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 Pulsating low-mass white dwarfs in the frame of new evolutionary sequences

2018 ◽  
Vol 620 ◽  
pp. A196 ◽  
Author(s):  
Leila M. Calcaferro ◽  
Alejandro H. Córsico ◽  
Leandro G. Althaus ◽  
Alejandra D. Romero ◽  
S. O. Kepler
Keyword(s):  
Stellar Evolution ◽  
Effective Temperature ◽  
Evolutionary Models ◽  
Long Period ◽  
Low Mass ◽  
Complete Set ◽  
Effective Temperatures ◽  
Binary Evolution ◽  
Stellar Masses ◽  
Gravity Mode

Context. Some low-mass white-dwarf (WD) stars with H atmospheres currently being detected in our galaxy, show long-period g(gravity)-mode pulsations, and comprise the class of pulsating WDs called extremely low-mass variable (ELMV) stars. At present, it is generally believed that these stars have thick H envelopes. However, from stellar evolution considerations, the existence of low-mass WDs with thin H envelopes is also possible. Aims. We present a thorough asteroseismological analysis of ELMV stars on the basis of a complete set of fully evolutionary models that represents low-mass He-core WD stars harboring a range of H envelope thicknesses. Although there are currently nine ELMVs, here we only focus on those that exhibit more than three periods and whose periods do not show significant uncertainties. Methods. We considered g-mode adiabatic pulsation periods for low-mass He-core WD models with stellar masses in the range [0.1554–0.4352] M⊙, effective temperatures in the range [6000–10 000] K, and H envelope thicknesses in the interval −5.8 ≲ log(MH/M⋆)≲ −1.7. We explore the effects of employing different H-envelope thicknesses on the adiabatic pulsation properties of low-mass He-core WD models, and perform period-to-period fits to ELMV stars to search for a representative asteroseismological model. Results. We found that the mode-trapping effects of g modes depend sensitively on the value of MH, with the trapping cycle and trapping amplitude larger for thinner H envelopes. We also found that the asymptotic period spacing, ΔΠa, is longer for thinner H envelopes. Finally, we found asteroseismological models (when possible) for the stars under analysis, characterized by canonical (thick) and by thin H envelope. The effective temperature and stellar mass of these models are in agreement with the spectroscopic determinations. Conclusions. The fact that we have found asteroseismological solutions with H envelopes thinner than canonical gives a suggestion of the possible scenario of formation of these stars. Indeed, in the light of our results, some of these stars could have been formed by binary evolution through unstable mass loss.

scholarly journals Prospects for the Discovery of Black Hole Binaries without Mass Accretion with Gaia

2016 ◽  
Vol 12 (S324) ◽  
pp. 41-42
Author(s):  
Norita Kawanaka ◽  
Masaki Yamaguchi ◽  
Tsvi Piran ◽  
Tomasz Bulik
Keyword(s):  
Mass Transfer ◽  
Black Holes ◽  
Black Hole ◽  
Orbital Period ◽  
Proper Motion ◽  
Binary Systems ◽  
Evolution Model ◽  
Black Hole Binaries ◽  
Black Hole Binary ◽  
Binary Evolution

AbstractWe study the prospect for Gaia to detect black hole binary systems without the mass transfer from their companion stars. Gaia will be able to discover Galactic black holes without mass accretion by detecting the proper motion of their companion stars. We evaluate the number of such black hole binaries which have the orbital period short enough to be detected by Gaia during its operation, taking into account the binary evolution model.

scholarly journals Hidden in Plain Sight: A double-lined White Dwarf Binary 26 pc away and a Distant Cousin

2021 ◽  
Author(s):  
Mukremin Kilic ◽  
A Bédard ◽  
P Bergeron
Keyword(s):  
High Resolution ◽  
Orbital Period ◽  
White Dwarf ◽  
White Dwarfs ◽  
Model Atmosphere ◽  
High Resolution Spectroscopy ◽  
Low Mass ◽  
Orbital Periods ◽  
Velocity Changes ◽  
Cool White Dwarfs

