Author name code: schadee ADS astronomy entries on 2022-09-14 author:"Schadee, Aert" ------------------------------------------------------------------------ Title: Book reviews Authors: Hermsen, W.; Stamm, W.; Nieuwenhuijzen, H.; Plez, B.; Koch-Miramond, L.; Schadee, A.; De Greve, J. P.; Icke, Vincent; Kresák, Ľ.; Dekker, E.; Bonnet-Bidaud, J. -M.; Foing, B. H. Bibcode: 1994SSRv...67..421H Altcode: No abstract at ADS Title: Book Review: The Cambridge guide to astronomical discovery / Cambridge U Press, 1992 Authors: Schadee, A. Bibcode: 1994SSRv...67..426S Altcode: 1994SSRv...67..426L No abstract at ADS Title: Book-Review - the Astronomy and Astrophysics Encyclopedia Authors: Maran, S. P.; Schadee, A. Bibcode: 1993SSRv...64..367M Altcode: No abstract at ADS Title: Book reviews Authors: Heintze, J. R. W.; van Genderen, A. M.; van Oss, R.; van der Klis, M.; Fárník, F.; Schadee, A.; Sylwester, J.; Torii, S.; Iwaniszewska, C.; Nieuwenhuijzen, H.; Kleczek, J.; Schwartz, S. J. Bibcode: 1993SSRv...64..363H Altcode: No abstract at ADS Title: Book Review: Space science dictionary I / Academia Praha ; Elsevier, 1990 Authors: Schadee, A. Bibcode: 1992SSRv...61R.425S Altcode: No abstract at ADS Title: Book Review: Molecular astrophysics / CUP, 1990 Authors: Schadee, A. Bibcode: 1991SSRv...58..191S Altcode: No abstract at ADS Title: Book reviews Authors: Hovenier, J. W.; Cornet, Gerard; De Greve, J. P.; Schadee, A.; Kresák, L.; Néeman, Y. Bibcode: 1991SSRv...58..189H Altcode: No abstract at ADS Title: Book reviews Authors: Iwanowska, W.; Sehnal, L.; van der Kruit, P. C.; Schadee, A.; Smoliński, J.; Longair, M. S.; Thé, P. S.; McLean, I. S. Bibcode: 1991SSRv...56..241I Altcode: No abstract at ADS Title: Book Review: Introduction to stellar astrophysics. Vol. 2: Stellar atmospheres / CUP, 1989 Authors: Schadee, A. Bibcode: 1991SSRv...56..245S Altcode: No abstract at ADS Title: Book Review: Introduction to stellar astrophysics Volume 1: Basic stellar observations and data / CUP, 1989 Authors: Schadee, A. Bibcode: 1990SSRv...54..452S Altcode: 1990SSRv...54..452B No abstract at ADS Title: De zon, een overzicht. Authors: Schadee, A. Bibcode: 1990Zenit..17..306S Altcode: No abstract at ADS Title: Book reviews Authors: Marov, M. Ya; Garmany, C. D.; Heck, André; Schadee, A.; McNally, D.; van der Kruit, P. C.; Pecker, J. -C.; de Jager, Cornelis; Somov, B. V. Bibcode: 1989SSRv...50..385M Altcode: No abstract at ADS Title: Preflare activity. Authors: Priest, E. R.; Gaizauskas, V.; Hagyard, M. J.; Schmahl, E. J.; Webb, D. F.; Cargill, P.; Forbes, T. G.; Hood, A. W.; Steinolfson, R. S.; Chapman, G. A.; Deloach, A. C.; Gary, G. A.; Jones, H. P.; Karpen, J. T.; Martres, M. -J.; Porter, J. G.; Schmieder, B.; Smith, J. B., Jr.; Toomre, J.; Woodgate, B.; Waggett, P.; Bentley, R.; Hurford, G.; Schadee, A.; Schrijver, J.; Harrison, R.; Martens, P. Bibcode: 1989epos.conf....1P Altcode: Contents: 1. Introduction. 2. Magnetohydrodynamic instability. 3. Preflare magnetic and velocity fields. 4. Coronal manifestations of preflare activity. Title: High resolution microwave and X-ray observations of solar flares Authors: Alissandrakis, C. E.; Schadee, A.; Kundu, M. R. Bibcode: 1988A&A...195..290A Altcode: This paper presents an analysis of high spatial resolution observations of 18 weak flares, carried out during the Solar Maximum Year in the microwave range, H-alpha, and soft X-rays, together with observations of the associated hard X-ray emission and the photospheric magnetic field. This combination of observations made it possible to obtain a picture of the flare geometry and the relative position of the various emissions, to study the change of the geometry during the flare, to estimate the electron temperature and emission measure of the thermal plasma, and to compute the contribution of the free-free process in the microwave emission. Results are interpreted as evidence for the presence of energetic electrons even in the post-burst phase of some flares. There was also found a clear case of homologous radio and X-ray bursts, one case of foot-point expansion with a relative velocity of 20 