Two New Planets from the Anglo-Australian Planet Search

Precise Doppler measurements from the Anglo-Australian Telescope (AAT) UCLES spectrometer reveal periodic Keplerian velocity variations in the stars HD 160691 and HD 27442. HD 160691 has a period of 743 days, a semiamplitude of 54 m s^-1, and a high eccentricity, e=0.62, typical of extrasolar planets orbiting beyond 0.2 AU. The minimum (Msini) mass of the companion is 1.97 M_J, and the semimajor axis is 1.65 AU. HD 27442 has a 415 day period, a semiamplitude of 32 m s^-1, and an eccentricity of 0.058. The minimum mass is 1.43 M_J, and the semimajor axis is 1.18 AU. This is the first extrasolar planet orbiting beyond 0.2 AU that is in a circular orbit similar to solar system planets. The photon-limited precision of AAT/UCLES measurements is 3 m s^-1 as demonstrated by stable stars and Keplerian fits to planet-bearing stars. In addition, we present confirmation of four previously announced planets. Based on observations obtained at the Anglo-Australian Telescope, Siding Spring, Australia.