scholarly journals Fundamental Parameters and the Helium Content of Eclipsing Spectroscopic Binaries

1978 ◽  
Vol 80 ◽  
pp. 433-436
Author(s):  
H.E. Jørgensen
Keyword(s):  
Stellar Evolution ◽  
Stellar Atmosphere ◽  
Spectroscopic Binaries ◽  
List Type ◽  
Type Number ◽  
Helium Content ◽  
Fundamental Parameters ◽  
Effective Temperatures ◽  
Hr Diagram

Today we know accurate masses, radii, surface gravities and luminosities or effective temperatures of a very small number of stars. There are several reasons for deriving accurate parameters of stars. I shall mention only four problems:(i)checking stellar evolution calculations, particularly calculations of isochrones, using binaries,(ii)derivation of helium content in stars of different age,(iii)checking log g derived from photometry and stellar atmosphere calculations,(iv)determination of accurate positions in the HR diagram to get an independent check on calibrations of photometric systems.

The atmosphere of subluminous B stars

1984 ◽  
Vol 105 ◽  
pp. 223-224
Author(s):  
U. Heber ◽  
K. Hunger ◽  
G. Jonas ◽  
R.P. Kudritzki
Keyword(s):  
List Type ◽  
Type Number ◽  
Low Resolution ◽  
B Stars ◽  
Helium Content ◽  
Sdb Stars ◽  
Large Aperture ◽  
Effective Temperatures

8 sdB stars have been analyzed for effective temperatures, gravity and helium content by means of LTE and NLTE model atmospheres (Heber et al., 1983). The analyses are based on the following observations: 1.)B&C IDS spectrograms obtained with ESO's 3.6m and 1.5m telescopes (4250–4800å at 29 å/mm, or, 4000–5000å at 59 å/mm).2.)IUE spectra in low resolution (6å) through the large aperture.3.)Johnson and Strömgren colours, which are taken from the literature.

An alert in the psycho-social-health intervention. A graphic testimony of a real case with autism spectrum disorder

2011 ◽  
Vol 26 (S2) ◽  
pp. 758-758
Author(s):  
J.A. García ◽  
A.S. Raya ◽  
E.S. del Arco
Keyword(s):  
Autism Spectrum ◽  
Real Case ◽  
List Type ◽  
Type Number ◽  
High Functioning ◽  
The Family ◽  
Pertinent Information ◽  
New Challenges ◽  
Professional Intervention

The graphic papers of Pablo, 14 years, diagnosed of autism of high functioning, serve as a sign of alert when facing what underlies after the specializing professional intervention.A few letters, a few drawings, and a few words that show the powerlessness, the suffering and the absence of contextual specific adequacy.In this work we study, from the analysis of a real case, some excellent aspects in the psychosociosanitary attention, such as:-The need for compilation of pertinent information-The need for elimination of prejudices-The need for respect to the family-The need for specialized formation-The need for search of a shared communicative code-The need for search of strategies of social interaction-The need for empathy-The need for search of contextual specific adequacy-The need for rigorous rules in the physical containment.-The need of a turned over of adapted information-The need to respect the psychoevolutive situation of the patient-The need to give priority to the person on the illness.A testimony that should serve as a warning for those institutions, administrations and professionals who are thinking of having put all the resources to its scope.A testimony that should serve to contribute information and new challenges to those other professionals who do not stop their determination of conceptual and/or clinical anxious research.

scholarly journals Photographic Observation of Stellar Occultations

1988 ◽  
Vol 98 ◽  
pp. 144-145
Author(s):  
A. Tomić ◽  
N. Čabrić ◽  
V. Čelebonović
Keyword(s):  
List Type ◽  
Type Number ◽  
The Moon ◽  
Photographic Observation ◽  
High Quality ◽  
Crucial Step ◽  
Stellar Occultations ◽  
On Line

Stellar occultations are usually observed visually, but this can also be done photographically. Our method has some advantages: –the obtained moments of contacts refer to the smoothed lunar limb,–the error in the determination of contacts is calculable,–the error may be less than in visual work,–the reduction of photographs is fast, due to the application of an “on-line” computer [1].In order to achieve all this, it is necessary to make a series of photographs of the Moon and the object being occulted before the first and after the last contact. This is a crucial step in our method, because the photographs must be of high quality. This demands two things: –the images of the occulted object and the Moon must be reliably recorded and–the illuminated limb of the Moon must give optimal darkening on the film.

scholarly journals Round table discussion of session F: convection and rotation

2006 ◽  
Vol 2 (S239) ◽  
pp. 443-445
Author(s):  
Ian W. Roxburgh
Keyword(s):  
Angular Velocity ◽  
Stellar Evolution ◽  
Differential Rotation ◽  
Round Table ◽  
Round Table Discussion ◽  
List Type ◽  
Type Number ◽  
Table Discussion ◽  
Convective Core ◽  
Late Stages

AbstractThe Session F round table. and audience, considered the following questions: (i)what determines the differential rotation in stellar convective zones?(ii)If there really is a rapid inward increase in angular velocity in giants will it have significant effects in the late stages of stellar evolution?(iii)How effective is penetration above a convective core?(iv)Why is the solar core nearly uniformly rotating?

