Exoplanet as a cosmic "flyweight"

WASP-3c has only about 15 earth masses

Light curve of the transit of Planet WASP-3b © University of Jena
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An international team of astrophysicists has discovered a new exoplanet: WASP-3c is the name of the celestial body, which is a true "flyweight" with "only" about 15 Earth masses or a Uranus mass.

"In addition, this is the first planet to be discovered with the new transit-time-variation method, " says Gracjan Maciejewski of the University of Jena. WASP-3c orbits the star WASP-3, about 700 light-years away in the constellation of Leier, write the Jena researchers together with colleagues of the Bulgarian Academy of Sciences in Sofia and the University of Torun, Poland, in the journal "Monthly Notices of the Royal Astronomical Society",

Circumnavigation in 3.75 days

Several years ago, another international team at WASP-3 discovered the planet WASP-3b. "This planet also played a crucial role in the discovery of WASP-3c, " explains Maciejewski. In their observations, the researchers became aware of periodic fluctuations in the orbital period of WASP-3b.

"Our calculations showed that these fluctuations, which are also called transit time variations, must be caused by another planet in the system, " says the Jena astrophysicist. WASP-3c takes exactly twice as long - 3.75 days - as the inner planet WASP-3b to orbit the common star.

Star WASP-3 © University of Jena

Irregularities in orbit

For their successful observations, the researchers used the 90 and 60 centimeter mirror telescopes of the University of Jena in Großschwabhausen and the Rozhen Observatory in Bulgaria. "We started watching WASP-3b in 2008 because its orbit seemed slightly eccentric, " recalls Professor Ralph Neuhäuser. display

"This is unusual and can point to very small, but measurable variations in the orbital parameters of a planet - caused by other planets, " said the director of the Astrophysical Institute and the observatory of the University of Jena. Thanks to the new method, the research team has now been able to detect the new planet WASP-3c based on the irregularities in the orbit of WASP-3b.

90-centimeter telescope in Grossschwabhausen University of Jena

Transit-time variation

Like other successful planet search methods, such as the transit method, transit time variation is an indirect method. "For a direct observation with a telescope, the planet is much too small and weak, " according to Neuh user. However, the new technology makes it possible to discover even planets with much lower mass than WASP-3c even with small telescopes.

"Certainly, " emphasizes Markus Mugrauer of the Astrophysical Institute of the University of Jena, "we have only been able to make this important discovery now because the instruments at the Jena University Observatory are only recently renewing The recently installed new CCD camera, which was used to acquire the pictures taken, is especially important. WASP-3c is the first planet discovered with the Jena Observatory in Gro schwabhausen.

(idw - University of Jena, 12.07.2010 - DLO)