Van Grootel, Valérie ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique stellaire théorique et astérosismologie
Baran, A.S.
Schuh, S.
Fox Machado, L.
Language :
English
Title :
Kepler detection of a new extreme planetary system orbiting the subdwarf-B pulsator KIC 10001893
Publication date :
October 2014
Journal title :
Astronomy and Astrophysics
ISSN :
0004-6361
eISSN :
1432-0746
Publisher :
EDP Sciences, Les Ulis, France
Volume :
570
Pages :
130
Peer reviewed :
Peer Reviewed verified by ORBi
Commentary :
KIC 10001893 is one out of 19 subdwarf B (sdB) pulsators observed by the Kepler spacecraft in its primary mission. In addition to tens of pulsation frequencies in the g-mode domain, its Fourier spectrum shows three weak peaks at very low frequencies, too low to be explained in terms of g-modes. The most convincing explanation is that we are seeing the orbital modulation of three Earth-size planets (or planetary remnants) in very tight orbits, that are illuminated by the strong stellar radiation. The orbital periods are P1=5.273, P2=7.807 and P3=19.48 hours and the period ratios P2/P1=1.481 and P3/P2=2.495 are very close to the 3:2 and 5:2 resonance respectively. One of the main pulsation modes of the star at 210.68 μHz corresponds to the third harmonic of the orbital frequency of the inner planet, suggesting that we see, for the first time in an sdB star, g-mode pulsations tidally excited by a planetary companion. The extreme planetary system that emerge from the Kepler data is very similar to the recent discovery of two Earth-size planets orbiting the sdB pulsator KIC 05807616 (Charpinet et al. 2011a).
