Discovery of the Fomalhaut C debris disc

Abstract

Fomalhaut is one of the most interesting and well studied nearby stars, hosting at least one planet, a spectacular debris ring, and two distant low-mass stellar companions (TW PsA and LP 876-10, a.k.a. Fomalhaut B & C). We observed both companions with Herschel, and while no disc was detected around the secondary, TW PsA, we have discovered the second debris disc in the Fomalhaut system, around LP 876-10. This detection is only the second case of two debris discs seen in a multiple system, both of which are relatively wide ($\gtrsim$3000 AU for HD 223352/40 and 158 kAU [0.77 pc] for Fomalhaut/LP 876-10). The disc is cool (24K) and relatively bright, with a fractional luminosity $L_{\mathrm{disc}}/L_{\star }=1.2\times 10^{-4}$, and represents the rare observation of a debris disc around an M dwarf. Further work should attempt to find if the presence of two discs in the Fomalhaut system is coincidental, perhaps simply due to the relatively young system age of 440 Myr, or if the stellar components have dynamically interacted and the system is even more complex than it currently appears.

Published in MNRAS Letters. Merry Xmas

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• First long-term activity study of AU Microscopii: a possible chromospheric cycle
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• No significant correlation between radial velocity planet presence and debris disc properties
• Observability of Debris Discs around M-stars
• Kuiper Belt Analogues in Nearby M-type Planet-host Systems
• Dancing with the Stars: Formation of the Fomalhaut triple system and its effect on the debris disks
• Non-Universal Stellar Initial Mass Functions: Large Uncertainties in Star Formation Rates at $z\approx 2-4$ and Other Astrophysical Probes
• A Deep Polarimetric Study of the Asymmetrical Debris Disk HD 106906
• A Dusty M5 Binary in the beta Pictoris Moving Group
• Simulations of the Fomalhaut System Within Its Local Galactic Environment
• ALMA imaging of the M-dwarf Fomalhaut C's debris disc
• The Possible Astrometric Signature of a Planetary-mass Companion to the Nearby Young Star TW Piscis Austrini (Fomalhaut B): Constraints from Astrometry, Radial Velocities, and Direct Imaging
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• The triple system AT Mic AB + AU Mic in the beta Pictoris Association
• What you see is not necessarily what you get: Interpreting near-infrared scattering phase functions of debris discs