Exoplanets & Habitability Seminar, May 16th, 2023 at 14:00h

We searched for companions of Hipparcos catalog stars from the proper motion anomaly (PMa) they induce on their host star. This quantity, defined as the difference between the short-term proper motion vectors measured by Gaia (2014-2017) and the long-term Hipparcos-Gaia proper motion (1991-2016), is a sensitive astrometric tracer of the presence of massive orbiting companions. Thanks to the precision of Gaia and the long Hip-Gaia time baseline, the median accuracy of the tangential velocity anomaly reaches 26 cm/s per parsec of distance. For nearby stars, this enables us to identify planetary mass companions. I will present the examples of the detection of exoplanets previously known from radial velocity (Eps Eri b, Eps Ind Ab, Pi Men b). In addition, we searched the Gaia EDR3 catalog for spatially resolved bound companions of nearby stars within 100pc, based on a common proper motion (CPM) approach. I will present an overview of our results on the PMa and CPM analyses. We obtain a binary fraction of 43% for the Hipparcos catalog stars, including several hundred planetary mass companion candidates. The characterisation of these exoplanet candidates using a combination of Gaia data (in particular the future DR4 epoch astrometry) with various observing techniques (imaging, interferometry, transits, radial velocity) appears particularly promising.

Date/Time: Tuesday 16th of May, 2 to 3 pm (Zürich time).

Zoom link: external pagehttps://ethz.zoom.us/j/68494577132call_made

Host: Thomas Birbacher