Gas and dust around A-type stars at tens of Myr: signatures of cometary breakup

Greaves, J. S.; Holland, W. S.; Matthews, B. C.; Marshall, J. P.; Dent, Wrf; Woitke, P.; Wyatt, M. C.; Matrà, Luca; Jackson, Alan P.

doi:10.1093/mnras/stw1569

Cited by 54 publications

(58 citation statements)

References 44 publications

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“…This method results in a measured total flux density of 17±3 mJy. Taking into account the ∼10% systematic flux uncertainty that applies to both data sets, there is no statistically significant difference between the ALMA 850 μm flux density and the JCMT/SCUBA2 850 μm flux density of 12.1±2.0 mJy (Greaves et al 2016; see also Song et al 2004).…”

Section: Alma Dust Continuummentioning

confidence: 88%

Radial Surface Density Profiles of Gas and Dust in the Debris Disk around 49 Ceti

Hughes

Lieman-Sifry

Flaherty

et al. 2017

ApJ

127

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We present ∼0 4 resolution images of CO(3-2) and associated continuum emission from the gas-bearing debris disk around the nearby A star 49 Ceti, observed with the Atacama Large Millimeter/Submillimeter Array (ALMA). We analyze the ALMA visibilities in tandem with the broadband spectral energy distribution to measure the radial surface density profiles of dust and gas emission from the system. The dust surface density decreases with radius between ∼100 and 310 au, with a marginally significant enhancement of surface density at a radius of ∼110 au. The SED requires an inner disk of small grains in addition to the outer disk of larger grains resolved by ALMA. The gas disk exhibits a surface density profile that increases with radius, contrary to most previous spatially resolved observations of circumstellar gas disks. While ∼80% of the CO flux is well described by an axisymmetric power-law disk in Keplerian rotation about the central star, residuals at ∼20% of the peak flux exhibit a departure from axisymmetry suggestive of spiral arms or a warp in the gas disk. The radial extent of the gas disk (∼220 au) is smaller than that of the dust disk (∼300 au), consistent with recent observations of other gasbearing debris disks. While there are so far only three broad debris disks with wellcharacterized radial dust profiles at millimeter wavelengths, 49 Ceti's disk shows a markedly different structure from two radially resolved gas-poor debris disks, implying that the physical processes generating and sculpting the gas and dust are fundamentally different.

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Section: Alma Dust Continuummentioning

confidence: 88%

Radial Surface Density Profiles of Gas and Dust in the Debris Disk around 49 Ceti

Hughes

Lieman-Sifry

Flaherty

et al. 2017

ApJ

127

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“…Later, more such objects were discovered, and the first statistical studies could be done (Lieman-Sifry et al 2016;Greaves et al 2016;Péricaud et al 2017). Our present list partly incorporates these earlier samples, and extends them to a full list of 17 dust-rich debris disks in the Solar neighborhood (Sec.…”

Section: Molecular Gas In Bright Debris Disksmentioning

confidence: 99%

Molecular Gas in Debris Disks around Young A-type Stars

Moór

Curé

Kóspál

et al. 2017

ApJ

107

176

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According to the current paradigm of circumstellar disk evolution, gas-rich primordial disks evolve into gas-poor debris disks composed of second-generation dust. To explore the transition between these phases, we searched for 12 CO, 13 CO, and C 18 O emission in seven dust-rich debris disks around young A-type stars, using ALMA in Band 6. We discovered molecular gas in three debris disks. In all these disks, the 12 CO line was optically thick, highlighting the importance of less abundant molecules in reliable mass estimates. Supplementing our target list by literature data, we compiled a volume-limited sample of dust-rich debris disks around young A-type stars within 150 pc. We obtained a CO detection rate of 11/16 above a 12 CO J=2-1 line luminosity threshold of ∼1.4×10 4 Jy km s −1 pc 2 in the sample. This high incidence implies that the presence of CO gas in bright debris disks around young A-type stars is likely more the rule than the exception. Interestingly, dust-rich debris disks around young FG-type stars exhibit, with the same detectability threshold as for A-type stars, significantly lower gas incidence. While the transition from protoplanetary to debris phase is associated with a drop of dust content, our results exhibit a large spread in the CO mass in our debris sample, with peak values comparable to those in protoplanetary Herbig Ae disks. In the particularly CO-rich debris systems the gas may have primordial origin, characteristic of a hybrid disk.

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“…The thermal emission of both dust belts has been resolved, at 12.5 and 17.9 μm for the inner disk (Wahhaj et al 2007) and at 70, 100, 160, and 450 μm for the outer disk (R13; Moór et al 2015b;Greaves et al 2016). Dust is detected up to 60 au in the inner disk and likely depleted below 30 au.…”

Section: Introductionmentioning

confidence: 96%

“…Yet, a handful of young systems exhibit a substantial amount of CO gas while having ages and dust properties of debris disks (Zuckerman et al 1995;Moór et al 2011Moór et al , 2015aDent et al 2014;Greaves et al 2016;Lieman-Sifry et al 2016;Marino et al 2016). They all harbor large quantities of dust, indicated by their fractional infrared luminosity L IR /L å ∼1×10 −3 and have ages between 15 and 50 Myr (Greaves et al 2016). The nature and origin of their molecular gas are not completely clear: it may be primordial gas preserved from photodissociation by self-shielding, or second-generation gas released by colliding comets or planetesimals.…”

Section: Introductionmentioning

confidence: 99%

First Scattered-light Images of the Gas-rich Debris Disk around 49 Ceti

Choquet

Milli

Wahhaj

et al. 2017

ApJL

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We present the first scattered-light images of the debris disk around 49 Ceti, a ∼40 Myr A1 main-sequence star at 59 pc, famous for hosting two massive dust belts as well as large quantities of atomic and molecular gas. The outer disk is revealed in reprocessed archival Hubble Space Telescope NICMOS-F110W images, as well as new coronagraphic H-band images from the Very Large Telescope SPHERE instrument. The disk extends from 1 1 (65 au) to 4 6 (250 au) and is seen at an inclination of 73°, which refines previous measurements at lower angular resolution. We also report no companion detection larger than 3M Jup at projected separations beyond 20 au from the star (0 34). Comparison between the F110W and H-band images is consistent with a gray color of 49 Ceti's dust, indicating grains larger than 2 μm. Our photometric measurements indicate a scattering efficiency/infrared excess ratio of 0.2-0.4, relatively low compared to other characterized debris disks. We find that 49 Ceti presents morphological and scattering properties very similar to the gas-rich HD 131835 system. From our constraint on the disk inclination we find that the atomic gas previously detected in absorption must extend to the inner disk, and that the latter must be depleted of CO gas. Building on previous studies, we propose a schematic view of the system describing the dust and gas structure around 49 Ceti and hypothetical scenarios for the gas nature and origin.

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Gas and dust around A-type stars at tens of Myr: signatures of cometary breakup

Cited by 54 publications

References 44 publications

Radial Surface Density Profiles of Gas and Dust in the Debris Disk around 49 Ceti

Radial Surface Density Profiles of Gas and Dust in the Debris Disk around 49 Ceti

Molecular Gas in Debris Disks around Young A-type Stars

First Scattered-light Images of the Gas-rich Debris Disk around 49 Ceti

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