HD 154672 b

HD 154672 b is an extrasolar planet located approximately 210 light-years away in the constellation of Ara, orbiting the metal-rich and aged star HD 154672. This planet has a minimum mass five times that of Jupiter and orbits at about 60% the distance between the Earth to the Sun. Its orbit is very elliptical, which causes temperatures on the planet to vary significantly as it proceeds along its orbit. This planet was discovered in Las Campanas Observatory on September 5, 2008 using the radial velocity method (Doppler spectroscopy). Along with HD 205739 b, the planets were the first to be discovered by the N2K Consortium using the Magellan Telescopes. Astronomers hoped to implement a survey called the N2K Consortium, a collaboration which uses Doppler spectroscopy to find radial velocity measurements of stars that hadn't been previously surveyed. The project searched particularly for gas giants with short orbits around metal-rich stars to find how the metallicity of the star and the mass of the planet are related. Radial velocity observations had been taken by the N2K program using the Magellan Telescopes' Magellan Inamori Kyocera Echelle spectrograph (MIKE) at Las Campanas Observatory in Chile since 2004. Based on these observations, the stars HD 154672 and HD 205739 were among those flagged as potential planetary host stars. The two stars were identified originally as having short-orbit hot Jupiter planets, but 3.5 years of additional observations revealed that the planetary candidates' orbits were far longer than initially anticipated. HD 154672 b's discovery was reported in the Astronomical Journal by the American Astronomical Society, appearing in the journal on October 7, 2008 alongside the planet HD 205739 b. The two planets were the first to be discovered by the N2K program that worked out of the Magellan telescopes. HD 154672 b was later observed by a different team of astronomers investigating the role of metallicity, or the amount of metal present in a star, in the formation of planets.