowski, M.; Merdjane, M.
Bibcode: 1998ESASP.417..345D
Altcode: 1998cesh.conf..345D
No abstract at ADS
Title: Low orbit high resolution solar physics with the solar
interferometer
Authors: Damé, L.
Bibcode: 1998AdSpR..21..295D
Altcode:
Following several years of design studies of Solar Interferometers
(mainly for Space Missions), we have reached a very complete and
mature mechanical and optical concept, as well as a comprehensive image
reconstruction scenario. Furthermore, we demonstrated recently, on a
laboratory representative breadboard -- but also directly on the Sun --
the feasibility and performances of the cophasing of two telescopes on
extended objects. This definitively proves the validity of the pupil
plane synchronous detection technique (applied to an extended object:
the Sun) that we proposed and developed since 1988, These recent
results really open the possibility to use and discover from solar
interferometers either on ground or in Space. With a 1 meter baseline
and 5 telescopes of 25 cm or so, permanent spatial resolution of 0.1''
on a 30'' field-of-view can be reached from the ground in the visible
while 0.02'' could be achieved in the far UV, from Space, all with an
adjustable spectral bandwidth of 0.01 to 10 nm.
Title: The MUST/3T Solar Interferometer: AN Interferometric Technology
Testbed on the Iss
Authors: Damé, L.
Bibcode: 1996ESASP.385..369D
Altcode: 1996ssu..conf..369D
No abstract at ADS
Title: Simultaneous UV and X-ray Observations of Coronal Bright Points
Authors: Bruner, M. E.; Nitta, N.; Wuelser, J. P.; Harvey, K.; Handy,
B.; Dame, L.
Bibcode: 1996AAS...188.8607B
Altcode: 1996BAAS...28..964B
High resolution ultraviolet filtergrams recorded during the 1992 and
1994 flights of the Solar Plasma Diagnostics Experiment (SPDE) sounding
rocket payload revealed a number of coronal bright points that were
simultaneously observed with the Yohkoh soft x-ray telescope. UV images
made at 1550 Angstroms/, which include substantial contributions from
the C IV resonance lines, reveal pairs of sources under the x-ray bright
points; consistent with the conventional interpretation of the latter
as un-resolved loops. The 1994 flight also recorded high resolution
EUV images at 171 and 195 Angstroms/, corresponding to strong lines
of Fe IX and Fe XII, respectively. Excellent correspondence was found
between coronal bright points seen in these lines, which are formed at
relatively low coronal temperatures (1 -- 2 x 10(6) k), and the 2 --
5 x 10(6) k that typifies the Yohkoh SXT images. In this study, we
use the Yohkoh database to study the temporal development of several
coronal bright points both before and after each rocket flight in order
to determine the stage of evolution of the sources at the epoch of the
flight. The relationship between the plasma properties of the sources
and their stages of evolution will be discussed.
Title: Coordinated SPDE rocket, YOHKOH and ground observations of
an emerging flux region and a filament
Authors: Damé, L.; Martic, M.; Brown, W. A.; Bruner, M. E.; Strong,
K.; Suematsu, Y.; Tsuneta, S.; Schmieder, B.
Bibcode: 1996AdSpR..17d.189D
Altcode: 1996AdSpR..17..189D
During the first flight of the Solar Plasma Diagnostic Experiment
(SPDE), May 12, 1992, we obtained UV filtergrams at high resolution
(full Sun 0.82'' spatial resolution in the 160 nm continuum, the
CIV lines and Lyman alpha) with the Ultraviolet Filtergrap Camera
(UVFC). Closely coordinated observations were obtained with the Soft
X-ray Telescope (SXT) of the Yohkoh satellite and from dedicated ground
programs in particular at Sacramento Peak, La Palma and Pic-du-Midi
observatories. With this unique set of data we cover the solar
atmosphere as a whole, from the temperature minimum to the high corona
with essential steps in the chromosphere and transition region. After
the necessary calibrations of the data set, we present the first results
of the multitemperature development of an emerging flux region and of
a filament that rapidly changed right during the rocket short lifetime.
Title: SIMURIS: a UV and XUV Mission for high resolution solar physics
Authors: Damé, L.; Derrien, M.; Kozlowski, M.; Antonucci, E.;
Ragazzoni, R.; Tondello, G.
Bibcode: 1996AdSpR..17d.377D
Altcode: 1996AdSpR..17..377D
Advances in electronics and servo-control allow to envisage extremely
high spatial resolution observations of the Sun through the use of
a compact array of phased telescopes. We present the SIMURIS Mission
(Solar Interferometric Mission for Ultrahigh Resolution Imaging and
Spectroscopy) which is the first to propose high resolution ultraviolet
imaging coupled to high time and spectral resolutions through the
use of an interferometric array of five 20 cm telescopes feeding a
subtractive double monochromator tunable over a large spectral range
and providing narrow band filtergrams. In addition to the ultraviolet
imaging interferometer SIMURIS has soft X-ray and EUV imagers and
spectrometers for complete coverage of the solar atmosphere.
Title: Instrumental prospects in solar interferometric imaging.
Authors: Damé, L.; Derrien, M.; Kozlowski, M.; Ruillier, C.
Bibcode: 1996joso.proc...52D
Altcode:
The authors briefly recall the concepts of the Solar Interferometer,
explain the constraints imposed by the measurement of a phase over
extended objects and present the laboratory and sky results of the
first solar interferometric experiment of cophasing.
Title: Global Oscillations at Low Frequency from the SOHO Mission
(GOLF)
Authors: Gabriel, A. H.; Grec, G.; Charra, J.; Robillot, J. -M.; Roca
Cortés, T.; Turck-Chièze, S.; Bocchia, R.; Boumier, P.; Cantin, M.;
Cespédes, E.; Cougrand, B.; Crétolle, J.; Damé, L.; Decaudin, M.;
Delache, P.; Denis, N.; Duc, R.; Dzitko, H.; Fossat, E.; Fourmond,
J. -J.; García, R. A.; Gough, D.; Grivel, C.; Herreros, J. M.;
Lagardère, H.; Moalic, J. -P.; Pallé, P. L.; Pétrou, N.; Sanchez,
M.; Ulrich, R.; van der Raay, H. B.
Bibcode: 1995SoPh..162...61G
Altcode:
The GOLF experiment on the SOHO mission aims to study the internal
structure of the sun by measuring the spectrum of global oscillations in
the frequency range 10−7 to 10−2 Hz. Bothp
andg mode oscillations will be investigated, with the emphasis on
the low order long period waves which penetrate the solar core. The
instrument employs an extension to space of the proven ground-based
technique for measuring the mean line-of-sight velocity of the viewed
solar surface. By avoiding the atmospheric disturbances experienced
from the ground, and choosing a non-eclipsing orbit, GOLF aims to
improve the instrumental sensitivity limit by an order of magnitude
to 1 mm s−1 over 20 days for frequencies higher than
2.10−4 Hz. A sodium vapour resonance cell is used in
a longitudinal magnetic field to sample the two wings of the solar
absorption line. The addition of a small modulating field component
enables the slope of the wings to be measured. This provides not only
an internal calibration of the instrument sensitivity, but also offers a
further possibility to recognise, and correct for, the solar background
signal produced by the effects of solar magnetically active regions. The
use of an additional rotating polariser enables measurement of the
mean solar line-of-sight magnetic field, as a secondary objective.