km/s at 6.16 cm, as well as some evidence of triggering of flares by disturbances moving with a velocity of 5000-13,000 km/s. Title: Coronal manifestations of preflare activity Authors: Schmahl, E. J.; Webb, D. F.; Woodgate, B.; Waggett, P.; Bentley, R.; Hurford, G.; Schadee, A.; Schrijver, J.; Harrison, R.; Martens, P. Bibcode: 1986epos.conf.1.48S Altcode: 1986epos.confA..48S A variety of coronal manifestations of precursors or preheating for flares are discussed. Researchers found that almost everyone with a telescope sees something before flares. Whether an all-encompassing scenario will ever be developed is not at all clear at present. The clearest example of preflare activity appears to be activated filaments and their manifestations, which presumably are signatures of a changing magnetic field. But researchers have seen two similar eruptions, one without any evidence of emerging flux (Kundu et al., 1985) and the other with colliding poles (Simon et al., 1984). While the reconnection of flux is generally agreed to be required to energize a flare, the emergence of flux from below (at least on short timescales and in compact regions) does not appear to be a necessary condition. In some cases the cancelling of magnetic flux (Martin, 1984) by horizontal motions instead may provide the trigger (Priest, 1985) Researchers found similarities and some differences between these and previous observations. The similarities, besides the frequent involvement of filaments, include compact, multiple precursors which can occur both at and near (not at) the flare site, and the association between coronal sources and activity lower in the atmosphere (i.e., transition zone and chromosphere). Title: Book-Review - Molecular Astrophysics Authors: Diercksen, G. H. F.; Huebner, W. F.; Langhoff, P. W.; Schadee, A. Bibcode: 1986SSRv...44..178D Altcode: No abstract at ADS Title: Book reviews Authors: Gurtovenko, E. A.; Kostik, R. I.; Tlamicha, A.; Zerull, R.; Schadee, Aert; Mészáros, A.; Néeman, Y.; Giese, R. H.; Sinclair, A. T.; Kleczek, J.; Trendelenburg, E. A.; Hillebrandt, Wolfgang; Sehnal, L.; de Graaff, W.; Slottje, C.; Courvisier, T.; van Beek, H. F.; Baud, B.; de Jager, C.; Danby, J. M. A.; Somov, B. V.; Cassinelli, J.; Verbunt, F. Bibcode: 1986SSRv...44..177G Altcode: No abstract at ADS Title: Preflare activity. Authors: Priest, E. R.; Gaizauskas, V.; Hagyard, M. J.; Schmahl, E. J.; Webb, D. F.; Cargill, P.; Forbes, T. G.; Hood, A. W.; Steinolfson, R. S.; Chapman, G. A.; Deloach, A. C.; Gary, G. A.; Jones, H. P.; Karpen, J. T.; Martres, M. -J.; Porter, J. G.; Schmieder, B.; Smith, J. B., Jr.; Toomre, J.; Woodgate, B.; Waggett, P.; Bentley, R.; Hurford, G.; Schadee, A.; Schrijver, J.; Harrison, R.; Martens, P. Bibcode: 1986NASCP2439....1P Altcode: Contents: 1. Introduction: the preflare state - a review of previous results. 2. Magnetohydrodynamic instability: magnetic reconnection, nonlinear tearing, nonlinear reconnection experiments, emerging flux and moving satellite sunspots, main phase reconnection in two-ribbon flares, magnetic instability responsible for filament eruption in two-ribbon flares. 3. Preflare magnetic and velocity fields: general morphology of the preflare magnetic field, magnetic field shear, electric currents in the preflare active region, characterization of the preflare velocity field, emerging flux. 4. Coronal manifestations of preflare activity: defining the preflare regime, specific illustrative events, comparison of preflare X-rays and ultraviolet, preflare microwave intensity and polarization changes, non-thermal precursors, precursors of coronal mass ejections, short-lived and long-lived HXIS sources as possible precursors. Title: Survey of an active region in H&alpha; and X-rays. Authors: Schadee, Aert; Martin, Sara F. Bibcode: 1986lasf.conf..360S Altcode: 1986lasf.symp..360S The authors studied Hale Active Region No. 16918 during almost 15 hours of simultaneous observation by Big Bear Solar Observatory (H&alpha;) and HXIS (3.5 - 5.5 keV) aboard SMM on 18 - 22 June 1980. Title: On the nature of small X-ray flux over active regions Authors: