WASP-34b: a near-grazing transiting sub-Jupiter-mass exoplanet in a hierarchical triple system

• Published in: Astronomy and astrophysics (Berlin) Vol. 526; p. A130
• Main Authors: Smalley, B., Anderson, D. R., Collier Cameron, A., Hellier, C., Lendl, M., Maxted, P. F. L., Queloz, D., Triaud, A. H. M. J., West, R. G., Bentley, S. J., Enoch, B., Gillon, M., Lister, T. A., Pepe, F., Pollacco, D., Segransan, D., Smith, A. M. S., Southworth, J., Udry, S., Wheatley, P. J., Wood, P. L., Bento, J.
• Format: Journal Article Web Resource
• Language: English
• Published: Les Ulis EDP Sciences 01.02.2011
• Subjects: Astronomy; Astrophysics - Earth and Planetary Astrophysics; Aérospatiale, astronomie & astrophysique; Earth, ocean, space; Exact sciences and technology; Physical, chemical, mathematical & earth Sciences; Physique, chimie, mathématiques & sciences de la terre; planets and satellites: general; Space science, astronomy & astrophysics; stars: individual: WASP-34; techniques: photometric; techniques: radial velocities; techniques: spectroscopic; White dwarf stars; techniques: radial velocities; Extrasolar planets; techniques: photometric; Hierarchical systems; stars: individual: WASP-34; Jupiter planet; Eccentric orbit; planets and satellites: general; Low-mass stars; techniques: spectroscopic; Radial velocity; Dwarf planet; Impact parameter; Solar type star
• ISSN: 0004-6361; 1432-0746; 1432-0746
• DOI: 10.1051/0004-6361/201015992

We report the discovery of WASP-34b, a sub-Jupiter-mass exoplanet transiting its 10.4-magnitude solar-type host star (1SWASP J110135.89-235138.4; TYC 6636-540-1) every 4.3177 days in a slightly eccentric orbit (e = 0.038 ± 0.012). We find a planetary mass of 0.59 ± 0.01 MJup and radius of \hbox{$1.22 ^{+0.11}_{-0.08}$} 1.2 2 -0.08 + 0.11  RJup. There is a linear trend in the radial velocities of 55 ± 4 m s-1 y-1 indicating the presence of a long-period third body in the system with a mass  ≳0.45 MJup at a distance of  ≳1.2 AU from the host star. This third-body is either a low-mass star, a white dwarf, or another planet. The transit depth ((RP/R∗)2 = 0.0126) and high impact parameter (b = 0.90) suggest that this could be the first known transiting exoplanet expected to undergo grazing transits, but with a confidence of only  ~80%.