The closest extremely low-mass white dwarf to the Sun

ABSTRACT We present the orbit and properties of 2MASS J050051.85−093054.9, establishing it as the closest (d ≈ 71 pc) extremely low-mass white dwarf to the Sun. We find that this star is hydrogen rich with $T_\textrm {eff}\approx 10\, 500$ K, log g ≈ 5.9, and, following evolutionary models, has a mass of ≈0.17 M⊙. Independent analysis of radial velocity and Transiting Exoplanet Survey Satellite(TESS) photometric time series reveals an orbital period of ≈9.5 h. Its high velocity amplitude ($K\approx 144~\textrm {km}\, \textrm {s}^{-1}$) produces a measurable Doppler beaming effect in the TESSlight curve with an amplitude of 1 mmag. The unseen companion is most likely a faint white dwarf. J0500−0930 belongs to a class of post-common envelope systems that will most likely merge through unstable mass transfer and in specific circumstances lead to Type Ia supernova explosions.

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Studying the Progenitors of Type Ia Supernovae via Lensing with the Kepler Survey

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312014652 ◽

2011 ◽

Vol 7 (S281) ◽

pp. 34-35

Author(s):

Rosanne Di Stefano

Keyword(s):

Mass Transfer ◽

White Dwarf ◽

Type Ia Supernovae ◽

Valuable Insight ◽

Common Envelope ◽

Type Ia ◽

Pass Through ◽

Ia Supernovae ◽

Insight Into

AbstractEvery model for the progenitors of Type Ia supernovae (SNe Ia) requires that binaries pass through an epoch during which a white dwarf (WD) orbits a non-degenerate star. Depending on the mass of the WD, the radius of its companion, and the orbital separation, the WD may lens its companion. The lensing event would be an antitransit, an increase in light from the companion that can rise to the level of a percent or more, during an interval of hours. Antitransits are periodic. By studying them we can determine the properties of both the WD and its companion, as well as the characteristics of the orbit. Lensing events of this type are almost certain to be observed by the Kepler mission, while some can even be detected by ground-based surveys. Antitransits and transits will both provide valuable insight into the end states of common envelope evolution and of stable mass transfer, resolving issues that must be understood before we can fully unravel the progenitor puzzle.

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

Serbian Astronomical Journal ◽

10.2298/saj2102025p ◽

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.

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A New Progenitor Model of Type Ia Supernovae

Highlights of Astronomy ◽

10.1017/s1539299600007723 ◽

1989 ◽

Vol 8 ◽

pp. 175-176

Author(s):

Izumi Hachisu ◽

Mariko Kato ◽

Hideyuki Saio

Keyword(s):

Mass Transfer ◽

White Dwarf ◽

Transfer Rate ◽

Mass Transfer Rate ◽

Supernova Explosion ◽

Core Mass ◽

Common Envelope ◽

Type Ia ◽

Red Giant ◽

Ia Supernovae

AbstractA new progenitor model of Type la supernovae (SNe Ia) is proposed. The model consists of a carbon-oxygen white dwarf (0.8-1.2 M⊙) and a low-mass red giant star (0.8-1.5 M⊙) with a helium core (0.2-0.4 M⊙). When a red giant fills its inner critical Roche lobe and its mass transfer rate exceeds a critical value, a common envelope state is realized. Then the mass accretion rate onto the white dwarf, i.e., the mass transfer rate is tuned up to be Ṁ= 8.5 × 10−7 (MWD/M⊙-0.52) M⊙ yr−1, where MWD is the mass of the white dwarf. This rate is high enough to suppress the hydrogen shell flashes, but too low for carbon to be ignited off-center. When the carbon-oxygen core mass grows to the Chandrasekhar limit during the common envelope phase, a Type la supernova explosion is expected to occur.

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The evolution of ultra-massive white dwarfs

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833822 ◽

2019 ◽

Vol 625 ◽

pp. A87 ◽

Cited By ~ 22

Author(s):

María E. Camisassa ◽

Leandro G. Althaus ◽

Alejandro H. Córsico ◽

Francisco C. De Gerónimo ◽

Marcelo M. Miller Bertolami ◽

...

