PARALLACTIC MOTION FOR COMPANION DISCOVERY: AN M-DWARF ORBITING ALCOR
- Department of Astronomy, Columbia University, 550 W 120th St, New York, NY 10027 (United States)
- Department of Astronomy, California Institute of Technology, 1200 E. California Blvd., MC 249-17, Pasadena, CA 91125 (United States)
- Astrophysics Department, American Museum of Natural History, Central Park West at W 79th St, New York, NY 10024 (United States)
- Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 OHA (United Kingdom)
- NASA Exoplanet Science Institute, California Institute of Technology, Pasadena, CA 91125 (United States)
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena CA 91109 (United States)
- Space Telescope Science Institute, 3700 San Martin Dr, Baltimore, MD 21218 (United States)
- Caltech Optical Observatories, California Institute of Technology, Pasadena, CA 91125 (United States)
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 approx6 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 (approx0.25 M{sub sun}) 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.
- OSTI ID:
- 21392321
- Journal Information:
- Astrophysical Journal, Vol. 709, Issue 2; Other Information: DOI: 10.1088/0004-637X/709/2/733; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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