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Parallactic Motion for Companion Discovery: An M-Dwarf Orbiting Alcor

Zimmerman, Neil and Oppenheimer, Ben R. and Hinkley, Sasha and Brenner, Douglas and Parry, Ian R. and Sivaramakrishnan, Anand and Hillenbrand, Lynne and Beichman, Charles and Crepp, Justin R. and Vasisht, Gautam and Roberts, Lewis C., Jr. and Burruss, Rick and King, David L. and Soummer, Rémi and Dekany, Richard and Shao, Michael and Bouchez, Antonin and Roberts, Jennifer E. and Hunt, Stephanie (2010) Parallactic Motion for Companion Discovery: An M-Dwarf Orbiting Alcor. Astrophysical Journal, 709 (2). pp. 733-740. ISSN 0004-637X.

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The A5V star Alcor has an M3-M4 dwarf companion, as evidenced by a novel astrometric technique. Imaging spectroscopy combined with adaptive optics coronagraphy allowed for the detection and spectrophotometric characterization of the point source at a contrast of ~6 J- and H-band magnitudes and separation of 1'' from the primary star. The use of an astrometric pupil plane grid allowed us to determine the projected separations between the companion and the coronagraphically occulted primary star to ≤3 mas precision at two observation epochs. Our measurements demonstrate common parallactic and proper motion over the course of 103 days, significantly shorter than the period of time needed for most companion confirmations through proper motion measurements alone. This common parallax method is potentially more rigorous than common proper motion, ensuring that the neighboring bodies lie at the same distance, rather than relying on the statistical improbability that two objects in close proximity to each other on the sky move in the same direction. The discovery of a low-mass (~0.25 M_☉) companion around a bright (V = 4.0 mag), nearby (d= 25 pc) star highlights a region of binary star parameter space that to date has not been fully probed.

Item Type:Article
Related URLs:
URLURL TypeDescription
Zimmerman, Neil0000-0001-5484-1516
Oppenheimer, Ben R.0000-0001-7130-7681
Hinkley, Sasha0000-0001-8074-2562
Beichman, Charles0000-0002-5627-5471
Crepp, Justin R.0000-0003-0800-0593
Vasisht, Gautam0000-0002-1871-6264
Roberts, Lewis C., Jr.0000-0003-3892-2900
Soummer, Rémi0000-0003-2753-2819
Additional Information:© 2010 American Astronomical Society. Print publication: Issue 2 (2010 February 1); received 2009 November 11; accepted for publication 2009 December 10; published 2010 January 6. The authors wish to express our appreciation toward Jean Mueller, Kajsa Peffer, Karl Dunscombe, and the Mountain Crew at Palomar Observatory. We thank Adam Burgasser and Emily Rice for sharing comparison spectra to aid in our classification of the companion star. We are also indebted to our anonymous referee and the Scientific Editor of the Journal, Steven Kawaler, for expediting our review process. Project 1640 is funded by National Science Foundation grants AST-0520822, AST-0804417, and AST-0908484. A portion of the research in this paper was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA) and was funded by Internal Research and Technology Development funds. In addition, part of this work was performed under a contract with the California Institute of Technology (Caltech) funded by NASA through the Sagan Fellowship Program. The members of the Project 1640 team are also grateful for support from the Cordelia Corporation, Hilary and Ethel Lipsitz, the Vincent Astor Fund, Judy Vale, Andrew Goodwin, and an anonymous donor. Facilities: Hale (PALAO, Project 1640)
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Cordelia CorporationUNSPECIFIED
Hilary and Ethel LipsitzUNSPECIFIED
Vincent Astor FundUNSPECIFIED
Subject Keywords:binaries: general; instrumentation: miscellaneous; stars: individual (Alcor); stars: low-mass, brown dwarfs; techniques: miscellaneous
Issue or Number:2
Record Number:CaltechAUTHORS:20100208-114355404
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Official Citation:Parallactic Motion for Companion Discovery: An M-Dwarf Orbiting Alcor Neil Zimmerman, Ben R. Oppenheimer, Sasha Hinkley, Douglas Brenner, Ian R. Parry, Anand Sivaramakrishnan, Lynne Hillenbrand, Charles Beichman, Justin R. Crepp, Gautam Vasisht, Lewis C. Roberts, Rick Burruss, David L. King, Rémi Soummer, Richard Dekany, Michael Shao, Antonin Bouchez, Jennifer E. Roberts, and Stephanie Hunt 2010 ApJ 709 733-740 doi: 10.1088/0004-637X/709/2/733
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:17416
Deposited By: Jason Perez
Deposited On:08 Feb 2010 23:45
Last Modified:20 Feb 2020 19:07

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