Title: Active phase stabilization at the I2T: implementation of the
ASSI table
Authors: Robbe, Sylvie; Sorrente, Beatrice; Cassaing, Frederic;
Rabbia, Yves; Rousset, Gerard; Dame, Luc; Cruzalebes, Pierre;
Schumacher, Gerard
Bibcode: 1994SPIE.2200..222R
Altcode: 1994aisi.conf..222R
We present the Active Stabilization in Stellar Interferometry (ASSI)
beam combining optical table which was installed on the 2- telescope
interferometer (I2T) of the Observatoire de la Cote d'Azur in 1993. To
achieve very high angular resolution, the 26- centimeter telescopes can
be positioned along a 140-meter North- South baseline. The limiting
magnitude of the instrument depends dramatically on its ability to
stabilize the fringe pattern despite the atmospheric disturbances. The
function of the ASSI table is to perform this task. Three adaptive
mirrors are used. The first two are fine pointing mirrors which correct
the fluctuations of the angle of arrival of the two wavefronts. The
other corrects the optical path difference fluctuations between the
two telescopes. These corrections, e.g. tip-tilt and piston phase, are
required to obtain high precision visibility measurements. We present
our first observing results obtained on bright stars that have allowed
the evaluation of the ASSI table performance in image tracking.
Title: Solar interferometric imaging from the moon
Authors: Dame, L.; Martic, M.; Porteneuve, J.
Bibcode: 1994AdSpR..14f..49D
Altcode: 1994AdSpR..14...49D
We present the concept of a Lunar Interferometer for Solar Physics. In
particular we explain the rationale for a compact 2D array and we
propose the use of a novel mechanical support structure based on linear
mounting rods - these optimizing room and mass issues for transportation
to the Moon.
Title: Solar interferometry: space and ground instrumental prospects
Authors: Dame, Luc
Bibcode: 1994SPIE.2200...35D
Altcode: 1994aisi.conf...35D
Recent advances in electronics and fast computer control allow to
envisage extremely high spatial resolution observations of the Sun
through the use of a compact array of phased telescopes. Several
space missions (SUN/SIMURIS, SUN-SV, MUST/SIMURIS) have been
proposed in that respect and will be briefly presented. Prospects
for use of the space techniques for a solar array on ground are also
indicated. Independently from the different mission concepts, solar
interferometric imaging presents a unique case in the domain of optical
aperture synthesis since the field- of-view is extended (larger than
the diffraction spot of a telescope) and because the high resolution
structures are evolving very rapidly and are naturally complex (low
fringe visibility). These severe constraints drive solar arrays'
design towards `compact' configurations (i.e. in which the spatial
frequencies plane is filled) and real-time `cophasing' (direct--
hardware--zeroing of phase fluctuations by fine delay lines). They also
influence the choice of the focal instrumentation which is optimum when
using a subtractive double monochromator tunable over a large spectral
range and providing narrow band filtergrams (up to 0.1 angstrom). We
review the concepts and design issues of a solar interferometer and
present numerical simulations and laboratory experiments of the system
required to cophase an array of telescopes on a complex and extended
field-of-view. Aperture configurations and image reconstruction are
also discussed as well as the specific real-time metrology aspects of
a ground array (atmospheric constraints derived from the performances
evaluation of the ASSI Program).
Title: The SIMURIS interferometric mission: Solar physics objectives
and model payload
Authors: Dame, L.; Rutten, R. J.; Thorne, A. P.; Vial, J. C.
Bibcode: 1994AdSpR..14d.167D
Altcode: 1994AdSpR..14..167D
We describe the SIMURIS Mission with emphasis on the scientific goals
and related capabilities of the major instruments of the model payload.
Title: Actively cophased interferometry with SUN/SIMURIS
Authors: Dame, Luc
Bibcode: 1993SPIE.1947..161D
Altcode:
The Solar Ultraviolet Network (SUN) is an instrument based on
interferometric concepts, and capable of observations with a spatial
resolution of 0.013' (10 km) on the Sun, in the UV and visible
wavelength ranges. In this paper we present results on fringe pattern
acquisition and stabilization as performed on a Mach-Zehnder set up
representative of the interferometer cophasing system. The system
algorithm is based on 'white light' fringe tracking controlled in a
reference interferometer by a synchronous detection. This servo-system
drives a two-stages delay line for real-time compensation of the optical
path delays. Acquisition capabilities and stability possibilities
are investigated as a function of flux and noise levels. Being
stabilized, actively cophased, and in a 'compact' configuration, the SUN
interferometer possesses remarkable imaging capabilities allowing high
resolution diffraction-limited imaging on an extended field of view
of 6 X 6 arcsec(superscript 2). The dynamics of reconstructed images
is superior to 400 for phase stabilities >= (lambda) /6 and photon
flux of approximately 10,000 ph s(superscript -1) pixel(superscript -1)
(on average). The SUN instrument is part of the Solar Interferometric
Mission for Ultrahigh Resolution Imaging and Spectroscopy (SIMURIS)
which was proposed to ESA in the framework of the Next Medium Size
Mission (M2) in November 1989, and which completed a First Phase of
Study in the context of the Space Station in August 1991.
Title: Golf: A resonance spectrometer for the observation of solar
oscillations I) Numerical model of the sodium cell response
Authors: Boumier, P.; Dame, L.
Bibcode: 1993ExA.....4...87B
Altcode:
GOLF (Global Oscillations at Low Frequencies) is an instrument to study
the line-of-sight velocity of the solar photosphere, to be flown on
the SOHO satellite in 1995. It uses a sodium vapour cell in resonance
scattering mode, in order to measure the absolute Doppler shift of
the solar sodium absorption lines. We have developed a model of the
resonance cell performance. We describe here the main characteristics
of the model, and report the most important results concerning the
performance of the cell and its dependance on temperature.
Title: Multitemperature Observations of an Emerging Flux Region
Authors: Bruner, M. E.; Acton, L. W.; Brown, W. A.; Lemen, J. R.;
Shine, R.; Strong, K. T.; Tarbell, T.; Dulk, G.; Tsuneta, S.; Bastian,
T.; Dame, L.
Bibcode: 1993BAAS...25.1179B
Altcode:
No abstract at ADS
Title: Observations of an Emerging Flux Region
Authors: Brown, W. A.; Acton, L. W.; Bruner, M. E.; Lemen, J. R.;
Shine, R.; Strong, K. T.; Tarbell, T.; Dulk, G.; Tsuneta, S.; Bastian,
T.; Dame, L.
Bibcode: 1993BAAS...25Q1214B
Altcode:
No abstract at ADS
Title: Prospects for very-high-resolution solar physics with the
Simuris interferometric mission.
Authors: Dame, L.; Martic, M.; Rutten, R. J.
Bibcode: 1993ESASP1157..119D
Altcode: 1993srfs.book..119D
Simuris - the Solar, Solar System, and Stellar Interferometric Mission
for Ultra-high Resolution Imaging and Spectroscopy - employs advanced
interferometric techniques. Its payload includes two major instruments,
which are the Solar Ultraviolet Network (SUN), an interferometric
array of four 20 cm telescopes on a 2 m baseline, and the Imaging
Fourier-Transform Spectrometer (IFTS), which uses light from a 40 cm
Gregory telescope. Both instruments have active pointing capabilities of
3 mas stability, and in addition SUN has an active co-phasing control
to 1/50th of a wavelength. EUV multi-layer telescopes complete the
payload for diagnostics of the very-high-temperature plasma.
Title: Stellar objectives of SIMURIS
Authors: Damé, L.; Coradini, M.; Foing, B.; Rutten, R. J.; Thorne,
A.; Vial, J. C.
Bibcode: 1993MmSAI..64..345D
Altcode:
No abstract at ADS
Title: SIMURIS: High-Resolution Solar Physics
Authors: Rutten, R. J.; Dame, L.
Bibcode: 1993ASPC...46..184R
Altcode: 1993mvfs.conf..184R; 1993IAUCo.141..184R
No abstract at ADS
Title: The SIMURIS interferometric mission: solar physics objectives
and model payload (invited paper)
Authors: Damé, L.; Coradini, M.; Foing, B.; Rutten, R. J.; Thorne,
A.; Vial, J. C.
