Characterization and Commissioning of the iLocater Spectrograph

University Of Notre Dame, Notre Dame IN

Investigators

Abstract

This project will complete the construction of a new instrument named iLocater that will search for exoplanets using a large telescope in Arizona. iLocater is an instrument called a spectrograph that spreads out the incoming light from stars and searches for the tiny color changes caused by planets moving in orbit around their star. The instrument compensates for the distorting effect of Earth’s turbulent atmosphere and can use small optical fibers to bring light from the telescope to the spectrograph. This feature allows scientists to see both the color changes caused by planets and the effects of the changing surface of stars which enable discovery and study of even smaller exoplanets that can currently be detected. iLocater is designed to be extremely stable to allow the detection of the incredibly small color change caused by planets to be measured. iLocater will undertake studies of exoplanetary systems to characterize their properties and assess their potential to support life. The project will supply training for graduate students in developing instrumentation and also summer research opportunities for undergraduate students The performance of modern Doppler instruments is dominated by the effects of stellar variability, an effect that imprints the signature of surface inhomogeneities and stochastic motions onto stellar spectra. Such astrophysical jitter imposes a noise floor by creating temporally changing asymmetries in the absorption lines of stellar spectra. This project will complete building a Doppler precision radial velocity instrument that uses adaptive optics (AO) and single-mode fibers (SMFs) on a large telescope to achieve high spectral resolution (R=132,000-273,000). The instrument, named iLocater, will be installed on the Large Binocular Telescope (LBT) in Arizona and operates at the diffraction limit at near-infrared (NIR) wavelengths (YJ-bands). The NIR bandpass is well suited to AO performance, is expected to be less susceptible to stellar variability, and provides access to the peak radiation of late-type stars where the Doppler amplitudes of planets are substantially larger than those orbiting G-type stars. The combination of high spectral resolution and high spatial resolution (41 mas) will facilitate novel research directions, such as studying planets orbiting close separation binaries. On completion iLocater will be available to many US astronomers who are within the LBT community for 30 nights/year and there will be public access to the iLocater data products. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.