A radial velocity study of CTCV J1300−3052

Mon. Not. R. Astron. Soc.

Dhillon

et al. 2016

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Section: Introductionmentioning

confidence: 88%

Hunting for eclipses: high-speed observations of cataclysmic variables

Hardy

Mon. Not. R. Astron. Soc.

Dhillon

et al. 2016

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“…During primary eclipse, the white dwarf and accretion disc are occulted, along with the bright spot, located where the accretion stream impacts the outer rim of the disc. The path of the gas stream is determined by the mass ratio, and so the detailed shape of the primary eclipse contains enough information to derive extremely precise masses that are consistent with conventional spectroscopic methods (see Tulloch et al 2009;Copperwheat et al 2010;Savoury et al 2012, for example). The photometric method has the advantage that it does not rely on detection of the light from the donor star, which is often invisible given the much brighter white dwarf and accretion disc, particularly for CVs with shorter orbital periods.…”

Section: Introductionmentioning

confidence: 99%

The evolutionary status of Cataclysmic Variables: eclipse modelling of 15 systems

Monthly Notices of the Royal Astronomical Society

Littlefair

Parsons

et al. 2019

We present measurements of the component masses in 15 Cataclysmic Variables (CVs) -6 new estimates and 9 improved estimates. We provide new calibrations of the relationship between superhump period excess and mass ratio, and use this relation to estimate donor star masses for 225 superhumping CVs. With an increased sample of donor masses we revisit the implications for CV evolution. We confirm the high mass of white dwarfs in CVs, but find no trend in white dwarf mass with orbital period. We argue for a revision in the location of the orbital period minimum of CVs to 79.6 ± 0.2 min, significantly shorter than previous estimates. We find that CV donors below the gap have an intrinsic scatter of only 0.005 R around a common evolutionary track, implying a correspondingly small variation in angular momentum loss rates. In contrast to prior studies, we find that standard CV evolutionary tracks -without additional angular momentum loss -are a reasonable fit to the donor masses just below the period gap, but that they do not reproduce the observed period minimum, or fit the donor radii below 0.1 M .

“…The validity of this assumption has recently been questioned by Spark & O'Donoghue (2015), through fast photometry observations of the dwarf nova OY Car. It is not yet completely clear that the results of Spark & O'Donoghue (2015) cannot be explained by flickering in the boundary layer and inner disc, and coupled with agreement between photometric and spectroscopic parameter estimates Savoury et al 2012) we feel an unobscured white dwarf is still a reasonable assumption to make.…”

Section: Phase-folded Average Light-curve Modellingmentioning

confidence: 77%

“…The bars in the top-left corners of each plot give an indication of the real error due to flickering. (Tulloch, Rodríguez-Gil & Dhillon 2009;Copperwheat et al 2012;Savoury et al 2012).…”

Section: Component Massesmentioning

confidence: 99%

PHL 1445: an eclipsing cataclysmic variable with a substellar donor near the period minimum

Monthly Notices of the Royal Astronomical Society

Littlefair

Baraffe

et al. 2015

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We present high-speed, three-colour photometry of the eclipsing dwarf nova PHL 1445, which, with an orbital period of 76.3 min, lies just below the period minimum of ∼82 min for cataclysmic variable stars. Averaging four eclipses reveals resolved eclipses of the white dwarf and bright spot. We determined the system parameters by fitting a parameterised eclipse model to the averaged lightcurve. We obtain a mass ratio of q=0.087 ± 0.006 and inclination i=85.2 ± 0.9 • . The primary and donor masses were found to be M w =0.73 ± 0.03 M and M d =0.064 ± 0.005 M , respectively. Through multicolour photometry a temperature of the white dwarf of T w =13200 ± 700 K and a distance of 220 ± 50 pc were determined.The evolutionary state of PHL 1445 is uncertain. We are able to rule out a significantly evolved donor, but not one that is slightly evolved. Formation with a brown dwarf donor is plausible; though the brown dwarf would need to be no older than 600 Myrs at the start of mass transfer, requiring an extremely low mass ratio (q=0.025) progenitor system. PHL 1445 joins SDSS 1433 as a sub-period minimum CV with a substellar donor. These existence of two such systems raises an alternative possibility; that current estimates for the intrinsic scatter and/or position of the period minimum may be in error.