scholarly journals Spectroscopic and photometric periods of six ultracompact accreting binaries

2020 ◽  
Vol 496 (2) ◽  
pp. 1243-1261 ◽  
Author(s):  
Matthew J Green ◽  
Thomas R Marsh ◽  
Philip J Carter ◽  
Danny Steeghs ◽  
Elmé Breedt ◽  
...  
Keyword(s):  
Orbital Period ◽  
White Dwarf ◽  
High Speed ◽  
Binary Systems ◽  
Direct Detection ◽  
Cataclysmic Variables ◽  
Central Star ◽  
Wide Field ◽  
Infrared Excess ◽  
Orbital Periods

ABSTRACT Ultracompact accreting binary systems each consist of a stellar remnant accreting helium-enriched material from a compact donor star. Such binaries include two related sub-classes, AM CVn-type binaries and helium cataclysmic variables, in both of which the central star is a white dwarf. We present a spectroscopic and photometric study of six accreting binaries with orbital periods in the range of 40–70 min, including phase-resolved VLT spectroscopy and high-speed ULTRACAM photometry. Four of these are AM CVn systems and two are helium cataclysmic variables. For four of these binaries we are able to identify orbital periods (of which three are spectroscopic). SDSS J1505+0659 has an orbital period of 67.8 min, significantly longer than previously believed, and longer than any other known AM CVn binary. We identify a Wide-field Infrared Survey Explorer (WISE) infrared excess in SDSS J1505+0659 that we believe to be the first direct detection of an AM CVn donor star in a non-direct impacting binary. The mass ratio of SDSS J1505+0659 is consistent with a white dwarf donor. CRTS J1028–0819 has an orbital period of 52.1 min, the shortest period of any helium cataclysmic variable. MOA 2010-BLG-087 is co-aligned with a K-class star that dominates its spectrum. ASASSN-14ei and ASASSN-14mv both show a remarkable number of echo outbursts following superoutbursts (13 and 10 echo outbursts respectively). ASASSN-14ei shows an increased outburst rate over the years following its superoutburst, perhaps resulting from an increased accretion rate.

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.

Origin of Very-Short Orbital-Period Binary Systems

1983 ◽  
Vol 72 ◽  
pp. 263-267
Author(s):  
Shigeki Miyaji
Keyword(s):  
Binary System ◽  
Globular Cluster ◽  
Orbital Period ◽  
Binary Systems ◽  
Main Sequence ◽  
Cataclysmic Variables ◽  
Close Binaries ◽  
X Ray ◽  
Evolutionary Scenario ◽  
Orbital Periods

Recent observations of four close binaries have established that there is a group of very-short orbital-period (VSOP) binaries whose orbital periods are less than 60 minutes. The VSOP binaries consist of both x-ray close binaries (4U1626-67; Middleditch et al. 1981 and 4U1916 -0.5; White and Swank 1982) and cataclysmic variables (AM CVn; Faulkner et al. 1972 and G61-29; Nather et al. 1981). Their orbital periods are too short to have a main-sequence companion. However, four binaries, none of them belongs to any globular cluster, are too abundant to be explained by capturing mechanism of a white dwarf. Therefore it seemed to be worth to present an evolutionary scenario from an original binary system which can be applied for all of VSOP binaries.

scholarly journals ZTF J1901+5309: a 40.6-min orbital period eclipsing double white dwarf system

2020 ◽  
Vol 494 (1) ◽  
pp. L91-L96 ◽  
Author(s):  
Michael W Coughlin ◽  
Kevin Burdge ◽  
E Sterl Phinney ◽  
Jan van Roestel ◽  
Eric C Bellm ◽  
...  
Keyword(s):  
Gravitational Wave ◽  
Orbital Period ◽  
White Dwarf ◽  
Binary Systems ◽  
Demographic Analysis ◽  
Effective Temperatures ◽  
Orbital Periods ◽  
High Cadence

ABSTRACT The Zwicky Transient Facility has begun to discover binary systems with orbital periods that are less than 1 h. Combined with dedicated follow-up systems, which allow for high-cadence photometry of these sources, systematic confirmation and characterization of these sources are now possible. Here, we report the discovery of ZTF J190125.42+530929.5, a 40.6-min orbital period, eclipsing double white dwarf binary. Both photometric modelling and spectroscopic modelling confirm its nature, yielding an estimated inclination of $i = 86.2^{+0.6}_{-0.2}\, \rm deg$ and primary and secondary effective temperatures of $\textrm{{T}}_\textrm{eff} = 28\,000^{+500}_{-500}$ and $17\,600^{+400}_{-400}\, \mathrm{ K}$, respectively. This system adds to a growing list of sources for future gravitational-wave detectors and contributes to the demographic analysis of double degenerates.

scholarly journals Eclipse timing variation of GK Vir: evidence of a possible Jupiter-like planet in a circumbinary orbit

2020 ◽  
Vol 497 (3) ◽  
pp. 4022-4029
Author(s):  
L A Almeida ◽  
E S Pereira ◽  
G M Borges ◽  
A Damineli ◽  
T A Michtchenko ◽  
...  
Keyword(s):  
Orbital Period ◽  
Binary Systems ◽  
Orbital Stability ◽  
Theoretical Description ◽  
Apsidal Motion ◽  
Variation Analysis ◽  
Third Body ◽  
Common Envelope ◽  
Cyclic Behaviour ◽  
Orbital Periods