Bibcode: 1993MmSAI..64..333D
Altcode:
No abstract at ADS
Title: The SUN/SIMURIS interferometer.
Authors: Dame, L.
Bibcode: 1992ESASP.354...71D
Altcode: 1992tsbi.rept...71D
The author presents the Solar Ultraviolet Network (SUN), which is a
four 20 cm diameter telescopes interferometer of 2 m baseline. SUN is
the major instrument of the SIMURIS Mission now under study by ESA for
a possible accommodation on the Space Station Freedom. SUN concepts and
design will be reviewed with emphasis on the unique particularities
of this cophased interferometer dedicated to imaging of complex and
extended objects.
Title: Study of an optimized configuration for interferometric
imaging of complex and extended solar structures.
Authors: Dame, L.; Martic, M.
Bibcode: 1992ESASP.354..201D
Altcode: 1992tsbi.rept..201D
The authors present image reconstruction by optical aperture synthesis
of complex and extended objects alike those to be observed with the
Solar Ultraviolet Network. They show, in particular, the importance
of a compact array when such observations are intended
Title: The lunar interferometer for solar physics.
Authors: Dame, L.; Martic, M.; Porteneuve, J.; Schnur, G. F. O.
Bibcode: 1992ESASP.354..123D
Altcode: 1992tsbi.rept..123D
The author present the concept of a Lunar Interferometer for Solar
Physics (LISP). In particular they explain the rationale for a compact
2D array and they propose the use of a novel mechanical support
structure based on linear mounting rods. These two conceptual choice
optimize imaging capacities and room and mass issues for transportation
to the Moon.
Title: Model payload and system design of the SIMURIS interferometric
mission
Authors: Dame, L.; Rutten, R. J.; Thorne, A. P.; Vial, J. C.
Bibcode: 1992wadc.iafcZ....D
Altcode:
SIMURIS (Solar, Solar System, and Stellar Interferometric Mission
for Ultrahigh Resolution Imaging and Spectroscopy) has been proposed
to ESA as a Mission in the context of the Space Station in November
1989 in answer to the Call for the Next Medium Size Mission (M2). It
has completed, since, an Assessment Study, and is now proceeding for
a Phase A. SIMURIS employs advanced interferometric techniques. The
payload includes two major instruments which are the Solar Ultraviolet
Network (SUN), an interferometric array of four 20-cm telescopes on
a 2-m baseline, and the Imaging Fourier Transform Spectrometer (IFTS)
which uses light from a 40-cm Gregory telescope. Both instruments have
active pointing capabilities of 3 milliarcsec stability, and SUN has,
in addition, an active cophasing control to 1/50th of a wavelength. EUV
multilayer telescopes complete the payload for diagnostics of the very
high temperature plasma. The SIMURIS model payload will be described
with emphasis on the system design of the interferometric aspects of
the instruments.
Title: The imaging Fourier transform spectrometer performance and
tolerance analysis.
Authors: Kruizinga, B.; Snijders, B.; Braam, B. C.; Thorne, A. P.;
Maxwell, J.; Dame, L.
Bibcode: 1992ESASP.344..290K
Altcode: 1992spai.rept..290K
An abstract and an outline of an analysis of the Imaging Fourier
Transform Spectrometer (IFTS), one of the core instruments of SIMURIS
(Solar Interferometric Mission for Ultrahigh Resolution Imaging
and Spectroscopy), is given. The quality of the optical system
(including diffraction effects and aberrations of the nominal system)
were evaluated. The performance figures were determined in the course
of the instrument design process. Detailed information on components
and other instrumental considerations lead to a readjustment of some
of the requirements. The tolerance analysis and its implications
were addressed. The influence of component manufacturing errors,
assembly and alignment errors, and environmental disturbances on the
optical quality were evaluated. The quality of the instrument including
tolerances was determined in terms of the following: spot sizes in the
detector, wavefront errors of interfering beams, pointing errors, and
accuracy of the selected center wavelength. For each of these aspects
the contributing optical components were identified. The permissable
error budget was distributed over these components. The component
tolerances were calculated.
Title: Solar Physics and Astrophysics at Interferometric Resolution
Authors: Dame, L.; Guyenne, T. -D.
Bibcode: 1992ESASP.344.....D
Altcode: 1992spai.rept.....D
No abstract at ADS
Title: SUN: the Solar Ultraviolet Network.
Authors: Dame, L.
Bibcode: 1992ESASP.344..171D
Altcode: 1992spai.rept..171D
The Solar Ultraviolet Network (SUN) is a space interferometer especially
designed to observe the solar fine structure from the photosphere
to the corona. It is a "compact" optical interferometer formed with
four telescopes of 20 cm diameter distributed non-redundantly on
a linear baseline of 2 meters. In addition to its intrinsic high
spatial resolution (10 km on the Sun at λ = 120 nm), SUN has an
elaborated focal plane instrument providing 6 simultaneous images
of high spectral resolution and tunable from the far UV to the near
IR. The compact array configuration, the cophased recording of fringes
and the spectral properties of the double monochromator of SUN, allow
interferometric imaging of the complex and extended solar structures
with exceptional detail.
Title: Solar physics and astrophysics at interferometric
resolution. Proceedings.
Authors: Dame, L.; Guyenne, T. D.
Bibcode: 1992spaa.book.....D
Altcode:
No abstract at ADS
Title: The imaging Fourier transform spectrometer optical design.
Authors: Kruizinga, B.; Snijders, B.; Braam, B. C.; Thorne, A. P.;
Maxwell, J.; Dame, L.
Bibcode: 1992ESASP.344..288K
Altcode: 1992spai.rept..288K
An abstract and an outline of a paper on the optical design of the
Imaging Fourier Transform Spectrometer (IFTS), one of the two main
instruments of SIMURIS (Solar Interferometric Mission for Ultrahigh
Resolution Spectroscopy) is presented. The following were studied:
the modes of operation, based on the scientific requirements; the
preliminary design of the telescope and the pointing system; a design
of one of the prefilters, the subtractive double monochromator;
the implementation of the FI and the imaging camera; photometry
and the detection system; the instruments housing, mechanisms, and
other mechanical aspects. The optimum quality of the entire system
was determined by an extensive ray tracing analysis. A preliminary
outline of the instrument's mechanical structure was generated.
Title: Interferometric imaging with the Solar Ultraviolet Network.
Authors: Dame, L.; Cornwell, T. J.
Bibcode: 1992ESASP.344..185D
Altcode: 1992spai.rept..185D
Extensive simulations have been performed to investigate the image
reconstruction potential of the Solar Ultraviolet Network. They
establish that excellent images are obtained with compact optical
arrays despite errors in visibility data caused by photon noise, beams'
mispointing and residual phase errors. Imaging fidelity in optical
interferometry, and with emphasis on extended objects, is a complex
function of flux level, source complexity, recombination errors,
and spatial frequency coverage of the so-called u,v plane. "Holes"
in the u,v coverage would result in artifacts and in a significant
degradation of the quality of the complex and extended images which
could be reconstructed from the data.
Title: Prospects with SIMURIS.
Authors: Dame, L.; Rutten, R. J.
Bibcode: 1992ESASP.344...21D
Altcode: 1992spai.rept...21D
The authors give an introductory overview of the SIMURIS payload by
briefly presenting its goals and concepts.
Title: Demonstration and performances of real-time fringe tracking:
a step towards cophased interferometers.
Authors: Dame, L.
