Tau1 Gruis (τ1 Gru / τ1 Gruis), also cataloged as HD 216435 and HR 8700, is a yellow dwarf star approximately 109 light-years away in the constellation of Grus (the Crane). The star is visible to the naked eye for some people, placing it in the Bright Star Catalogue. As of 2002, one extrasolar planet has been confirmed to orbit the star.
Gruis is a yellow dwarf star
of the possible spectral type
of G0-3 V-IV. It is thought that the star has about 1.25 times more mass than the Sun
, a probable large radius
, and about 3.6 times more luminosity
. Due to its unusually brightness, at least one source suspects that the star may be a highly evolved subgiant star
. It is though that Tau1
Gruis is about 1.4 times more enriched with elements heavier than hydrogen
, making a high abundance of iron
likely. The Ca-II H line of the star suggests that it is chromospherically inactive, making its age significant older than previously predicted.
On September 17
, a team of astronomers lead by Geoffrey Marcy
announced the discovery of a giant planet around Tau1
Gruis. The radial velocity
measurements suggest that the star has a companion with at least 1.23 times the mass of Jupiter
. The planet's orbit stays inside the system's habitable zone
for most of its revolution around the star, though at apoapsis
, the planet falls outside of this zone.