Abstract We present high-resolution spectroscopy of two nearby white dwarfs with inconsistent spectroscopic and parallax distances. The first one, PG 1632+177, is a 13th magnitude white dwarf only 25.6 pc away. Previous spectroscopic observations failed to detect any radial velocity changes in this star. Here, we show that PG 1632+177 is a 2.05 d period double-lined spectroscopic binary (SB2) containing a low-mass He-core white dwarf with a more-massive, likely CO-core white dwarf companion. After L 870-2, PG 1632+177 becomes the second closest SB2 white dwarf currently known. Our second target, WD 1534+503, is also an SB2 system with an orbital period of 0.71 d. For each system, we constrain the atmospheric parameters of both components through a composite model-atmosphere analysis. We also present a new set of NLTE synthetic spectra appropriate for modeling high-resolution observations of cool white dwarfs, and show that NLTE effects in the core of the Hα line increase with decreasing effective temperature. We discuss the orbital period and mass distribution of SB2 and eclipsing double white dwarfs with orbital constraints, and demonstrate that the observed population is consistent with the predicted period distribution from the binary population synthesis models. The latter predict more massive CO + CO white dwarf binaries at short (<1 d) periods, as well as binaries with several day orbital periods; such systems are still waiting to be discovered in large numbers.

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 Mass Transfer and Evolution in Long-Period Binary Systems

1986 ◽  
Vol 7 ◽  
pp. 185-187 ◽  
Author(s):  
R. F. Webbink
Keyword(s):  
Mass Transfer ◽  
Binary Systems ◽  
Cataclysmic Variables ◽  
Type Systems ◽  
Close Binary ◽  
Orbital Energy ◽  
Long Period ◽  
Short Period ◽  
Binary Evolution ◽  
Helium Star

In the earliest studies of close binary evolution (Paczynski 1967; Kippenhahn, Kohl, and Weigert 1967; Plavec, et al. 1968), it was assumed that the total mass and orbital angular momentum of a binary system are conserved during mass transfer. This assumption of convenience actually succeeds quite well in producing model post-mass-transfer binaries which closely resemble classical Algol-type systems, and helium-star binaries such as KS Per and u Sgr as well (Plavec 1973; Schonberner and Drilling 1983). Among longer-period interacting binaries, however, there are strong reasons to believe that these simple assumptions break down. For example, it is well-known that single stars may lose a very substantial fraction of their mass in a stellar wind during ascent of the giant and asymptotic-giant branches (e.g., Kudritzki and Reimers 1978). In addition, many highly-evolved short-period binaries, such as the cataclysmic variables, appear to owe their origins to very long-period progenitors (Paczynski 1976; Ritter 1976; Webbink 1976). These latter systems evidently evolved through a common envelope phase (Paczynski 1976; Meyer and Meyer-Hofmeister 1979), in which the giant progenitor of the present white dwarf devoured its companion star, and ultimately was divested of its envelope by the release of orbital energy as that companion spiralled toward its core.

scholarly journals Evolutionary Scenarios for Double Degenerate Systems

1996 ◽  
Vol 158 ◽  
pp. 459-460
Author(s):  
P. B. Marks ◽  
M. J. Sarna ◽  
R. C. Smith
Keyword(s):  
Mass Transfer ◽  
Orbital Period ◽  
White Dwarf ◽  
Massive Star ◽  
Roche Lobe ◽  
Orbital Parameters ◽  
Common Envelope ◽  
Orbital Periods ◽  
Two Phases ◽  
The Masses

There are presently eight double degenerate systems with well determined orbital parameters, their periods being either a few hours or a few days (Marsh, Dhillon & Duck 1995; Marsh 1995). The masses of the primaries and secondaries lie in the range 0.15… 0.45M⊙.We calculate two evolutionary scenarios (Sarna, Marks & Smith 1996); the first is Algol-type evolution with two phases of stable mass transfer, and the second involves first a stage of common envelope (CE) evolution followed by a stage of stable mass transfer. In both calculations we assume non-conservative mass transfer by which we mean that the total mass and angular momentum of the system are not conserved. For both scenarios we start our calculations after the first stage of mass transfer has finished. In all calculations the primary is the initially more massive star that filled its Roche lobe and transferred material to the secondary during the first phase of mass transfer, hence the secondary is the star that fills its Roche lobe in our calculations. The system’s orbital period decreases and then increases until the system detaches; we are left with a detached white dwarf/white dwarf binary with an orbital period of the order of hours or of days (see Table 1). There must exist some bifurcation period below which the systems evolve towards orbital periods of the order of hours and above which the systems evolve to periods of the order of several days.

scholarly journals Discovery of Eight Recycled Pulsars – The Swinburne Intermediate Latitude Pulsar Survey

2000 ◽  
Vol 177 ◽  
pp. 33-34
Author(s):  
Russell T. Edwards
Keyword(s):  
Orbital Period ◽  
White Dwarf ◽  
Binary Systems ◽  
Integration Time ◽  
Two Systems ◽  
Low Mass ◽  
Average Profile