Bibcode: 1992ESASP.344..277D
Altcode: 1992spai.rept..277D
Imaging of complex and extended objects by the Solar Ultraviolet
Network (SUN) require a real-time monitoring of the coalignment and
cophasing functions of the interferometer. The cophasing of the input
beams, i.e. the equalization (zero-ing) of the optical path delays,
is specific to interferometry, and is required to high precision if
diffraction limited imaging with the interferometer is expected. The
author reports preliminary results on fringe pattern acquisition and
stabilization as performed on a Mach-Zehnder set up representative of
the interferometer cophasing system. The system algorithm is based on
"white light" fringe tracking controlled in a reference interferometer
by a synchronous detection. This servo-system drives a two-stages delay
line for realtime compensation of the optical path delays. Acquisition
capacities and stability possibilities are investigated as a function
of flux and noise levels.
Title: Laboratory Demonstration of Realtime Monitoring of a Two-Beam
Interferometer by a Synchronous Detection Technique
Authors: Dame, L.
Bibcode: 1992ESOC...39.1169D
Altcode: 1992hrii.conf.1169D
No abstract at ADS
Title: Imaging with a Compact Optical Interferometer - Influence of
Photon Noise Pointing and Phase Errors on Image Dynamic
Authors: Dame, L.; Cornwell, T. J.
Bibcode: 1992ESOC...39..815D
Altcode: 1992hrii.conf..815D
No abstract at ADS
Title: Design Rationale of the Solar Ultraviolet Network / Sun
Authors: Dame, L.; Acton, L.; Bruner, M. E.; Connes, P.; Cornwell,
T. J.; Curdt, W.; Foing, B. H.; Hammer, R.; Harrison, R.; Heyvaerts,
J.; Karabin, M.; Marsch, E.; Martic, M.; Mattic, W.; Muller, R.;
Patchett, B.; Roca-Cortes, T.; Rutten, R. J.; Schmidt, W.; Title,
A. M.; Tondello, G.; Vial, J. C.; Visser, H.
Bibcode: 1992ESOC...39..995D
Altcode: 1992hrii.conf..995D
No abstract at ADS
Title: TRC 4: Correlation of the Tmin fine structure with the
chromospheric bright points
Authors: Martic, Milena; Dame, Luc; Bruner, M. E.; Foing, Bernard H.
Bibcode: 1991AdSpR..11e.241M
Altcode: 1991AdSpR..11..241M
Simultaneous ground based observations in the Ca II K2V
line and high resolution UV filtergrams (at λ160 nm) obtained during
the 4th rocket flight of TRC (Transition Region Camera) were used for
comparative studies of the fine structure in active regions, network,
and supergranulation cells interior. In this paper we report similar
time evolution and spatial correspondence between chromospheric cell
bright points and continuum emission form the solar Tmin region. These
results support the existence of a standing wave phenomena in the
cell interiors.
Title: A solar interferometric mission for ultrahigh resolution
imaging and spectroscopy: SIMURIS
Authors: Damé, L.; Acton, L.; Bruner, M.; Connes, P.; Cornwell, T.;
Foing, B. H.; Heyvaerts, J.; Lemaire, P.; Martić, M.; Muller, R.;
Porteneuve, J.; Roca Cortés, T.; Riehl, J.; Rutten, R.; Séchaud,
M.; Smith, P.; Thorne, A. P.; Title, A. M.; Vial, J. -C.; Visser,
H.; Weigelt, G.
Bibcode: 1991AdSpR..11a.383D
Altcode: 1991AdSpR..11..383D
SIMURIS is an interferometric investigation of the very fine structure
of the solar atmosphere from the photosphere to the corona. It was
proposed to ESA /1/, November 30 1989, for the Next Medium Size
Mission - M2, and accepted in February 1990 for an Assessment Study
in the context of the Space Station. The main scientific objectives
will be outlined, and the ambitious model payload featuring the Solar
Ultraviolet Network (SUN), a 2 m long monolithic array of 4 telescopes
of Ø20 cm, and the Imaging Fourier Transform Spectrometer (IFTS),
an UV and Visible Imaging Fourier Transform Spectrometer coupled to
a Ø40 cm Gregory, described.
Title: Solar physics at ultrahigh resolution from the space station
with the Solar Ultraviolet Network (SUN)
Authors: Damé, L.; Acton, L.; Bruner, M.; Connes, P.; Cornwell,
T.; Foing, B.; Heyvaerts, J.; Lemaire, P.; Martić, M.; Muller, R.;
Roca Cortés, T.; Riehl, J.; Rutten, R.; Title, A. M.; Vial, J. -C.;
Visser, H.; Weigelt, G.
Bibcode: 1991AdSpR..11e.267D
Altcode: 1991AdSpR..11..267D
The SUN experiment is a UV and visible Space Interferometer aimed at
ultra-high resolution in the solar atmosphere. It has been proposed
to ESA as part of the SIMURIS Mission Proposal which has recently
been accepted for an Assessment Study in the framework of the
Space Station. The 4 × 20 cm telescopes of the SUN linear array are
non-redundantly placed to cover a 2 m baseline, and the instrument makes
full use of stabilized interferometry potential, the 4 telescopes being
co-aligned and co-phased on a reference field on the sun. After a brief
outline of the scientific objectives, the concept of the instrument
is described, and its image reconstruction potential is illustrated.
Title: Preliminary performance of a 4-point resonance scattering
experiment to access long-period global oscillations from space
Authors: Boumier, P.; Bocchia, R.; Damé, L.; Martic, M.; Pallé,
P.; van der Raay, H. B.; Robillot, J. M.; Roca Cortés, T.
Bibcode: 1991AdSpR..11d.199B
Altcode: 1991AdSpR..11..199B
The first data of a SOHO-GOLF type instrument are presented
hereafter. The slopes of the solar sodium lines profiles D1 and
D2, and their variations with the excursion of the working point
are shown. Two methods of determining the oscillation velocity are
compared, one usually used with 2-point spectrometers and one using
the 4-point information. We show that the second method gives spectra
which are significantly less noisy in the very low frequency range
(up to 300 μHz). For higher frequencies, terrestrial atmospheric
fluctuations alter the measurement, and as far as ground based
instruments are concerned, the 4-point method loses its efficiency
if the magnetic modulation commutation time (in our case 20 seconds)
is not significantly reduced.
Title: SIMURIS: Solar, Solar System and Stellar Interferometric
Mission for Ultrahigh Resolution Imaging and Spectroscopy
Authors: Coradini, M.; Dame, L.; Foing, B.
Bibcode: 1991ssss.book.....C
Altcode:
No abstract at ADS
Title: Rocket observations and modelling of flux-tubes
Authors: Foing, Bernard H.; Dame, Luc; Martic, Milena
Bibcode: 1991AdSpR..11e.245F
Altcode: 1991AdSpR..11..245F
The solar observations at high angular resolution have led to the
discovery that the solar magnetic field is structured in filamentary
fields at the photospheric level. Manifestations of these fluxtubes can
be diagnosed with EUV images (with the Transition Region Camera Rocket
Experiment, TRC) at 220nm in the middle photosphere, at 160nm in the
temperature minimum region or in the Ly alpha and C IV lines formed
at temperatures 20 000K and 100 000K in the transition region. In the
frame of a thin flux tube modelling of the TRC data, the vertical
variation of tube parameters and the conditions for thermalisation
in the upper photosphere are discussed. We consider constraints from
EUV observations on current models of flux-tubes and coronal loops
including non LTE calculations, dynamic and magnetic effects.
Title: Possibilities for quantification and reduction of solar
velocity noise induced by active regions
Authors: Ulrich, R. K.; Dame, L.; Martic, M.