ABSTRACT Eclipse timing variation analysis has become a powerful method to discover planets around binary systems. We applied this technique to investigate the eclipse times of GK Vir. This system is a post-common envelope binary with an orbital period of 8.26 h. Here, we present 10 new eclipse times obtained between 2013 and 2020. We calculated the O−C diagram using a linear ephemeris and verified a clear orbital period variation (OPV) with a cyclic behaviour. We investigated if this variation could be explained by the Applegate mechanism, the apsidal motion, or the light travel time (LTT) effect. We found that the Applegate mechanism would hardly explain the OPV with its current theoretical description. We obtained using different approaches that the apsidal motion is a less likely explanation than the LTT effect. We showed that the LTT effect with one circumbinary body is the most likely cause for the OPV, which was reinforced by the orbital stability of the third body. The LTT best solution provided an orbital period of ∼24 yr for the outer body. Under the assumption of coplanarity between the external body and the inner binary, we obtained a Jupiter-like planet around the GK Vir. In this scenario, the planet has one of the longest orbital periods, with a full observational baseline, discovered so far. However, as the observational baseline of GK Vir is smaller than twice the period found in the O−C diagram, the LTT solution must be taken as preliminary.

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 The Effective Temperature Distribution Function of Cataclysmic Variable White Dwarfs

1987 ◽  
Vol 93 ◽  
pp. 47-51
Author(s):  
E.M. Sion
Keyword(s):  
Distribution Function ◽  
Temperature Distribution ◽  
Orbital Period ◽  
White Dwarf ◽  
White Dwarfs ◽  
Cataclysmic Variables ◽  
Cataclysmic Variable ◽  
Term Evolution ◽  
Effective Temperatures

AbstractWith the recent detection of direct white dwarf photospheric radiation from certain cataclysmic variables in quiescent (low accretion) states, important implications and clues about the nature and long-term evolution of cataclysmic variables can emerge from an analysis of their physical properties. Detection of the underlying white dwarfs has led to a preliminary empirical CV white dwarf temperature distribution function and, in a few cases, the first detailed look at a freshly accreted while dwarf photosphere. The effective temperatures of CV white dwarfs plotted versus orbital period for each type of CV appears to reveal a tendency for the cooler white dwarf primaries to reside in the shorter period systems. Possible implications are briefly discussed.

scholarly journals The Spin Periods of Magnetic Cataclysmic Variables

2004 ◽  
Vol 190 ◽  
pp. 216-229 ◽  
Author(s):  
A. J. Norton ◽  
R. V. Somerscales ◽  
G. A. Wynn
Keyword(s):  
Orbital Period ◽  
Magnetic Moment ◽  
White Dwarf ◽  
Magnetic Moments ◽  
Cataclysmic Variables ◽  
Intermediate Polars ◽  
Magnetic Cataclysmic Variables ◽  
Remarkable Agreement

AbstractWe have used a model of magnetic accretion to investigate the rotational equilibria of magnetic cataclysmic variables (MCVs). This has enabled us to derive a set of equilibrium spin periods as a function of orbital period and magnetic moment which we use to estimate the magnetic moments of all known intermediate polars. We further show how these equilibrium spin periods relate to the polar synchronisation condition and use these results to calculate the theoretical histogram describing the distribution of magnetic CVs as a function of Pspin/Porb. We demonstrate that this is in remarkable agreement with the observed distribution assuming that the number of systems as a function of white dwarf magnetic moment is distributed according to .

scholarly journals Origin of the orbital period change in contact binary stars

2019 ◽  
Vol 28 (06) ◽  
pp. 1950044 ◽  
Author(s):  
V. V. Sargsyan ◽  
H. Lenske ◽  
G. G. Adamian ◽  
N. V. Antonenko
Keyword(s):  
Orbital Period ◽  
Binary Stars ◽  
Binary Systems ◽  
Binary Star ◽  
Period Change ◽  
Mass Asymmetry ◽  
Contact Binary Stars ◽  
Contact Binary ◽  
Energy Formula ◽  
Orbital Periods

The evolution of contact binary star systems in mass asymmetry (transfer) coordinate is considered. The orbital period changes are explained by an evolution in mass asymmetry towards the symmetry (symmetrization of binary system). It is predicted that decreasing and increasing orbital periods are related, respectively, with the nonoverlapping and overlapping stage of the binary star during its symmetrization. A huge amount of energy [Formula: see text][Formula: see text]J is converted from the potential energy into internal energy of the stars during the symmetrization. As shown, the merger of stars in the binary systems, including KIC 9832227, is energetically an unfavorable process. The sensitivity of the calculated results to the values of total mass and orbital angular momentum is analyzed.

scholarly journals Recurrent Novae: What Do We Know about Them?

2011 ◽  
Vol 7 (S281) ◽  
pp. 154-161 ◽  
Author(s):  
G. C. Anupama
Keyword(s):  
White Dwarf ◽  
Binary Systems ◽  
Accretion Rate ◽  
Cataclysmic Variables ◽  
Type Ia Supernovae ◽  
Type Ia ◽  
Ia Supernovae ◽  
Nova Outbursts ◽  
Nova Outburst

AbstractRecurrent novae (RNe) belong to the group of cataclysmic variables that exhibit nova outbursts at intervals on the order of decades. They are rare, with 10 Galactic RNe known to date. Two are known in the LMC, while there are a few suspected RNe in M31. Nova outburst models require a high accretion rate on a massive white dwarf to explain the recurring nova outbursts, making this class of objects one of the most likely progenitor binary systems of Type Ia supernovae. The observational properties of the known Galactic recurrent novae are presented here, together with some discussion on the recent outbursts of RS Ophiuchi (2006), U Scorpii (2010), and T Pyxidis (2011).

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