Multiple emission line components in detached post-common-envelope binaries

Tappert, C.; Gänsicke, B. T.; Rebassa‐Mansergas, A.; Schmidtobreick, L.; Schreiber, M. R.

doi:10.1051/0004-6361/201116833

Cited by 16 publications

(19 citation statements)

References 39 publications

(19 reference statements)

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“…This accretion rate is more consistent with a wind accretion, and is an order of magnitude lower than the wind accretion rate inferred for similar pre-CVs (Debes 2006;Tappert et al 2011;Parsons et al 2012a). This supports the idea that CME and prominence activity may provide a stochastic source of accretion material.…”

Section: The Current Evolutionary State Of Qs Virsupporting

confidence: 75%

The crowded magnetosphere of the post-common-envelope binary QS Virginis

Parsons

Hill

Marsh

et al. 2016

Mon. Not. R. Astron. Soc.

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We present high speed photometry and high resolution spectroscopy of the eclipsing post common envelope binary QS Virginis (QS Vir). Our UVES spectra span multiple orbits over more than a year and reveal the presence of several large prominences passing in front of both the M star and its white dwarf companion, allowing us to triangulate their positions. Despite showing small variations on a timescale of days, they persist for more than a year and may last decades. One large prominence extends almost three stellar radii from the M star. Roche tomography reveals that the M star is heavily spotted and that these spots are longlived and in relatively fixed locations, preferentially found on the hemisphere facing the white dwarf. We also determine precise binary and physical parameters for the system. We find that the 14, 220 ± 350 K white dwarf is relatively massive, 0.782 ± 0.013M ⊙ , and has a radius of 0.01068 ± 0.00007R ⊙ , consistent with evolutionary models. The tidally distorted M star has a mass of 0.382 ± 0.006M ⊙ and a radius of 0.381 ± 0.003R ⊙ , also consistent with evolutionary models. We find that the magnesium absorption line from the white dwarf is broader than expected. This could be due to rotation (implying a spin period of only ∼700 seconds), or due to a weak (∼100kG) magnetic field, we favour the latter interpretation. Since the M star's radius is still within its Roche lobe and there is no evidence that its over-inflated we conclude that QS Vir is most likely a pre-cataclysmic binary just about to become semi-detached.

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Section: The Current Evolutionary State Of Qs Virsupporting

confidence: 75%

The crowded magnetosphere of the post-common-envelope binary QS Virginis

Parsons

Hill

Marsh

et al. 2016

Mon. Not. R. Astron. Soc.

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“…These emission lines originate from the white dwarf's chromosphere as a result of accretion of material from the wind of the M star. They have been seen in other close white dwarf plus main‐sequence binaries and reliably track the motion of the white dwarf (Tappert et al ). A list of the unambiguously detected emission lines from the white dwarf is given in Table , though there are likely to be additional lines at longer wavelengths which are obscured by the dominant M star.…”

Section: Resultsmentioning

confidence: 81%

An accurate mass and radius measurement for an ultracool white dwarf

Parsons

Gänsicke²,

Marsh³

et al. 2012

Monthly Notices of the Royal Astronomical Society

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Studies of cool white dwarfs in the solar neighbourhood have placed a limit on the age of the Galactic disk of 8-9 billion years. However, determining their cooling ages requires the knowledge of their effective temperatures, masses, radii, and atmospheric composition. So far, these parameters could only be inferred for a small number of ultracool white dwarfs for which an accurate distance is known, by fitting their spectral energy distributions (SEDs) in conjunction with a theoretical mass-radius relation. However, the mass-radius relation remains largely untested, and the derived cooling ages are hence model-dependent. Here we report direct measurements of the mass and radius of an ultracool white dwarf in the double-lined eclipsing binary SDSS J013851.54-001621.6. We find M(WD)=0.529+/-0.010Msol and R(WD)=0.0131+/-0.0003Rsol. Our measurements are consistent with the mass-radius relation and we determine a robust cooling age of 9.5 billion years for the 3570K white dwarf. We find that the mass and radius of the low mass companion star, M(sec)=0.132+/-0.003Msol and R(sec)=0.165+/-0.001Rsol, are in agreement with evolutionary models. We also find evidence that this >9.5 Gyr old M5 star is still active, far beyond the activity lifetime for a star of its spectral type. This is likely caused by the high tidally-enforced rotation rate of the star. The companion star is close to filling its Roche lobe and the system will evolve into a cataclysmic variable in only 70 Myr. Our direct measurements demonstrate that this system can be used to calibrate ultracool white dwarf atmospheric models.Comment: 9 pages, 9 figures and 4 tables. Accepted for publication in MNRA