Bibcode: 1991AdSpR..11d.203U
Altcode: 1991AdSpR..11..203U
Active regions on the solar surface induce a velocity signal in a
variety of measurements of doppler shifts including the integrated
sunlight measurements made by resonance cells using the NaD lines. These
signals may be an important limitation on the ability of the GOLF
investigation to detect solar g-modes. Although the power spectrum of
this velocity signal is not well studied, it is in principal possible
to develop techniques based on other properties of the spectral line
to isolate the active region induced component and remove it from
the observed velocity. This paper describes efforts to develop such
a method and verify its utility using ground-based measurements.
Title: The Solar Ultraviolet Network (SUN) (With 3 Figures)
Authors: Damé, L.
Bibcode: 1991mcch.conf...73D
Altcode:
No abstract at ADS
Title: SIMURIS: a High Resolution Solar Physics Interferometric
Mission in Answer to the Chromospheric and Coronal Heating Problem
(With 2 Figures)
Authors: Damé, L.
Bibcode: 1991mcch.conf...66D
Altcode:
No abstract at ADS
Title: Possible scenarios of coronal loops reconnection/heating
processes to be observed at high spatial resolution
Authors: Dame, L.; Heyvaerts, J.; Foing, B. H.
Bibcode: 1991AdSpR..11a.327D
Altcode: 1991AdSpR..11..327D
Recent improvements in interferometric techniques could allow to
achieve 0.01 arcsec angular resolution on the Sun, i.e. 10 km. Such
a high resolution is of direct interest to understand the coronal
loop structure since current observations at low resolution cannot
distinguish between major dissipation/heating theories which all involve
very small scale dissipating processes. Three simplified scenarios of
loop instabilities are investigated in this paper and the resulting fine
structure and contrast that they might induce on observable quantities
(temperature, density) are deduced.
Title: The imaging fourier transform spectrometer for the SIMURIS
mission
Authors: Foing, B. H.; Dame, L.; Thorne, A. P.; Lemaire, P.
Bibcode: 1991AdSpR..11a.387F
Altcode: 1991AdSpR..11..387F
The Solar Interferometric Mission for Ultrahigh Resolution Imaging and
Spectroscopy (SIMURIS) is an interferometric investigation in space
at ultraviolet and visible wavelengths aimed at reconnaissance of
solar features at angular scales from 0.3 to 0.01 arcsec. The Imaging
Fourier Transform Spectrometer (IFTS) is, with the Solar Ultraviolet
Network (SUN), one of the core instruments of the proposed SIMURIS
mission. It consists of a 40 cm Gregory telescope feeding a double
grating pre-dispersive spectrometer before entering a Fourier transform
spectrometer for a field of 10 × 10 arcsec2 at 0.3 arcsec
resolution. The SIMURIS/IFTS requires upgrading of existing FTS down
to 120 nm, with imaging capabilities. For the IFTS imaging a detector
with fast readout must be used. There are also demanding constraints
on the real time processing, and the subsequent important data rate,
and requirements on an upgraded instrument pointing system (IPS),
within the resources and capabilities of the Space Station.
Title: Laboratory experiments on fringe-pattern acquisition and
stabilization
Authors: Dame, Luc; Beal, Denis; Sorrente, Beatrice; Prieto, Eric
Bibcode: 1990SPIE.1237..639D
Altcode:
No abstract at ADS
Title: Optical recombination tolerances of the Solar Ultraviolet
Network
Authors: Dame, Luc; Moreau, Bernard G.; Riehl, Jacques
Bibcode: 1990SPIE.1237..654D
Altcode:
No abstract at ADS
Title: Magnetic Field Modulation Issues for Improving Global Solar
Oscillation Measurements from Space
Authors: Damé, L.; Ulrich, R. K.; Martić, M.; Boumier, P.
Bibcode: 1990LNP...367..265D
Altcode: 1990psss.conf..265D
The measurement of global oscillations of the Sun from space will
provide the ultimate means by which we will assess the existence, and
hopefully observe some of the expected gravity modes. The SOHO-GOLF
experiment, with a 4-point measurement in the line profile (resonance
scattering method with a variable magnetic field applied to a sodium
cell), may be able to distinguish between magnetic effects and true
velocities. In this paper we characterize the effects of the magnetic
fields and active regions on all aspects of the solar D lines in
order to determine the best way to extract this signal from the solar
background noise. These preliminary findings are then used to quantify
the precision requirements for the GOLF Magnetic Field Modulation
measurement method.
Title: High Resolution Solar Physics from the Space Station with
Interferometric Techniques: The Solar Ultraviolet Network (SUN) -
Instrument &Objectives
Authors: Damé, L.; Acton, L.; Bruner, M.; Connes, P.; Cornwell, T.;
Foing, B.; Heyvaerts, J.; Jalin, R.; Lemaire, Ph.; Martic, M.; Moreau,
B.; Muller, R.; Roca Cortés, T.; Riehl, J.; Rutten, R.; Title, A. M.;
Vial, J. -C.; Visser, H.; Weigelt, G.
Bibcode: 1990PDHO....7..262D
Altcode: 1990dysu.conf..262D; 1990ESPM....6..262D
No abstract at ADS
Title: Solar Ultraviolet Network: an interferometric investigation
of the fundamental solar astrophysical scales
Authors: Dame, Luc; Moreau, Bernard G.; Cornwell, Timothy J.;
Visser, H.; Title, Alan M.; Acton, Loren W.; Aime, Claude; Braam,
Bart M.; Bruner, Marilyn E.; Connes, Pierre; Faucherre, Michel; Foing,
B. H.; Haisch, Bernhard M.; Hoekstra, Roel; Heyvaerts, Jean; Jalin,
Rene; Lemaire, Philippe; Martic, Milena; Muller, R.; Noens, J. C.;
Porteneuve, Jacques; Schulz-Luepertz, E.; von der Luehe, Oskar
Bibcode: 1989SPIE.1130..126D
Altcode:
The Solar UV Network (SUN) presently proposed is an interferometric
system, based on the principles of stabilized interferometry, which
will be capable of solar observations with spatial resolutions better
than 0.013 arcsec. SUN will consist of four 20-cm diameter telescopes
aligned nonredundantly on a 2-m baseline. SUN is judged to be ideally
deployable by the NASA Space Station, if implemented on a pointing
platform whose performance is of the order of the Instrument Pointing
System flown on Spacelab 2. The compact, nonredundant configuration of
SUN's telescopes will allow high-resolution imaging of a 2 x 2 arcsec
field on the solar disk.
Title: ASSI: an optimized fringe tracking stellar interferometer.
Authors: Damé, L.; Decaudin, M.; Faucherre, M.; Boutry, P.; Martic,
M.; Coron, N.; Bourbon, M.; Carteron, J. -R.; Dambier, G.; Jegoudez,
G.; Haro, J.; Lagardère, H.; Leblanc, J.; Lepeltier, J. P.; Lizambert,
C.; Bourdet, G.; Moreau, B.; Jalin, R.; Séchaud, M.; Rabbia, Y.;
Schumacher, G.; Dugué, M.
Bibcode: 1989SPIE.1114..225D
Altcode:
The authors present the ASSI (Active Stabilization in Stellar
Interferometry) interferometric experiment presently under realisation
for use with the 2-Telescope interferometer of CERGA (I2T). They
review the principles and expected performances of the system and,
in particular, the real time, flux optimized, fringe tracking system
that they developed using synchronous detection technique on cooled
silicium diodes in the near infrared.
Title: High Resolution Diagnostic of the Mesocells in the Solar
Temperature Minimum Region
Authors: Martič, M.; Damé, L.
Bibcode: 1989ASIC..263..207M
Altcode: 1989ssg..conf..207M
No abstract at ADS
Title: The GOLF helioseismometer on board SOHO.