Schadee, Aert Bibcode: 1986AdSpR...6f..41S Altcode: 1986AdSpR...6...41S Long-lived weak X-ray flux is often observed in active regions. The speculation that this flux is the collective result of a manifold of ``nanoflares'' is investigated. Modelling nanoflares as instantaneously energized loops, it is shown that these loops cannot be shorter than 10 000 km. A modest number of loops with lengths ranging from 10 000 to 30 000 km and electron densities of (1 - 3) × 1011 cm-3 could produce the observed X-ray flux. Title: Can nanoflares produce weak X-ray sources? Authors: Schadee, Aert Bibcode: 1986lasf.conf..356S Altcode: 1986lasf.symp..356S Long-lived weak X-ray flux is often observed in active regions. The speculation that this flux is the collective result of a manifold of nanoflares is investigated. Modelling nanoflares as instantaneously energized loops, it is shown that these loops cannot be shorter than 10,000 km. A modest number of loops with lengths ranging from 10,000 to 30,000 km and electron densities of (1 - 3)×1011cm-3 could produce the observed X-ray flux. Title: Identification of two X-ray miniflares with Hα-subflares Authors: Schadee, A.; Gaizauskas, V. Bibcode: 1984AdSpR...4g.117S Altcode: 1984AdSpR...4..117S Active regions show many short-lived emissions in the 3.5 - 5.5 keV range that are 100 to 1000 times weaker than ``normal'' X-ray flares. The hypothesis that they may well be miniflares is supported by the simultaneous occurrence of 2 Hα-subflares at the site of weak X-ray sources. Title: Relationships of a growing magnetic flux region to flares Authors: Martin, S. F.; Bentley, R. D.; Schadee, A.; Antalova, A.; Kucera, A.; Dezső, L.; Gesztelyi, L.; Harvey, K. L.; Jones, H.; Livi, S. H. B.; Wang, J. Bibcode: 1984AdSpR...4g..61M Altcode: 1984AdSpR...4...61M Some sites for solar flares are known to develop where new magnetic flux emerges and becomes abutted against opposite polarity pre-existing magnetic flux (review by Galzauskas/1/). We have identified and analyzed the evolution of such flare sites at the boundaries of a major new and growing magnetic flux region within a complex of active regions, Hale No. 16918. This analysis was done as a part of a continuing study of the circumstances associated with flares in Hale Region 16918, which was designated as an FBS target during the interval 18 - 23 June 1980. We studied the initiation and development of both major and minor flares in Hα images in relation to the identified potential flare sites at the boundaries of the growing flux region and to the general development of the new flux. This study lead to our recognition of a spectrum of possible relationships of growing flux regions to flares as follows: (1) intimate interaction with adjacent old flux - flare sites centered at new/old flux boundary, (2) forced or ``intimidated'' interaction in which new flux pushes old field having lower flux density towards a neighboring old polarity inversion line where a flare then takes place, (3) ``influential'' interaction - magnetic lines of force over an old polarity inversion line, typically containing a filament, reconnect to the new emerging flux; a flare occurs with erupting filament when the magnetic field overlying the filament becomes too weak to prevent its eruption, (4) inconsequential interaction - new flux region is too small or has wrong orientation for creating flare conditions, (5) incidental - flare occurs without any significant relationship to new flux regions. Title: Enhanced X-Ray Emission above 3.5-KEV in Active Regions in the Absence of Flares Authors: Schadee, A.; de Jager, C.; Svestka, Z. Bibcode: 1983SoPh...89..287S Altcode: We demonstrate that even in the absence of flares there are very often volumes of hot plasma in the corona above active regions with temperatures in excess of 10 million degrees. Characteristics of this hot plasma and its time variations seem to be different in active regions of different phase of development. These hot plasma regions are sources of very weak, but clearly recognizable, X-ray emission above 3.5 keV. Long-lived X-ray brightenings, 104 times