Frequently Asked Questions (FAQ)
Yes, but the required inputs (Teff, log(g), mass, radius, distance, and GALEX FUV and NUV flux densities) must be entered manually via this form on the home page.
This is because we query the NExSci archive for these parameters, which only contains information regarding exoplanet host stars.
This is because we query the NExSci archive for these parameters, which only contains information regarding exoplanet host stars.
GALEX was an all sky survey that measured FUV and NUV photometry for stars of all ages and masses and therefore many M and K stars have this data available.
Further, stellar FUV and NUV flux originates in the chromosphere and transition region, overlapping heavily with the formation temperatures of the EUV.
The EUV forms in the transition region and corona, with most of the shorter EUV wavelengths (<400 Å) originating from the hottest coronal layers and the bulk of the EUV wavelengths (400-912 Å) coming from the transition region. To constrain the full upper atmosphere with corona requires contemporaneous X-ray and UV measurements, and since that's not readily available for all exoplanet host stars, the models do not include coronae.
That being said, the GALEX measurements are sufficient to constrain the temperature structure in the chromosphere and transition region (up to 200,000 K), and so we are able to confidently predict the majority of the EUV spectrum.
The EUV forms in the transition region and corona, with most of the shorter EUV wavelengths (<400 Å) originating from the hottest coronal layers and the bulk of the EUV wavelengths (400-912 Å) coming from the transition region. To constrain the full upper atmosphere with corona requires contemporaneous X-ray and UV measurements, and since that's not readily available for all exoplanet host stars, the models do not include coronae.
That being said, the GALEX measurements are sufficient to constrain the temperature structure in the chromosphere and transition region (up to 200,000 K), and so we are able to confidently predict the majority of the EUV spectrum.
If your star has no GALEX measurement: A proxy can be identified from this table [INSERT TABLE]
If your star only has a GALEX detection in one band: We will estimate the flux density in the missing band with the following relations:
If your star only has a GALEX detection in one band: We will estimate the flux density in the missing band with the following relations:
For Early M Stars: log10(FUV) = (1.14±0.03) * log10(NUV) - (1.17±0.09) (Richey-Yowell et al. 2023)
For Late M Stars: log10(FUV) = (0.96±0.02) * log10(NUV) - (0.43±0.04) (Richey-Yowell et al. 2023)
If a detection is flagged as an upper or lower limit: We will return all models that satisfy the condition, returning the model that most closely matches the limit as the “Best Match”
Try searching by ICRS coordinates OR enter the parameters manually through the drop-down link on the Home page.
Our search function queries multiple databases, and one of these resources may be down temporarily. You may enter the parameters manually or try again at a later time.
Wavelengths are given in Angstroms and are in vacuum. Please note that the wavelength grid is not uniformly spaced. The flux densities are given in ergs/cm2/s/Å and are scaled to the stellar surface.
The models are computed with high wavelength sampling (Δλ = 0.01 Å) at wavelengths below 6000 Å and lower wavelength sampling above 6000 Å (Δλ ≥ 3 Å). Additional wavelength points are added to each non-LTE emission line.
There is no added noise to the models. The apparent noisiness is the result of thousands of emission lines that are included in our models.