scholarly journals Pre-main sequence multiple systems

2010 ◽  
Vol 6 (S270) ◽  
pp. 41-44
Author(s):  
Hervé Bouy
Keyword(s):  
Main Sequence ◽  
Eclipsing Binaries ◽  
Observational Constraints ◽  
Evolutionary Models ◽  
Multiple Star ◽  
Multiple Systems ◽  
Stellar Radius ◽  
Stellar Formation ◽  
Powerful Approach ◽  
Special Case

AbstractIt is now well established that the majority of young stars are found in multiple systems, so that any theory of stellar formation must account for their existence and properties. Studying the properties of multiple star systems therefore represents a very powerful approach to place observational constraints on star formation theories. Additionally, multiple systems offer other advantages. They provide the most accurate and unambiguous way to measure masses, using orbital fitting and Kepler's laws, and even the stellar radius in the special case of eclipsing binaries. They also allow to compare the properties of 2 coeval objects with different masses, providing important tests for the evolutionary models.

scholarly journals Eclipsing binary stars as tests of stellar evolutionary models and stellar ages

2008 ◽  
Vol 4 (S258) ◽  
pp. 161-170 ◽  
Author(s):  
Keivan G. Stassun ◽  
Leslie Hebb ◽  
Mercedes López-Morales ◽  
Andrej Prša
Keyword(s):  
Binary Stars ◽  
Main Sequence ◽  
Magnetic Activity ◽  
Eclipsing Binaries ◽  
Evolutionary Models ◽  
Main Sequence Stars ◽  
Eclipsing Binary ◽  
Eclipsing Binary Stars ◽  
Sequence Components ◽  
Low Mass

AbstractEclipsing binary stars provide highly accurate measurements of the fundamental physical properties of stars. They therefore serve as stringent tests of the predictions of evolutionary models upon which most stellar age determinations are based. Models generally perform very well in predicting coeval ages for eclipsing binaries with main-sequence components more massive than ≈1.2 M⊙; relative ages are good to ~5% or better in this mass regime. Low-mass main-sequence stars (M < 0.8 M⊙) reveal large discrepancies in the model predicted ages, primarily due to magnetic activity in the observed stars that appears to inhibit convection and likely causes the radii to be 10–20% larger than predicted. In mass-radius diagrams these stars thus appear 50–90% older or younger than they really are. Aside from these activity-related effects, low-mass pre–main-sequence stars at ages ~1 Myr can also show non-coevality of ~30% due to star formation effects, however these effects are largely erased after ~10 Myr.

scholarly journals Introductory Remarks on Spectroscopic Parameters

1973 ◽  
Vol 18 ◽  
pp. 73-76
Author(s):  
Helmut A. Abt
Keyword(s):  
Positive Result ◽  
Spectral Type ◽  
Spectroscopic Data ◽  
Main Sequence ◽  
Multiple Star ◽  
Spectroscopic Parameters ◽  
Multiple Systems ◽  
Visual Systems

I hope that you will excuse a relative newcomer to this field and a spectroscopist for presenting his views, which may be somewhat different than those of others. I would like to enumerate the aims of research on visual systems and the needs of the field, particularly for spectroscopic data, as I see them.I. Aims of Multiple-Star Astronomy. (1). Statistics of multiple systems. We would like to know the fraction of stars that are visually double, triple, etc. and in each case as a function of spectral type. For instance, is the frequency of visual doubles the same for Population II stars as for Population I stars? Or are the frequencies of visual doubles the same for stars off the main sequence as for their antecedents on the main sequence? For such information a negative result on duplicity is as important as a positive result, i.e. we wish to know which stars are not seen to be visually double as well as which ones are seen as doubles.

scholarly journals Mixing in the SMC Stars: Implication for Cepheids

2000 ◽  
Vol 176 ◽  
pp. 381-382
Author(s):  
D. Cordier ◽  
T. Lejeune ◽  
Y. Lebreton ◽  
M.-J. Goupil
Keyword(s):  
Chemical Composition ◽  
Observational Data ◽  
Main Sequence ◽  
Observational Constraints ◽  
Evolutionary Models ◽  
Mixing Length ◽  
Instability Strip ◽  
Mixing Parameters ◽  
Low Metallicity ◽  
Red Giant