Survey for Duplicity Frequencies: Status and Prospects

1992 ◽  
Vol 135 ◽  
pp. 266-272
Author(s):  
Paul Couteau
Keyword(s):  
Stellar Evolution ◽  
List Type ◽  
Type Number ◽  
Complete Set ◽  
The Mean ◽  
Large Telescopes

I.We recall the main surveys: J. Herschel (1826), W. Struve (1825), A.W. Burnham and G.W. Hough (1880), R.G. Aitken and W.J. Hussey (1910), R. Jonckeere and T.E. Espin (1910), W.H. van den Bos (1925), R.A. Rossiter (1950). Presently the classical surveys are continuing with P. Muller, W.D. Heintz, and P. Couteau. The interferometric survey with large telescopes is carried out at CHARA.II.The results of old surveys, up to 1950, amount to 700 known orbits out of more than 35000 found binaries. The new surveys since 1965, both visual and interferometric, had checked 4000 new binaries giving already about 30 orbits. The periods are shorter and shorter: the mean period is 200 years for Struve (1825) binaries, 75 years for Aitken’s (1910), 25 years for Couteau and Muller’s (1970), and 7 years for CHARA’s. The number of known orbits increases exponentially with time.III.The “classical” surveys will have to be performed again within fifty years with refractors.The interferometric and aperture syntheses surveys will be able to observe every binary, even those in contact with each other. With HIPPARCOS’ results, astronomers will dispose of a complete set of data for new theories of stellar evolution.

The Separation of Principal Stresses in Photo-Elastic Analysis

1946 ◽  
Vol 50 (432) ◽  
pp. 974-985 ◽  
Author(s):  
E. K. Frankl
Keyword(s):  
Stress Pattern ◽  
Design Tool ◽  
Complete Analysis ◽  
List Type ◽  
Elastic Analysis ◽  
Type Number ◽  
Principal Stresses ◽  
Suitable Material ◽  
Polarised Light

The photo-elastic method can be used for either of two main purposes:a)As a qualitative design tool to obtain indications of possibly unsuspected sources of stress concentration.(b)As a means of obtaining a complete analysis of a two-dimensional stress problem, i.e., the determination of the separate magnitudes of the principal stresses at any point, as well as the direction of the principal planes relative to some axis of reference.All that is required for (a) is the stress pattern which becomes visible and can be photographed when a loaded model cut from a sheet of suitable material is placed in a field of circularly polarised light.

scholarly journals Can Stellar Atmospheres be in Quasi-Static Equilibrium in the Presence of Magnetic Fields?

1981 ◽  
Vol 93 ◽  
pp. 276-277
Author(s):  
Kyoji Nariai
Keyword(s):  
Magnetic Fields ◽  
Stellar Atmosphere ◽  
Stellar Atmospheres ◽  
Stellar Surface ◽  
Static Equilibrium ◽  
List Type ◽  
Type Number

Among the observational astronomers it is quite customary to assume potential magnetic fields in calculating the strength and the direction of the magnetic fields on the stellar surface. People use this assumption because 1.it is easy to calculate,2.it is possible to fit the observations with the calculations to some extent using the parameters inherent to the model,3.at a first glance, there is no difficulty in assuming both potential magnetic fields and static stellar atmosphere because they do not interact each other (except at the pole).

scholarly journals Sub-luminous blue stars and white dwarfs

1959 ◽  
Vol 10 ◽  
pp. 33-37
Author(s):  
Jesse L. Greenstein
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
White Dwarfs ◽  
List Type ◽  
Type Number ◽  
Horizontal Branch ◽  
Horizontal Branch Stars ◽  
Growth Of Knowledge ◽  
Hot Subdwarfs ◽  
Hr Diagram

Sub-luminous stars of high temperature show a wide variety of spectra and physical properties. Vorontsov-Velyaminov has called this region of the HR diagram the “blue-white sequence”. I wish to discuss the fainter members of this class. The growth of knowledge of colors and spectra has been rapid compared to that of the luminosities, and unfortunately only rough location in the HR diagram is yet possible. Figure 1 shows the general location and subdivision of sub-luminous stars. I shall discuss: (1)Old novae.(2)Horizontal-branch stars.(3)Hot subdwarfs.(4)White dwarfs.

scholarly journals An Astrometric Catalog of Four Million Stars

1990 ◽  
Vol 141 ◽  
pp. 482-482 ◽  
Author(s):  
V. V. Nesterov ◽  
V. S. Kisliuk ◽  
H. I. Potter
Keyword(s):  
Comparative Studies ◽  
List Type ◽  
Full Information ◽  
Type Number ◽  
Proper Motions ◽  
Methods Of Determination ◽  
General Reduction

The goal of the present study is (1)Completion of a general reduction of the Carte du Ciel astrophotographic catalogs, measurement of the positions in them on modern astronegatives, derivation of proper motions and compilation of a catalog of stars to magnitude 12.5.(2)Copying the data of all 272 volumes of astrophotographic catalogues onto magnetic tapes (all together 8.5 million measurements).(3)Measurement of modern astronegatives on FON-OBZOR-S and FOKAT-Y programs.(4)Studies of the magnitude equation of the AGK3 catalog and other catalogs which will be presumably used as reference catalogs.(5)Development and comparative studies of several methods of determination of equatorial coordinates on the basis of full information on astronegative measurements. Application of these methods to compilation of the catalog of 4 million stars.

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