Optical Studies of 20 Longer-Period Cataclysmic Binaries1

Thorstensen, J. R.; Peters, C. S.; Skinner, Julie N.

doi:10.1086/657021

Cited by 36 publications

(34 citation statements)

References 50 publications

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“…The observational data here are the same as in K06, except that we have included some additional long-period CVs from Thorstensen et al (2010). The calibration of SpT based on V−K photometric colors is the same as in K06.…”

Section: Donor Spectral Typesmentioning

confidence: 99%

The Evolution of Cataclysmic Variables as Revealed by Their Donor Stars

Knigge

Baraffe

Patterson

2011

ApJS

585

879

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We present an attempt to reconstruct the complete evolutionary path followed by cataclysmic variables (CVs), based on the observed mass-radius relationship of their donor stars. Along the way, we update the semi-empirical CV donor sequence presented previously by one of us, present a comprehensive review of the connection between CV evolution and the secondary stars in these systems, and reexamine most of the commonly used magnetic braking (MB) recipes, finding that even conceptually similar ones can differ greatly in both magnitude and functional form. The great advantage of using donor radii to infer mass-transfer and angular-momentum-loss (AML) rates is that they sample the longest accessible timescales and are most likely to represent the true secular (evolutionary average) rates. We show explicitly that if CVs exhibit long-term mass-transfer-rate fluctuations, as is often assumed, the expected variability timescales are so long that other tracers of the mass-transfer rate-including white dwarf (WD) temperatures-become unreliable. We carefully explore how much of the radius difference between CV donors and models of isolated main-sequence stars may be due to mechanisms other than mass loss. The tidal and rotational deformation of Roche-lobe-filling stars produces 4.5% radius inflation below the period gap and 7.9% above. A comparison of stellar models to mass-radius data for non-interacting stars suggests a real offset of 1.5% for fully convective stars (i.e., donors below the gap) and 4.9% for partially radiative ones (donors above the gap). We also show that donor bloating due to irradiation is probably smaller than, and at most comparable to, these effects. After calibrating our models to account for these issues, we fit self-consistent evolution sequences to our compilation of donor masses and radii. In the standard model of CV evolution, AMLs below the period gap are assumed to be driven solely by gravitational radiation (GR), while AMLs above the gap are usually described by an MB law first suggested by Rappaport et al. We adopt simple scaled versions of these AML recipes and find that these are able to match the data quite well. The optimal scaling factors turn out to be f GR = 2.47 ± 0.22 below the gap and f MB = 0.66 ± 0.05 above (the errors here are purely statistical, and the standard model corresponds to f GR = f MB = 1). This revised model describes the mass-radius data significantly better than the standard model. Some of the most important implications and applications of our results are as follows. (1) The revised evolution sequence yields correct locations for the minimum period and the upper edge of the period gap; the standard sequence does not. (2) The observed spectral types of CV donors are compatible with both standard and revised models. (3) A direct comparison of predicted and observed WD temperatures suggests an even higher value for f GR , but this comparison is sensitive to the assumed mean WD mass and the possible existence of mass-transfer-rate fluctuations. (4) The pred...

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Section: Donor Spectral Typesmentioning

confidence: 99%

The Evolution of Cataclysmic Variables as Revealed by Their Donor Stars

Knigge

Baraffe

Patterson

2011

ApJS

585

879

View full text Add to dashboard Cite

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“…The instrumentation, observing protocols, data reduction, and analysis were as described by Thorstensen et al (2010).…”

Section: Spectroscopy and Radial Velocitiesmentioning

confidence: 99%

“…The convolution function used to measure radial velocities from the of Hα line (see Schneider & Young 1980;and Thorstensen et al 2010 separated by 1830 km s −1 . This weighted the steep sides of the line profile, outside the line core.…”

