Phoenix EUV Grid and Stellar UV Spectra (PEGASUS)

The Phoenix EUV Grid and Stellar UV Spectra (PEGASUS) project is a web tool that helps users quickly find a complete spectrum for an exoplanet host star, including the extreme ultraviolet (EUV) portion. A star’s EUV radiation, located at 100-1000 Å, affects the evolution, atmospheric stability, and habitability of close-orbiting planets. However, it is currently impossible to take stellar EUV measurements directly. 

The current beta version of the PEGASUS web tool allows users to input the name or coordinates of an exoplanet host star (M or K spectral type) and identifies a generalized high resolution (Δλ < 0.01 Å) synthetic spectrum from a grid of ~1,500 PHOENIX models. PHOENIX is an established code for modeling stellar atmospheres, and has been identified as the next best option when observed UV spectra are not available.

When users search for a target star in the PEGASUS web tool, the application automatically fills in the required inputs based on existing NASA data catalogs. The properties needed to produce a spectrum are the star’s effective temperature Teff, surface gravity log(g), mass, radius, and distance from Earth, as well as its far ultraviolet (FUV) and near ultraviolet (NUV) flux densities as recorded by NASA’s Galaxy Evolution Explorer (GALEX).

PEGASUS is a collaboration between team members from NASA’s Goddard Space Flight Center, the University of Maryland, and the University of Arizona’s Lunar and Planetary Lab. A full version of the web tool is currently in the works. 

Access the PEGASUS web tool (beta version) and learn more here.