We present precision radial velocity ( RV ) data that reveal a multiple exoplanet system orbiting the bright nearby G5V star 61Â Virginis .
Our 4.6 years of combined Keck/HIRES and Anglo-Australian Telescope precision RVs indicate the hitherto unknown presence of at least three planets orbiting this well-studied star .
These planets are all on low-eccentricity orbits with periods of 4.2 , 38.0 , and 124.0 days , and projected masses ( M \sin { i } ) of 5.1 , 18.2 , and 24.0 M _ { \oplus } , respectively .
Test integrations of systems consistent with the RV data suggest that the configuration is dynamically stable .
Depending on the effectiveness of tidal dissipation within the inner planet , the inner two planets may have evolved into an eccentricity fixed-point configuration in which the apsidal lines of all three planets corotate .
This conjecture can be tested with additional observations .
We present a 16-year time series of photometric observations of 61Â Virginis , which comprise 1194 individual measurements , and indicate that it has excellent photometric stability .
No significant photometric variations at the periods of the proposed planets have been detected .
This new system is the first known example of a G-type Sun-like star hosting a Super-Earth mass planet .
It joins HDÂ 75732 ( 55Â Cnc ) , HDÂ 69830 , GJÂ 581 , HDÂ 40307 , and GJÂ 876 as a growing group of exoplanet systems that have multiple planets orbiting with periods less than an Earth-year .
The ubiquity of such systems portends that space-based transit-search missions such as KEPLER and COROT will find many multi-transiting systems .