Astrophys. J., 788, 2 (2014/June-2)
WASP-12b and HAT-P-8b are members of triple star systems.
BECHTER E.B., CREPP J.R., NGO H., KNUTSON H.A., BATYGIN K., HINKLEY S., MUIRHEAD P.S., JOHNSON J.A., HOWARD A.W., MONTET B.T., MATTHEWS C.T. and MORTON T.D.
Abstract (from CDS):
We present high spatial resolution images that demonstrate that WASP-12b and HAT-P-8b orbit the primary stars of hierarchical triple star systems. In each case, two distant companions with colors and brightnesses consistent with M dwarfs co-orbit the hot Jupiter planet host as well as one another. Our adaptive optics images spatially resolve the secondary around WASP-12, previously identified by Bergfors et al. and Crossfield et al. into two distinct sources separated by 84.3±0.6 mas (21±3 AU). We find that the secondary to HAT-P-8, also identified by Bergfors et al., is in fact composed of two stars separated by 65.3±0.5 mas (15±1 AU). Our follow-up observations demonstrate physical association through common proper motion. HAT-P-8 C has a particularly low mass, which we estimate to be 0.18±0.02 M☉ using photometry. Due to their hierarchy, WASP-12 BC and HAT-P-8 BC will enable the first dynamical mass determination for hot Jupiter stellar companions. These previously well studied planet hosts now represent higher-order multi-star systems with potentially complex dynamics, underscoring the importance of diffraction-limited imaging and providing additional context for understanding the migrant population of transiting hot Jupiters.
astrometry - stars: individual: (WASP-12, HAT-P-8) - techniques: high angular resolution - techniques: photometric
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