AbstractWe have conducted a pulsar survey of intermediate Galactic latitudes (5° &lt; |b| &lt; 15°) at 20 cm. The survey has been highly successful, discovering 58 new pulsars, eight of which are recycled, in only ∼14 days of integration time. One pulsar has a very narrow (2° FWHM) average profile for the pulsar’s period (278 ms). The six new recycled binary systems provide valuable information on the formation of white dwarf pulsar binaries. Two systems have massive white dwarf companions (&gt; 0.57 M⊙and &gt; 1.2 M⊙), while another has a low mass (∼ 0.2 M⊙) companion in a 23.3-d orbit, residing the well-known orbital period “gap”.

scholarly journals Phases of Mass Transfer from Hot Subdwarfs to White Dwarf Companions and Their Photometric Properties

2021 ◽  
Vol 922 (2) ◽  
pp. 245
Author(s):  
Evan B. Bauer ◽  
Thomas Kupfer
Keyword(s):  
Mass Transfer ◽  
White Dwarf ◽  
Binary Systems ◽  
Galactic Plane ◽  
Large Fraction ◽  
Transfer Phase ◽  
Star Models ◽  
Nuclear Burning ◽  
Hot Subdwarfs ◽  
Orbital Periods

Abstract Binary systems of a hot subdwarf B (sdB) star + a white dwarf (WD) with orbital periods less than 2–3 hr can come into contact due to gravitational waves and transfer mass from the sdB star to the WD before the sdB star ceases nuclear burning and contracts to become a WD. Motivated by the growing class of observed systems in this category, we study the phases of mass transfer in these systems. We find that because the residual outer hydrogen envelope accounts for a large fraction of an sdB star’s radius, sdB stars can spend a significant amount of time (∼tens of megayears) transferring this small amount of material at low rates (∼10−10–10−9 M ⊙ yr−1) before transitioning to a phase where the bulk of their He transfers at much faster rates ( ≳10−8 M ⊙ yr−1). These systems therefore spend a surprising amount of time with Roche-filling sdB donors at orbital periods longer than the range associated with He star models without an envelope. We predict that the envelope transfer phase should be detectable by searching for ellipsoidal modulation of Roche-filling objects with P orb = 30–100 minutes and T eff = 20,000–30,000 K, and that many (≥10) such systems may be found in the Galactic plane after accounting for reddening. We also argue that many of these systems may go through a phase of He transfer that matches the signatures of AM CVn systems, and that some AM CVn systems associated with young stellar populations likely descend from this channel.

scholarly journals Helium white dwarf cooling in PSR J0751+1807 and PSR J1012+5307

2000 ◽  
Vol 177 ◽  
pp. 637-640
Author(s):  
Ene Ergma ◽  
J. Antipova ◽  
M. J. Sarna
Keyword(s):  
Orbital Period ◽  
White Dwarf ◽  
Close Binary ◽  
Cooling History ◽  
Dipole Radiation ◽  
Spin Period ◽  
Binary Pulsars ◽  
History Of ◽  
Low Mass ◽  
Binary Evolution

It is accepted that formation of a binary millisecond (or recycled) pulsar with a low–mass companion may be explained as the end–point of close binary evolution in which an old pulsar is spun–up by accretion from the secondary (Alpar et al., 1982). After detachment from the Roche lobe, the pulsar spin period starts to change due to magneto–dipole radiation and the white dwarf begins to cool down. In this paper we shall discuss the cooling history of helium core low–mass white dwarfs in the short orbital period millisecond binary pulsars PSR J0751+1807 and PSR J1012+5307 (Ergma, Sarna, &amp; Antipova 1999).

scholarly journals The Chemical Composition and Orbital Parameters of Barium Stars

2000 ◽  
Vol 177 ◽  
pp. 277-284 ◽  
Author(s):  
Laimons Začs
Keyword(s):  
Mass Transfer ◽  
Chemical Composition ◽  
White Dwarf ◽  
Large Sample ◽  
Orbital Parameters ◽  
Long Period ◽  
Abundance Anomalies ◽  
Orbital Periods

The observational relation between s-process abundance anomalies and orbital periods for barium stars is discussed and compared with mass-transfer simulations. Recent detailed abundance analyses of a large sample of single-lined long-period binaries provide evidence that all giants with white dwarf companions are likely to have abundance anomalies.

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