Effective temperatures of cataclysmic-variable white dwarfs as a probe of their evolution

Pala, A. F.; Gänsicke, B. T.; Townsley, Dean M.; Boyd, David; Cook, Michael J.; Martino, D. de; Godon, Patrick; Haislip, J.; Henden, A. A.; Hubený, I.; Ivarsen, K.; Kafka, S.; Knigge, Christian; Lacluyzé, A.; Long, Knox S.; Marsh, T. R.; Monard, B.; Moore, J. P.; Myers, Gordon; Nelson, Peter; Nogami, Daisaku; Oksanen, A.; Pickard, R.; Poyner, G.; Reichart, D.; Pérez, D.; Schreiber, M. R.; Shears, Jeremy; Sion, E. M.; Stubbings, Rod; Szkody, Paula; Zorotovic, M.

doi:10.1093/mnras/stw3293

Cited by 80 publications

(113 citation statements)

References 121 publications

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“…a short-period binary containing a white dwarf accreting from a Roche-lobe filling low-mass companion. Whereas the double-peaked morphology of the emission lines confirms the presence of a circumstellar gas disc, CVs typically have much stronger Balmer (and often helium) lines [63][64][65][66] , and no example of a CV with a white dwarf as hot as ≃ 28 000 K dominating the optical spectrum is known 67,68 .…”

Section: Data Availabilitymentioning

confidence: 98%

Accretion of a giant planet onto a white dwarf star

Gänsicke

Schreiber

Toloza

et al. 2019

Nature

180

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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Section: Data Availabilitymentioning

confidence: 98%

Accretion of a giant planet onto a white dwarf star

Gänsicke

Schreiber

Toloza

et al. 2019

Nature

180

166

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“…The orbital period distribution is the main tool to study the evolution of CVs, as it presents features in key points that allow us to understand their behaviour. As a consequence of the angular momentum loss and the mechanisms driving it, CVs move from long orbital periods and high mass transfer rates to short orbital periods and low mass transfer rates Paczynski & Sienkiewicz 1983;Townsley & Gänsicke 2009;Goliasch & Nelson 2015;Pala et al 2017). The evolu-E-mail: Jabrilib@eso.org tion proceeds in this way until the system reaches the "period minimum" at ∼ 76-80 minutes (Knigge 2006;Gänsicke et al 2009) in which the donor turns into a brown dwarf.…”

Section: Introductionmentioning

confidence: 99%

Disentangling cataclysmic variables in Gaia’s HR diagram

Abril

Schmidtobreick

Ederoclite

et al. 2019

Monthly Notices of the Royal Astronomical Society: Letters

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Cataclysmic Variables (CVs) are interacting binaries consisting of at least three components that control their colour and magnitude. Using Gaia we here investigate the influence of the physical properties of these binaries on their position in the Hertzsprung-Russell diagram (HR-diagram). The CVs are on average located between the main sequence and the white dwarf regime, the maximum density being at G BP − G RP ∼ 0.56 and G abs ∼ 10.15. We find a trend of the orbital period with colour and absolute brightness: with decreasing period, the CVs become bluer and fainter. We also identify the location of the various CV sub-types in the HR-diagram and discuss the possible location of detached CVs, going through the orbital period gap.

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“…A general description of the program for temperature determination is given in Pala et al (2017). The number of HST orbits used for each system varied based on their quiescent magnitude.…”

Section: Observationsmentioning

confidence: 99%

“…The amplitude of this variation is slightly less in the UV (0.3-0.4 in magnitude units) compared to 0.5 mag (Dai et al 2016) in the optical, although Mennickent et al (1999) note a large optical variation of the humps during their 11 year study. The model fitting of the UV spectrum by Pala et al (2017) determined the white dwarf has a temperature of 15,014±638 K and contributes 83% of the UV light. The larger amplitude of the orbital modulation in the optical would be consistent with an origin associated with the accretion disk.…”

Section: Rz Leomentioning

confidence: 99%

“…Since the Woudt et al (2012) observations were accomplished using the Swift UVOT with a filter centered at 2246Å, it is possible that the variability at longer UV wavelengths has lower amplitude due to the high temperature of the accreting areas. Pala et al (2017) determined a white dwarf temperature of 16,855±801 K for CC Scl from the average spectrum, but note that the white dwarf only contributes about 35% of the total UV flux (using a power law or constant flux additon for the remainder) and so the temperature is not very reliable. At outburst, the X-ray and UVOT data of Woudt et al (2012) show only the primary spin period and not the harmonic (although the optical shows the harmonic at varying amplitudes).…”

Section: Sclmentioning

confidence: 99%

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Hubble Space Telescope Ultraviolet Light Curves Reveal Interesting Properties of CC Sculptoris and RZ Leonis

Szkody¹,

Mukadam²,

Toloza³

et al. 2017

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Permanent WRAP URL:http://wrap.warwick.ac.uk/86770 Copyright and reuse:The Warwick Research Archive Portal (WRAP) makes this work by researchers of the University of Warwick available open access under the following conditions. Copyright © and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable the material made available in WRAP has been checked for eligibility before being made available.Copies of full items can be used for personal research or study, educational, or not-for-profit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. Publisher's statement:Reproduced by permission of the AAS. Abstract Time-tag ultraviolet data obtained on the Hubble Space Telescope in 2013 reveal interesting variability related to the white dwarf spin in the two cataclysmic variables RZ Leo and CC Scl. RZ Leo shows a period at 220 s and its harmonic at 110 s, thus identifying it as a likely Intermediate Polar (IP). The spin signal is not visible in a short single night of ground-based data in 2016, but the shorter exposures in that data set indicate a possible partial eclipse. The much larger UV amplitude of the spin signal in the known IP CC Scl allows the spin of 389 s, previously only seen at outburst, to be visible at quiescence. Spectra created from the peaks and troughs of the spin times indicate a hotter temperature of several thousand degrees during the peak phases, with multiple components contributing to the UV light.

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Effective temperatures of cataclysmic-variable white dwarfs as a probe of their evolution

Cited by 80 publications

References 121 publications

Accretion of a giant planet onto a white dwarf star

Accretion of a giant planet onto a white dwarf star

Disentangling cataclysmic variables in Gaia’s HR diagram

Hubble Space Telescope Ultraviolet Light Curves Reveal Interesting Properties of CC Sculptoris and RZ Leonis

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