Discovery of an unusual bright eclipsing binary with the longest known period: TYC 2505-672-1/MASTER OT J095310.04+335352.8

¹ Lomonosov Moscow State UniversityPhysics Department, Leninskie Gory, 1, 119991 Moscow, Russia
e-mail: lipunov2007@gmail.com
² Lomonosov Moscow State University, Sternberg Astronomical Institute, Universitetsky prospekt, 13, 119234 Moscow, Russia
³ Special Astrophysical Observatory, Nizhnij Arkhyz, Zelenchukskiy reg., 369167 Karachai-Cherkessian Republic, Russia
⁴ Kourovka Astronomical Observatory, Ural Federal University, Lenin ave. 51, 620000 Ekaterinburg, Russia
⁵ Applied Physics Institute, Irkutsk State University, 20, Gagarin blvd, 664003 Irkutsk, Russia
⁶ Blagoveschensk State Pedagogical University, Lenin str., 104, Blagoveschensk, 675000 Amur region, Russia
⁷ Kislovodsk Mountain Astronomical Station of the Pulkovo observator, Gagarin str., 100, 357700 Kislovodsk, Russia

Received: 15 May 2015
Accepted: 3 February 2016

Abstract

We report on the MASTER Global Robotic Net discovery of an eclipsing binary, MASTER OT J095310.04+335352.8, previously known as unremarkable star TYC 2505-672-1, which displays extreme orbital parameters. The orbital period P = 69.1 yr is more than 2.5 times longer than that of ε-Aurigae, which is the previous record holder. The light curve is characterized by an extremely deep total eclipse with a depth of more than 4.5 mag, which is symmetrically shaped and has a total duration of 3.5 yr. The eclipse is essentially gray. The spectra acquired with the Russian 6 m BTA telescope both at minimum and maximum light mainly correspond to an M0-1III–type red giant, but the spectra taken at the bottom of eclipse show small traces of a sufficiently hot source. The observed properties of this system can be better explained as the red giant eclipsed by a large cloud (the disk) of small particles surrounding the invisible secondary companion.