AAVSO: American Association of Variable Star Observers

Modern V Photometry of the Eclipsing Triple System b Persei (Abstract)

Volume 42 number 2 (2014)

Donald F. Collins
Warren Wilson College, 138 College View Drive, Swannanoa, NC 28778; dcollins@warren-wilson.edu
Jason Sanborn
Lowell Observatory, Northern Arizona University, 1400 West Mars Hill Road, Flagstaff, AZ 86001; jaisen1@lowell.edu
Robert T. Zavala
U.S. Naval Observatory Flagstaff Station, 10391 West Naval Observatory Road, Flagstaff, AZ; bzavala@nofs.navy.mil


(Abstract only) A Complete CCD light curve in V of the bright (V ~ 4.6) ellipsoidal variable star b Persei (not beta Persei) has been obtained between November 2013 and February 2014. We recover the small-amplitude 0.065-mag. variation of the ellipsoidal light curve. The period of the ellipsoidal light curve from the 2013-2014 observing season is found to be 1.5273 ± 0.0015 days, consistent with older observations. b Persei is known to be a triple star system in which several AAVSO contributors recorded the first ever observed eclipse near February 5-6, 2013, of the inner AB stars by the third star C, which has a 702-day edge-on orbit. This eclipse was predicted based on an astrometric orbit from observations with the Navy Precision Optical Interferometer (NPOI). The NPOI provides stellar positions to milliarcsecond precision. We will present results of the orbital analysis of the triple system. The next primary eclipse of b Per is expected near January 12, 2015, and will last about two days. High time-resolution multi-color photometry will be extremely useful as we try to understand the evolutionary states of the close binary in b Per. The close binary may be a non-eclipsing Algol-like system or perhaps evolving towards a mass-transferring Algol-like stage. Time series observations from widely-distributed observers should be able to resolve the eclipse of the individual A and B components of b Persei, thus gaining hidden information about this rarely-observed system. The high brightness of this system enables precision photometry with small telescopes or finder scopes and entry-level filtered monochrome CCD cameras, which are widely available to amateurs worldwide.