XO-5b: A Transiting Jupiter-sized Planet with a 4 Day Period

The star XO-5 (GSC 02959-00729, V = 12.1, G8 V) hosts a Jupiter-sized, R_p = 1.15 +/- 0.12 R_J, transiting extrasolar planet, XO-5b, with an orbital period of 4.2 days. The planet's mass, M_p = 1.15 +/- 0.08 M_J, and surface gravity, g_p = 22 +/- 5 m s^-2, are large for its orbital period compared to most other transiting planets. However, the deviation from the M_p-P relationship for XO-5b is not as large as for GJ 436b, HAT-P-2b, and XO-3b. By coincidence, XO-5 overlies the extreme H I plume that emanates from the interacting galaxy pair NGC 2444/NGC 2445 (Arp 143).