Authors: Dame, Luc
Bibcode: 1988ESASP.286..367D
Altcode: 1988ssls.rept..367D
The authors present the GOLF (Global Oscillations at Low Frequencies)
investigation that was recently accepted on board the SOHO satellite
of the ESA/NASA Solar Terrestrial Science Programme. The GOLF
instrument is an improved version of ground based instruments using
the resonant-scattering spectrometric technique to measure global
velocities of the Sun and Stars. It has the unique capability of a 4
points measurement in the line profile for both the global velocity
and magnetic field measurements.
Title: GOLF: Simulations of the re-emission of the resonance cell.
Authors: Boumier, P.; Dame, Luc
Bibcode: 1988ESASP.286..425B
Altcode: 1988ssls.rept..425B
Applied to the GOLF (Global Oscillations at Low Frequencies)
helioseismometric instrument to be flown on SOHO, the authors
analyse the re-emission process in the resonance cell, heart of
the instrument. The cell is filled with a sodium vapor and absorbs
selectively in the two sodium lines D1 and D2. The authors simulated
the different influence of the physical parameters (cell geometry,
temperature) and report herein the temperature analysis which allow
to constrain the nominal temperature working point and the required
stability, as a function of the operational conditions (orbital
velocity variation).
Title: GOLF: Global Oscillations at Low Frequencies for the SOHO
mission
Authors: Gabriel, A. H.; Bocchia, R.; Bonnet, R. M.; Cesarsky, C.;
Christensen-Dalsgaard, J.; Dame, L.; Delache, Ph.; Deubner, F. L.;
Foing, B.; Fossat, E.
Bibcode: 1988sohi.rept...13G
Altcode:
The GOLF (global oscillations at low frequencies) SOHO (solar
heliospheric observatory) mission is described. It aims to study
the internal structure of the Sun by measuring the spectrum of free
global oscillations. GOLF will measure both p and g mode oscillations,
with emphasis on low order long period waves which penetrate the
solar core. The instrument aims to measure frequencies between 10-7
and 6 10-3 Hz, with a sensitivity of 1 mm/s. The method involves an
extension to space of the ground based technique for measuring the mean
line-of-sight velocity of the solar surface. A sodium vapor resonance
scattering filter is used in a longitudinal magnetic field to sample the
two wings of the solar absorption line. The use of a modulating magnetic
field provides a continuous internal calibration of the sensitivity. By
adding an additional rotating polarizer, measurements are also made
of the average solar magnetic field. Efforts are made to correct the
data for the spurious effects caused by solar magnetic active regions.
Title: Active stabilization in stellar interferometry (ASSI):
progress report on the two bandpass fringe tracking interferometer.
Authors: Damé, L.; Faucherre, M.; Bourdet, G.; Decaudin, M.; Jegoudez,
G.; Rabbia, Y.; Aubry, G.; Passedat, G.
Bibcode: 1988ESOC...29.1079D
Altcode: 1988hrii.conf.1079D
The authors report the progress done on the new interferometric
table presently beeing built at LPSP for use with the 2-telescope
interferometer of CERGA (I2T). The instrument is featuring an accurate
fine pointing (shared quad-cell type ecartometer set up) and a real
time, flux optimized, white light fringe tracking using the synchronous
detection technique. After a short justification of the adopted
technique, the authors review some of the particularities of their
apparatus, their need, and the gain in performances that they provide.
Title: Oscillatory Properties of Meso-Scale Intensity Structures at
Chromospheric Level
Authors: Dame, L.; Martic, M.
Bibcode: 1988IAUS..123..433D
Altcode:
The authors show the evidence at chromospheric level (Ca II K line)
of meso structures, "mesocells", reminiscent of the mesogranulation by
their spatial size (8 Mm). These cells present very regular oscillations
in intensity, preferably in the 3 - 5 min period range, and it is shown
that the phase of the sustaining wave extends smoothly (coherently)
over the mesocell area.
Title: Tilt correction in stabilized interferometry: difficulties
and remedies.
Authors: Faucherre, M.; Damé, L.; Decaudin, M.; Boutry, P.; Chirouze,
M.; Jegoudez, G.; Lagardère, H.; Rabbia, Y.; Terrier, G.; Vakili, F.
Bibcode: 1988ESOC...29.1093F
Altcode: 1988hrii.conf.1093F
Real-time tilt correction proposed for the I2T at CERGA will be
operationnal in June 88. The construction of this active tracking system
raised some interesting questions that the authors state in this paper,
together with appropriate solutions. They focus here on problems common
to most stellar interferometers: how to get a constant magnification
for pupil image and pupil-star distance whatever the baseline? How to
measure and minimize path delays introduced by tilt correction mirrors
or other moving elements? The authors end up with a discussion on
field rotation compensation and its implication on the optical design.
Title: Rocket flight observations of the meso-scale structure in
the temperature minimum region
Authors: Martic, M.; Dame, L.
Bibcode: 1988AdSpR...8g.173M
Altcode: 1988AdSpR...8..173M
A time sequence of high resolution images, obtained during the last
rocket flight of the Transition Region Camera, was used to make
a detailed study of the mesostructures in the Temperature Minimum
Region. In our previous investigations we showed that meso-scale
structures of 8 Mm spatial size observed in the chromosphere (Ca II K
line) possess a characteristic oscillatory behaviour. Here, we present
a new evidence of large amplitude intensity variations with a clearly
defined 3 min. oscillation period involving all the mesocells of 105
× 105 arcsec2 field on the quiet sun.
Title: Performances of an actively stabilized stellar interferometer
(ASSI): faint magnitudes, low fringe contrast measurements and
operationality
Authors: Dame, L.; Faucherre, M.
Bibcode: 1987ESASP.273..205D
Altcode: 1987ois..work..205D
The authors describe the performances of a new approach to long baseline
Michelson interferometry using a real time active stabilization of
the central fringe position ("fringe tracking"). In this approach the
monitoring function (star pointing and optical path delay information)
is clearly dissociated (and flux optimized) from the scientific analysis
function, in which time integration and stability are favored, for
evident reasons of precision on the fringe contrast measurement.
Title: A test-bed for space interferometry: SPI
Authors: Faucherre, M.; Dame, L.; Stachnik, R. V.; Traub, W. A.
Bibcode: 1987ESASP.273..197F
Altcode: 1987ois..work..197F
The Space Platform Interferometer (SPI), a 20-m two-mirror Michelson
interferometer, which can reach magnitude 14 at UV and visible
wavelengths, is described. The SPI is attached to a platform serviced
from the space station. In addition to its ability to produce unique
science in the UV, SPI is intended to demonstrate the feasibility
of larger projects in the field. Dynamical behavior of the structure
in the gravity gradient environment and fringe stabilization at low
photon rate are studied by picking up an adjacent bin (in the near
IR) on the same object and using it to track the white light fringe
in a separate differential interferometer. The same subsystem also
corrects for tilt. Active control of critical parameters ensures
optical rigidity. Performances are evaluated in low orbit.
Title: Diagnostics of solar coronal loops at interferometric angular
resolution
Authors: Foing, B. H.; Faucherre, M.; Dame, L.
Bibcode: 1987ESASP.273..217F
Altcode: 1987ois..work..217F
The advent of very high angular resolution (equivalent to 20 km on the
sun) for extreme ultraviolet observations would allow to diagnose the
fine structure in density and temperature of solar coronal loops. In the
framework of the variety and uncertainties of the existing theoretical
models of loops, the high angular resolution is of particular importance
to estimate the filling factor of loops by hot and cool material, to
measure radial gradients of temperature and density, to observe flows,
spatiotemporal evolution due to heating mechanisms and interaction
between loops.
Title: Solar interferometry with a 4-aperture non-redondant and
stabilised network
Authors: Dame, L.; Aime, C.; Faucherre, M.; Heyvaerts, J.
