April 14, 2003
(PLANETQUEST) -- A planetary companion has been detected circling the star HD 73256, bringing to 106 the total number of planets thus far discovered orbiting stars other than our Sun. The planet is one of a class known as "hot jupiters" -- gas giants located in tight orbits extremely close to their parent stars.
The discovery was made by a team of European astronomers carrying out precise Doppler observations at the La Silla Observatory in Chile. Their method of detection, called radial velocity, or Doppler spectroscopy, infers the presence of an unseen companion because of the back-and-forth movement it induces in the host star. This movement is detectable as a periodic red shift and blue shift in the star's spectral lines. (For more about this method, see the article Finding Planets.)
With a magnitude of 8.08, the host star can be viewed with binoculars or a low-powered telescope in the southern sky. The star is slightly larger than our Sun and is located 119 light-years away in the constellation Canis Major.
The planetary companion is a gas giant with a derived mass nearly twice that of Jupiter. Its orbit is nearly circular and lasts just over two-and-half days.
The discovery was made as part of the Coralie Planet Search Program, an ongoing survey that has discovered eight extrasolar planets to date.
