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Undercover Stars Among Exoplanet Candidates

Date:
March 18, 2005
Source:
European Southern Observatory
Summary:
An international team of astronomers have accurately determined the radius and mass of the smallest core-burning star known until now.
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This is a comparison between the newly found low-mass star OGLE-TR-122b and the Sun and Jupiter. OGLE-TR-122b, while still 96 times as massive as Jupiter, is only 16% larger than this giant planet. It weighs 1/11th the mass of the Sun and has 1/8th of its diameter. (credits: Sun image: SOHO/ESA; Jupiter: Cassini/NASA/JPL/University of Arizona/ESA)

An international team of astronomers have accurately determined the radius and mass of the smallest core-burning star known until now.

The observations were performed in March 2004 with the FLAMES multi-fibre spectrograph on the 8.2-m VLT Kueyen telescope at the ESO Paranal Observatory (Chile). They are part of a large programme aimed at measuring accurate radial velocities for sixty stars for which a temporary brightness "dip" has been detected during the OGLE survey.

The astronomers find that the dip seen in the light curve of the star known as OGLE-TR-122 is caused by a very small stellar companion, eclipsing this solar-like star once every 7.3 days.

This companion is 96 times heavier than planet Jupiter but only 16% larger. It is the first time that direct observations demonstrate that stars less massive than 1/10th of the solar mass are of nearly the same size as giant planets. This fact will obviously have to be taken into account during the current search for transiting exoplanets.

In addition, the observations with the Very Large Telescope have led to the discovery of seven new eclipsing binaries, that harbour stars with masses below one-third the mass of the Sun, a real bonanza for the astronomers.


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The above story is based on materials provided by European Southern Observatory. Note: Materials may be edited for content and length.


Cite This Page:

European Southern Observatory. "Undercover Stars Among Exoplanet Candidates." ScienceDaily. ScienceDaily, 18 March 2005. <www.sciencedaily.com/releases/2005/03/050309120637.htm>.
European Southern Observatory. (2005, March 18). Undercover Stars Among Exoplanet Candidates. ScienceDaily. Retrieved May 30, 2015 from www.sciencedaily.com/releases/2005/03/050309120637.htm
European Southern Observatory. "Undercover Stars Among Exoplanet Candidates." ScienceDaily. www.sciencedaily.com/releases/2005/03/050309120637.htm (accessed May 30, 2015).

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