weaker than a flare, but lasting up to 10 hr occur predominantly along the H∥ = 0 line, apparently low in the corona. After major flares, long-lived X-ray emission is also radiated from tops of arches extending high into the corona. Some other long-lived sources, far from the H∥ = 0 line, may be associated with newly emerging flux. Short-lived X-ray sources, with fluxes ranging from subflare levels to 10−3 times the flare flux, last for 2 to more than 30 min and are probably microflares. They seem to be most frequent in growing young active regions and appear often in areas with newly emerging flux. Title: Radio, X-ray, and optical observations of the flare of June 13, 1980, at 6h22m UT Authors: Kattenberg, A.; Allaart, M.; de Jager, C.; Schadee, A.; Schrijver, J.; Shibasaki, K.; Švestka, Z.; van Tend, W. Bibcode: 1983SoPh...88..315K Altcode: A subflare of importance Sf was observed on June 13, 1980 simultaneously by instruments aboard the Solar Maximum Mission (SMM) and various ground based observatories. We describe and compare different kinds of observations, with emphasis on the Hard X-Ray Imaging Spectrometer (HXIS) images and spectra, and on the one-dimensional microwave images with high time and spatial resolution, obtained with the Westerbork Synthesis Radio Telescope (WSRT). The fast electrons causing the X-ray and microwave impulsive bursts had a common acceleration source, but the burst were produced at the opposite footpoints of the loops involved, with microwaves emitted near to a sunspot penumbra. The flare (of a `compact' type) was probably triggered by an emerging flux, and two possible interpretations of this process are briefly discussed. Title: Pre-Flare and Post-Flare X-Ray Variations in Active Regions Authors: Svestka, Z.; Schadee, A. Bibcode: 1983SoPh...86..267S Altcode: Extremely low background noise of the HXIS experiment aboard the SMM made it possible to detect > 3.5 keV X-ray emissions from non-flaring active regions which are 103-104 times weaker than the X-ray flux from flares. Short-lived X-ray bursts and long-lived X-ray enhancements of various intensities seem to characterize active regions in different phases of their development. After major two-ribbon flares, giant X-ray arches are seen in the corona, slowly decaying for many hours after the flare end. Associated with these arches appear to be quasi-periodic flare-like variations of purely coronal nature. Title: The Queen's Flare - its Structure and Development - Precursors Pre-Flare Brightenings and Aftermaths Authors: de Jager, Cornelis; Machado, Marcos E.; Schadee, Aert; Strong, Keith T.; Švestka, Zdeněk; Woodgate, Bruce E.; van Tend, W. Bibcode: 1983SoPh...84..205D Altcode: We continue previous research on the limb flare of 30 April, 1980, 20:20 UT, observed in X-rays by several instruments aboard the Solar Maximum Mission (SMM). It is shown quantitatively that the flare originated in an emerging magnetically confined kernel (diameter ∼ 20″) which existed for about ten to fifteen minutes, and from which energetic electrons streamed, in at least two injections, into a previously existing complicated magnetic loop system thus forming a less bright but extended and long-lived tongue. The tongue had a length of ∼ 35 000 km and lasted ∼ 90 min in X-rays (∼ 10 keV); at lower energies (∼ 0.7 keV) it was larger (∼ 80 000 km) and lasted longer. The total number of energetic electrons (≈ 1037) initially present in the kernel is of the same order as the number present in the tongue after the kernel's decline. This gives evidence that the energetic electrons in the tongue originated mainly in the kernel. The electron number densities in the kernel and tongue at maximum brightness were ∼ 4.5 × 1011 and ∼ 1 × 1011 cm#X2212;3, respectively. During the first eight minutes of its existence the tongue was hotter than the kernel, but it cooled off gradually. Its decline in intensity and temperature was exponential; energy was lost by radiation and by conduction through the footpoints of the loop system. These footpoints have a cross-section of only ∼ 3 × 106 km2. This small value, as