Отчет Сао Ран 2013 Sao Ras Report 93
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A Volume-Limited Survey of Mcp Stars Within 100Pc I: Fundamental Parameters and Chemical Abundances
Mon. Not. R. Astron. Soc. 000, 1{?? (2018) Printed 15 November 2018 (MN LATEX style file v2.2) A Volume-Limited Survey of mCP Stars Within 100pc I: Fundamental Parameters and Chemical Abundances J. Sikora,1;2 G. A. Wade,2 J. Power,1;2;4 C. Neiner3 1Department of Physics, Engineering Physics & Astronomy, Queen's University, Kingston, ON Canada, K7L 3N6 2Department of Physics and Space Science, Royal Military College of Canada, PO Box 17000 Kingston, Ontario K7K 7B4, Canada 3LESIA, Observatoire de Paris, PSL University, CNRS, Sorbonne Universit, Univ. Paris Diderot, Sorbonne Paris Cit, 5 place Jules Janssen, 92195 Meudon, France 4Large Binocular Telescope Observatory, 933 North Cherry Avenue, Tucson, AZ 85721, USA Accepted 2018 Nov. 13 ABSTRACT We present the first results of a volume-limited survey of main sequence (MS) magnetic chemically peculiar (mCP) stars. The sample consists of all identified intermediate- mass MS stars (mCP and non-mCP) within a heliocentric distance of 100 pc as de- termined using Hipparcos parallaxes. The two populations are compared in order to determine the unique properties that allow a small fraction of MS stars with masses & 1:4 M to host strong, large scale magnetic fields. A total of 52 confirmed mCP stars are identified using published magnetic, spectroscopic, and photometric observations along with archived and newly obtained spectropolarimetric (Stokes V ) observations. We derive the fundamental parameters (effective temperatures, luminosities, masses, and evolutionary states) of the mCP and non-mCP populations using homogeneous analyses. A detailed analysis of the mCP stars is performed using the llmodels code, which allows observed spectral energy distributions to be modeled while incor- porating chemical peculiarities and magnetic fields. -
New and Improved Rotational Periods of Magnetic CP Stars from ASAS-3
MNRAS 000, 1–18 (2019) Preprint 18 February 2020 Compiled using MNRAS LATEX style file v3.0 New and improved rotational periods of magnetic CP stars from ASAS-3, KELT and MASCARA data Klaus Bernhard,1,2⋆ Stefan Hummerich,¨ 1,2 Ernst Paunzen3 1Bundesdeutsche Arbeitsgemeinschaft fur¨ Ver¨anderliche Sterne e.V. (BAV), Berlin, Germany 2American Association of Variable Star Observers (AAVSO), Cambridge, USA 3Department of Theoretical Physics and Astrophysics, Masaryk University, Kotl´aˇrsk´a2, 611 37 Brno, Czech Republic Accepted XXX. Received YYY; in original form ZZZ ABSTRACT Magnetic chemically peculiar (mCP) stars allow the investigation of such diverse phe- nomena as atomic diffusion, magnetic fields and stellar rotation. The aim of the present investigation is to enhance our knowledge of the rotational properties of mCP stars by increasing the sample of objects with accurately determined rotational periods. To this end, archival photometric time-series data from the ASAS-3, KELT and MASCARA surveys were employed to improve existing rotational period information and derive rotational periods for mCP stars hitherto not known to be photometric variables. Our final sample consists of 294 mCP stars, a considerable amount of which (more than 40%) are presented here as photometric variables for the first time. In addition, we identified 24 mCP star candidates that show light variability in agreement with rotational modulation but lack spectroscopic confirmation. The rotational period dis- tribution of our sample agrees well with the literature. Most stars are between 100Myr and 1Gyr old, with an apparent lack of very young stars. No objects were found on the zero age main sequence; several stars seem to have evolved to the subgiant stage, albeit well before the first dredge-up. -
Multiplicity Among Chemically Peculiar Stars
Astronomy & Astrophysics manuscript no. (will be inserted by hand later) Multiplicity among chemically peculiar stars II. Cool magnetic Ap stars⋆,⋆⋆ F. Carrier1, P. North2, S. Udry1, and J. Babel3 1 Observatoire de Gen`eve, CH-1290 Sauverny, Switzerland 2 Institut d’Astronomie de l’Universit´ede Lausanne, CH-1290 Chavannes-des-bois, Switzerland 3 Office F´ed´eral de la Statistique, Espace de l’Europe 10, CH-2010 Neuchˆatel, Switzerland Received / Accepted Abstract. We present new orbits for sixteen Ap spectroscopic binaries, four of which might in fact be Am stars, and give their orbital elements. Four of them are SB2 systems: HD 5550, HD 22128, HD 56495 and HD 98088. The twelve other stars are : HD 9996, HD 12288, HD 40711, HD 54908, HD 65339, HD 73709, HD 105680, HD 138426, HD 184471, HD 188854, HD 200405 and HD 216533. Rough estimates of the individual masses of the components of HD 65339 (53 Cam) are given, combining our radial velocities with the results of speckle interferometry and with Hipparcos parallaxes. Considering the mass functions of 74 spectroscopic binaries from this work and from the literature, we conclude that the distribution of the mass ratio is the same for cool Ap stars as for normal G dwarfs. Therefore, the only differences between binaries with normal stars and those hosting an Ap star lie in the period distribution: except for the case of HD 200405, all orbital periods are longer than (or equal to) 3 days. A consequence of this peculiar distribution is a deficit of null eccentricities. There is no indication that the secondary has a special nature, like e.g. -
