Know The Star, Know the Planet. IV. A Stellar Companion to the Host star of the Eccentric Exoplanet HD 8673b
astro-ph.SR
/ Authors
Lewis C. Roberts,, Brian D. Mason, Christopher R. Neyman, Yanqin Wu, Reed L. Riddle, J. Christopher Shelton, John Angione, Christoph Baranec, Antonin Bouchez, Khanh Bui
and 21 more authors
Rick Burruss, Mahesh Burse, Pravin Chordia, Ernest Croner, Hillol Das, Richard G. Dekany, Stephen Guiwits, David Hale, John Henning, Shrinivas Kulkarni Nicholas Law, Dan McKenna, Jennifer Milburn, Dean Palmer, Sujit Punnadi, A. N. Ramaprakash, Jennifer E. Roberts, Shriharsh P. Tendulkar, Thang Trinh, Mitchell Troy, Tuan Truong, Jeff Zolkower
/ Abstract
HD 8673 hosts a massive exoplanet in a highly eccentric orbit (e=0.723). Based on two epochs of speckle interferometry a previous publication identified a candidate stellar companion. We observed HD 8673 multiple times with the 10 m Keck II telescope, the 5 m Hale telescope, the 3.63 m AEOS telescope and the 1.5m Palomar telescope in a variety of filters with the aim of confirming and characterizing the stellar companion. We did not detect the candidate companion, which we now conclude was a false detection, but we did detect a fainter companion. We collected astrometry and photometry of the companion on six epochs in a variety of filters. The measured differential photometry enabled us to determine that the companion is an early M dwarf with a mass estimate of 0.33-0.45 M?. The companion has a projected separation of 10 AU, which is one of the smallest projected separations of an exoplanet host binary system. Based on the limited astrometry collected, we are able to constrain the orbit of the stellar companion to a semi-major axis of 35{60 AU, an eccentricity ? 0.5 and an inclination of 75{85?. The stellar companion has likely strongly in uenced the orbit of the exoplanet and quite possibly explains its high eccentricity.