well as photographs in a CIV UV emission line, suggests a highly filamentary structure of the system; this is further supported by the finding that the tongue had a `filling factor' of ∼ 10#X2212;2. Several faint X-ray brightenings (≲ 0.005 of the flare's maximum intensity) were observed at various locations along the solar limb for several hours before and after the flare. At ∼ 30 min before the flare's onset a faint (≲ 0.02) flare precursor occurred, coinciding in place and shape with the flare. First the kernel precursor was brightest but the tongue precursor increased continuously in brightness and was the brightest part of the precursor some 10-15 min after the first visibility of the kernel precursor, until the start of the main flare. This suggests (weak) continuous electron acceleration in the tongue during a period of at least 30 min. The main flare was caused by strong emergence of magnetic field followed by two consecutive field line reconnections and accelerations in a small loop system, causing footpoint heating. Subsequently plasma streamed (convectively) into a pre-existing system of larger loops, forming the tongue. Title: 3.5 keV X-ray Emission in Absence of Flares Authors: Schadee, A.; de Jager, C.; Svestka, Z. Bibcode: 1983BAAS...15R.704S Altcode: No abstract at ADS Title: The limb flare of 1980 April 30 as seen by the hard X-ray imaging spectrometer Authors: van Beek, H. F.; de Jager, C.; Schadee, A.; Svestka, Z.; Boelee, A.; Duijveman, A.; Galama, M.; Hoekstra, R.; Hoyng, P.; Fryer, R.; Simnett, G. M.; Imhof, J. P.; LaFleur, H.; Maseland, H. V. A. M.; Mels, W. M.; Schrijver, J.; van der Laan, J. J. M.; van Rens, P.; van Tend, W.; Werkhoven, F.; Willmore, A. P.; Wilson, J. W. G.; Machado, M. E.; Zandee, W. Bibcode: 1981ApJ...244L.157V Altcode: X-ray imaging of the limb event of 1980 April 30 shows that the flaring involved two distinct components: a pointlike component, which was the source of the initial hard X-ray burst and an extensive tongue reaching some 30,000 km above the limb. The tongue had a higher temperature than the other parts of the structure and seemed to be enhanced by energetic electrons that derived their energy from the initial source. Title: Structural development of the X-ray limb flare of 30 April 1980 Authors: de Jager, C.; Hoyng, P.; Lafleur, H.; Schadee, A.; Svestka, Z.; van Beek, H. F.; van Tend, W.; Fryer, R.; Simnett, G. M. Bibcode: 1981AdSpR...1m.251D Altcode: 1981AdSpR...1..251D We describe the development of the limb flare of 30 April 1980, 20:20 UT, as observed by the Hard X-ray Imaging Spectrometer (HXIS) aboard the Solar Maximum Mission (SMM). It consisted of a short-lived bright nucleus (FWHM < 10,000 km), just inside the Sun's limb; a longer lasting tongue, extending to a height of ~ 30,000 km, and a more complicated feature, approximately situated at the Sun's limb. The tongue was a pre-existing magnetic structure that started emitting X-rays only a few seconds after the bright nucleus, and which had a slightly higher temperature than the nucleus; its X-ray emission may be caused by electrons escaped from the nucleus. Title: Solar maximum mission experiment: Early results of the hard X-ray imaging experiment Authors: Boelee, A.; de Jager, C.; Duijveman, A.; Galama, M.; Hoekstra, R.; Hoyng, P.; Imhof, J. P.; Lafleur, H.; Maseland, H. V. A. M.; Mels, W. A.; Schadee, A.; Schrijver, J.; Svestka, Z.; van Beek, H. F.; van Rens, P.; van der Laan, J. J. M.; van Tend, W.; Werkhoven, F.; Wiersma, G.; Zandee, W.; Simnett, G. M.; Charlton, C. P.; Fryer, R.; Willmore, A. P.; Wilson, J. W. G.; Machado, M. E. Bibcode: 1981AdSpR...1m.255B Altcode: 1981AdSpR...1R.255B We have selected four widely different flares from the early period of operations of the Hard X-Ray Imaging Spectrometer (HXIS) on SMM to illustrate the characteristic imaging properties of this experiment. For the small flare of April 4, 1980, we demonstrate the instrument's capability for locating a compact source. In the weak, but extensive, flare of April 6 we show how well the instrument can display spatial structure, and also the low level of the