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A&A 394, 151–169 (2002) Astronomy DOI: 10.1051/0004-6361:20021122 & c ESO 2002 Astrophysics Multiplicity among chemically peculiar stars II. Cool magnetic Ap stars,, F. Carrier1, P. North2,S.Udry1, and J. Babel3 1 Observatoire de Gen`eve, 1290 Sauverny, Switzerland 2 Institut d’Astronomie de l’Universit´e de Lausanne, 1290 Chavannes-des-bois, Switzerland 3 Office F´ed´eral de la Statistique, Espace de l’Europe 10, 2010 Neuchˆatel, Switzerland Received 16 May 2002 / Accepted 12 July 2002 Abstract. We present new orbits for sixteen Ap spectroscopic binaries, four of which might in fact be Am stars, and give their orbital elements. Four of them are SB2 systems: HD 5550, HD 22128, HD 56495 and HD 98088. The twelve other stars are: HD 9996, HD 12288, HD 40711, HD 54908, HD 65339, HD 73709, HD 105680, HD 138426, HD 184471, HD 188854, HD 200405 and HD 216533. Rough estimates of the individual masses of the components of HD 65339 (53 Cam) are given, combining our radial velocities with the results of speckle interferometry and with Hipparcos parallaxes. Considering the mass functions of 74 spectroscopic binaries from this work and from the literature, we conclude that the distribution of the mass ratio is the same for cool Ap stars and for normal G dwarfs. Therefore, the only differences between binaries with normal stars and those hosting an Ap star lie in the period distribution: except for the case of HD 200405, all orbital periods are longer than (or equal to) 3 days. A consequence of this peculiar distribution is a deficit of null eccentricities. -
Magnetic Field of CP Stars. Observational Aspects
Magnetic stars, 2004, 33-63 Magnetic field of CP stars. Observational aspects Romanyuk I. I. Special Astrophysical Observatory of RAS, Nizhny Arkhyz 369167, Russia Abstract. Observed parameters of magnetic CP stars are discussed. The extreme value of the longitudinal component Bextr is shown to reflect adequately the real field on the surface of the star Bs, linear relationship between these parameters is found. Magnetic field models are presented for 90 well understood MCP stars, their comparative analysis is made. It is shown that for 24 stars from the list of Landstreet and Mathys (2000) contributions of octupole component, responsible in the models of these authors for the contrast in the surface magnetic field strength between the magnetic poles and equator, differ depending on the rotational velocity. For 17 single fast rotators the magnetic field increases towards the poles in comparison with dipolar field, while for the slow rotators the indicated contrast is less than the dipolar. Such an effect is not noticed for binary stars. Relationship between rotational velocity, temperature and magnetic field for different groups of CP stars are found. The photometric indices describing the anomalies of the continuum are shown to increase inside rather narrow tempera- ture intervals with increasing period in each of them. The magnetic field reaches the greatest value in stars with rotational periods from 5 to 10 days. Key words: stars: chemically peculiar { stars: magnetic fields { methods: ob- servational 1 Introduction The General catalog of CP stars (Renson et al. 1991) contains 6700 objects, mainly brighter than 11m. Half of them are Am stars, the discovery of magnetic field in their atmospheres is questionable yet. -
A Catalog of Stellar Magnetic Rotational Phase Curves
A&A 430, 1143–1154 (2005) Astronomy DOI: 10.1051/0004-6361:20034563 & c ESO 2005 Astrophysics A catalog of stellar magnetic rotational phase curves V. D. Bychkov1,2,L.V.Bychkova1, and J. Madej3 1 Special Astrophysical Observatory of the Russian Academy of Sciences, Nizhnij Arkhyz, 369167 Russia e-mail: [email protected] 2 Isaac Newton Institute of Chile, SAO Branch, Nizhnij Arkhyz, 369167 Russia 3 Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warszawa, Poland Received 22 October 2003 / Accepted 20 September 2004 Abstract. Magnetized stars usually exhibit periodic variations of the effective (longitudinal) magnetic field Be causedbytheir rotation. We present a catalog of magnetic rotational phase curves, Be vs. the rotational phase φ, and tables of their parameters for 136 stars on the main sequence and above it. Phase curves were obtained by the least squares fitting of sine wave or double wave functions to the available Be measurements, which were compiled from the existing literature. Most of the catalogued objects are chemically peculiar A and B type stars (127 stars). For some stars we also improved or determined periods of their rotation. We discuss the distribution of parameters describing magnetic rotational phase curves in our sample. Key words. catalogs – stars: fundamental parameters – stars: magnetic fields – stars: rotation 1. Introduction in that group of stars (Borra et al. 1981; Brown & Landstreet 1987). Also, highly evolved stars on the horizontal branch of Strong global magnetic fields can be found in most chemi- giants do not have global-scale magnetic fields (El’kin 1992). cally peculiar (CP) stars on the upper main sequence of the Recently, Smirnov et al.