A sun in the spectroscopic binary IM Pegasi, the guide star for the Gravity Probe B mission

Marsden, S. C. and Berdyugina, S. V. and Donati, J.-F. and Eaton, J. A. and Williamson, M. H. and Ilyin, I. and Fischer, D. A. and Munoz, M. and Isaacson, H. and Ratner, M. I. and Semel, M. and Petit, P. and Carter, B. D. (2005) A sun in the spectroscopic binary IM Pegasi, the guide star for the Gravity Probe B mission. The Astrophysical Journal, 634 (2, Par). L173-L176. ISSN 0004-637X

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We present the first detection of the secondary of the spectroscopic binary system IM Pegasi (HR 8703), the guide star for the NASA-Stanford relativity gyroscope mission Gravity Probe B. In support of this mission, high-resolution echelle spectra of IM Peg have been obtained on an almost nightly basis. Applying the technique of least-squares deconvolution, we achieve very high signal-to-noise ratio line profiles and detect the orbit of the secondary of the system. Combining almost 700 new radial velocity measurements of both the primary and secondary of the system with previous measurements, we derive improved orbital parameters of the IM Peg system. Using these estimates along with the previously determined range of orbital inclination angles for the system, we find that the primary of IM Peg is a giant of mass 1.8 +/- 0.2 M-circle dot while the secondary is a dwarf of mass 1.0 +/- 0.1 M-circle dot.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Published version made accessible, in accordance with the copyright policy of the publisher.
Faculty / Department / School: Historic - Faculty of Sciences - Department of Biological and Physical Sciences
Date Deposited: 18 Apr 2010 03:34
Last Modified: 24 Mar 2017 03:14
Uncontrolled Keywords: binaries; spectroscopic; stars; IM Pegasi
Fields of Research : 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Identification Number or DOI: 10.1086/498941
URI: http://eprints.usq.edu.au/id/eprint/7470

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