Vol. 525In section 10. Planets and planetary systems2 December 2010

A fourth planet orbiting upsilon Andromedae

by S. Curiel, J. Canto, L. Georgiev, C. Chavez, and A. Poveda, A&A 525, A78 alt

The star upsilon And has been known to be harboring a system of three planets since 1999. By combining data taken by several instruments since 1994, Curiel et al. are able to to discover an outer fourth planet to the system. This planet, upsilon And e, has an Msini value (the planetary mass multiplied by the sine of the orbital inclination) of 1.06 Mjup, it orbits the star in 10.5 years on a very circular orbit. It is a close analog to our Jupiter. However, contrary to our Solar System, the three inner planets are also giant planets. upsilon And e appears to lie in an island of orbital stability that had been previously reported, hinting at an efficient planet formation mechanism able to put planets wherever they are dynamically stable.