The Lowest Mass Exoplanet: 6 - 8 Earth-Masses. Artist renderings and data for the three planets orbiting GJ 876

Inner 6-8 Earth-Mass Planet orbiting GJ 876 and its two Jupiters.

Artist rendering of three Planets orbiting GJ 876. Outer Planets have masses of 2.5 and 0.8 Jupiter-masses. The new inner planet has a mass of 7.5 Earth-masses (for inclination = 50 deg). Note: 1 Jupiter-mass = 318 Earth-masses. For permission to use/reproduce this image, contact Lynette Cook at lynette@spaceart.org. Cook's SpaceArt

Artist rendering of three planets orbiting GJ 876, with zoom on 6-8 Earth-mass planet.(Asteroid is in foreground.) For permission to use/reproduce this image, contact Lynette Cook at lynette@spaceart.org. Cook's SpaceArt

Close-up of 6-8 Earth-mass planet orbiting GJ 876 (artist rendering). For permission to use/reproduce this image, contact Lynette Cook at lynette@spaceart.org. Cook's SpaceArt

Inner 6-8 Earth-Mass Planet orbiting GJ 876 and its two Juptiers. New 6-8 Earth-mass planet (rendered by artist Trent Schindler at the National Science Foundation. )

A fly-through animation of the Gliese 876 System. (rendered by artist Trent Schindler at the National Science Foundation. )

Animation of the Gliese 876 System, from above. (rendered by artist Trent Schindler at the National Science Foundation. )

Actual velocity measurements (points) of the star, GJ 876, versus time (Julian Date) between 1996 - 2005. All Doppler measurements were made at the Keck 1 telescope. The velocities are reproduced with a theoretical 3-planet model (solid line) that includes gravitational interactions among planets. The differences (residuals) between observed and theoretical velocities are at bottom, with RMS = 5.5 m/s.

Spectrum from starlight split into its composite colors, all gathered by the Keck Telescope, "HIRES" spectrometer that was upgraded with a new imaging digital camera (CCD array), new optics that were optimized for Doppler planet hunting by the California & Carnegie Planet Search Team . This spectrum "Doppler shifts" to the left and right, as the star wobbles in space due to the gravitational pull from the planets.