New NLTE Model SEDs For OB Stars (NLTE-OBGRID)
Primary Investigator: Ralph Bohlin
HLSP Authors: Ralph Bohlin, Jessica Krick, Karl Gordon, Ivan Hubeny
Primary Reference(s): Bohlin et al. 2022
Citations: See ADS Statistics
Ivan Hubeny has updated the TLusty OB NLTE model SED grids of Lanz & Hubeny (2003) and Lanz & Hubeny (2007) using a more complete hydrogen atom to produce more realistic IR flux predictions. In particular, the new NLTE spectra have a much better description of line confluences and of the contribution to the opacity in very high series members. In addition, there are improvements in the treatment of the hydrogen and He II continua from high levels, inclusion of more scattering opacity sources, and updates to the physics of level dissolution. Each model has 29957 points at constant spectral resolution of R=5000 and a micro-turbulent velocity of 2 km/s. The Asplund et al. (2009) element abundances are used for computing the spectra.
The grid contains 1082 model pairs of spectra and continua and covers effective temperature Teff in the range 15,000-55,000 K and surface gravity log(g) between 1.75 and 4.75, with steps of 0.25. The steps in Teff are 1,000 K between 15,000 and 29,000 K and 2,500 K between 30,000 and 55,000 K. As Teff rises, more of the unstable lower surface gravities are omitted. There are five metallicity values log Z=[M/H] of 0.301, 0.000, -0.301, -0.70, and -1.00, which correspond to Z=2, 1, 0.5, 0.2, and 0.1, where Z=1 is the solar value. The continuum spectra have a coarser wavelength scale than the spectra.
Both ASCII text and FITS versions of the SEDs are provided. The wavelengths are in Angstroms measured in vacuum, while the fluxes are in erg/cm2/s/Angstrom.
The SEDs are sorted into subdirectories "b-star" or "o-star", and have the following file naming convention:
- <modcode> = Encapsulates the stellar parameters for this model. Example: z02t23000g325v2.
- <z##> = Metallicity, examples: "z02" corresponds to Z=0.2, "z20" corresponds to Z=2.0
- <t#####> = Effective tempreature, examples: "t42500" corresponds to Teff = 42,500 K
- <g###> = log(g), example: "g325" corresponds to a log(g) = 3.25
- <v2> = Microturbulent velocity, which is set to 2 km/s for all SEDs.
- "r5000" = a reminder that the spectral resolution is in steps of a constant 5000 Angstroms
- <type> = "spec" or "cont" for the spectrum and continuum SEDs, respectively.
- <ext> = "txt" or "fits" for ASCII text or FITS versions of the SEDs.
Data file types:
|_spec.txt, _spec.fits||SED spectra.|
|_cont.txt, _cont.fits||SED continua.|
Download the set of SED models using the curl scripts provided. curl is likely already installed on most operating systems; if not, consult the official page for installation instructions prior to running these download scripts. The total size of the SED model grid after downloading them through the shell scripts are provided for reference in the table below.
|Star Types||SED FITS Files||SED ASCII Files|
|B Stars||hlsp_nlte-obgrid_tlusty208_model_b-star_r5000_v1_bulk-dl-fits.sh (~654 MB)||hlsp_nlte-obgrid_tlusty208_model_b-star_r5000_v1_bulk-dl-txt.sh (~1.3 GB)|
|O Stars||hlsp_nlte-obgrid_tlusty208_model_o-star_r5000_v1_bulk-dl-fits.sh (~244 MB)||hlsp_nlte-obgrid_tlusty208_model_o-star_r5000_v1_bulk-dl-txt.sh (~472 MB)|