Astrophysics Seminar: Prof. Jonathan Crass, University of Notre Dame


Location: 184 Nieuwland Science Hall (View on map )

Finding Earth-like planets among the noise: Enabling next-generation precision radial velocity measurements

Prof. Jonathan Crass
University of Notre Dame

As we embark on the path to characterize nearby terrestrial worlds, new technologies are required to drive discovery. Highlighted as a key goal in recent strategic recommendations including the 2018 National Academies of Science (NAS) “Exoplanet Science Strategy” report, characterization of rocky worlds requires extremely precise radial velocity (EPRV) measurements to provide mass, density, and orbital information. While the scientific motivation to advance the capabilities of EPRV instruments is well documented, the path to reaching the required 1-10 cm/s RV precision is less clear. Performance of modern Doppler instruments is no longer dominated by instrument systematics, but instead 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.

The NASA-NSF EPRV working group recently published a strategic pathway to overcome current limitations of EPRV instruments on the way achieving the precisions needed to detect Earth-like planets around Sun-like stars. One of the key technologies recommended for study are diffraction-limited spectrographs. iLocater is one of these new types of instruments and is under development at Notre Dame for the dual 8.4m diameter Large Binocular Telescope (LBT). iLocater uses “extreme” adaptive optics (AO) to efficiently inject diffraction-limited starlight into single-mode fibers (SMFs) at near-infrared wavelengths. This offering several technical benefits for EPRV science including increased resolution, elimination of modal noise and a reduced instrument volume.

I will present the findings of the NASA-NSF EPRV working group in addition to giving and overview and update of the iLocater program. iLocater is being integrated and tested at Notre Dame over the next two years with first-light expected at the LBT in 2023.

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