From YY Boo (eclipsing binary) via J1407 (ringed companion) to WD 1145+017 (white dwarf with debris disk) (Abstract)

Volume 46 number 1 (2018)

Franz-Josef (Josch) Hambsch

Oude Bleken 12, Mol 2400, Belgium; hambsch@telenet.be

Abstract

(Abstract only) Several years ago by accident I observed YY Boo outside of an eclipse and was very surprised to see a short term periodic variation of about 0.1 mag. That was completely unexpected and it initiated an international campaign by amateurs to identify the cause of these variations. It turned out that YY Boo showed a pulsation period of about 88 min in addition to being an Algol type eclipsing binary. Hence it turned out that YY Boo has become a new member of a class of pulsating eclipsing binary systems with, at that time, the second largest amplitude after BO Her. Since August 2011, I have had a remote observatory (ROAD) under pristine skies in Chile. It has been a production facility since day one of operation. Via the AAVSO Alert Notice 462 of June 25, 2012, I came to know about the interesting star 1SWASP J140747.93-394542.6 (“J1407”; V=12.3 mag), which underwent a series of deep eclipsing events during April/May 2007. The event lasted about 52 days with changes in brightness of the star by 0.5 to 3 magnitudes according to the Alert Notice. Nightly observations were asked for, which I started on June 27 and have continued ever since. A first paper where observations from ROAD were taken up gave a possible period in the range of 3.5 to 13.8 years. Hence the coming years will be crucial to keep up observations of this interesting object. Finally, in 2015 I was asked by B. Gänsicke (U. Warwick) to observe the interesting object WD 1145+017. In this context I also got to know Bruce Gary who had observed this object already for some time and joined the pro-am team to contribute observations from Chile. WD 1145+017 was observed in the period 2015 November to 2016 July to characterize the transiting behavior of the white dwarf by dust clouds produced by an asteroid orbiting the star. The object was discovered by Kepler and the observed activity was enhanced drastically during the observing period.