AbstractWe compare the recent OGLE 2 data of stars in the Small Magellanic Cloud (SMC) with stellar evolutionary models of low metallicity computed with the updated and numerically accurate code CESAM. The conversion between theoretical and observational data has been carefully done using the BaSel Library. This enables us to derive new observational constraints at SMC chemical composition: on the overshooting parameter αover during the main sequence, and on the mixing-length parameter αMLT for the red giant branch. The occurrence of an instability strip-crossing episode is strongly related to these mixing parameters.

scholarly journals Identification of binary and multiple systems in TGAS using the Virtual Observatory

2017 ◽  
Vol 12 (S330) ◽  
pp. 225-226
Author(s):  
F. Jiménez-Esteban ◽  
E. Solano
Keyword(s):  
Binary Systems ◽  
Virtual Observatory ◽  
Multiple Star ◽  
Multiple Systems ◽  
Multiple Stars ◽  
Stellar Formation ◽  
Virtual Observatory Tools ◽  
Formation And Evolution ◽  
Collapsing Cloud ◽  
Cloud Core

AbstractBinary and multiple stars have long provided an effective method of testing stellar formation and evolution theories. In particular, wide binary systems with separations > 20,000 au are particularly challenging as their physical separations are beyond the typical size of a collapsing cloud core (5,000 - 10,000 au). We present here a preliminary work in which we make use of the TGAS catalogue and Virtual Observatory tools and services (Aladin, TOPCAT, STILTS, VOSA, VizieR) to identify binary and multiple star candidate systems. The catalogue will be available from the Spanish VO portal (http://svo.cab.inta-csic.es) in the coming months.

scholarly journals Eclipsing Binaries in Dynamically Interacting Close, Multiple Systems

Galaxies ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 9
Author(s):  
Tamás Borkovits
Keyword(s):  
Orbital Period ◽  
Eclipsing Binaries ◽  
Detection Methods ◽  
Stellar Systems ◽  
Short Term ◽  
Multiple Star ◽  
Multiple Systems ◽  
History Of ◽  
Dynamical Information

Close, compact, hierarchical, and multiple stellar systems, i.e., multiples having an outer orbital period from months to a few years, comprise a small but continuously growing group of the triple and multiple star zoo. Many of them consist of at least one eclipsing pair of stars and, therefore, exhibit readily observable short-term dynamical interactions among the components. Thus, their dynamical and astrophysical properties can be explored with high precision. In this paper we present an overview of the history of the search for additional components around eclipsing binaries from the first serendipitous discoveries to more systematic recent studies. We describe the different observational detection methods and discuss their connections to the different kinds of astrophysical and dynamical information that can be mined from different datasets. Moreover, the connection amongst the observable phenomena and the long-term dynamics of such systems is also discussed.

scholarly journals The Hipparcos Double and Multiple Star Solutions

1998 ◽  
Vol 11 (1) ◽  
pp. 539-541
Author(s):  
F. Mignard
Keyword(s):  
Detailed Data ◽  
Multiple Star ◽  
Multiple Systems ◽  
Multiple Stars ◽  
Different Types ◽  
Hipparcos Catalogue ◽  
Double And Multiple Stars

Abstract The Hipparcos Catalogue provides general astrometric and photometric information on double and multiple stars in specific fields of the main Catalogue and detailed data on the components in the various sections of a dedicated annex: the Double and Multiple Systems Annex (DMSA). Overall statistics of these solutions are presented for the 13211 entries of this annex and the different types of solutions are outlined.

scholarly journals Interferometric Investigations of Eclipsing Binaries as a Key to an Improved Distance Scale

2006 ◽  
Vol 2 (S240) ◽  
pp. 496-498
Author(s):  
K. Shabun ◽  
A. Richichi ◽  
U. Munari ◽  
A. Siviero ◽  
B. Pacsysnki
Keyword(s):  
Spectral Type ◽  
Effective Temperature ◽  
Binary Systems ◽  
Angular Separation ◽  
Eclipsing Binaries ◽  
Multiple Systems ◽  
Long Baseline ◽  
Global Calibration ◽  
Empirical Calibration ◽  
Full Solution

