scholarly journals Statistics of CP Stars in a Magnitude-Limited Sample: The Bright Star Catalogue

1993 ◽  
Vol 138 ◽  
pp. 629-633 ◽  
Author(s):  
H. Schneider
Keyword(s):  
Incomplete Data ◽  
Main Sequence ◽  
Open Clusters ◽  
Bright Star ◽  
Limited Sample ◽  
The Past ◽  
Star Catalogue ◽  
General Catalogue ◽  
The Moment ◽  
Ap Stars

AbstractIn the past several authors investigated the incidence of CP Stars among field stars of the upper main sequence, e.g. Jaschek&Jascheck (1967), Wolff (1968), Abt (1979), or in open clusters e.g. Young&Martin (1973), Hartoog (1976), North&Cramer (1981). But the published values seem not to be very precise or universal because of the use of incomplete data bases like Osawa’s list (1965) or the old version of the Bright Star Catalogue or the concentration on selected samples e.g. open clusters. Only Smith (1973) gave realistic values in the case of CP1 stars.In the meantime two decades passed and many new observations were obtained. In 1982 a new version of the Bright Star Catalogue with better spectral classifications was issued and a supplement to the BS catalogue was published (1983). Furthermore, Renson and co-workers presented 1991 their General Catalogue of Am and Ap Stars (in the following abbreviated to GCAAS). Now the moment has come to establish new and hopefully more precise values of the incidence of CP Stars using the new version of the Bright Star Catalogue and its supplement as the data base.

scholarly journals Helium, [Fe/H] Abundances and the HR (Log TEFF, MBol) Diagram With Hipparcos Data of The Four Nearest Open Clusters: Hyades, Coma Berenices, The Pleiades and Praesepe

1998 ◽  
Vol 11 (1) ◽  
pp. 565-565
Author(s):  
G. Cayrel de Strobel ◽  
R. Cayrel ◽  
Y. Lebreton
Keyword(s):  
Main Sequence ◽  
Open Clusters ◽  
Main Sequence Stars ◽  
Spectroscopic Analyses ◽  
Solar Metallicity ◽  
Metal Abundances ◽  
The Mean ◽  
The Moment ◽  
The One ◽  
Best Fit

After having studied in great detail the observational HR diagram (log Teff, Mbol) composed by 40 main sequence stars of the Hyades (Perryman et al.,1997, A&A., in press), we have tried to apply the same method to the observational main sequences of the three next nearest open clusters: Coma Berenices, the Pleiades, and Praesepe. This method consists in comparing the observational main sequence of the clusters with a grid of theoretical ZAMSs. The stars composing the observational main sequences had to have reliable absolute bolometric magnitudes, coming all from individual Hipparcos parallaxes, precise bolometric corrections, effective temperatures and metal abundances from high resolution detailed spectroscopic analyses. If we assume, following the work by Fernandez et al. (1996, A&A,311,127), that the mixing-lenth parameter is solar, the position of a theoretical ZAMS, in the (log Teff, Mbol) plane, computed with given input physics, only depends on two free parameters: the He content Y by mass, and the metallicity Z by mass. If effective temperature and metallicity of the constituting stars of the 4 clusters are previously known by means of detailed analyses, one can deduce their helium abundances by means of an appropriate grid of theoretical ZAMS’s. The comparison between the empirical (log Teff, Mbol) main sequence of the Hyades and the computed ZAMS corresponding to the observed metallicity Z of the Hyades (Z= 0.0240 ± 0.0085) gives a He abundance for the Hyades, Y= 0.26 ± 0.02. Our interpretation, concerning the observational position of the main sequence of the three nearest clusters after the Hyades, is still under way and appears to be greatly more difficult than for the Hyades. For the moment we can say that: ‒ The 15 dwarfs analysed in detailed in Coma have a solar metallicity: [Fe/H] = -0.05 ± 0.06. However, their observational main sequence fit better with the Hyades ZAMS. ‒ The mean metallicity of 13 Pleiades dwarfs analysed in detail is solar. A metal deficient and He normal ZAMS would fit better. But, a warning for absorption in the Pleiades has to be recalled. ‒ The upper main sequence of Praesepe, (the more distant cluster: 180 pc) composed by 11 stars, analysed in detail, is the one which has the best fit with the Hyades ZAMS. The deduced ‘turnoff age’ of the cluster is slightly higher than that of the Hyades: 0.8 Gyr instead of 0.63 Gyr.

scholarly journals The number of Be stars compared with the number of B stars, taking into account the specific physical characteristics of Be stars

1994 ◽  
Vol 162 ◽  
pp. 356-357
Author(s):  
D. Briot ◽  
J. Zorec
Keyword(s):  
Spectral Type ◽  
Bright Star ◽  
Physical Parameters ◽  
Emission Characteristics ◽  
Be Stars ◽  
Constant Mass ◽  
B Stars ◽  
The Past ◽  
Star Catalogue

