Can gas in young debris disks be constrained 
by their radial brightness profiles?

Krivov, A. V.; Herrmann, F.; Brandeker, Alexis; Thébault, P.

doi:10.1051/0004-6361/200912917

Cited by 26 publications

(40 citation statements)

References 67 publications

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“…Such a radial profile that rises outward with a sharp outer edge contrasts with those derived for the archetypal disks Vega (Su et al 2005;Krivov et al 2006;Müller et al 2010;Sibthorpe et al 2010) and β Pictoris (Golimowski et al 2006;Thébault & Wu 2008;Krivov et al 2009;Vandenbussche et al 2010). In these disks, the derived geometrical optical thickness typically falls off with a moderate r −1.5 relationship beyond the peak value, i.e.…”

Section: Resultsmentioning

confidence: 67%

Modelling the huge,Herschel-resolved debris ring around HD 207129

Löhne

Augereau

Ertel

et al. 2012

A&A

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124

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Debris disks, which are inferred from the observed infrared excess to be ensembles of dust, rocks, and probably planetesimals, are common features of stellar systems. As the mechanisms of their formation and evolution are linked to those of planetary bodies, they provide valuable information. The few well-resolved debris disks are even more valuable because they can serve as modelling benchmarks and help resolve degeneracies in modelling aspects such as typical grain sizes and distances. Here, we present an analysis of the HD 207129 debris disk, based on its well-covered spectral energy distribution and Herschel/PACS images obtained in the framework of the DUNES (DUst around NEarby Stars) programme. We use an empirical power-law approach to the distribution of dust and we then model the production and removal of dust by means of collisions, direct radiation pressure, and drag forces. The resulting best-fit model contains a total of nearly 10 −2 Earth masses in dust, with typical grain sizes in the planetesimal belt ranging from 4 to 7 µm. We constrain the dynamical excitation to be low, which results in very long collisional lifetimes and a drag that notably fills the inner gap, especially at 70 µm. The radial distribution stretches from well within 100 AU in an unusual, outward-rising slope towards a rather sharp outer edge at about 170-190 AU. The inner edge is therefore smoother than that reported for Fomalhaut, but the contribution from the extended halo of barely bound grains is similarly small. Both slowly self-stirring and planetary perturbations could potentially have formed and shaped this disk.

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Section: Resultsmentioning

confidence: 67%

Modelling the huge,Herschel-resolved debris ring around HD 207129

Löhne

Augereau

Ertel

et al. 2012

A&A

Self Cite

124

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“…Dust grains also orbit with sub-Keplerian velocity but their pace depends on size and composition. Velocity difference between gas and dust induces grain migration within the disk (Takeuchi & Artymowicz 2001;Krivov et al 2009). Grains with angular velocities larger/smaller than that of the gas lose/gain angular momentum and drift inward/outward until they are in corotation with the gas.…”

Section: Discussionmentioning

confidence: 99%

“…Grains with angular velocities larger/smaller than that of the gas lose/gain angular momentum and drift inward/outward until they are in corotation with the gas. Based on their models, Krivov et al (2009) found that even in gaseous debris disks with gasto-dust mass ratio of 100, the grains' lifetime will be very limited -typically less than 2×10 4 yr -because collisions occur between radially drifting grains with unequal sizes. Applying these findings for the case of HD 21997, we conclude that the grains must be replenished and are of secondary origin.…”

Section: Discussionmentioning

confidence: 99%

ALMA CONTINUUM OBSERVATIONS OF A 30 Myr OLD GASEOUS DEBRIS DISK AROUND HD 21997

Moór

Juhász

Kóspál

et al. 2013

ApJ

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Circumstellar disks around stars older than 10 Myr are expected to be gas-poor. There are, however, two examples of old (30-40 Myr) debris-like disks containing a detectable amount of cold CO gas. Here we present ALMA and Herschel Space Observatory observations of one of these disks, around HD 21997, and study the distribution and origin of the dust and its connection to the gas. Our ALMA continuum images at 886 µm clearly resolve a broad ring of emission within a diameter of ∼4. ′′ 5, adding HD 21997 to the dozen debris disks resolved at (sub)millimeter wavelengths. Modeling the morphology of the ALMA image with a radiative transfer code suggests inner and outer radii of ∼55 and ∼150 AU, and a dust mass of 0.09 M ⊕ . Our data and modeling hints at an extended cold outskirt of the ring. Comparison with the morphology of the CO gas in the disk reveals an inner dust-free hole where gas nevertheless can be detected. Based on dust grain lifetimes, we propose that the dust content of this gaseous disk is of secondary origin produced by planetesimals. Since the gas component is probably primordial, HD 21997 is one of the first known examples of a hybrid circumstellar disk, a so-far little studied late phase of circumstellar disk evolution.

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“…We then follow the same procedure as in Thébault & Augereau (2005) and Krivov et al (2009) and record, at regularly spaced time intervals, the positions of all remaining particles. The disc's spatial structure is progressively obtained by adding up these instantaneous snapshots until all particles have been removed either dynamically or collisionally.…”

Section: Methodsmentioning

confidence: 99%

Debris discs in binaries: a numerical study

Thébault

Marzari

Augereau

2010

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Context. Debris disc analysis and modelling provide crucial information about the structure and the processes at play in extrasolar planetary systems. In binary systems, this issue is more complex because the disc should also respond to the companion star's perturbations. Aims. We explore the dynamical evolution of a collisionally active debris disc for different initial parent body populations, diverse binary configurations, and optical depths. We focus on the radial extent and size distribution of the disc in a stationary state. Methods. We numerically followed the evolution of 10 5 massless small grains, initially produced from a circumprimary disc of parent bodies following a size distribution in dN ∝ s −3.5 ds . Grains were submitted to both stars' gravity and radiation pressure. In addition, particles were assigned an empirically derived collisional lifetime. Results. For all the binary configurations, the disc extends far beyond the critical semi-major axis a crit for orbital stability. This is due to the steady production of small grains, placed by radiation pressure on eccentric orbits reaching beyond a crit . The amount of matter beyond a crit depends on the balance between collisional production and dynamical removal rates: it increases for more massive discs, as well as for eccentric binaries. Another important effect is that, in the dynamically stable region, the disc is depleted from its smallest grains. Both results could lead to observable signatures. Conclusions. We have shown that a companion star can never fully truncate a collisionally active disc. For eccentric companions, grains in the unstable regions can contribute significantly to the thermal emission in the mid-IR. Discs with sharp outer edges, especially bright ones such as HR4796A, are probably shaped by other mechanisms.

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Can gas in young debris disks be constrained by their radial brightness profiles?

Cited by 26 publications

References 67 publications

Modelling the huge,Herschel-resolved debris ring around HD 207129

Modelling the huge,Herschel-resolved debris ring around HD 207129

ALMA CONTINUUM OBSERVATIONS OF A 30 Myr OLD GASEOUS DEBRIS DISK AROUND HD 21997

Debris discs in binaries: a numerical study

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