Advanced science.  Applied technology.


Connecting Stars to Planets: Capability Development for M-Dwarf Characterization, 15-R8902

Principal Investigators
Joshua Kammer
Thomas Greathouse
Vincent Hue
Kurt Retherford
Amanda Bayless
Todd Veach
Chris Sneden
Chris Packham
Lindsay Fuller
Inclusive Dates 
01/01/19 to 07/01/20


It is not currently technologically feasible to directly measure the surface composition of a planet outside of our Solar System and yet the overall habitability of a planet is dependent on its internal structure, mineralogy, and atmosphere. However, stars and planets form at roughly the same time and of the same overall starting material. Therefore, we can acquire high resolution spectra of the star, measure the stellar elemental abundances, and extrapolate the likely planetary interior structure and mineralogy using mass-radius models. Historically, stellar abundances for FGK-type stars have been measured in the optical band with very high spectral resolution instruments, because there are a variety of elemental lines available. Unfortunately, the optical band is not as favorable for the cooler M-dwarfs, which are both fainter at optical wavelengths and dominated by large molecular bands that make abundance determination difficult. These weak or blended optical lines result in large error bars in the abundance measurements. Therefore, the use of near-to-mid infrared wavelengths (1-5 microns) is preferable because M-dwarfs are much brighter, have cleaner spectra, and yield more reliable abundance. However, to date the stellar abundances for only a handful of elements in approximately 150 M-dwarfs have been determined in the near-infrared.


First, we further developed an existing model of stellar spectra and elemental line analysis to determine consistent and accurate estimation of M-dwarf abundances from near-infrared spectra. Second, the results of this data analysis expanded upon an existing database of stellar properties, filling in critical gaps in our knowledge of M-dwarf properties. Lastly, because the infrared wavelengths are not well accessible from the ground, we developed and proposed for dedicated near-infrared (NIR) space flight instruments.


We accomplished all our objectives such that we were able to test our NIR stellar abundance methodology on ground-based data. Using our background and test cases, we have applied for three NASA announcements of opportunities: Astrophysics Research and Analysis for a sub-orbital balloon, Exoplanet Research Program to further develop our abundance technique, and Astrophysics Pioneers for a sub-orbital balloon.