Unmasking Stellar Variability: Hierarchical Bayesian methods for characterization of low-mass planets with EPRV spectroscopy

Project: Research project

Project Details

Description

Exoplanets are planets that orbit stars other than the Sun. One approach for detecting exoplanets looks for a wobble of a star due to the gravitational pull of any orbiting planets. The motion of the star causes changes in the observed color of starlight. The signal of Earth-like exoplanets is very small and can be obscured by or confused with other variations in the star. This challenge is problematic when seeking the signal of an exoplanet. The investigators will characterize the changes that occur due to variations in the star by analyzing starlight. The results will provide a new approach to differentiate the signals of rocky planets from stellar variability. If successful, these new methods will contribute to the detection of potentially Earth-like planets. This research serves our national interest by promoting the progress of science and developing new methods for finding planets. Increasing the reliability of planet detections has the potential to increase public trust in science. The methods and tools developed will be available for researchers and teachers of college-level courses.The detection of low-mass exoplanets is challenging due to the very small signal that low-mass exoplanets induce on the time series of stellar spectra. Another issue is that the effects of stellar activity on the spectra are not sufficiently understood and may hide or mimic a planetary signal. In recent years, progress has been made thanks to the improvements in quality of spectra from new extreme precision radial velocity (EPRV) spectrometers. The increased stability, resolution and/or wavelength coverage of these instruments provides new opportunities for addressing the profound effect that stellar activity plays in obscuring planetary signals or, perhaps worse, mimicking a planetary signal which can lead to false exoplanet detections. Changes in the shapes of spectral lines contain information about stellar activity relevant for disentangling the effects of stellar activity from true Doppler shifts due to low-mass exoplanets. The investigators aim to develop statistical methods that specifically enhance the ability to detect small Doppler shifts and line shape changes, so as to improve the understanding of the effects of stellar activity on spectra. The investigators will develop methods for robust estimation of individual spectral line properties that will be used to build an advanced statistical model for non-planetary radial velocity signals. The methods will be tested using spectra from stars observed by two EPRV spectrometers in order to evaluate the consistency of the methods across different spectrographs. Student research assistants will be recruited from underrepresented minorities and public engagement material will be developed.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.
StatusActive
Effective start/end date9/1/228/31/25

Funding

  • National Science Foundation: $511,163.00

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