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Title: The solar neighborhood. XXX. Fomalhaut C

LP 876-10 is a nearby active M4 dwarf in Aquarius at a distance of 7.6 pc. The star is a new addition to the 10 pc census, with a parallax measured via the REsearch Consortium On Nearby Stars (RECONS) astrometric survey on the Small and Moderate Aperture Research Telescope System's 0.9 m telescope. We demonstrate that the astrometry, radial velocity, and photometric data for LP 876-10 are consistent with the star being a third bound stellar component to the Fomalhaut multiple system, despite the star lying nearly 6° away from Fomalhaut A in the sky. The three-dimensional separation of LP 876-10 from Fomalhaut is only 0.77 ± 0.01 pc, and 0.987 ± 0.006 pc from TW PsA (Fomalhaut B), well within the estimated tidal radius of the Fomalhaut system (1.9 pc). LP 876-10 shares the motion of Fomalhaut within ∼1 km s{sup –1}, and we estimate an interloper probability of ∼10{sup –5}. Neither our echelle spectroscopy nor astrometry are able to confirm the close companion to LP 876-10 reported in the Washington Double Star Catalog (WSI 138). We argue that the Castor Moving Group to which the Fomalhaut system purportedly belongs, is likely to be a dynamical stream, and hencemore » membership to the group does not provide useful age constraints for group members. LP 876-10 (Fomalhaut C) has now risen from obscurity to become a rare example of a field M dwarf with well-constrained age (440 ± 40 Myr) and metallicity. Besides harboring a debris disk system and candidate planet, Fomalhaut now has two of the widest known stellar companions.« less
Authors:
 [1] ; ;  [2] ; ;  [3] ; ; ; ; ;  [4] ;  [5] ;  [6] ;  [7] ;  [8]
  1. Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627 (United States)
  2. US Naval Observatory, 3450 Massachusetts Avenue, NW, Washington, DC 20392 (United States)
  3. Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States)
  4. Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30302-4106 (United States)
  5. Leiden Observatory, Leiden University, P.O. Box 9513, 2300-RA Leiden (Netherlands)
  6. Department of Physics and Astronomy, Hunter College, 695 Park Avenue, New York, NY 10065 (United States)
  7. US Naval Observatory, Flagstaff Station, P.O. Box 1149, Flagstaff, AZ 86002-1149 (United States)
  8. Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States)
Publication Date:
OSTI Identifier:
22340068
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (New York, N.Y. Online); Journal Volume: 146; Journal Issue: 6; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; APERTURES; CATALOGS; DISTANCE; DWARF STARS; LIMITING VALUES; METALLICITY; PLANETS; PROBABILITY; RADIAL VELOCITY; ROTATION; SKY; SPECTROSCOPY; STARS; STREAMS; TELESCOPES; THREE-DIMENSIONAL CALCULATIONS