instrument background. In the 1B flare of April 7 we are able to locate positions of the X-ray emission in the soft and hard channels, and estimate the positional variations of the emission patches. Finally, in the IN flare of April 10, which produced the strongest hard X-ray burst we have seen so far, we repeat some of the studies made for the April 7 event, and also demonstrate the capability of the HXIS instrument to study the development, with high time resolution, of individual 8'' × 8'' elements of the flare. Title: Structural development of the X-ray limb flare of 30 April 1980. Authors: de Jager, C.; Fryer, R.; Hoyng, P.; Lafleur, H.; Schadee, A.; Simnett, G. M.; Svestka, Z.; van Beek, H. F.; van Tend, W. Bibcode: 1981hea..conf..251D Altcode: No abstract at ADS Title: Solar Maximum Mission experiment: early results of the hard X-ray imaging experiment. Authors: Simnett, G. M.; Boelee, A.; Charlton, C. P.; de Jager, C.; Duijveman, A.; Fryer, R.; Galama, M.; Hoekstra, R.; Hoyng, P.; Imhof, J. P.; Lafleur, H.; Machado, M. E.; Maseland, H. V. A. M.; Mels, W. A.; Schadee, A.; Schrijver, J.; Svestka, Z.; van Beek, H. F.; van Rens, P.; van der Laan, J. J. M.; van Tend, W.; Werkhoven, F.; Wiersma, G.; Willmore, A. P.; Wilson, J. W. G.; Zandee, W. Bibcode: 1981hea..conf..255S Altcode: No abstract at ADS Title: Errata: "On the Zeeman effect in electronic transitions of diatomic molecules" [J. Quant. Spectrosc. Radiat. Transfer, Vol. 23, p. 517 - 531 (1978)]. Authors: Schadee, A. Bibcode: 1980JQSRT..23..533S Altcode: No abstract at ADS Title: Unique definitions for the band strength and the electronic-vibrational dipole moment of diatomic molecular radiative transitions. Authors: Schadee, A. Bibcode: 1978JQSRT..19..451S Altcode: No abstract at ADS Title: On the Zeeman effect in electronic transitions of diatomic molecules. Authors: Schadee, A. Bibcode: 1978JQSRT..19..517S Altcode: No abstract at ADS Title: Theory of First Rotational Lines in Transitions of Diatomic Molecules Authors: Schadee, A. Bibcode: 1975A&A....41..203S Altcode: Summary. Correct expressions for the energies of the first rotational levels (those with J < A + S) and the H6nl-London factors for transitions involving these levels are derived for doublet and triplet states and transitions in diatomic molecular spectra. Key words: first rotational lines H6nl-London factors - interstellar lines spectroscopy Title: Honl-London Factors for 3H-32 and 3L'-~J1 Transitions with Intermediate Coupling Authors: Schadee, A. Bibcode: 1975A&A....41..213S Altcode: Summary. H6nl-London factors of rotational lines for 3H - and - 3H transitions of diatomic molecules are calculated, allowing for non-zero values of both the splitting constant of the state and the coupling constant Y of the H state. Key words: H6nl-London factors molecular spectro sco py Title: Book reviews Authors: van de Stadt, Herman; Rawer, Karl; Schadee, A.; Noyes, R. W.; Bleeker, J. A. M.; Wittenberg, H.; de Graaff, W.; Akasofu, S. -I.; Hooykaas, R.; Bappu, M. K. V.; Atanasijević, I.; Icke, Vincent; van der Valk, F.; Kresàk, L.; Müller, Edith A. Bibcode: 1975SSRv...17..159V Altcode: No abstract at ADS Title: On the Normalization of H6nl-London Factors Authors: Schadee, A. Bibcode: 1971A&A....14..401S Altcode: A new normalization of -London factors, which govern the intensity distribution within a molecular band, is presented. Problems posed by previous normalizations are solved. Key worde: -London factors - molecular spectroscopy Title: An Upper Limit of the Swan Band Intensity in a Sunspot Spectrum Authors: Schadee, Aert Bibcode: 1970SoPh...15..345S Altcode: There is no evidence for the C2(0,1) band in an investigated sunspot spectrum. Upper limits are given for the band intensity. Title: On the oscillator strengths of MgO and F2. Authors: Main, R. P.; Schadee, A. Bibcode: 1969JQSRT...9..713M Altcode: No abstract at ADS Title: Zirconium Isotope Ratios in the S-Type Star HR 1105 Authors: Schadee, Aert; Davis, Dorothy N. Bibcode: 1968ApJ...152..169S Altcode: The spectrum of the bright non-variable star HR 1105 was studied at 3 A/mm; it is S