Volume 528, April 2011
|Number of page(s)||7|
|Published online||01 March 2011|
A search for star-planet interactions in the υ Andromedae system at X-ray and optical wavelengths
Hamburger Sternwarte, Hamburg University,
2 Universität Göttingen, Institut für Astrophysik, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
3 Carnegie Institution of Washington, Department of Terrestrial Magnetism, 5241 Broad Branch Road N.W., Washington, DC 20015, USA
Received: 27 October 2010
Accepted: 8 January 2011
Context. Close-in, giant planets are expected to influence their host stars via tidal or magnetic interaction. But are these effects in X-rays strong enough in suitable targets known so far to be observed with today’s instrumentation?
Aims. The υ And system, an F8V star with a Hot Jupiter, was observed to undergo cyclic changes in chromospheric activity indicators with its innermost planet’s period. We aim to investigate the stellar chromospheric and coronal activity over several months.
Methods. We therefore monitored the star in X-rays as well as at optical wavelengths to test coronal and chromospheric activity indicators for planet-induced variability, making use of the Chandra X-ray Observatory as well as the echelle spectrographs FOCES and HRS at Calar Alto (Spain) and the Hobby-Eberly Telescope (Texas, US).
Results. The stellar activity level is low, as seen both in X-rays as in Ca ii line fluxes; the chromospheric data show variability with the stellar rotation period. We do not find activity variations in X-rays or in the optical that can be traced back to the planet.
Conclusions. Gaining observational evidence of star-planet interactions in X-rays remains challenging.
Key words: planet-star interactions / stars: activity / stars: coronae / stars: chromospheres / X-rays: stars / X-rays: individuals: υ Andromedae
© ESO, 2011
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