FOMALHAUT'S DEBRIS DISK AND PLANET: CONSTRAINING THE MASS OF FOMALHAUT B FROM DISK MORPHOLOGY

By Eugene Chiang, E. Kite, P. Kalas, James R. Graham, M. Clampin. 2008

174 citations recorded by the source corpus.

Following the optical imaging of exoplanet candidate Fomalhaut b (Fom b), we present a numerical model of how Fomalhaut's debris disk is gravitationally shaped by a single interior planet. The model is simple, adaptable to other debris disks, and can be extended to accommodate multiple planets. If Fom b is the dominant perturber of the belt, then to produce the observed disk morphology it must have a mass Mpl < 3MJ, an orbital semimajor axis apl > 101.5 AU, and an orbital eccentricity epl = 0.11–0.13. These conclusions are independent of Fom b's photometry. To not disrupt the disk, a greater mass for Fom b demands a smaller orbit farther removed from the disk; thus, future astrometric measurement of Fom b's orbit, combined with our model of planet–disk interaction, can be used to determine the mass more precisely. The inner edge of the debris disk at a ≈ 133 AU lies at the periphery of Fom b's chaotic zone, and the mean disk eccentricity of e ≈ 0.11 is secularly forced by the planet, supporting predictions made prior to the discovery of Fom b. However, previous mass constraints based on disk morphology rely on several oversimplifications. We explain why our constraint is more reliable. It is based on a global model of the disk that is not restricted to the planet's chaotic zone boundary. Moreover, we screen disk parent bodies for dynamical stability over the system age of ∼ 100 Myr, and model them separately from their dust grain progeny; the latter's orbits are strongly affected by radiation pressure and their lifetimes are limited to ∼ 0.1 Myr by destructive grain–grain collisions. The single planet model predicts that planet and disk orbits be apsidally aligned. Fomalhaut b's nominal space velocity does not bear this out, but the astrometric uncertainties may be large. If the apsidal misalignment proves real, our calculated upper mass limit of 3MJ still holds. If the orbits are aligned, our model predicts Mpl = 0.5MJ, apl = 115 AU, and epl = 0.12. Parent bodies are evacuated from mean-motion resonances with Fom b; these empty resonances are akin to the Kirkwood gaps opened by Jupiter. The belt contains at least 3M⊕ of solids that are grinding down to dust, their velocity dispersions stirred so strongly by Fom b that collisions are destructive. Such a large mass in solids is consistent with Fom b having formed in situ.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/22b543b547e63f18693bd5f8fda21e528c803a3e

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Citations in the corpus

• Dynamical effects of stellar mass-loss on a Kuiper-like belt (2011, background): “…is good, e.g. HR4796 (Wyatt et al. 1999; Moerchen et al. 2011), HD191089 (Churcher, Wyatt & Smith 2010), Fomalhaut (Kalas, Graham & Clampin 2005; Chiang et al. 2009), other explanations have been put forward for inner holes, such as planet formation (Kenyon & Bromley 2004; Smith et al. 2009)…”
• ANCIENT PLANETARY SYSTEMS ARE ORBITING A LARGE FRACTION OF WHITE DWARF STARS (2010, background): “The gravitational field of a major planet often defines the edge of a debris disk, as per Neptune and the Kuiper Belt or the outermost ”b” planet that orbits the star HR 8799 (Marois et al 2008; Su et al 2009; Chiang et al. 2009).”
• Imaging Extrasolar Giant Planets (2016, background): “…be made by combining spatially-resolved disk structures (a truncated, offset dust ring encircling Fomalhaut and a warped inner disk surrounding β Pic b) and observed orbital motion (e.g., Chiang et al. 2009; Dawson et al. 2011; Kalas et al. 2013; Beust et al. 2014; Millar-Blanchaer et al. 2015).”
• Debris disc stirring by secular perturbations from giant planets (2009, background): “Its orbital elements are estimated atepl = 0.11, and apl = 115 AU, with an upper limit of3MJ for the mass (Chiang et al. 2009).”
• EVIDENCE FOR A DISTANT GIANT PLANET IN THE SOLAR SYSTEM (2016, background): “Generally speaking, coherent dynamical structures in particle disks can either be sustained by self-gravity (Tremaine 1998; Touma et al. 2009) or by gravitational shepherding facilitated by an extrinsic perturber (Goldreich & Tremaine 1982; Chiang et al. 2009).”
• NEW DEBRIS DISKS AROUND YOUNG, LOW-MASS STARS DISCOVERED WITH THE SPITZER SPACE TELESCOPE (2009, unknown): “The recent reported discoveries of Fomalhaut b (Kalas et al. 2008; Chiang et al. 2009) and a possible planet orbiting Beta Pic (Lagrange et al. 2009) support the hypothesis that planets can directly influence debris disk structure.”
• Protoplanetary Disks and Their Evolution (2011, background): “The gravitational effect of planets on debris disks has been diagnosed in Fomalhaut (Chiang et al. 2009), postulated in β Pic (Mouillet et al. 1997), and suspected in others (Wyatt 2008, and references therein).”
• PROBING FOR EXOPLANETS HIDING IN DUSTY DEBRIS DISKS: DISK IMAGING, CHARACTERIZATION, AND EXPLORATION WITH HST/STIS MULTI-ROLL CORONAGRAPHY (2014, background): “Such collisional replenishment of dust-rich CS particles can continue throughout the lifetime of the system (Carpenter et al. 2005; Roccatagliata et al. 2009; Panić et al. 2013).”