Section: Spectroscopy and Radial Velocitiesmentioning

confidence: 99%

SDSS J162520.29+120308.7 – a new SU Ursae Majoris star in the period gap

Olech

Miguel

Otulakowska

et al. 2011

A&A

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We report results of an extensive world-wide observing campaign devoted to the recently discovered dwarf nova SDSS J162520.29+120308.7 (SDSS J1625). The data were obtained during the July 2010 eruption of the star and in August and September 2010 when the object was in quiescence. During the July 2010 superoutburst SDSS J1625 clearly displayed superhumps with a mean period of P sh = 0.095942(17) days (138.16 ± 0.02 min) and a maximum amplitude reaching almost 0.4 mag. The superhump period was not stable, decreasing very rapidly at a rate of Ṗ = −1.63(14) • 10 −3 at the beginning of the superoutburst and increasing at a rate of Ṗ = 2.81(20)•10 −4 in the middle phase. At the end of the superoutburst it stabilized around the value of P sh = 0.09531(5) day.During the first twelve hours of the superoutburst a low-amplitude double wave modulation was observed whose properties are almost identical to early superhumps observed in WZ Sge stars. The period of early superhumps, the period of modulations observed temporarily in quiescence and the period derived from radial velocity variations are the same within measurement errors, allowing us to estimate the most probable orbital period of the binary to be P orb = 0.09111(15) days (131.20 ± 0.22 min). This value clearly indicates that SDSS J1625 is another dwarf nova in the period gap. Knowledge of the orbital and superhump periods allows us to estimate the mass ratio of the system to be q ≈ 0.25. This high value poses serious problems both for the thermal and tidal instability (TTI) model describing the behaviour of dwarf novae and for some models explaining the origin of early superhumps.

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confidence: 99%

“…We report here CV orbital periods measured over the last several decades using the Hiltner 2.4m and McGraw-Hill 1.3m telescopes at MDM Observatory on Kitt Peak, Arizona, mostly with radial-velocity spectroscopy. While most of our results have been published in peer-reviewed articles (see, e.g., Thorstensen et al 2016;Thorstensen & Skinner 2012;Thorstensen et al 2015Thorstensen et al , 2010, many periods we have determined remain unpublished.To make our CV periods available more quickly, and prevent duplication of effort, we present in Table 1 some of our heretofore unpublished P orb s, some of which are refinements of previously-known periods. The instrumentation, observing protocols, reduction, and analysis are described in the papers cited above.…”

mentioning

confidence: 99%

New or Improved Orbital Periods of Cataclysmic Binaries

et al. 2017

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Wilder Laboratory Hanover, NH 1. EXPLANATION Cataclysmic variables (CVs) are close binary star systems in which a white dwarf accretes mass from a low-mass companion via Roche-lobe overflow. Warner (1995) presents a comprehensive review.The most significant observable number for a CV is its orbital period P orb . We report here CV orbital periods measured over the last several decades using the Hiltner 2.4m and McGraw-Hill 1.3m telescopes at MDM Observatory on Kitt Peak, Arizona, mostly with radial-velocity spectroscopy. While most of our results have been published in peer-reviewed articles (see, e.g., Thorstensen et al. 2016;Thorstensen & Skinner 2012;Thorstensen et al. 2015Thorstensen et al. , 2010, many periods we have determined remain unpublished.To make our CV periods available more quickly, and prevent duplication of effort, we present in Table 1 some of our heretofore unpublished P orb s, some of which are refinements of previously-known periods. The instrumentation, observing protocols, reduction, and analysis are described in the papers cited above. We are confident of the choices of cycle count between observations. For references on these stars, see SIMBAD and the online lists maintained by ASAS-SN, the Catalina surveys, and MASTER. Downes et al. (2001) give references for long-known CVs (see also Downes et al. 2005).

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Optical Studies of 20 Longer-Period Cataclysmic Binaries1

Cited by 36 publications

References 50 publications

The Evolution of Cataclysmic Variables as Revealed by Their Donor Stars

The Evolution of Cataclysmic Variables as Revealed by Their Donor Stars

SDSS J162520.29+120308.7 – a new SU Ursae Majoris star in the period gap

New or Improved Orbital Periods of Cataclysmic Binaries

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