Bibcode: 1987ESASP.273..189D
Altcode: 1987ois..work..189D
The design of a solar interferometer is intrinsically complex since
many requirements, often found separately, and difficult by themselves,
are brought together: UV spectral range, limb observations, resolved
structures (low contrast) and time resolution. The stabilized
interferometry technique, applied to a non-redundant array of 4
telescopes, provides an elegant solution to those complex problems.
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: Observation and Oscillatory Properties of Mesostructures in
the Solar Chromosphere
Authors: Dame, L.; Martic, M.
Bibcode: 1987ApJ...314L..15D
Altcode:
Two-dimensional filtergrams of a 90 x 90-arcsec solar field, obtained
with time resolution 12 s and spatial resolution 1 arcsec using a
Halle birefringent filter (bandwidth 60 pm) centered on the blue peak
of the Ca II K line and a CCD array on the Vacuum Tower Telescope at
Sacramento Peak Observatory in a 20-min observing run on November 11,
1983, are presented and analyzed. Cells of extent about 8 Mm (i.e.,
on the scale of mesogranulation) are observed and found to exhibit
significant intensity variations of period 3-5 min, the phase cells
determined by Fourier analysis being of about the same size as the
observed structures. The possibility that mesogranulation may be
closely related to the 5-min solar oscillation is discussed.
Title: Structures fines chromosphériques: nouveaux résultats de
la caméra de la région de transition.
Authors: Foing, B. H.; Dame, L.; Vial, J. C.; Gouttebroze, P.; Martic,
M.; Bonnet, R. M.
Bibcode: 1987JAF....29...15F
Altcode:
No abstract at ADS
Title: La haute résolution en physique solaire: perspectives pour
l'avenir.
Authors: Damé, L.; Foing, B.; Vial, J. C.
Bibcode: 1987JAF....29...16D
Altcode:
No abstract at ADS
Title: Interférométrie stellaire stabilisée: une approche nouvelle
plus performante et plus précise.
Authors: Dame, L.; Bourdet, G.; Faucherre, M.
Bibcode: 1987JAF....29Q..15D
Altcode:
No abstract at ADS
Title: XSST/TRC rocket observations of 13 July 1982 flare.
Authors: Foing, B. H.; Bonnet, R. M.; Dame, L.; Bruner, M.; Acton,
L. W.; Brown, W. A.
Bibcode: 1986lasf.conf..319F
Altcode: 1986lasf.symp..319F
The authors analyse the UV filtergrams of the 13 July
1982 solar flare, taken by the Transition Region Camera,
during the third flight of the joint Lockheed/LPSP rocket
experiment XSST/TRC. From the calibrated intensities of the flare
components, they estimate directly the Lyα line flux (from 230 to
650×103erg cm-2s-1sr-1),
differentially the C IV line flux (from 30 to 130×103erg
cm-2s-1sr-1), and the excess of 160 nm
continuum temperature brightness (from 100 to 250K) over the underlying
plage. No detectable variation is observed in the 220-nm channel
formed in the medium photosphere. These values are small compared to
other observed or calculated equivalent quantities from Machado model
of flare F1. The authors estimate the corresponding power required to
heat the temperature minimum accordingly over the 1200 Mm2
area, to be 3.6×1025erg s-1 for this small
X-ray C6 flare, 7 minutes after the ground based observed flare maximum.
Title: New ultra-violet filtergrams and results from the transition
region camera rocket experiment
Authors: Damé, L.; Foing, B. H.; Martic, M.; Bruner, M.; Brown, W.;
Decaudin, M.; Bonnet, R. M.
Bibcode: 1986AdSpR...6h.273D
Altcode: 1986AdSpR...6..273D
The rocket-borne solar ultra-violet telescope named Transition Region
Camera (T.R.C.) was launched successfully for the fourth time on
25th october 1985. Calibrated photographic images of the sun were
obtained at Lyman alpha and in two adjacent bands at 156 nm and 169
nm. The angular resolution achieved was equivalent to 0.7 arcsec. Fine
structures in Lyman alpha were observed in the network and above
supergranular cells. From the 156 nm filtergram (including a strong C
IV contribution) and the 169 nm filtergram, we study the differential
contribution of the C IV lines and of the continuum emission, from
the quiet sun, an active region and at the limb.
Title: On the origin of the blue continuum of white-light flares
Authors: Dame, L.; Vial, J. -C.
Bibcode: 1985ApJ...299L.103D
Altcode:
A new model for white-light flares is proposed in order to explain
the observed blue continuum (i.e., the higher contrast longward of
the Balmer jump, around 4000 A). Its broad temperature plateau between
60,000 and 90,000 K is compatible with chromospheric evaporation. The
predicted UV emission, computed here in the Si IV resonance lines
(1402 and 1393 A), is, however, too large by two orders of magnitude,
as compared to the emission from weak flares. Because of the lack of a
comprehensive set of measurements in white-light flares, the validity
of such a model is still open.
Title: Meso-Scale Structures - an Oscillatory Phenomenon
Authors: Dame, L.
Bibcode: 1985tphr.conf..244D
Altcode:
No abstract at ADS
Title: The Chromospheric Dynamic of Fine Structures
Authors: Dame, L.
Bibcode: 1985tphr.conf..241D
Altcode:
No abstract at ADS
Title: The chromospheric dynamics of fine structures.
Authors: Dame, L.
Bibcode: 1985MPARp.212..241D
Altcode:
A Ca II K line movie is presented, which directly enhances the intricate
imbrication of the inner cell emission in fine structures (the "bright
points") and the underlying waves driven mechanism. The exceptionally
high spatial and temporal resolutions (0.5 arcsec and 5 s) of this
52 minutes laps time movie clearly illustrate the non-linear though
very regular brightenings of fine structures by seemingly incoming
wavefronts.
Title: Hundredths of Arcsec Resolutions with New Optical Correctors
on Deep UV Photoresist
Authors: Dame, L.; Decaudin, M.
Bibcode: 1985LNP...233..128D
Altcode: 1985hrsp.proc..128D
This paper describes new optical correctors which are phase conjugated
to a mirror and allow, in most cases, a residual distorsion of the
outgoing wavefront as low as λ/40 (16 nm) peak to peak. Such a high
resolution system is possible with deep U.V. photoresist correctors
registered at 257 nm in a diverging Michelson-Twyman interferometer
directly by the mirror to be corrected itself, without any intermediary
steps. Some results obtained with this technique are given. They show
the potential interest of this method for optical imaging system in
space involving large mirror and/or ultraviolet imaging.
Title: Meso-scale structures: an oscillatory phenomenon?
Authors: Dame, L.
Bibcode: 1985MPARp.212..244D
Altcode:
A 20 minutes time sequence of simultaneous filtergrams taken in
the blue peak of the Ca II K line and magnetic field maps taken
in the photospheric line Fe 6302.5 Å is used to investigate the
phase coherence of the 3 - 5 minutes oscillation. The extent of the
coherence eddies in the calcium line is typically 8 Mm (11 arcsec)
which is comparable to the dimension of the "mesogranulation" observed
by November et al. (1979). The extension of this phase coherence of
the oscillatory wavefront is only slightly influenced by the period
of the wave in the 3 - 5 minutes range. The same analysis done on
the magnetic field gives a totally different picture with an extended
phase coherence on active regions superimposed to a "noisy background".
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: Intensity oscillations in the calcium - K line
Authors: Gouttebroze, P.; Dame, L.; Malherbe, J. -M.
