Hunting for planets around other stars

Image of the "second Jupiter" GJ 504b (top right). The host star's light has been suppressed both mechanically and by image analysis methods, leaving colorful remnants. Zoom Image
Image of the "second Jupiter" GJ 504b (top right). The host star's light has been suppressed both mechanically and by image analysis methods, leaving colorful remnants. [less]

The discovery and study of exoplanets – planets around stars other than the Sun – is one of the most exciting fields of current astronomy. MPIA astronomers have been involved in a number of interesting exoplanet discoveries, such as the 13-billion-year-old planetary pair HIP 11952b and c, or HIP 13044b, a planet that appears to have originated in another galaxy.

Most exoplanets are discovered indirectly. But one MPIA specialty is the imaging of exoplanets - a challenging task, as those planets are usually lost in their host star's glare. Such images, which call for the physical masking of the star (coronagraphy) and sophisticated data analysis, include that of GJ 504 b, the coldest and probably also the lightest planet imaged up to that time (image right), and the "Super-Jupiter" κ And b.

First global surface map of a brown dwarf Zoom Image
First global surface map of a brown dwarf

MPIA researchers are also involved in detecting exoplanets indirectly: By detecting a host star's tiny wobble caused by a planet's tiny gravitational tug (radial velocity method and astronometric detection), or by the slight dimming of a host star as a planet passes between the star and the observer (transit method).

Some of our research concerns not planets, but intermediate objects known as brown dwarfs, which are too massive to be planets, but not massive enough to become brightly shining stars. The techniques for observing brown dwarfs are the same as for exoplanets. And the first surface map of a brown dwarf, produced by MPIA researchers in late 2013, is not only an interesting scientific result in its own right - it also points towards a time when astronomers will be able to map the surface features of Jupiter- or Saturn-like exoplanets.

Last but not least, MPIA is active in using spectroscopy to characterize the chemical and thermal properties of exoplanet atmospheres. By modeling such atmospheres, we also prepare for one of the most exciting tasks that lies ahead: the search for an exoplanet that harbors life.

 
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