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Title: FIRST PRECISION LIGHT CURVE ANALYSIS OF THE NEGLECTED EXTREME MASS RATIO SOLAR-TYPE BINARY HR BOOTIS

HR Bootis is a neglected binary that is found to be a solar-type (G2V) extreme mass ratio binary (EMRB). It was discovered by Hanley and Shapley in 1940. Surprisingly, little has been published in the intervening years. In 1999 it was characterized by a 0.31587 day orbital period. Since that time it has been observed by various observers who have determined ∼20 timings of minimum light over the past ∼15,000 orbits. Our observations in 2012 represent the first precision curves in the BVR{sub c}I{sub c} Johnson–Cousins wavelength bands. The light curves have rather low amplitudes, averaging some 0.5 magnitudes, yet they exhibit total eclipses, which is typical of the rare group of solar-type EMRBs. An improved linear ephemeris was computed along with a quadratic ephemeris showing a decaying orbit, which indicates magnetic breaking may be occurring. The light curve solution reveals that HR Boo is a contact system with a somewhat low 21% Roche-lobe fill-out but a mass ratio of q = 4.09 (0.2444), which defines it as an EMRB. Two spots, both hot, were allowed to iterate to fit the light curve asymmetries. Their radii are 32° and 16°. Both are high-latitude polar spots indicative of strong magnetic activity.more » The shallow contact yet nearly equal component temperatures makes it an unusual addition to this group.« less
Authors:
 [1] ; ;  [2] ;  [3] ;  [4] ;  [5]
  1. Faculty Research Associate, Pisgah Astronomical Research Institute, One Pari Drive, Rosman, NC 28772 (United States)
  2. Astronomy Group, Physics and Engineering Department, Bob Jones University, 1700 Wade Hampton Boulevard, Greenville, SC 29614 (United States)
  3. University of Victoria and Guest Observer, Dominion Astrophysical Observatory (Canada)
  4. Physics Department, Auburn University, 206 Allison Lab, Auburn, Alabama, 36849 (United States)
  5. University of South Carolina, Lancaster, 476 Hubbard Drive, Lancaster, SC 29720 (United States)
Publication Date:
OSTI Identifier:
22520238
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (Online); Journal Volume: 149; Journal Issue: 4; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AMPLITUDES; ASYMMETRY; BINARY STARS; DIAGRAMS; ECLIPSE; MAIN SEQUENCE STARS; MASS; MATHEMATICAL SOLUTIONS; ORBITS; ROCHE EQUIPOTENTIALS; STAR EVOLUTION; VISIBLE RADIATION