Discovery of a Substellar Companion orbiting the Giant Star iota Draconis

Press Release: Astronomers find First Planet orbiting a Giant Star
(also see UCSD press release)

Radial Velocity Curve
last updated: February 14, 2008

Spectroscopic Orbital Elements
element fitted value estimated uncertainty
Period P 511.0 days 0.1 days
Periastron Time T0 JD 2452015.4 0.2 days
Longitude of Periastron ω 94°
Eccentricity e 0.71 0.01
Mass Function f(m) 5.34⋅10−7Msun 0.2⋅10−7 Msun

⇒ m2sin(i) = 8.8 MJup

The above fit also contains an additional linear trend, probably belonging to another component in the system. The orbit is not constrained at all yet, but the period will be rather long. The additional linear trend was not included the 2002 paper, since it was not seen at that time yet; it only became apparent after two periods had been covered. The fitted linear trend is:
-15.8 m/s

Discovery of a Substellar Companion to the K2 III Giant ι Draconis
Sabine Frink, David S. Mitchell, Andreas Quirrenbach, Debra A. Fischer, Geoffrey W. Marcy, R. Paul Butler
ApJ 576, 478, 2002
[ps-file] (532 k) [pdf-file] (203 k)