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, & Antipova 1999).

scholarly journals Low–Mass He WDs and Millisecond Pulsars Age Determination

2000 ◽  
Vol 177 ◽  
pp. 631-632
Author(s):  
J. Antipova ◽  
Ene Ergma ◽  
M. J. Sarna
Keyword(s):  
Neutron Stars ◽  
Orbital Period ◽  
Time Scale ◽  
Age Determination ◽  
Close Binary ◽  
Orbital Parameters ◽  
History Of ◽  
Low Mass ◽  
Binary Evolution ◽  
Red Giant

It is accepted that the formation of a millisecond binary pulsar (MBP) 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 red giant (Bhattacharaya & van den Heuvel 1991). In this paper we shall discuss the cooling properties of the helium white dwarfs (WD) in short orbital period MBP systems PSR J0437–4715, PSR J0751+1807 and PSR J1012+5307, without referring to the rotational history of neutron stars (NS).Below we discuss observational data for several system for which the results of our calculations (Sarna, Antipova, & Muslimov 1998; Sarna, Ergma, & Antipova 1999) may be applied, by taking into account the orbital parameters of the system, the pulsar spin-down time, and the WD cooling time-scale.

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 Evolutionary and pulsational properties of low-mass white dwarf stars with oxygen cores resulting from close binary evolution

2004 ◽  
Vol 347 (1) ◽  
pp. 125-136 ◽  
Author(s):  
L. G. Althaus ◽  
A. H. Córsico ◽  
A. Gautschy ◽  
Z. Han ◽  
A. M. Serenelli ◽  
...  
Keyword(s):  
White Dwarf ◽  
Close Binary ◽  
Dwarf Stars ◽  
White Dwarf Stars ◽  
Low Mass ◽  
Binary Evolution

scholarly journals ANALYZING THE BINARY PULSARS ABOVE THE SPIN-UP LINE

2013 ◽  
Vol 23 ◽  
pp. 111-114
Author(s):  
YUANYUE PAN ◽  
NA WANG ◽  
CHENGMIN ZHANG
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Field Strength ◽  
Orbital Period ◽  
Dipole Radiation ◽  
Spin Period ◽  
Binary Pulsars ◽  
Proportional Relation ◽  
Period Derivative ◽  
Line Relationship

With accretion of mass from an evolving companion star, a neutron star can be spun up to an equilibrium period, which is set by the Kepler orbital period at the magnetosphere radius, expressed as a proportional relation between the spin period and magnetic field strength. The spin-up line relationship can be also expressed as a relation between period (P) and period derivative (Ṗ) for the pulsars with dipole radiation. All binary pulsars should lie below the spin-up line, if they accrete the sufficient masses from companions. So, we investigate the distribution of isolated and binary pulsars in the period (P) and magnetic field (B) diagram to see their positions relative to the spin-up line. It is found that the eight binary pulsars (of total 172) are above the spin-up line, thus we analyze their properties and present the possible process of their formations.

scholarly journals Supernovae from massive stars with extended tenuous envelopes

2018 ◽  
Vol 612 ◽  
pp. A61 ◽  
Author(s):  
Luc Dessart ◽  
Sung-Chul Yoon ◽  
Eli Livne ◽  
Roni Waldman
Keyword(s):  
Massive Stars ◽  
Constant Width ◽  
Core Material ◽  
Close Binary ◽  
Reverse Shock ◽  
Halo Structure ◽  
Deposited Energy ◽  
Dense Shell ◽  
Low Mass ◽  
Binary Evolution

Massive stars with a core-halo structure are interesting objects for stellar physics and hydrodynamics. Using simulations for stellar evolution, radiation hydrodynamics, and radiative transfer, we study the explosion of stars with an extended and tenuous envelope (i.e. stars in which 95% of the mass is contained within 10% or less of the surface radius). We consider both H-rich supergiant and He-giant progenitors resulting from close-binary evolution and dying with a final mass of 2.8–5 M⊙. An extended envelope causes the supernova (SN) shock to brake and a reverse shock to form, sweeping core material into a dense shell. The shock-deposited energy, which suffers little degradation from expansion, is trapped in ejecta layers of moderate optical depth, thereby enhancing the SN luminosity at early times. With the delayed 56Ni heating, we find that the resulting optical and near-IR light curves all exhibit a double-peak morphology. We show how an extended progenitor can explain the blue and featureless optical spectra of some Type IIb and Ib SNe. The dense shell formed by the reverse shock leads to line profiles with a smaller and near-constant width. This ejecta property can explain the statistically narrower profiles of Type IIb compared to Type Ib SNe, as well as the peculiar Hα profile seen in SN 1993J. At early times, our He-giant star explosion model shows a high luminosity, a blue colour, and featureless spectra reminiscent of the Type Ib SN 2008D, suggesting a low-mass progenitor.

scholarly journals V479 And: CV, LMXB, or Symbiotic?

