Poster Open Access


David Wilson; The Mega-MUSCLES Collaboration

M dwarf stars have emerged as ideal targets for exoplanet observations. Their small radii aids planetary discovery, their close-in habitable zones allow short observing campaigns, and their red spectra provide opportunities for transit spectroscopy with JWST. The potential of M dwarfs has been underlined by remarkable systems such as the seven Earth-sized planets orbiting TRAPPIST-1 and the habitable-zone planet around Proxima Centauri. 


Assessing the characteristics of such planets requires a firm understanding of how M dwarfs differ from the Sun, beyond just their smaller size and mass. Of particular importance are the time-variable, high-energy ultraviolet and x-ray regions of the M dwarf spectral energy distribution (SED), which can influence the chemistry and lifetime of exoplanet atmospheres, as well as their surface radiation environments. Unfortunately, those wavebands are extremely faint for most M dwarfs, requiring too large an investment of telescope time to obtain data at most stars.

The Measurements of the Ultraviolet Spectral Characteristics of Low-mass Exoplanetary Systems (Mega-MUSCLES) Treasury project, together with the precursor MUSCLES project, will produce full SEDs of a representative sample of M dwarfs, covering a wide range of stellar mass, age, and planetary system architecture. We have obtained x-ray and ultraviolet data for 12 stars using the Hubble, Chandra and XMM space telescopes, along with state-of-the-art DEM modelling to fill in the unobservable extreme ultraviolet regions. Our completed SEDs will be available as a community resource, with the aim that a close MUSCLES analogue should exist for most M dwarfs of interest.

Files (2.1 MB)
Name Size
1.8 MB Download
264.2 kB Download
All versions This version
Views 2727
Downloads 2525
Data volume 46.2 MB46.2 MB
Unique views 2626
Unique downloads 2424


Cite as