It is very important for the understanding of the Be phenomenon, and particularly for locating a possible Be phase in the evolutionary track of B stars, to accurately determine the proportion of Be stars among all B stars. This type of study was already made several times in the past. Results obtained generally show a maximum Be frequency around spectral type B2 then a decrease towards late spectral types. Actually Be stars do not have the same characteristics as “normal” B stars and we have to take this into account in the determination of the ratio : number of Be stars / number of B stars. We use the Bright Star Catalogue (Hoffleit & Jaschek 1982) and the Supplement to the Bright Star Catalogue (Hoffleit, Saladyga & Wlasuk 1983) containing stars V= 7.10 and brighter. This study needed to be made separately for the different spectral types because:- Physical parameters of B stars are very different from B0 to B9;- Emission characteristics of Be stars vary very much, with a decrease from B0e to B9e.We successively consider three effects which can influence the frequency of Be stars:- The over-luminosity of Be stars as compared with B stars;- Spectral type changes during constant mass evolution;- Spectral type changes due to the fast rotation of Be stars.

scholarly journals Seismology of Pulsating Ap Stars: Results From The Past Decade, Prospects For The Next

1993 ◽  
Vol 139 ◽  
pp. 122-131
Author(s):  
Jaymie M. Matthews
Keyword(s):  
Main Sequence ◽  
Rotation Period ◽  
The Past ◽  
Low Degree ◽  
Ap Stars ◽  
Ir Photometry ◽  
Roap Star ◽  
High Overtone

AbstractSince the discovery of the first rapidly oscillating Ap (roAp) star in 1978 by Kurtz, this class of magnetic chemically-peculiar pulsators has grown to over two dozen. The eigenfrequency spectra of roAp stars (with periods of ∼ 6 – 15 min) are consistent with nonradial p- modes of low degree and high overtone n, not unlike the Sun's five-minute oscillations seen in integrated light. However, unlike the Sun, the strong global dipole fields of roAp stars significantly affect the pulsations.Although much of the effort in the last decade has been towards detecting new roAp candidates and refining the frequencies of known variables, initial “seismic” analyses have already yielded important results. Measurements of fundamental frequency spacings constrain the luminosities and radii of some roAp stars. In addition, mode splitting provides: (1) an independent determination of rotation period, even in the absence of longer-term light variations; (2) limits on the rotational inclination i and magnetic obliquity β; and (3) an indication of the relative internal field strengths of certain roAp stars. Very recently, the temperature - optical depth structure of the atmosphere of HR 3831 was inferred from optical and IR photometry of its oscillations.Judging from current developments, the next decade promises exciting results on both observational and theoretical fronts. Several roAp stars have now been monitored for over a decade, allowing us to investigate long-term period changes due to evolution, binarity, etc. Eigenfrequency models for stars in the mass and radius range appropriate for Ap stars are becoming available, as well as explicit treatments of the perturbations due to magnetic fields. Armed with these, we may be able to place some roAp stars on a theoretical (or “asteroseismological H-R“) diagram to derive independently their masses and main-sequence ages.

scholarly journals Plans for A New Edition of the Bright Star Catalogue

1977 ◽  
Vol 35 ◽  
pp. 151-151
Author(s):  
Dorrit Hoffleit ◽  
Carlos Jaschek
Keyword(s):  
Double Star ◽  
Spectroscopic Binaries ◽  
Bright Star ◽  
Proper Motions ◽  
The Third ◽  
Star Catalogue ◽  
Naval Observatory ◽  
General Catalogue ◽  
The Press ◽  
The U.S

Almost any star catalogue becomes obsolescent as soon as it comes off the press. It is now twelve years since the third edition of the Yale Bright Star Catalogue was published in 1964. In the intervening years numerous important new results have appeared, notably the Jaschek et al Catalogue of MK Spectral Classes, the Lick Double Star Catalogue, the U.S. Naval Observatory Catalogue of UBV Magnitudes, the Abt and Biggs Bibliography of Radial Velocities, the Third Edition and three Supplements of the General Catalogue of Variahle Stars, the SAO Catalogue with proper motions reduced to the FK4 system, several new lists of spectroscopic binaries, and a great many shorter compilations. Consequently well in excess of 20,000 entries in the third edition of the Bright Star Catalogue need up-dating.

On The Radii of Ap Stars

1976 ◽  
Vol 32 ◽  
pp. 49-55 ◽  
Author(s):  
F.A. Catalano ◽  
G. Strazzulla
Keyword(s):  
Observational Data ◽  
Line Width ◽  
Main Sequence ◽  
Main Sequence Stars ◽  
Ap Stars

SummaryFrom the analysis of the observational data of about 100 Ap stars, the radii have been computed under the assumption that Ap are main sequence stars. Radii range from 1.4 to 4.9 solar units. These values are all compatible with the Deutsch's period versus line-width relation.

