scholarly journals Observed binary populations reflect the Galactic history

2020 ◽  
Vol 641 ◽  
pp. A163 ◽  
Author(s):  
J. Vos ◽  
A. Bobrick ◽  
M. Vučković
Keyword(s):  
Mass Transfer ◽  
Main Sequence ◽  
Fine Tuning ◽  
Red Giants ◽  
Core Mass ◽  
The Galaxy ◽  
History Of ◽  
Low Mass ◽  
Orbital Periods ◽  
Binary Evolution

Context. Wide hot subdwarf B (sdB) binaries with main-sequence companions are outcomes of stable mass transfer from evolved red giants. The orbits of these binaries show a strong correlation between their orbital periods and mass ratios. The origins of this correlation have, so far, been lacking a conclusive explanation. Aims. We aim to find a binary evolution model which can explain the observed correlation. Methods. Radii of evolved red giants, and hence the resulting orbital periods, strongly depend on their metallicity. We performed a small but statistically significant binary population synthesis study with the binary stellar evolution code MESA. We used a standard model for binary mass loss and a standard metallicity history of the Galaxy. The resulting sdB systems were selected based on the same criteria as was used in observations and then compared with the observed population. Results. We have achieved an excellent match to the observed period-mass ratio correlation without explicitly fine-tuning any parameters. Furthermore, our models produce a very good match to the observed period-metallicity correlation. We predict several new correlations, which link the observed sdB binaries to their progenitors, and a correlation between the orbital period, metallicity, and core mass for subdwarfs and young low-mass helium white dwarfs. We also predict that sdB binaries have distinct orbital properties depending on whether they formed in the Galactic bulge, thin or thick disc, or the halo. Conclusions. We demonstrate, for the first time, how the metallicity history of the Milky Way is imprinted in the properties of the observed post-mass transfer binaries. We show that Galactic chemical evolution is an important factor in binary population studies of interacting systems containing at least one evolved low-mass (Minit <  1.6 M⊙) component. Finally, we provide an observationally supported model of mass transfer from low-mass red giants onto main-sequence stars.

scholarly journals Y Cygni?

1992 ◽  
Vol 151 ◽  
pp. 235-243
Author(s):  
Alan H. Batten
Keyword(s):  
Binary Systems ◽  
Main Sequence ◽  
Evolutionary Process ◽  
Roche Lobe ◽  
System A ◽  
The Galaxy ◽  
Complete Study ◽  
History Of ◽  
Interacting Systems ◽  
Binary Evolution

It is often assumed that a binary begins to interact when one of its components makes contact with its Roche lobe, thus “switching on” a new evolutionary process. The example of Y Cygni is used to illustrate the view that the whole lifetime of a binary helps to determine whether or not its components will interact. Of particular importance is the interval between the formation of a binary and the arrival of its components on the main sequence, during which probably all binaries are interacting. Barring accidents, the properties of the components when they reach the main sequence will define the whole subsequent history of the system, including whether or not there will be subsequent phases of interaction triggered by contact with the Roche lobe. Like any other mechanical system a binary will tend towards the state of lowest energy consistent with the constraints on it. This it can do by losing mass, equalizing the component masses, or reducing its separation. We therefore expect systems to tend to small masses to mass-ratios of unity, or to coalesce into single stars. In any given system, probably all three tendencies exist, but one dominates. For example, W Ursae Majoris systems may be fusing into single stars. The rotation, chemical composition, and magnetic fields of the component stars may modify the evolution of a binary and be responsible for the variety of interacting systems that we observe. Most interacting pairs are losing mass to the interstellar medium, so a complete study of binary evolution must consider not only the dynamical, but also the chemical, effects of binary systems on the evolution of the Galaxy.

scholarly journals Influence of the initial orbital period and accretion efficiency on the low-mass binary evolution

2021 ◽  
pp. 25-30
Author(s):  
J. Petrovic
Keyword(s):  
Mass Transfer ◽  
Orbital Period ◽  
White Dwarf ◽  
Binary Systems ◽  
Evolutionary Models ◽  
Stable Case ◽  
Long Period ◽  
Low Mass ◽  
Orbital Periods ◽  
Binary Evolution

This paper presents detailed evolutionary models of low-mass binary systems (1.25 + 1 M?) with initial orbital periods of 10, 50 and 100 days and accretion efficiency of 10%, 20%, 50%, and a conservative assumption. All models are calculated with the MESA (Modules for Experiments in Stellar Astrophysics) evolutionary code. We show that such binary systems can evolve via a stable Case B mass transfer into long period helium white dwarf systems.

scholarly journals Are sdAs helium core stars?