AbstractBinary and multiple systems constitute one of the main tools for obtaining fundamental stellar parameters, such as masses, radii, effective temperatures and distances. One especially fortunate, and at the same time rare, occurrence is that of double-lined eclipsing binaries with well-detached components. In this special case, it is possible to obtain a full solution of all orbital and stellar parameters, with the exception of the effective temperature of one star, which is normally estimated from spectral type or derived from atmospheric analysis of the spectrum. Long-baseline interferometry at facilities such as the ESO VLTI is beginning to have the capability to measure directly the angular separation and the angular diameter of some selected eclipsing binary systems, and we have proposed such observations with the AMBER instrument. In particular, we aim at deriving directly the effective temperature of at least one of the components in the proposed system, thereby avoiding any assumptions in the global solution through the Wilson–Devinney method. We will also obtain an independent check of the results of this latter method for the distance to the system. This represents the first step towards a global calibration of eclipsing binaries as distance indicators. Our results will also contribute to the effective temperature scale for hot stars. The extension of this approach to a wider sample of eclipsing binaries could provide an independent method to assess the distance to the LMC. The observations will extend accurate empirical calibration to spectral type O9 – B0.

scholarly journals Radiative-transfer modelling of funnel flows

2007 ◽  
Vol 3 (S243) ◽  
pp. 83-94
Author(s):  
Tim J. Harries
Keyword(s):  
Numerical Methods ◽  
Radiative Transfer ◽  
Emission Line ◽  
Main Sequence ◽  
Line Profiles ◽  
Stellar Radius ◽  
Transfer Modelling ◽  
Synthetic Line ◽  
Made In ◽  
Geometry And Kinematics

AbstractEmission line profiles from pre-main-sequence objects accreting via magnetically-controlled funnel flows encode information on the geometry and kinematics of the material on stellar radius scales. In order to extract this information it is necessary to perform radiative-transfer modelling of the gas to produce synthetic line profiles. In this review I discuss the physics that needs to be included in such models, and the numerical methods and assumptions that are used to render the problem tractable. I review the progress made in the field over the last decade, and summarize the main successes and failures of the modelling work.

scholarly journals The Census of Exoplanets in Visual Binaries: Population Trends from a Volume-Limited Gaia DR2 and Literature Search

2021 ◽  
Vol 8 ◽  
Author(s):  
Clémence Fontanive ◽  
Daniella Bardalez Gagliuffi
Keyword(s):  
Planetary Systems ◽  
Multiple Star ◽  
Multiple Systems ◽  
Binary Separation ◽  
Extensive Search ◽  
Short Period ◽  
Massive Component ◽  
Low Mass ◽  
Cool Gas ◽  
Gaia Dr2

We present results from an extensive search in the literature and Gaia DR2 for visual co-moving binary companions to stars hosting exoplanets and brown dwarfs within 200 pc. We found 218 planet hosts out of the 938 in our sample to be part of multiple-star systems, with 10 newly discovered binaries and 2 new tertiary stellar components. This represents an overall raw multiplicity rate of 23.2 ± 1.6 % for hosts to exoplanets across all spectral types, with multi-planet systems found to have a lower stellar duplicity frequency at the 2.2-σ level. We found that more massive hosts are more often in binary configurations, and that planet-bearing stars in multiple systems are predominantly observed to be the most massive component of stellar binaries. Investigations of the multiplicity of planetary systems as a function of planet mass and separation revealed that giant planets with masses above 0.1 MJup are more frequently seen in stellar binaries than small sub-Jovian planets with a 3.6-σ difference, a trend enhanced for the most massive (&gt;7 MJup) short-period (&lt;0.5 AU) planets and brown dwarf companions. Binarity was however found to have no significant effect on the demographics of low- mass planets (&lt;0.1 MJup) or warm and cool gas giants (&gt;0.5 AU). While stellar companion mass appears to have no impact on planet properties, binary separation seems to be an important factor in the resulting structure of planetary systems. Stellar companions on separations &lt;1000 AU can play a role in the formation or evolution of massive, close-in planets, while planets in wider binaries show similar properties to planets orbiting single stars. Finally, our analyses indicate that numerous stellar companions on separations smaller than 1–3 arcsec likely remain undiscovered to this date. Continuous efforts to complete our knowledge of stellar multiplicity on separations of tens to hundreds of AU are essential to confirm the reported trends and further our understanding of the roles played by multiplicity on exoplanets.

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