* Astronomy

Title: WASP-34b: a near-grazing transiting sub-Jupiter-mass exoplanet in a hierarchical triple system
Authors: B. Smalley (Keele University), D.R. Anderson, A. Collier Cameron, C. Hellier, M. Lendl, P.F.L. Maxted, D. Queloz, A.H.M.J. Triaud, R.G. West, S.J. Bentley, B. Enoch, M. Gillon, T.A. Lister, F. Pepe, D. Pollacco, D. Segransan, A.M.S. Smith, J. Southworth, S. Udry, P.J. Wheatley, P.L. Wood, J. Bento

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 M_Jup and radius of 1.22 ^{+0.11}_{-0.08} R_Jup. There is a linear trend in the radial velocities of 55±4 m/s/y indicating the presence of a long-period third body in the system with a mass > 0.45 M_Jup at a distance of >1.2 AU from the host star. This third-body is either a low-mass star, white dwarf, or another planet. The transit depth ((R_P/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%.

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