2017 ◽  
Vol 26 (1) ◽  
Author(s):  
Ingrid Pelisoli ◽  
S. O. Kepler ◽  
Detlev Koester
Keyword(s):  
Main Sequence ◽  
Galactic Disk ◽  
Physical Nature ◽  
Sloan Digital Sky Survey ◽  
Distance Modulus ◽  
Main Sequence Stars ◽  
Sky Survey ◽  
Balmer Lines ◽  
Low Mass ◽  
Binary Evolution

AbstractEvolved stars with a helium core can be formed by non-conservative mass exchange interaction with a companion or by strong mass loss. Their masses are smaller than 0.5 M⊙. In the database of the Sloan Digital Sky Survey (SDSS), there are several thousand stars which were classified by the pipeline as dwarf O, B and A stars. Considering the lifetimes of these classes on the main sequence, and their distance modulus at the SDSS bright saturation, if these were common main sequence stars, there would be a considerable population of young stars very far from the galactic disk. Their spectra are dominated by Balmer lines which suggest effective temperatures around 8 000-10 000 K. Several thousand have significant proper motions, indicative of distances smaller than 1 kpc. Many show surface gravity in intermediate values between main sequence and white dwarf, 4.75 < log g < 6.5, hence they have been called sdA stars. Their physical nature and evolutionary history remains a puzzle. We propose they are not H-core main sequence stars, but helium core stars and the outcomes of binary evolution. We report the discovery of two new extremely-low mass white dwarfs among the sdAs to support this statement.

scholarly journals Asteroseismological Probing of the Thermal Evolution of White Dwarf Stars

1992 ◽  
Vol 9 ◽  
pp. 643-645
Author(s):  
G. Fontaine ◽  
F. Wesemael
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Main Sequence ◽  
Thermal Evolution ◽  
Sequence Evolution ◽  
Helium Burning ◽  
Dwarf Stars ◽  
White Dwarf Stars ◽  
The Galaxy ◽  
Low Mass

AbstractIt is generally believed that the immediate progenitors of most white dwarfs are nuclei of planetary nebulae, themselves the products of intermediate- and low-mass main sequence evolution. Stars that begin their lifes with masses less than about 7-8 M⊙ (i.e., the vast majority of them) are expected to become white dwarfs. Among those which have already had the time to become white dwarfs since the formation of the Galaxy, a majority have burnt hydrogen and helium in their interiors. Consequently, most of the mass of a typical white dwarf is contained in a core made of the products of helium burning, mostly carbon and oxygen. The exact proportions of C and 0 are unknown because of uncertainties in the nuclear rates of helium burning.

scholarly journals Classical Novae – Before and After Outburst

1988 ◽  
Vol 108 ◽  
pp. 226-231
Author(s):  
Mario Livio
Keyword(s):  
White Dwarf ◽  
Main Sequence ◽  
Orbital Parameters ◽  
Classical Novae ◽  
Classical Nova ◽  
Before And After ◽  
Low Mass ◽  
Orbital Periods ◽  
Thermonuclear Runaway ◽  
Nova Outburst

Classical nova (CN) and dwarf nova (DN) systems have the same binary components (a low-mass main sequence star and a white dwarf) and the same orbital periods. An important question that therefore arises is: are these systems really different ? (and if so, what is the fundamental difference ?) or, are these the same systems, metamorphosing from one class to the other ?The first thing to note in this respect is that the white dwarfs in DN systems are believed to accrete continuously (both at quiescence and during eruptions). At the same time, both analytic (e.g. Fujimoto 1982) and numerical calculations show, that when sufficient mass accumulates on the white dwarf, a thermonuclear runaway (TNR) is obtained and a nova outburst ensues (see e.g. reviews by Gallagher and Starrfield 1978, Truran 1982). It is thus only natural, to ask the question, is the fact that we have not seen a DN undergo a CN outburst (in about 50 years of almost complete coverage) consistent with observations of DN systems ? In an attempt to answer this question, we have calculated the probability for a nova outburst not to occur (in 50 years) in 86 DN systems (for which at least some of the orbital parameters are known).

scholarly journals Case AD, AR, and AS binary evolution and their possible connections with W UMa binaries

2019 ◽  
Vol 492 (2) ◽  
pp. 2731-2738 ◽  
Author(s):  
Dengkai Jiang
Keyword(s):  
Parameter Spaces ◽  
Short Period ◽  
Contact Binaries ◽  
Low Mass ◽  
Orbital Periods ◽  
The Difference ◽  
Binary Evolution ◽  
Detached Binaries ◽  
Period Limit ◽  
The Moment

