White Dwarf Circumstellar Disks: Observations

Farihi, Jay

doi:10.1002/9783527636570.ch5

Cited by 10 publications

(8 citation statements)

References 139 publications

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“…Two extreme cases that can result in zero radial width, and likely a short-lived and completely gaseous disk, are asteroids disrupted either within 1) r < r s 1R or 2) r < 1R < r s . Relatively narrow rings should result when these conditions are minimally avoided (see Figure 12; Farihi 2011;Rocchetto et al 2015). Furthermore, all dust disks should have sharp outer edges, as any optically thin material is quickly dragged into regions of high surface density ( Figure 14; Bochkarev & Rafikov 2011).…”

Section: Formation and Structure Of Debris Within The Roche Limitmentioning

confidence: 99%

Circumstellar debris and pollution at white dwarf stars

Farihi

2016

New Astronomy Reviews

291

265

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Circumstellar disks of planetary debris are now known or suspected to closely orbit hundreds of white dwarf stars. To date, both data and theory support disks that are entirely contained within the preceding giant stellar radii, and hence must have been produced during the white dwarf phase. This picture is strengthened by the signature of material falling onto the pristine stellar surfaces; disks are always detected together with atmospheric heavy elements. The physical link between this debris and the white dwarf host abundances enables unique insight into the bulk chemistry of extrasolar planetary systems via their remnants. This review summarizes the body of evidence supporting dynamically active planetary systems at a large fraction of all white dwarfs, the remnants of first generation, main-sequence planetary systems, and hence provide insight into initial conditions as well as long-term dynamics and evolution.

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Section: Formation and Structure Of Debris Within The Roche Limitmentioning

confidence: 99%

Circumstellar debris and pollution at white dwarf stars

Farihi

2016

New Astronomy Reviews

291

265

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“…Farihi (2011) first noted that the highest LIR/L * occur only for relatively cool, dusty white dwarfs. This trend is consistent with an increasing area available to emitting solids interior to the fixed stellar Roche radius with decreasing stellar luminosity and temperature; the radius at which grains will rapidly sublimate moves inwards as a white dwarf ages (Rocchetto et al, in preparation).…”

Section: A Few Discs Around Old White Dwarfsmentioning

confidence: 99%

Signs of a faint disc population at polluted white dwarfs

Bergfors¹,

Farihi²,

Dufour³

et al. 2014

Monthly Notices of the Royal Astronomical Society

104

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Observations of atmospheric metals and dust discs around white dwarfs provide important clues to the fate of terrestrial planetary systems around intermediate mass stars. We present Spitzer Infrared Array Camera observations of 15 metal polluted white dwarfs to investigate the occurrence and physical properties of circumstellar dust created by the disruption of planetary bodies. We find subtle infrared excess emission consistent with warm dust around KUV 15519+1730 and HS 2132+0941, and weaker excess around the DZ white dwarf G245-58, which, if real, makes it the coolest white dwarf known to exhibit a 3.6µm excess and the first DZ star with a bright disc. All together our data corroborate a picture where (1) discs at metal-enriched white dwarfs are commonplace and most escape detection in the infrared (possibly as narrow rings), (2) the discs are long lived, having lifetimes on the order of 10 6 yr or longer, and (3) the frequency of bright, infrared detectable discs decreases with age, on a timescale of roughly 500 Myr, suggesting large planetesimal disruptions decline on this same timescale.

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“…The tidally-disrupted asteroid model has seen continued success since its inception, and is considered the standard model for metal-enriched white dwarfs. In the intervening decade, an enormous amount of observational progress has occurred (for a detailed review, see Farihi 2011), all of which supports the accretion of asteroid-like debris in dynamically active, post-main sequence planetary systems (Veras et al 2013). …”

Section: Tidally-destroyed Planetesimalsmentioning

confidence: 99%

ALMA and Herschel observations of the prototype dusty and polluted white dwarf G29-38

Farihi

Wyatt

Greaves

et al. 2014

Monthly Notices of the Royal Astronomical Society

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ALMA Cycle 0 and Herschel 1 PACS observations are reported for the prototype, nearest, and brightest example of a dusty and polluted white dwarf, G29-38. These long wavelength programs attempted to detect an outlying, parent population of bodies at 1 − 100 AU, from which originates the disrupted planetesimal debris that is observed within 0.01 AU and which exhibits L IR /L * = 0.039. No associated emission sources were detected in any of the data down to L IR /L * ∼ 10 −4 , generally ruling out cold dust masses greater than 10 24 − 10 25 g for reasonable grain sizes and properties in orbital regions corresponding to evolved versions of both asteroid and Kuiper belt analogs. Overall, these null detections are consistent with models of long-term collisional evolution in planetesimal disks, and the source regions for the disrupted parent bodies at stars like G29-38 may only be salient in exceptional circumstances, such as a recent instability. A larger sample of polluted white dwarfs, targeted with the full ALMA array, has the potential to unambiguously identify the parent source(s) of their planetary debris.

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White Dwarf Circumstellar Disks: Observations

Abstract: 1 Here, the terms near-, mid-, and far-infrared refer to the wavelength ranges 1 − 5 µm, 5 − 30 µm, and 30 − 200 µm, though alternative divisions and definitions exist (Mclean 1997).

Cited by 10 publications

References 139 publications

Circumstellar debris and pollution at white dwarf stars

Circumstellar debris and pollution at white dwarf stars

Signs of a faint disc population at polluted white dwarfs

ALMA and Herschel observations of the prototype dusty and polluted white dwarf G29-38

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