Development of environment-controlled enclosures for the Network of Robotic Echelle Spectrographs

Las Cumbres Observatory Global Telescope Network, Goleta CA

Investigators

Abstract

Just a few decades ago, scientists discovered the first planets around other stars. Since then, it has become apparent that these "exoplanets" are very common in the universe, and a large catalog of them has been compiled. Detailed followup study is generally difficult, owing to the faintness of their light, but is vital to understanding the exoplanets and their contribution to a chain of reasoning that ultimately bears on the question of how common life itself might be elsewhere in the universe. Very specialized instrumentation is needed to study exoplanets thoroughly once they are detected, and the shortage of that instrumentation is a significant bottleneck addressed by the construction of the Las Cumbres Observatory Global Telescope (LCOGT), a worldwide network of primarily 1-meter telescopes. LCOGT will be equipped, through recent NSF funding, with precise spectrographs appropriate to exoplanet study. The current proposal addresses an improvement to the instrumentation in the form of a better enclosure that will be thermally controlled to allow optimum spectrographic precision to be achieved. The prototype to be constructed will demonstrate an important element in overall system performance. The LCOGT project addresses a specific recommendation of the ASTRO 2010 (decadal) report calling for making increased telescope time available to radial velocity (RV) exoplanet work, even if limiting precision were not improved from then-current levels. LCOGT will roughly double the nationwide capacity for RV studies of exoplanets, and will allow accuracy of 3m/s in exposure times of less that an hour for stars brighter than V=12. With its multiple locations, LCOGT provides a powerful combination of quantity and quality of data acquisition. The ultimate LCOGT spectrographs are cross-dispersed echelles with resolving power R=53,000 and almost full wavelength coverage over 380-860 nm, designed for efficiency, stability, and ease of wavelength calibration. The new enclosure design is called an "igloo", and is carefully insulated and temperature-controlled. An RV accuracy of 3 m/s requires temperature control to +/- 1 C. The NRES system will enable astronomers to characterize exoplanet candidate host stars, validate transiting companions, search for multiple planetary systems, and derive masses and orbital elements for a wide range of planets. Candidates will be supplied by ground-based transit surveys, such as HATnet, SuperWASP, and Qatar, and from NASA's TESS mission. The LCOGT project is active in education, operating an extensive program of student observing on their telescopes. Numerous students from high-school to university seniors are employed as interns. Designs developed for LCOGT are open-source, and science data are made available to the community. Funding for this project is being provided by NSF's Division of Astronomical Sciences through its Advanced Technologies and Instrumentation program.