Steps Towards Achieving Precision Radial Velocities in the NIR: Developing and Testing Techniques with a 1.75um cutoff H2RG array for a Pathfinder Instrument

Pennsylvania State Univ University Park, University Park PA

Investigators

Abstract

It has not been long since the only known planets resided in our solar system. Today, world-wide planet-finding efforts have identified over 400 planets orbiting more than 300 stars, and the contrast in properties between many of these systems and our solar system is challenging our understanding of planetary formation and evolution. The Holy Grail of planet-finding has always been to identify objects with near-Earth masses orbiting in the habitable zone of the host star. These planets offer the opportunity to search for evidence of life and thereby develop a better perspective on how it originated and flourished on Earth. The detection of Earth-like planetary masses through the reflex motion of the host star requires either extremely high velocity precision measurements of moderate mass stars - beyond the capabilities of today's best instruments - or the study of low-mass main-sequence (i.e. M spectral type) stars. Because the latter are also very cool, they are faint and the target list is very short for optical studies even with the world's largest telescopes. Dr. Suvrath Mahadevan at the Penn State University plans to upgrade an existing near-infrared laboratory spectrograph that has pioneered some of the techniques used in the above-mentioned discoveries and to apply that spectrograph at the Hobby-Eberly 9-m telescope toward the discovery of Earth-mass planets orbiting low-mass stars. In the near-IR, cool stars are bright and replete with narrow absorption features suitable for radial velocity analysis. Dr. Mahadevan is taking a reasonable and cost-effective approach by employing a sensitivity-cutoff detector array to greatly reduce the cooling requirements of the instrument and Fabry-Perot etalons and gas cells developed for the telecom industry to accomplish accurate wavelength calibration. Soon, this small but experienced group of scientists and students will bring a new instrument to make use of an important spectral region in the study of extrasolar planets. Funding for this work is being provided by NSF's Division of Astronomical Sciences through its Advanced Technologies and Instrumentation program.