* Astronomy

Title: The sub-Jupiter mass transiting exoplanet WASP-11b
Authors: R. G. West, A. Collier Cameron, L. Hebb, Y. C. Joshi, D. Pollacco, E. Simpson, I. Skillen, H. C. Stempels, P. J. Wheatley, D. Wilson, D. Anderson, S. Bentley, F. Bouchy,  D. Christian, B. Enoch, N. Gibson, G. Hébrard, C. Hellier, B. Loeillet, M. Mayor, P. Maxted, I. McDonald, C. Moutou, F. Pont, D. Queloz, A. M. S. Smith, B. Smalley, R. A. Street, and S. Udry

We report the discovery of a sub-Jupiter mass exoplanet transiting a magnitude V = 11.6 host star 1SWASP J030928.54+304024.7. A simultaneous fit to the transit photometry and radial-velocity measurements yield a planet mass M_{p} = 0.53 ±0.07  {M_{J}}, radius R_{p} = 0.91^_~{R_{J}} and an orbital period of 3.722465^{+0.000006}_ days. The host star is an early to mid-K dwarf, with a spectral analysis yielding an effective temperature of 4800 ±100K and log g = 4.45 ±0.2. It is amongst the smallest, least massive and lowest luminosity stars known to harbour a transiting exoplanet. WASP-11b is the third least strongly irradiated transiting exoplanet discovered to date, experiencing an incident flux _{p} = 1.9 x 10^8ergs^-1cm^-2 and having an equilibrium temperature T_{eql} = 960 ±70K.

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