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“…We conclude that we do not detect a radial velocity variation of the white dwarf, with an upper limit on its radial The forbidden oxygen and sulphur lines detected in the spectrum of WD J0914+1914 have not been observed in any accreting or detached white dwarf binary. Accretion from the wind of a low-mass companion does result in photospheric metal contamination in these binaries 79 , however, their abundances derived from spectroscopic analysis are broadly consistent with solar abundances of the accreted material, with strong absorption lines of calcium, iron, magnesium and silicon 14,16,80 .…”

Section: Data Availabilitymentioning

confidence: 82%

Accretion of a giant planet onto a white dwarf star

Gänsicke

Schreiber

Toloza

et al. 2019

Nature

182

166

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The detection of a dust disc around G29-38 1 and transits from debris orbiting WD 1145+017 2 confirmed that the photospheric trace metals found in many white dwarfs 3 arise from the accretion of tidally disrupted planetesimals 4 . The composition of these planetesimals is similar to that of rocky bodies in the inner solar system 5 . Gravitationally scattering planetesimals towards the white dwarf requires the presence of more massive bodies 6 , yet no planet has so far been detected at a white dwarf. Here we report optical spectroscopy of a ≃ 27 750 K hot white dwarf that is accreting from a circumstellar gaseous disc composed of hydrogen, oxygen, and sulphur at a rate of ≃ 3.3 × 10 9 g s −1 . The composition of this disc is unlike all other known planetary debris around white dwarfs 7 , but resembles predictions for the makeup of deeper atmospheric layers of icy giant planets, with H 2 O and H 2 S being major constituents. A giant planet orbiting a hot white dwarf with a semi-major axis of ≃ 15 solar radii will undergo significant evaporation with expected mass loss rates comparable to the accretion rate onto the white dwarf. The orbit of the planet is most likely the result of gravitational interactions, indicating the presence of additional planets in the system. We infer an occurrence rate of spectroscopically detectable giant planets in close orbits around white dwarfs of ≃ 10 −4 . WD J091405.30+191412.25 (WD J0914+1914) was initially classified as a close interacting white dwarf binary on the basis of a weak Hα emission line detected in its spectrum obtained by the Sloan Digital Sky Survey (SDSS) 8 . Upon closer inspection of this spectrum, we identified additional emission lines of oxygen (O I at wavelengths 7,774Å and 8,446Å), and an emission line near 4,068Å that we tentatively identified as [S II]. The line flux ratios of the hydrogen and oxygen lines are extremely atypical for any white dwarf binary, casting doubt on the published classification.We obtained deep spectroscopy of this star using the X-Shooter spectrograph on the Very Large Telescope of the European Southern Observatory (see Fig. 1) which confirms the presence of [S II] (4,068Å), and contains additional emission lines of [O I] (6,300Å and 6,363Å) as well as a blend of O I and S I lines near 9,200Å.The double-peaked morphology of the Hα and the O I (8,446Å) emission lines (see Fig. 1) indicates an origin in a circumstellar gas disc 9 , reminiscent of several white dwarfs with dusty and gaseous planetary debris discs 10, 11 . However, the spectra of all known gaseous debris discs are dominated by the emission lines of the Ca II triplet (8,600Å), with weaker lines of Fe II, which are absent in the X-Shooter observations of WD J0914+1914. Moreover, none of the other gaseous debris discs around white dwarfs show Hα emission.

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Multiple emission line components in detached post-common-envelope binaries

Cited by 16 publications

References 39 publications

The crowded magnetosphere of the post-common-envelope binary QS Virginis

The crowded magnetosphere of the post-common-envelope binary QS Virginis

An accurate mass and radius measurement for an ultracool white dwarf

Accretion of a giant planet onto a white dwarf star

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