Exoplanets: Vatican Observatory adjunct scholar Dante Minniti (Pontifical University of Santiago, Chile) was a member of a team of astronomers from Europe, the US, Chile, and Australia who have discovered a planetary system around a nearby M dwarf star with at least one super-Earth planet in its habitable zone. This star, GJ 667C, is a triple-star system located 22 light years from Earth; it can be found in the sky near the curving tail of the constellation Scorpius. The key to this discovery was a new data analysis technique to find radial velocity (RV) measurements that derives the Doppler measurement and other instrumental effects using a least-squares approach, rather than the technique previously used by the HARPS team.

The conference organized by Gabor, “Search for Life Beyond the Solar System: Exoplanets, Biosignatures & Instruments” held in Tucson in March 17-21, 2014, brings together an interdisciplinary community to examine the interface of exoplanet observations, early and extreme forms of life on Earth, atmospheric biomarkers, and planet-finding telescopes. Gabor’s expertise in this area up to now has been in the development of the instrumentation used in these studies.

Link to: ebi2014.org

A proposed optical fiber connection between VATT and the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) detector at the Large Binocular Telescope on Mt. Graham has an important exoplanet implication. NASA’s Kepler spacecraft has produced several thousand possible transit detections so far, but a true verification can only be made if a spectroscopic follow-up of a given candidate shows radial velocity variations in agreement with the period from the light curve and with an amplitude appropriate for a planetary mass. It is hoped that the VATT and PEPSI could be operated for many nights during a year and thus sample an orbital period domain not accessible to any other facility in the world.

When one observes an exoplanet as it passes its host star, the dip in the observed brightness of the system is directly correlated to the atmosphere of the exoplanet. From the shape (depth, width, etc.) of the eclipse signal, one can determine the molecular abundances and temperature profile of the planet’s atmosphere. However, many of these exoplanets orbit about sometimes fairly active stars. When these stars have spots, it can affect the lightcurve. Gabor and LPL graduate student Zellem (an alumnus of the Vatican Observatory Summer School, VOSS 2007) are looking into using VATT to study the photometric brightness of a few key exoplanetary systems over a long period of time (at least for a season, initially) to better constrain the starspot sizes.

Specola Vaticana
Vatican Observatory

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e.mail: staff@specola.va


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