THE INNER DEBRIS STRUCTURE IN THE FOMALHAUT PLANETARY SYSTEM

Kate Y.L. Su, George H. Rieke, Denis Defrére, Kuo Song Wang, Shih Ping Lai, David J. Wilner, Rik Van Lieshout, Chin Fei Lee

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

Fomalhaut plays an important role in the study of debris disks and small bodies in other planetary systems. The proximity and luminosity of the star make key features of its debris, like the water ice line, accessible. Here we present ALMA cycle 1, 870 μm (345 GHz) observations targeted at the inner part of the Fomalhaut system with a synthesized beam of 0.″45 × 0.″37 (∼3 AU linear resolution at the distance of Fomalhaut) and an rms of 26 μJy beam-1. The high angular resolution and sensitivity of the ALMA data enable us to place strong constraints on the nature of the warm excess revealed by Spitzer and Herschel observations. We detect a point source at the star position with a total flux consistent with thermal emission from the stellar photosphere. No structures that are brighter than 3σ are detected in the central 15 AU × 15 AU region. Modeling the spectral energy distribution using parameters expected for a dust-producing planetesimal belt indicates a radial location in the range of ∼8-15 AU. This is consistent with the location where ice sublimates in Fomalhaut, i.e., an asteroid-belt analog. The 3σ upper limit for such a belt is <1.3 mJy at 870 μm. We also interpret the 2 and 8-13 μm interferometric measurements to reveal the structure in the inner 10 AU region as dust naturally connected to this proposed asteroid belt by Poynting-Robertson drag, dust sublimation, and magnetically trapped nanograins.

Original languageEnglish (US)
Article number45
JournalAstrophysical Journal
Volume818
Issue number1
DOIs
StatePublished - Feb 10 2016

Keywords

  • circumstellar matter
  • planetary systems
  • radio lines: stars
  • stars: individual (Fomalhaut)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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