ABSTRACT Close detached binaries were theoretically predicted to evolve into contact by three subtypes of case A binary evolution, cases AD, AR, and AS, which correspond to the formation of contact during dynamic-, thermal-, and nuclear-time-scale mass transfer phases, respectively. It is unclear, however, what is the difference between contact binaries in these subtypes, and whether all of these subtypes can account for the formation of observed W Ursae Majoris (W UMa) binaries. Using Eggleton’s stellar evolution code with the non-conservative assumption, I obtained the low-mass contact binaries produced by cases AD, AR, and AS at the moment of contact and their parameter spaces. The results support that the progenitors of low-mass contact binaries are detached binaries with orbital periods shorter than $\sim 2\!-\!5\,$ d, and their borderlines depend strongly on the primary mass. In addition, the period–colour relations for cases AR and AS can be in better agreement with that for observed W UMa candidates, but case AD shows a significantly worse agreement. Moreover, cases AR and AS can produce a short-period limit (corresponding to a low-mass limit) at almost any age, e.g. from young age ($\sim 0.2\,$ Gyr) to old age ($\sim 13\,$ Gyr), agreeing with observed W UMa binaries in star clusters, but no such limit occurs for case AD at any age. These results support that cases AR and AS, as opposed to case AD, can lead to W UMa binaries (including young W UMa binaries).

scholarly journals The Evolutionary Status of the Secondaries of Cataclysmic Binaries

1983 ◽  
Vol 72 ◽  
pp. 257-262
Author(s):  
H. Ritter
Keyword(s):  
Probability Distribution ◽  
Main Sequence ◽  
The Other ◽  
Initial Mass ◽  
Evolutionary Status ◽  
Mass Ratio ◽  
Main Sequence Stars ◽  
Cataclysmic Binaries ◽  
Low Mass ◽  
Orbital Periods

ABSTRACTIt is shown that the secondary components of cataclysmic binaries with orbital periods of less than ~10 hours are indistinguishable from ordinary low-mass main-sequence stars and that, therefore, they are essentially unevolved. On the other hand, it is shown that, depending on the mass ratio of the progenitor system, the secondary of a cataclysmic binary could be significantly evolved. The fact that nevertheless most of the observed secondaries are essentially unevolved can be accounted for by assuming that the probability distribution for the initial mass ratio is not strongly peaked towards unity mass ratio.

scholarly journals Super-Eddington Accretion in the Formation of Low-Mass X-ray Binaries and Millisecond Pulsars

1997 ◽  
Vol 163 ◽  
pp. 828-829 ◽  
Author(s):  
R. F. Webbink ◽  
V. Kalogera
Keyword(s):  
Mass Transfer ◽  
Initial Phase ◽  
Transfer Rate ◽  
Birth Rate ◽  
Mass Transfer Rate ◽  
Millisecond Pulsars ◽  
X Ray ◽  
Low Mass ◽  
Orbital Periods ◽  
X Ray Binaries

AbstractConsiderations of donor star stability, age, and mass transfer rate show that low-mass X-ray binaries and binary millisecond pulsars with orbital periods longer than a few days must have survived an initial phase of super-Eddington mass transfer. We review the physical arguments leading to this conclusion, and examine its implications for the apparent discrepancy between the death rate for low-mass X-ray binaries and the birth rate of binary millisecond pulsars.

scholarly journals Stellar statistics along the ecliptic and the impact on the K2 mission concept

2014 ◽  
Vol 14 (2) ◽  
pp. 165-172 ◽  
Author(s):  
Andrej Prša ◽  
Annie Robin ◽  
Thomas Barclay
Keyword(s):  
Main Sequence ◽  
Target Selection ◽  
Ecliptic Plane ◽  
Galactic Latitude ◽  
Gold Mine ◽  
Main Sequence Stars ◽  
Satellite Attitude ◽  
The Galaxy ◽  
Orbital Periods ◽  
The Impact

AbstractK2 is the mission concept for a repurposedKeplermission that uses two reaction wheels to maintain the satellite attitude and provide ~81 days of coverage for ten 105 deg2fields along the ecliptic in the first 2.5 years of operation. We examine stellar populations based on the updated Besançon model of the Galaxy, comment on the general properties for the entire ecliptic plane, and provide stellar occurrence rates in the first six tentative K2 campaigns grouped by spectral type and luminosity class. For each campaign we distinguish between main the sequence stars and giants, and provide their density profile as a function of galactic latitude. We introduce the crowding metric that serves for optimized target selection across the campaigns. For all main sequence stars we compute the expected planetary occurrence rates for three planet sizes: 2–4, 4–8 and 8–32 R⊕with orbital periods up to 50 days. In conjunction with Gaia and the upcoming Transiting Exoplanet Survey Satellite and Plato missions, K2 will become a gold mine for stellar and planetary astrophysics.

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