Chelovek.RU/Человек.RU

Chelovek RU ◽  
2020 ◽  
pp. 18-53
Author(s):  
Sergei Avanesov ◽  
Keyword(s):  
Family History ◽  
Great Distance ◽  
Point Of View ◽  
The Past ◽  
Russian Philosopher ◽  
True Meaning ◽  
The Future ◽  
Pavel Florensky ◽  
The Moment

Abstract. The article analyzes the autobiography of the famous Russian philosopher, theologian and scientist Pavel Florensky, as well as those of his texts that retain traces of memories. According to Florensky, the personal biography is based on family history and continues in children. He addresses his own biography to his children. Memories based on diary entries are designed as a memory diary, that is, as material for future memories. The past becomes actual in autobiography, turns into a kind of present. The past, from the point of view of its realization in the present, gains meaning and significance. The au-thor is active in relation to his own past, transforming it from a collection of disparate facts into a se-quence of events. A person can only see the true meaning of such events from a great distance. Therefore, the philosopher remembers not so much the circumstances of his life as the inner impressions of the en-counter with reality. The most powerful personality-forming experiences are associated with childhood. Even the moment of birth can decisively affect the character of a person and the range of his interests. The foundations of a person's worldview are laid precisely in childhood. Florensky not only writes mem-oirs about himself, but also tries to analyze the problems of time and memory. A person is immersed in time, but he is able to move into the past through memory and into the future through faith. An autobi-ography can never be written to the end because its author lives on. However, reaching the depths of life, he is able to build his path in such a way that at the end of this path he will unite with the fullness of time, with eternity.

Five Years and Count(er)ing: Memoir after Memoir

CounterText ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 26-32
Author(s):  
Norbert Bugeja
Keyword(s):  
Guest Editor ◽  
Arab Countries ◽  
National Museum ◽  
Terror Attack ◽  
Special Issue ◽  
The Past ◽  
Personal Perspectives ◽  
The Moment ◽  
Ongoing Project

In this retrospective piece, the Guest Editor of the first number of CounterText (a special issue titled Postcolonial Springs) looks back at the past five years from various scholarly and personal perspectives. He places particular focus on an event that took place mid-way between the 2011 uprisings across a number of Arab countries and the moment of writing: the March 2015 terror attack on the Bardo National Museum in Tunis, which killed twenty-two people and had a profound effect on Tunisian popular consciousness and that of the post-2011 Arab nations. In this context, the author argues for a renewed perspective on memoir as at once a memorial practice and a political gesture in writing, one that exceeds concerns of genre and form to encompass an ongoing project of political re-cognition following events that continue to remap the agenda for the region. The piece makes a brief final pitch for Europe's need to re-cognise, within those modes of ‘articulacy-in-difficulty’ active on its southern borders, specific answers to its own present quandaries.

INSTITUTE OF TRIAL BY JURY IN THE RUSSIAN EMPIRE: ORIGIN AND DEVELOPMENT

2020 ◽  
Author(s):  
Rafael Komiljonov
Keyword(s):  
Russian Empire ◽  
Jury Trial ◽  
Judicial Process ◽  
The Past ◽  
Russian State ◽  
Administration Of Justice ◽  
Jury System ◽  
The Russian Empire ◽  
The Moment

The article examines the Genesis of the institution of jury trial in the Russian Empire from the moment of its introduction to the end of the Provisional government. It is noted that the emergence of a trial with the participation of jurors was influenced by Western models of the judicial process, and the forms of participation of citizens in the administration of justice that previously existed on the territory of the Russian state were taken into account. The role that the jury system has played with some success in the search for truth, justice, and the implementation of effective and independent justice in the past centuries is particularly highlighted.

scholarly journals Wooden Buildings in Market Squares of Polish Small Towns: Bielsk Podlaski and Kleszczele—The Issue of Preserving and Restoring Historical Values of Market Spaces

2021 ◽  
Vol 13 (12) ◽  
pp. 6779
Author(s):  
Aleksander Owerczuk
Keyword(s):  
Small Towns ◽  
The Past ◽  
Rapid Changes ◽  
Individual Market ◽  
The Moment

In the past centuries, small towns in Podlaskie Voivodeship were dominated by wooden buildings. Nowadays, there are not many of them left. However, they can still be found in the centers of towns, including some market squares. These are often inconspicuous objects, mainly wooden houses. This paper discusses the issue of the significance of wooden buildings, especially houses, in maintaining and restoring historic values of market spaces in small towns of Podlaskie Voivodeship in the examples of Bielsk Podlaski and Kleszczele. The research determined the moment of rapid changes, during which most marketplace buildings lost their historic form. The existing condition was analyzed in terms of its historical values. Conclusions were formulated on the scope and type of restoration works for individual market squares. Finally, general conclusions from the research on the market squares of Bielsk Podlaski and Kleszczele were presented.

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