Resolving the planetesimal belt of HR 8799 with ALMA

Booth, Mark; Jordán, Andrés; Casassus, S.; Hales, Antonio; Dent, W. R. F.; Faramaz, Virginie; Matrà, Luca; Barkats, D.; Brahm, R.; Cuadra, Jorge

doi:10.1093/mnrasl/slw040

Cited by 107 publications

(153 citation statements)

References 24 publications

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“…Images reveal the disks' morphology and the spatial distribution of their dust, and multiwavelength imagery additionally traces particles of different sizes. As millimeter-sized grains are the most efficient emitters at long wavelengths, far-IR/millimeter images map the spatial distribution of the thermal emission of large grains and, indirectly, the location of their planetesimal parent bodies (e.g., Booth et al 2016Booth et al , 2017. Micron-sized particles are inefficient emitters, but efficiently scatter the starlight at wavelengths comparable to their size.…”

Section: Introductionmentioning

confidence: 99%

HD 104860 and HD 192758: Two Debris Disks Newly Imaged in Scattered Light with the Hubble Space Telescope

Choquet

Bryden

Perrin

et al. 2018

ApJ

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We present the first scattered-light images of two debris disks around the F8 star HD104860 and the F0V star HD192758, respectively ∼45 and ∼67pc away. We detected these systems in the F110W and F160W filters through our reanalysis of archival Hubble Space Telescope (HST) NICMOS data with modern starlight-subtraction techniques. Our image of HD104860 confirms the morphology previously observed by Herschel in thermal emission with a well-defined ring at a radius of ∼114au inclined by ∼58°. Although the outer edge profile is consistent with dynamical evolution models, the sharp inner edge suggests sculpting by unseen perturbers. Our images of HD192758 reveal a disk at radius ∼95au inclined by ∼59°, never resolved so far. These disks have low scattering albedos of 10% and 13%, respectively, inconsistent with water ice grain compositions. They are reminiscent of several other disks with similar inclination and scattering albedos: Fomalhaut, HD92945, HD202628, and HD207129. They are also very distinct from brighter disks in the same inclination bin, which point to different compositions between these two populations. Varying scattering albedo values can be explained by different grain porosities, chemical compositions, or grain size distributions, which may indicate distinct formation mechanisms or dynamical processes at work in these systems. Finally, these faint disks with large infrared excesses may be representative of an underlying population of systems with low albedo values. Searches with more sensitive instruments on HST or on the James Webb Space Telescope and using state-of-the art starlightsubtraction methods may help discover more of such faint systems.

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Section: Introductionmentioning

confidence: 99%

HD 104860 and HD 192758: Two Debris Disks Newly Imaged in Scattered Light with the Hubble Space Telescope

Choquet

Bryden

Perrin

et al. 2018

ApJ

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“…In the first method, following Booth et al (2016), we fit the data in the image plane by producing dirty images for each model (discussed more below). For the second and more standard method, we use each model to predict visibilities and then compare those results with the actual visibility data.…”

Section: Debris Disc Modellingmentioning

confidence: 99%

“…Visibilities do not need to be calculated for each model, and the number of calls to, e.g., CASA is greatly reduced. We carry out the MCMC modelling in the image plane based on the method described in Booth et al (2016). A trial two-component model is constructed using a debris ring and central emission (as described above).…”

Section: Image Planementioning

confidence: 99%

“…where I are the data from the dirty image, Mi is the current model, and σ = 374 µJy is the σRMS of the dirty image multiplied by the beam size in pixels (see Booth et al 2016). …”

Section: Image Planementioning

confidence: 99%

“…In particular, the MCMC quickly converged on the debris disc morphology; most of the best fit geometrical parameters are well within the 1σ results of those derived from fitting to the visibilities. If only the disc geometry is needed, then image-plane fitting could be a reasonable approach, as advocated by Booth et al (2016). Furthermore, a preliminary best model could be selected by fitting in the image-plane, particularly as using poor starting conditions can have a major impact on the required links for an MCMC to converge and fitting visibilities can be time-consuming.…”

Section: Comparison Between Approachesmentioning

confidence: 99%

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1.3 mm ALMA Observations of the Fomalhaut Debris System

White¹,

Boley²,

Dent³

et al. 2016

Mon. Not. R. Astron. Soc.

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We present ALMA Band 6 observations (1.3 mm/233 GHz) of Fomalhaut and its debris disc. The observations achieve a sensitivity of 17 µJy and a resolution of 0.28 arcsec (2.1 au at a distance of 7.66 pc), which are the highest resolution observations to date of the millimetre grains in Fomalhaut's main debris ring. The ring is tightly constrained to 139 +2 −3 au with a FWHM of 13 ± 3 au, following a Gaussian profile. The millimetre spectral index is constrained to α mm = −2.73 ± 0.13. We explore fitting debris disc models in the image plane, as well as fitting models using visibility data directly. The results are compared and the potential advantages/disadvantages of each approach are discussed.The detected central emission is indistinguishable from a point source, with a most probable flux of 0.90±0.12 mJy (including calibration uncertainties). This implies that any inner debris structure, as was inferred from far-Infrared observations, must contribute little to the total central emission. Moreover, the stellar flux is less than 70% of that predicted by extrapolating a black body from the constrained stellar photosphere temperature. This result emphasizes that unresolved inner debris components cannot be fully characterized until the behaviour of the host star's intrinsic stellar emission at millimetre wavelengths is properly understood.

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Circumstellar Discs: What Will Be Next?

Kral¹,

Clarke²,

Wyatt³

2017

Handbook of Exoplanets

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This prospective chapter gives our view on the evolution of the study of circumstellar discs within the next 20 years from both observational and theoretical sides. We first present the expected improvements in our knowledge of protoplanetary discs as for their masses, sizes, chemistry, the presence of planets as well as the evolutionary processes shaping these discs. We then explore the older debris disc stage and explain what will be learnt concerning their birth, the intrinsic links between these discs and planets, the hot dust and the gas detected around main sequence stars as well as discs around white dwarfs.

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Resolving the planetesimal belt of HR 8799 with ALMA

Cited by 107 publications

References 24 publications

HD 104860 and HD 192758: Two Debris Disks Newly Imaged in Scattered Light with the Hubble Space Telescope

HD 104860 and HD 192758: Two Debris Disks Newly Imaged in Scattered Light with the Hubble Space Telescope

1.3 mm ALMA Observations of the Fomalhaut Debris System

Circumstellar Discs: What Will Be Next?

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