Gliese 176

Gliese 176 UAE: красный (Russian Red) Russian Red is a Union Star system with fourteen planets, one of which is a so called Super Earth, planet Sara Seager. The world and all planets are colonized and utilized. For Union System info see: Russian Red, system

Epoch J2000.0      Equinox J2000.0 Constellation    Taurus Right ascension    04h 42m 55.7749s Declination    +18° 57′ 29.399″ Apparent magnitude (V)    9.95 Characteristics Spectral type    M2V B−V color index    1.523 ± 0.025 Variable type    BY Dra Astrometry Radial velocity (Rv)    26.4105 ± 0.0004 km/s Proper motion (μ)    RA: 656.744±0.166 mas/yr Dec.: −1116.790±0.104 mas/yr Parallax (π)    106.32 ± 0.60 mas Distance    30.7 ± 0.2 ly (9.41 ± 0.05 pc) Absolute magnitude (MV)    10.10 ± 0.06 Details Mass    0.50 ± 0.03 M☉ Radius    0.4525±0.0221 R☉ Luminosity    0.0337±0.0018 L☉ Temperature    3679±77 K Metallicity [Fe/H]    –0.1 ± 0.2 dex Rotation    40.00 ± 0.11 days Rotational velocity (v sin i)    ≤0.8 km/s Age    0.56 Gyr Other designations BD+18° 683, HD 285968, HIP 21932, Ross 33 Database references SIMBAD    data Extrasolar Planets Encyclopaedia    data

Pre Astro

Gliese 176 is a red dwarf in the constellation of Taurus. Based upon parallax measurements from the Hipparcos mission, it is located approximately 30 light-years away.[1] The star is orbited by a Super-Earth.

Planetary system A planetary companion to Gliese 176 was announced in 2008.[6] Radial velocity observations with the Hobby-Eberly Telescope (HET) showed a 10.24-day periodicity, which was interpreted as being caused by a planet. With a semi-amplitude of 11.6 m/s, its minimum mass equated to 24.5 Earth masses, or approximately 1.4 Neptune masses.

Observations with the HARPS spectrograph could not confirm the 10.24-day variation.[2] Instead, two other periodicities were detected at 8.78 and 40.0 days, with amplitudes below the HET observational errors. The 40-day variation coincides with the rotational period of the star and is therefore caused by activity, but the shorter-period variation is not explained by activity and is therefore caused by a planet. Its semi-amplitude of 4.1 m/s corresponds to a minimum mass of 8.4 Earth masses, making the planet a Super-Earth.

In an independent study, observations with Keck-HIRES also failed to confirm the 10.24-day signal.[7] An 8.77-day periodicity - corresponding to the planet announced by the HARPS team - was detected to intermediate significance, though it was not deemed significant enough to claim a planetary cause with their data alone.