Keyword(s):

Phase Separation ◽

White Dwarf ◽

White Dwarfs ◽

Outer Boundary ◽

Asymptotic Giant Branch ◽

Type Ia ◽

Chemical Profiles ◽

Supernova Explosions ◽

Carbon Burning ◽

The Impact

Ultra-massive white dwarfs are powerful tools used to study various physical processes in the asymptotic giant branch (AGB), type Ia supernova explosions, and the theory of crystallization through white dwarf asteroseismology. Despite the interest in these white dwarfs, there are few evolutionary studies in the literature devoted to them. Here we present new ultra-massive white dwarf evolutionary sequences that constitute an improvement over previous ones. In these new sequences we take into account for the first time the process of phase separation expected during the crystallization stage of these white dwarfs by relying on the most up-to-date phase diagram of dense oxygen/neon mixtures. Realistic chemical profiles resulting from the full computation of progenitor evolution during the semidegenerate carbon burning along the super-AGB phase are also considered in our sequences. Outer boundary conditions for our evolving models are provided by detailed non-gray white dwarf model atmospheres for hydrogen and helium composition. We assessed the impact of all these improvements on the evolutionary properties of ultra-massive white dwarfs, providing updated evolutionary sequences for these stars. We conclude that crystallization is expected to affect the majority of the massive white dwarfs observed with effective temperatures below 40 000 K. Moreover, the calculation of the phase separation process induced by crystallization is necessary to accurately determine the cooling age and the mass-radius relation of massive white dwarfs. We also provide colors in the Gaia photometric bands for our H-rich white dwarf evolutionary sequences on the basis of new model atmospheres. Finally, these new white dwarf sequences provide a new theoretical frame to perform asteroseismological studies on the recently detected ultra-massive pulsating white dwarfs.

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Gaia Data Release 2 catalogue of extremely low-mass white dwarf candidates

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz1876 ◽

2019 ◽

Vol 488 (2) ◽

pp. 2892-2903 ◽

Cited By ~ 12

Author(s):

Ingrid Pelisoli ◽

Joris Vos

Keyword(s):

White Dwarf ◽

Theoretical Models ◽

Dwarf Stars ◽

Single Star ◽

Common Envelope ◽

White Dwarf Stars ◽

Final Sample ◽

Data Release ◽

Low Mass ◽

Binary Evolution

ABSTRACT Extremely low-mass white dwarf stars (ELMs) are M < 0.3 M⊙ helium-core white dwarfs born either as a result of a common-envelope phase or after a stable Roche lobe overflow episode in a multiple system. The Universe is not old enough for ELMs to have formed through single-star evolution channels. As remnants of binary evolution, ELMs can shed light onto the poorly understood phase of common-envelope evolution and provide constraints to the physics of mass accretion. Most known ELMs will merge in less than a Hubble time, providing an important contribution to the signal to be detected by upcoming space-based gravitational wave detectors. There are currently less than 150 known ELMs; most were selected by colour, focusing on hot objects, in a magnitude-limited survey of the Northern hemisphere only. Recent theoretical models have predicted a much larger space density for ELMs than estimated observationally based on this limited sample. In order to perform meaningful comparisons with theoretical models and test their predictions, a larger well-defined sample is required. In this work, we present a catalogue of ELM candidates selected from the second data release of Gaia (DR2). We have used predictions from theoretical models and analysed the properties of the known sample to map the space spanned by ELMs in the Gaia Hertzsprung–Russell diagram. Defining a set of colour cuts and quality flags, we have obtained a final sample of 5762 ELM candidates down to Teff ≈ 5000 K.

