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dc.contributor.authorManser, Christopherpt_BR
dc.contributor.authorGänsicke, Borispt_BR
dc.contributor.authorFusillo, Nicola Pietro Gentilept_BR
dc.contributor.authorAshley, Richard P.pt_BR
dc.contributor.authorBreedt, Elmépt_BR
dc.contributor.authorHollands, Markpt_BR
dc.contributor.authorIzquierdo, Paulapt_BR
dc.contributor.authorPelisoli, Ingrid Domingospt_BR
dc.date.accessioned2020-07-23T03:40:37Zpt_BR
dc.date.issued2020pt_BR
dc.identifier.issn0035-8711pt_BR
dc.identifier.urihttp://hdl.handle.net/10183/212350pt_BR
dc.description.abstractA total of 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 ii 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 ratio 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 ii emission lines as 0.067±0.0420.025 per cent. This corresponds to an occurrence rate for a dusty debris disc to have an observable gaseous component in emission as 4 ± 42 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 ii 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.en
dc.format.mimetypeapplication/pdfpt_BR
dc.language.isoengpt_BR
dc.relation.ispartofMonthly notices of the royal astronomical society. Oxford. Vol. 493, no. 2 (Apr. 2020), p. 2127–2139pt_BR
dc.rightsOpen Accessen
dc.subjectAnãs brancaspt_BR
dc.subjectAccretion, accretion discsen
dc.subjectLine: profilesen
dc.subjectPoeira cosmicapt_BR
dc.subjectCircumstellar matteren
dc.subjectWhite dwarfsen
dc.titleThe frequency of gaseous debris discs around white dwarfspt_BR
dc.typeArtigo de periódicopt_BR
dc.identifier.nrb001114937pt_BR
dc.type.originEstrangeiropt_BR


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