type with some features of type M. The wavelengths of isotopes of ZrO were computed and used to improve the molecular constants by comparison with laboratory measurements. Direct use of isotope shifts is not possible. The isotope ratios of zirconium in HR 1105 were estimated by fitting elaborately computed ZrO profiles to the observed spectrum in a limited, supposedly uncon- taminated, region. Two sets of isotope ratios which best match the stellar spectrum were found: (a) a terrestrial mixture, but with a high abundance of unstable Zr93, i.e., Zr93/Zr9° ~ ~, and (b) the ratios Zr91/Zr90, Zr92/Zr90, and Zr94/Zr9° larger by a factor of 2 or 3 than the terrestrial ratios, with Zr93 at low abundance. The present observations do not permit a choice between these two possible isotopic mixtures. An upper limit to Zr96 is probably less than 10 per cent of the Zr content. No trace of strong lines of ZrO'7 or ZrO'8 was found. Thus Zr isotopes produced by the s-process apparently differ, in this star, from the terrestrial values, and the supposed production of 018 has probably not occurred Title: Molecular Band Intensities in G and K Stars Authors: Schadee, Aert Bibcode: 1968ApJ...151..239S Altcode: Intensities of CO, CH, C2, and CN bands are studied for G and K stars with various surface gravities and metal content, assuming different C, N, and 0 compositions. Atmospheric models are based on a scaled, solar T(r) relation A simple method predicts the molecular intensities accurately, and it is therefore not necessary to work out the equilibria of all possible C, N, and 0 compounds in detail. The dependences of the computed band intensities on the metal content, Teff, and g are discussed and found to be in agreement with the observations. The possibilities of determining CNO abundances from ob- served band intensities are also discussed. The molecular equilibria are dominated by the association of CO, which is complete for stars later than KO. Two independent spectral features are required to deter- mine the C and 0 abundances, like the G-band and an [Oi] line in oxygen-rich giants. In oxygen-rich dwarfs, there is oniy one easily observable feature, the G-band, which yields a relation between 0 and C. In carbon-rich stars the C2 and CH intensities are not independent since each is a function of the abun- dance difference between carbon and oxygen. For oxygen-rich dwarfs and carbon-rich stars the second datum required to derive 0 and C can only be obtained from infrared CO observations. The nitrogen abundance may be determined from CN bands for carbon-rich stars, if the C - 0 abundance difference is known, and for oxygen-rich stars, if both the carbon and the oxygen abundances are known. The division of late-type stars into oxygen-rich and carbon-rich is extremely sharp; differences of more than 1 per cent from the mathematical equality 0 = C places a star in either class. All bands of C and N compounds are formed near r 0.1 in carbon-rich stars and, except for CO, near r 1 or 2 in oxygen-rich stars. Especially in the latter stars, the optical depth of formation (r) is a function of the CNO composition, and since the carbon depletion is a critical function of both r and the CNO composi- tion, an a priori assumption of (r) in determining abundances may lead to erroneous results Title: Zr isotope ratios in HR 1105. Authors: Schadee, A.; Davis, D. N. Bibcode: 1967PASP...79..437S Altcode: No abstract at ADS Title: Zirconium Isotope Ratios in HR 1105 Authors: Schadee, A.; Davis, D. N. Bibcode: 1967PASP...79Q.437S Altcode: No abstract at ADS Title: The Solar Line at λ8668 Å Interpreted as CN Authors: Schadee, Aert Bibcode: 1967ApJ...147..363S Altcode: No abstract at ADS Title: On the Rotational Temperature of a Sunspot Authors: Schadee, Aert Bibcode: 1966ApJ...145..348S Altcode: No abstract at ADS Title: Reduction of Molecular Line Intensities Authors: Schadee, A. Bibcode: 1966IAUS...26...92S Altcode: No abstract at ADS Title: The formation of molecular lines in the solar spectrum (Errata: 17 537) Authors: Schadee, A. Bibcode: 1964BAN....17..311S Altcode: No abstract at ADS