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The Song of KOI-54

Dr. Valeri Makarov, Astrometry Department, US Naval Observatory, Washington, DC
When Sep 28, 2017
from 10:30 AM to 12:00 PM
Where USNO, Building 56, Large Conference Room
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Time:  10:30 (coffee/cookies);  Talk 11:00-12:00 Noon.

Abstract:  Beside a trove of transiting exoplanets, the NASA Kepler mission has discovered a number of interesting and unexpected astrophysical phenomena. The important class of heartbeat variable stars is one of these discoveries. The bright star HD 187091 = KOI-54 is the most deeply studied prototype of the class. Its 4 years-long light curve shows strictly periodic pulses with an amplitude of ~0.7% and a period of 41.8 days, as well as much smaller oscillations with apparently modulated amplitudes. Coupled with precise radial velocity measurements (Welsh+ 2011), the commonly accepted interpretation is a binary system of nearly identical A-type stars in highly eccentric orbits (e = 0.83). The physical model is complex, involving tidal interaction, mutual irradiation, and stellar pulsations in free g-modes. The high-frequency oscillation is interpreted as the interference of pulsation modes, which are exactly 91st and 90th harmonics of the orbital frequency. Are we sure this is the right interpretation? No, because there are many unsolved puzzles. We applied advanced methods of data processing to the archival Kepler data for KOI-54 and found an alternative, purely mathematical description of the modulated oscillation as a single-mode sinusoidal variation with a quantized range of frequencies. There are only 6 discrete frequencies, and their time sequence can be interpreted as a musical score. Our attempt at sonification of this sequence resulted in a tune, called the song of KOI-54, which will be played in the end.

Brief Bio:  Valeri Makarov graduated from the Mat-Mech Faculty of the Leningrad State University, Astronomy Chair, in 1983. He earned his Ph.D. degree at the same university in 1988 with a thesis on "digital processing of astronomical images". Dr. Makarov worked in the Astrometry Department of the Pulkovo Observatory in 1987 - 1993, and then he worked as forskningadjunkt (research fellow) for 7 years at the Copenhagen University Observatory on the Hipparcos, Tycho, Tycho-2, and Gaia projects of space astrometry. In 2000 - 2003, Dr. Makarov worked at USNO through a contract with USRA, mostly on the FAME space astrometry project. Valeri accepted a Key Staff Scientist position at JPL and Caltech (NExScI) in 2003 to work on the Space Interferometry Mission. In 2010, Dr. Makarov returned to USNO as Astronomer, and then Supervisory Astronomer. His research interests include space astrometry, data processing, active/binary stars, and tidal dynamics. Dr. Makarov is author and co-author of ~100 published papers in refereed journals.

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