The unbiased frequency of planetary signatures around single and binary white dwarfs using Spitzer and Hubble

Wilson, T. G.; Farihi, Jay; Gänsicke, B. T.; Swan, Andrew

doi:10.1093/mnras/stz1050

Cited by 104 publications

(87 citation statements)

References 99 publications

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“…These white dwarfs with metal absorption line features are hence called polluted white dwarfs (PWDs). The observed relative metal abundances in these PWDs are comparable to the Earth's composition with some deviations, see references in Wilson et al (2019) and Fig. 5.…”

Section: Polluted White Dwarf Abundancessupporting

confidence: 58%

The atmospheres of rocky exoplanets

Herbort

Woitke

Helling

et al. 2020

A&A

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Context. Little is known about the interaction between atmospheres and crusts of exoplanets so far, but future space missions and ground-based instruments are expected to detect molecular features in the spectra of hot rocky exoplanets. Aims. We aim to understand the composition of the gas in an exoplanet atmosphere which is in equilibrium with a planetary crust. Methods. The molecular composition of the gas above a surface made of a mixture of solid and liquid materials was determined by assuming phase equilibrium for given pressure, temperature, and element abundances. We study total element abundances that represent different parts of the Earth’s crust (continental crust, bulk silicate Earth, mid oceanic ridge basalt), CI chondrites and abundances measured in polluted white dwarfs. Results. For temperatures between ~600 and ~3500 K, the near-crust atmospheres of all considered total element abundances are mainly composed of H2O, CO2, and SO2 and in some cases of O2 and H2. For temperatures ≲500 K, only N2-rich or CH4-rich atmospheres remain. For ≳3500 K, the atmospheric gas is mainly composed of atoms (O, Na, Mg, and Fe), metal oxides (SiO, NaO, MgO, CaO, AlO, and FeO), and some metal hydroxides (KOH and NaOH). The inclusion of phyllosilicates as potential condensed species is crucial for lower temperatures, as they can remove water from the gas phase below about 700 K and inhibit the presence of liquid water. Conclusions. Measurements of the atmospheric composition could, in principle, characterise the rock composition of exoplanet crusts. H2O, O2 and CH4 are natural products from the outgassing of different kinds of rocks that had time to equilibrate. These are discussed as biomarkers, but they do emerge naturally as a result of the thermodynamic interaction between the crust and atmosphere. Only the simultaneous detection of all three molecules might be a sufficient biosignature, as it is inconsistent with chemical equilibrium.

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Section: Polluted White Dwarf Abundancessupporting

confidence: 58%

The atmospheres of rocky exoplanets

Herbort

Woitke

Helling

et al. 2020

A&A

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“…Throughout the last decade sufficiently large and unbiased samples of white dwarfs have been established to determine the occurrence rate of (i) observable dust discs around, and (ii) photospheric pollution of white dwarfs, as 1 -3 per cent and 25 -50 per cent, respectively (Zuckerman et al 2003;Farihi et al 2009;Zuckerman et al 2010;Girven et al 2011;Koester et al 2014;Rocchetto et al 2015;Wilson et al 2019;Rebassa-Mansergas et al 2019). However, the prevalence of detectable gaseous components in emission to these debris discs is so far unconstrained.…”

Section: Introductionmentioning

confidence: 99%

The frequency of gaseous debris discs around white dwarfs

Manser

Gänsicke

Fusillo

et al. 2020

Monthly Notices of the Royal Astronomical Society

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1 -3 per cent of white dwarfs are orbited by planetary dusty debris detectable as infrared emission in excess above the white dwarf flux. In a rare subset of these systems, a gaseous disc component is also detected via emission lines of the Ca 8600 Å triplet, broadened by the Keplerian velocity of the disc. We present the first statistical study of the fraction of debris discs containing detectable amounts of gas in emission at white dwarfs within a magnitude and signal-to-noise limited sample. We select 7705 single white dwarfs spectroscopically observed by the Sloan Digital Sky Survey (SDSS) and Gaia with magnitudes g 19. We identify five gaseous disc hosts, all of which have been previously discovered. We calculate the occurrence rate of a white dwarf hosting a debris disc detectable via Ca emission lines as 0.067 ± 0.042 0.025 per cent. This corresponds to an occurrence rate for a dusty debris disc to have an observable gaseous component in emission as 4 ± 4 2 per cent. Given that variability is a common feature of the emission profiles of gaseous debris discs, and the recent detection of a planetesimal orbiting within the disc of SDSS J122859.93+104032.9, we propose that gaseous components are tracers for the presence of planetesimals embedded in the discs and outline a qualitative model. We also present spectroscopy of the Ca triplet 8600 Å region for 20 white dwarfs hosting dusty debris discs in an attempt to identify gaseous emission. We do not detect any gaseous components in these 20 systems, consistent with the occurrence rate that we calculated.

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“…WD 1052+273: Several studies unsuccessfully searched for a dust disk and an IR-excess around this rather bright WD (Wilson et al 2019).…”

Section: Search For Pulsation In Twenty-one Wds 197mentioning

confidence: 99%

A Search for Pulsation in Twenty-One White Dwarfs

Paunzen

Handler

Janík

et al. 2020

RMxAA

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Well-defined astrophysical constraints of white dwarfs (WDs), such as on the presence or absence of pulsational variability, are very much needed to refine and develop current models. Because these stars are rather faint and variability periods are mostly below one hour, only a very limited amount of space-based data is currently available for these objects. We present about 68 hours of highquality ground-based photometric time-series data for twenty-one WDs acquired at five different observatories. No new pulsators were detected but the derived upper limits of variability, which are typically on the order of only a few mmags, provide important input for pulsation models.

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The unbiased frequency of planetary signatures around single and binary white dwarfs using Spitzer and Hubble

Cited by 104 publications

References 99 publications

The atmospheres of rocky exoplanets

The atmospheres of rocky exoplanets

The frequency of gaseous debris discs around white dwarfs

A Search for Pulsation in Twenty-One White Dwarfs

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