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The PEGASUS webtool identifies a generalized high resolution (Δλ < 0.01 Å) synthetic extreme ultraviolet (EUV; 100-1000 Å) spectrum for a searched target exoplanet host star (M or K spectral type) from a grid of ~1,500 PHOENIX spectra with Teff = 2500 - 5044 K, log(g) = 4.45 - 5.32 cm/s2, and M = 0.08 - 0.89 Msun.
Required inputs for returning a spectrum are Teff, log(g), mass, radius, distance, and GALEX FUV and NUV flux densities.
Teff, log(g), and mass are used for two purposes:
The PEGASUS webtool queries the NExSci catalog for Teff, log(g), mass, radius, and distance. Please confirm that the values you select are correct for your target. Clicking on the NExSci hyperlink on the modal with returned values will navigate you to that star's NASA Exoplanet Archive Summary page, which may provide additional options for stellar parameters.
The PEGASUS webtool queries GALEX catalog 6/7 for FUV and NUV flux densities. It queries the catalog by RA and dec, which have been corrected for proper motion via the values returned by the GAIA EDR3 catalog.
If you make use of the synthetic spectra downloaded from the PEGASUS webtool, please cite Peacock et al. (2023).
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The data file naming convention is as follows:
PEGASUS.<SpT>.Teff=<Teff>.logg=<logg>.TRgrad=<TRgrad>.cmtop=<cmtop>.cmin=<cmin>.fits
Where
<SpT> = Spectral subtype of the model
<Teff> = Effective Temperature of the model in K
<logg> = Log of the surface gravity of the model in cm s2
<TRgrad> = Log of the temperature gradient in the transition region in K dyne-1 cm2
<cmtop> = Log of the column mass at the top of the chromosphere (absolute value) in g cm-2
<cmin> = Log of the column mass at the temperature minimum (absolute value) in g cm-2
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Python Script to Run
from astropy.io import fits
import matplotlib.pyplot as plt
spec = fits.getdata('PEGASUS.M0.Teff=3850.logg=4.78.TRgrad=8.5.cmtop=6.5.cmin=3.5.fits',1)
plt.plot(spec['WAVELENGTH'],spec['FLUX'])
plt.suptitle('Synthetic EUV spectrum for <STAR>')
plt.xlabel('Wavelength (Å)')
plt.ylabel('Flux Density (erg/cm2/s/Ang)')
plt.xrange(100,1000)
plt.show()