A Synthetic Spectrum and Light‐Curve Analysis of the Cataclysmic Variable IX Velorum

Linnell, Albert P.; Godon, Patrick; Hubený, I.; Sion, E. M.; Szkody, Paula

doi:10.1086/517965

Cited by 34 publications

(47 citation statements)

References 75 publications

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“…For example, Table 10 shows that the best-fit (standard) model predicts 3 ( 2) longperiod and 16 ( 35) short-period, pre-bounce CVs within 100 pc. Observationally, there are two known long-period, nonmagnetic nova-like systems with P orb 6 hr that might fall within this volume: IX Vel (Perryman et al 1997;Linnell et al 2007) and V3885 Sgr (Perryman et al 1997;Linnell et al 2009). Both have d 100 pc as measured by Hipparcos.…”

Section: Normalization and Space Densitiesmentioning

confidence: 93%

The Evolution of Cataclysmic Variables as Revealed by Their Donor Stars

Knigge

Baraffe

Patterson

2011

ApJS

548

863

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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: Normalization and Space Densitiesmentioning

confidence: 93%

The Evolution of Cataclysmic Variables as Revealed by Their Donor Stars

Knigge

Baraffe

Patterson

2011

ApJS

548

863

View full text Add to dashboard Cite

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“…However, these mixed results are characteristic of NL systems in high state as well. While some NLs have been successfully modeled with standard disk spectra (e.g., IX Vel, V3885 Sgr, V794 Aql, RZ Gru; Godon et al 2007;Linnell et al 2007Linnell et al , 2009Bisol et al 2012) others appear impossible to model with standard disk spectra (e.g., RW Sex, V751 Cyg, V380 Oph, UX UMa, QU Car; Linnell et al 2008aLinnell et al , 2008bLinnell et al , 2010Zellem et al 2009). The results of the statistical study of Puebla et al (2007) suggest that the temperature profile of the standard disk model be revised at least in the innermost parts of the disk in order to properly model some of the disk-dominated CV systems.…”

Section: Discussionmentioning

confidence: 99%

Spectroscopy From the Hubble Space Telescope Cosmic Origins Spectrograph of the Southern Nova-Like Bb Doradus in an Intermediate State

Godon

Sion

Gänsicke

et al. 2016

ApJ

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We present a spectral analysis of the Hubble Space Telescope Cosmic Origins Spectrograph spectrum of the southern VY Scl nova-like variable BB Doradus, obtained as part of a Cycle 20 HST/COS survey of accreting white dwarfs in cataclysmic variables.BB Dor was observed with COS during an intermediate state with a low mass accretion rate, thereby allowing an estimate of the white dwarf temperature. The results of our spectral analysis show that the white dwarf is a significant far ultraviolet component with a temperature of ∼35,000-∼50,000 K, assuming a 0.80 M ⊙ WD mass (log(g) = 8.4). The disk with a mass accretion rate of ≈ 10 −10 M ⊙ yr −1 contributes about 1/5 to 1/2 of the far ultraviolet flux.

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“…They proposed three possibilities: 1) the truncation of disk at some inner disk radius, 2) setting a region of constant temperature for inner disk regions and 3) the inner disk radius could be greater than R WD . The first possibility could be caused by a WD magnetic field disk disruption or due to inner disk evaporation (Linnell et al, 2007). In the former case, the necessary magnetic field intensity would bear a strong X-Ray emission or coherent pulsations due to the rotation of the spot of accretion, but neither of them were observed.…”

Section: Discussionmentioning

confidence: 99%

“…These models are known as: "disk atmospheres". In the subsequent years, the WD's emission, orbital phase and disk rim influence on model spectrum were included (Linnell et al, 2007;Linnell & Hubeny, 1996). This generation of models is capable to reproduce some photospheric spectral features as well as the broadening of lines due to disk rotation, however some problems still persist.…”

Section: Continuummentioning

confidence: 99%