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Critical Mass for Merging in Double White Dwarfs

International Astronomical Union Colloquium ◽

10.1017/s0252921100100053 ◽

1989 ◽

Vol 114 ◽

pp. 450-453

Author(s):

Izumi Hachisu ◽

Mariko Kato

Keyword(s):

Mass Transfer ◽

Gravitational Radiation ◽

White Dwarf ◽

Binary Stars ◽

White Dwarfs ◽

Radiation Effect ◽

Critical Mass ◽

Mass Transfer Rate ◽

Roche Lobe ◽

Common Envelope

We examine whether or not double white dwarfs are ultimately merging into one body. It has been argued that such a double white dwarf system forms from some intermediate-mass binary stars and will merge due to the gravitational radiation which decreases the separation of binary. After filling the inner critical Roche lobe, the less massive component begins to transfer its mass to the more massive one. When the mass transfer rate exceeds a some critical value, a common envelope is formed. If the common envelope is hydrostatic, the mass transfer is tuned up to be a some value which depends only on the white dwarf mass, radius, and the Roche lobe size. The mass transfer from the less massive to the more massive components leads the separation to increase. On the other hand, the gravitational radiation effect reduces the separation. Which effect wins determines the fate of double white dwarfs, that is, whether merging or not merging. Since the formula of the gravitational radiation effect is well known, we have studied the mass accretion rate in common envelope phase of double white dwarfs assuming the Roche lobe size is as small as 0.03 R⊙ or 0.1 R⊙.

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Population Synthesis of Type Ia SNe: Constraining Free Parameters from Observations

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312015128 ◽

2011 ◽

Vol 7 (S281) ◽

pp. 240-243

Author(s):

Maxwell Moe ◽

Rosanne Di Stefano

Keyword(s):

Mass Transfer ◽

First Principles ◽

Type Ia Supernovae ◽

Population Synthesis ◽

Common Envelope ◽

Tidal Interactions ◽

Type Ia ◽

Free Parameters ◽

Binary Evolution ◽

Ia Supernovae

AbstractComputing the rate of Type Ia supernovae (SNe Ia) from first principles is difficult because there are large uncertainties regarding several key binary processes such as common envelope evolution, tidal interactions, and the efficiency of mass transfer. Fortunately, a range of observational parameters of binaries in intermediate stages of evolution can help us model these processes in a way that is likely to mirror the true binary evolution. We discuss how this observationally-motivated approach may have the effect of increasing the predicted rate of single degenerate progenitors of SNe Ia, while simultaneously decreasing the number of double degenerate progenitors.

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The White Dwarf Binary Pathways Survey – IV. Three close white dwarf binaries with G-type secondary stars

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3815 ◽

2020 ◽

Vol 501 (2) ◽

pp. 1677-1689

Author(s):

M S Hernandez ◽

M R Schreiber ◽

S G Parsons ◽

B T Gänsicke ◽

F Lagos ◽

...

Keyword(s):

Spectral Type ◽

White Dwarf ◽

Binary Stars ◽

Cataclysmic Variable ◽

Common Envelope ◽

History Of ◽

Low Mass ◽

Orbital Periods ◽

M Dwarf

ABSTRACT Constraints from surveys of post-common envelope binaries (PCEBs) consisting of a white dwarf plus an M-dwarf companion have led to significant progress in our understanding of the formation of close white dwarf binary stars with low-mass companions. The white dwarf binary pathways project aims at extending these previous surveys to larger secondary masses, i.e. secondary stars of spectral-type AFGK. Here, we present the discovery and observational characterization of three PCEBs with G-type secondary stars and orbital periods between 1.2 and 2.5 d. Using our own tools as well as MESA, we estimate the evolutionary history of the binary stars and predict their future. We find a large range of possible evolutionary histories for all three systems and identify no indications for differences in common envelope evolution compared to PCEBs with lower mass secondary stars. Despite their similarities in orbital period and secondary spectral type, we estimate that the future of the three systems is very different: TYC 4962-1205-1 is a progenitor of a cataclysmic variable system with an evolved donor star, TYC 4700-815-1 will run into dynamically unstable mass transfer that will cause the two stars to merge, and TYC 1380-957-1 may appear as supersoft source before becoming a rather typical cataclysmic variable star.

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