Astrometry: Europe's star power

Astrometry of Galactic Star-Forming Region G48.61+0.02 with VERA

We performed the astrometry of H2O masers in the Galactic star-forming region G48.61 + 0.02 with the VLBI Exploration of Radio Astrometry (VERA). We derived a trigonometric parallax of 199 ± 7 μas, which corresponds to a distance of 5.03 ± 0.19 kpc. The distance to G48.61 + 0.02 is about a half of its far kinematic distance, which was often assumed previously. This distance places G48.61 + 0.02...

Star power.

SIM Grid Star Observations: Astrometry with a New High Dynamic Range Imaging Device

First astrometric and photometric applications of the logarithmically scaled HDRC4 imager (developed by the Institut f ur Mikroelektronik Stuttgart, IMS, Germany) are presented. To test the HDRC4 imager at the telescope, a cooled camera had to be constructed by modifying a camera designed by IMS. First observations were performed with various telescopes at Hamburg Observatory, Germany. These s...

Combining Astrometry and Spectroscopy

Orbital solutions for binary or multiple stellar systems that combine astrometry (e.g., position angles and angular separations) with spectroscopy (radial velocities) have important advantages over astrometric-only or spectroscopic-only solutions. In many cases they allow the determination of the absolute masses of the components, as well as the distance. Yet, these kinds of combined solutions ...

Exoplanet search with astrometry

Searching for extrasolar planets by direct detection is extremely challenging for current instrumentation. Indirect methods, that measure the effect of a planet on its host star, are much more promising and have indeed led to the discovery of nearly all extrasolar systems known today. While the most successful method thus far is the radial velocity technique, new interferometric instruments lik...