Bibcode: 1984MmSAI..55..245G
Altcode:
An analysis is undertaken of a time sequence of quiet sun filtergrams
taken in the core of the K line, in order to investigate the oscillatory
properties of the chromosphere. The physical significance of these
intensity variations and their diagnostic capabilities are discussed,
and an oscillatory power vs. frequency and mean intensity diagram
is noted to indicate the different behaviors of bright regions
dominated by low frequency waves and darker regions dominated by high
frequency waves. A diagnostic wavenumber-frequency diagram indicates
two oscillatory power concentrations which approximately correspond to
acoustic and gravity waves, in chromospheric conditions. A theoretical
diagnostic diagram computed on the basis of a solar atmosphere model
exhibits a 'g-1' chromospheric mode; this corresponds almost exactly
to the location of the observed ridge.
Title: Small-Scale Dynamical Processes in the Solar Chromosphere
Authors: Dame, L.
Bibcode: 1984ssdp.conf...54D
Altcode:
Two time series of high resolution and long duration observations - H
line spectra and filtergrams in the core of the K-line - were analyzed
to investigate the physical and oscillatory properties of chromospheric
fine structures. Time-resolved spectroscopy of the H-line data and
frequency analysis (frequency maps, diagram brightness-frequency) of the
K-line filtergrams allow to draw a coherent picture of the relationships
between the chromospheric field of oscillation and the "cell points".
Title: Ultraviolet resolution of large mirrors via Hartmann tests
and two-dimensional fast Fourier transform analysis.
Authors: Dame, L.; Vakili, F.
Bibcode: 1984OptEn..23..759D
Altcode:
Large mirrors appear to be limited in resolution by their medium scale
defects (mirror surface "ripples" of small amplitude and of 4 to 12
cycles per diameter). The ultraviolet resolutions of the Pic du Midi
(PDM) 2 m mirror, the Canada-France-Hawaii (CFH) 3.6 m mirror, and
the Space Telescope (ST) 2.4 m mirror have been studied. Hartmann
screen tests were used to determine the wavefront error of the PDM
and CFH mirrors, while only semiquantitative reports were used in the
case of the ST mirror. Point spread function and modulation transfer
function were determined by two-dimensional fast Fourier transform
analysis, a necessary technique in the ultraviolet, where the small
phase defects of mirrors are no longer negligible (and also because
the mirrors' irregularities do not possess a particular arrangement
or a given symmetry). If the three mirrors appear to be nearly limited
by diffraction in the visible (except the CFH), in the ultraviolet at
Lyman a 121.6 nm the resolution is inferior by more than a factor of 10
to the diffraction-limited resolution. While the ultra-violet wavelength
range and very high resolution (0.014 arcsec with a diffrac-tion-limited
Space Telescope at Lyman a) are highly desirable, such a limitation
imposed by mirror surface quality has to be mentioned. The effects
of the correlation length, amplitude of defects, and Hartmann screen
sampling are presented, as well as some comments on the inadequacy
in the ultraviolet of analytical methods compared to two-dimensional
numerical simulations.
Title: Observation and analysis of intensity oscillations in the
solar K-line
Authors: Dame, L.; Gouttebroze, P.; Malherbe, J. -M.
Bibcode: 1984A&A...130..331D
Altcode:
Chromospheric oscillations are investigated with a time sequence
of filtergrams of the sun taken in the core of the Ca II K-line at
the Sacramento Peak Observatory. The relations between oscillation
frequency and wavenumber are analyzed, as are those between frequency
and mean intensity. Intensity analysis reveals that low frequency waves
are associated mainly with bright (chromospheric network) regions,
while the '3-min' oscillation dominates in cell interiors. As the mean
brightness of the observed region increases, the high frequency limit
of oscillatory power decreases. This is interpreted as the decrease of
the resonance frequency of the chromospheric cavity with increasing
temperatures, which confirms the chromospheric origin of the 3-min
oscillations. Diagnostic diagrams suggest that both acoustic and
internal gravity waves occur in the chromosphere and appear to have
a modal structure.
Title: On the possible use of deep U.V. photoresists correctors to
obtain the ultimate U.V. resolution of space borne telescopes.
Authors: Dame, L.; Bonnet, R. M.; Artzner, G. E.
Bibcode: 1984SPIE..445..318D
Altcode:
Large space-borne telescopes are limited in their ultraviolet resolution
by their large and medium scale (20 - 30 cm) surface irregularities
(ripples). The authors present the principle, instrumentation and
first results of a new interferometric method using a Michelson-Twyman
configuration (diverging light beams) that allows to engrave on
deep U.V. photoresists a phase compensating plate which permit to
revocer, partly or entirely, the diffraction limited resolution of the
telescope. The corrector that they obtain is a phase compensating plate
in reflection with highs and lows on its surface perfectly conjugated
in negative, with the primary mirror surface irregularities.
Title: A UV Corrector for Large Space-Borne Telescopes
Authors: Dame, L.
Bibcode: 1984ssdp.conf...90D
Altcode:
A new interferometric method is presented which allows for the creation
of a primary mirror corrector of small size and of very high precision
(a few nanometers of surface distortions). This corrector allows the
suppression of large and medium scale defects (classical aberrations,
ripples up to 10 - 20 cycles per diameter). Used with space-borne
telescopes, such correctors would allow extremely high resolution
(hundreds of arcsecs) while their use on ground-based telescopes
could improve the resolution of short-exposure imagery (speckle)
when limitation is a result of the telescope quality rather than the
seeing conditions.
Title: White-light radiation from semi-empirical flare models.
Authors: Dame, L.; Cram, L.
Bibcode: 1983SoPh...87..329D
Altcode:
We show that some recently published semi-empirical models for solar
flares predict a significant flux of visible continuum radiation,
due to bound-free radiation from hydrogen atoms and H−
ions in the chromospheric flare. The ratio of the emergent intensity in
one flare model to that in the quiet Sun is more than 100% at the head
of the Balmer continuum for a flare close to the limb, and 8% at disk
centre. The predicted flare spectrum has a relatively strong Balmer
jump. We compare the theoretical flare continuum with observations and
find disagreement in several important respects. The main disagreements
are: (1) the fact that few flares are observed to emit a white-light
continuum, while the models suggest that they should do so; (2)
the prediction of a strong Balmer jump, which is not observed in
most white-light flares; and (3) the absence of a `blue continuum'
in the theoretical prediction. We conclude that observations of flare
continua provide useful constraints on semi-empirical models, and that
at present the models do not satisfy these constraints.
Title: High spatial and temporal resolution observations of the
solar CA II H line
Authors: Cram, L. E.; Dame, L.
Bibcode: 1983ApJ...272..355C
Altcode:
A 24 minute time series of photographic Ca II H line spectra made with
high spatial and spectral resolution has been analyzed to provide data
on the range of line profile variations in the quiet sun. Distribution
functions of the line-core intensity and the ratio of emission peak
intensities are exhibited and are used to classify the associated
line profiles. It is shown that the range of profile variation is
significantly larger than that covered by the models A-F of Vernazza,
Avrett, and Loeser, especially in relation to the darkest profiles
in which no core emission can be detected. Time-resolved spectra are
used to show that the 3-minute chromospheric oscillation involves
upward-propagating excitation which leads to intense heating in the
cell points. It is conjectured that these observations provide a direct
picture of the processes responsible for a significant part of the
nonradiative heating of the quiet chromosphere.
Title: Space-time Analysis of Oscillations Observed in the Solar Ca
II Resonance Lines
Authors: Dame, L.; Gouttebroze, P.
Bibcode: 1982BAAS...14..922D
Altcode:
No abstract at ADS
Title: Relationships between CaII H Line Fine Structure and the
Integrated Solar H Line
Authors: Damé, L.; Cram, L.
Bibcode: 1981BAAS...13..829D
Altcode:
No abstract at ADS
Title: Radiative Processes in White-Light Flares
Authors: Damé, L.; Cram, L.
Bibcode: 1981BAAS...13Q.820D
Altcode:
No abstract at ADS