R. Szabó, Gy. M. Szabó, G. Dálya
Aims. Hot Jupiters are thought to belong to single-planet systems. Somewhat surprisingly, about one quarter of hot Jupiters were reported to exhibit Transit Timing Variations (TTVs). The aim of this paper is to identify the origin of this observation. Methods. We present TTV frequencies and amplitudes of hot Jupiters in Kepler Q0--6 data with Fourier analysis. Results. We identified 29 systems with TTV above 4-sigma confidence, about half of them exhibiting multiple TTV frequencies. Thirteen of these objects (HAT-P-7b, KOI-13, 127, 188, 196, 203, 225, 254, 428, 607, 774, 897, 1176) likely show TTVs due to a systematic observational effect: long cadence data sampling is regularly shifted transit-by-transit, interacting with the transit light curves and introducing a periodic bias. In case of other systems, the activity and rotation of the host star can modulate light curves and explain the observed TTVs. After excluding the systems that were inadequately sampled or showed signs of stellar rotation, we ended up with 16 systems. Nine of them show only one significant period (KOI-131, 186, 256, 882, 897, 1003, 1152, 1448, 1543), others exhibit multiple periods (KOI-823, 977, 1285, 1382, 1452, 1540, 1546). The number of significant periods ranges from 2 (KOI-977, 1382) to 10 (KOI-1546). Conclusions. The few hot Jupiters with periodic TTVs that we cannot explain with systematics from observation, stellar rotation, activity or inadequate sampling may be good candidates for hot Jupiters in multiple systems or even hosting an exomoon.
View original:
http://arxiv.org/abs/1207.7229
No comments:
Post a Comment