A Transiting Extrasolar Ring System: Indirect Evidence for Exosatellite Formation?
Presented by Eric Mamajek
University of Rochester
Thursday, October 8, 2015
11:00 A.M. in 169-336
The young star 1SWASP J140747.93-394542.6 ("J1407") is a 16-million-year-old pre-main sequence star in Sco-Cen, the nearest OB association. In 2012, we reported that time series photometry data from the SuperWASP and ASAS programs show that the star J1407 had a series of extremely complex eclipses over a two-month span in early 2007, with ~95% of the star's light blocked out near minimum. The star J1407 shows no evidence for accretion nor any circumstellar disk blueward of the WISE4 IR band. The eclipses have been modeled as due to a set of (at least 30) concentric dust rings with total mass of approximately 1 Earth mass, with radii ranging from approximately 30-90 million km. There is at least one very clean gap in the ring system at radius ~0.4 AU which may be cleared by a sub-Earth-size exosatellite. While popularly described as a "super-Saturn" with "rings", given the age of the system, and the size and inferred mass of the rings, it seems plausible that we are detecting a circumplanetary (or protoexosatellite) disk. The disk would appear to fill a non-negligible fraction of its Hill radius, and the appearance of gaps would suggest that system is in the process of spawning exosatellites. I will summarize the current knowledge about the J1407
system: including archival and on-going photometric searches for additional eclipses, imaging and Doppler constraints on the companion of the ringed companion, and future prospects for discovering eclipsing disks girding young exoplanets and substellar objects.
JPL Contact: Wes Traub (3-5508)
About the Speaker
Eric Mamajek received a M.Sc. in Physics in 2000 at the University of New South Wales, ADFA, then went on to the University of Arizona to earn his M.S. and Ph.D. in Astronomy in 2001 and 2004, respectively. He was awarded a Clay Postdoctoral Fellowship (4 years) at the Harvard-Smithsonian Center for Astrophysics in 2004. He was an Assistant Professor in the Department of Physics and Astronomy from 2008-2013, during which time he took leave to work as an Associate Astronomer at the Cerro Tololo Inter-American Observatory in Chile. He is now an Associate Professor of Physics and Astronomy at the University of Rochester. His research focuses on the formation and evolution of exoplanets and their host stars in our galactic neighborhood, stellar ages, kinematics, rotation, activity, and star clusters and associations.