The MUSCLES Treasury Survey
Measurements of the Ultraviolet Spectral Characteristics
of Low-mass Exoplanetary Systems



Extrasolar planets orbiting M dwarfs may represent our best chance to discover habitable worlds in the coming decade. The ultraviolet spectrum incident upon both Earth-like and Jovian planets is critically important for proper modeling of their atmospheric heating and chemistry. In order to provide a more realistic input for atmospheric models of planets orbiting low-mass stars, we have acquired ultraviolet and X-ray observations of 8 M dwarf* and 4 K dwarf exoplanet host stars using the Hubble Space Telescope, the Chandra X-ray Observatory, and XMM-Newton. For all the stars, we have assembled panchromatic 5 A - 5.5 micron spectral energy distributions (SEDs), available for download on MAST. This website is designed to be a community resource for studies of exoplanetary atmospheres.
*We recently created a panchromatic SED of Proxima Centauri and made it available on MAST.

MUSCLES Treasury Survey Targets:

The High-Level Science Products and Access Instructions: All the MUSCLES High-Level Science Products are hosted on MAST. We recommend downloading Primary Data Products #3 or #4 for each star. The constant spectral resolution files (#3) will be smaller in size (3.6 MB) than the variable spectral resolution files (#4, 106 MB).

This screenshot from MAST shows example hyperlinks that users should use to download the full panchromatic SEDs. To download GJ 436's primary data product #3 in FITS format, select the link highlighted by the green box. To download GJ 1214's primary data product #4 in FITS format, select the link highlighted by the red box.

Reading in and plotting the downloaded data: The README file provides a full description of the data and should be read through by all users, but we summarize briefly how you can quickly read-in and plot an SED in Python and IDL.

This example is specifically for the file "hlsp_muscles_multi_multi_gj436_broadband_v10_adapt-const-res-sed.fits", which is highlighted in the green box in the figure.

Python:
from astropy.io import fits
import matplotlib.pyplot as plt
spec = fits.getdata('hlsp_muscles_multi_multi_gj436_broadband_v10_adapt-const-res-sed.fits',1)
plt.plot(spec['WAVELENGTH'],spec['FLUX'])
plt.xlabel('Wavelength (Angstroms)')
plt.ylabel('Flux Density (erg/cm^2/s^1/A^1)')
plt.show()

IDL:
data_436 = MRDFITS(path+'hlsp_muscles_multi_multi_gj436_broadband_v10_adapt-const-res-sed.fits',1,head_436)
wave = data_436.wavelength
flux = data_436.flux
error = data_436.error
plot,wave,flux,xs=1,ys=1,xr=[10,50000],yr=[0.001,10000]*1d-15,/ylog,/xlog,TITLE='GJ 436; MUSCLES Example',xtitle='Wavelength (Ang)',ytitle='Observed Flux Density (erg/cm2/s/Ang)',charsize=1.75

Papers describing the MUSCLES Treasury Survey:

The Original MUSCLES Pilot Survey:

Example papers that have utilized MUSCLES data products:

The MUSCLES Team:

Acknowledgement: If you download and use the MUSCLES spectra for scientific analysis, we request that you cite France et al. 2016 and include the following brief acknowledgement: "This work has made use of the MUSCLES Treasury Survey High-Level Science Products; doi:10.17909/T9DG6F."

The MUSCLES website is hosted by the Center for Astrophysics and Space Astronomy, University of Colorado. The MUSCLES logo was designed by Sarah LeVine.