2011 ◽  
Vol 7 (S281) ◽  
pp. 113-116
Author(s):  
Diego González Buitrago ◽  
Gagik Tovmassian ◽  
Juan Echevarría ◽  
Sergey Zharikov ◽  
Takamitsu Miyaji ◽  
...  
Keyword(s):  
Orbital Period ◽  
Main Sequence ◽  
Compact Object ◽  
Close Binary System ◽  
Close Binary ◽  
Stellar Winds ◽  
Primary Star ◽  
Giant Star ◽  
X Ray ◽  
Low Mass

AbstractV479 And is a 14.26 hour, close binary system, comprised of a G8-K0 star departing from the main sequence and a compact primary star accreting matter from the donor. The object is an X-ray source, modulated with the orbital period. This, and the presence of an intense He II line, leads us to speculate that the compact object is a magnetic white dwarf. However, we do not find strong constraints on the upper mass limit of the compact object, and we may have a neutron star in a low mass X-ray binary instead of a cataclysmic variable. The orbital period is certainly too short for the donor star to be an evolved giant star, so classifying this object as a symbiotic binary may be a big stretch; however there is an evidence that the mass transfer occurs via stellar winds, rather than through the L1 point of Roche filling secondary, a phenomenon more common for symbiotic stars.

scholarly journals Superoutbursts and Superhumps of SU UMa Stars

1988 ◽  
Vol 108 ◽  
pp. 238-239
Author(s):  
Yoji Osaki ◽  
Masahito Hirose
Keyword(s):  
Accretion Disk ◽  
Orbital Period ◽  
White Dwarf ◽  
Binary Systems ◽  
Roche Lobe ◽  
Light Curves ◽  
Close Binary ◽  
Dwarf Novae ◽  
Dwarf Nova ◽  
Close Binary Systems

SU UMa stars are one of subclasses of dwarf novae. Dwarf novae are semi-detached close binary systems in which a Roche-lobe filling red dwarf secondary loses matter and the white dwarf primary accretes it through the accretion disk. The main characteristics of SU UMa subclass is that they show two kinds of outbursts: normal outbursts and superoutbursts. In addition to the more frequent narrow outbursts of normal dwarf nova, SU UMa stars exhibit “superoutbursts”, in which stars reach about 1 magnitude brighter and stay longer than in normal outburst. Careful photometric studies during superoutburst have almost always revealed the “superhumps”: periodic humps in light curves with a period very close to the orbital period of the system. However, the most curious of all is that this superhump period is not exactly equal to the orbital period, but it is always longer by a few percent than the orbital period.

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

2019 ◽  
Vol 488 (2) ◽  
pp. 2892-2903 ◽  
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.

scholarly journals X-ray and optical observations of BY Cam

1996 ◽  
Vol 158 ◽  
pp. 213-214 ◽  
Author(s):  
Gavin Ramsay ◽  
Paul A. Mason
Keyword(s):  
Power Spectrum ◽  
Orbital Period ◽  
White Dwarf ◽  
Optical Observations ◽  
Optical Data ◽  
Spin Orbit ◽  
Side Band ◽  
X Ray ◽  
Beat Period ◽  
Spin Period

We present preliminary results of an analysis of X-ray and optical data of the asynchronous AM Her star BY Cam [1]. We use X-ray data from EXOSAT (0.1… 50 keV), Ginga (1.5… 50 keV) and ROSAT (0.1…2.0 keV) and optical data obtained during a 45-day campaign in 1994.There are 4 known periods: the orbital period (201.30 m), the spin period of the white dwarf (199.3303 m), a spin-orbit beat period (14.15 d) and a side-band period (197.4 m). The detection of this side-band period lends credence to the theory of [2], who suggest that for a stream accreting, diskless, magnetic CV a frequency, f = 2ωspin − Ωorb (=197.399 m), will appear as a strong spike in the power spectrum for certain systems. Wu & Mason (this volume) discuss a competing model where Pspin = 197.4 m.

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