Low Resolution Stellar Library (LOWLIB)
Primary Investigator: Guy Worthey
HLSP Authors: Guy Worthey, Tathagata Pal, Islam Khan
Primary Reference(s): Pal et al. 2023
Citations: See ADS Statistics
"Stellar libraries" are collections of stellar spectra. Such libraries find use in population synthesis studies, stellar parameter estimation, exposure time calculators, mission planning, and education.
This HLSP contains 513 stellar spectra in FITS files. The spectra are flux calibrated, dereddened, and shifted to zero velocity. Observed with three low resolution gratings from the HST Space Telescope Imaging Spectrograph(STIS) and then merged into one continuous spectrum, these spectra cover roughly 0.2 < λ < 1 μm at λ/Δλ about 1000. This "HST Low Resolution Stellar Library" extends and supersedes NGSL, the "Next Generation Stellar Library," and comes as a companion to the Hot Star Library (Khan & Worthey 2018, A&A, 615, 115).
The metadata file has the following naming convention:
All spectra files have the following naming convention:
- <target> is the target name, such as "hd011964"
- <prodType> is either "spect" or "preview"
- <ext> is either "fits" or "png"
Data file types:
The metadata file of the spectral library
|The merged, continuous spectra of three low-resolution STIS gratings, which are fluxed, dereddened, and shifted to zero velocity|
The preview image of each spectrum
The data extension (first extension) of the _metadata.csv file contains literature Teff, log g, [Fe/H], dust extinction (AV), K0 scattered light count rate, and other metadata such as star names and standard photometry. Note that B and V are as observed (not dereddened), but M_V_0 is dereddened. The " Av Src" column is for V-band extinction AV: 1 - Koleva & Vazdekis (2012, A&A, 538, A143), 2 - the HLSP team's derivation based on comparison with synthetic templates, or 3 - Drimmel et al (2003, A&A, 409, 205).
The description of the columns in the catalog file
|Simbad name||-||Simbad identifier|
|MAST file||-||MAST filename|
|Teff (K)||K||Effective temperature|
Apparent B band Vega magnitude
|V (mag)||mag||Apparent V band Vega magnitude|
|Plx (mas)||mas||Simbad parallax|
(MV)0 , Absolute V band Vega magnitude
Slit off-center correction
|Vr (km/s)||km/s||Radial velocity|
Scattered light count rate at 2000A
|Av||mag||V -band Extinction|
|Av Src||-||Source reference of extinction|
Mg II 2800 index
|Hbeta (mag)||mag||Hβ index|
|Note||-||Note about the object|
The data extension (first extension) of the _spect.fits files are multi-extension FITS files. Each HDU description is the following. Casual users should choose extension 4 wavelength and fully corrected flux.
|FITS Extension||HDU Type||Description|
|HDU 1||Primary HDU||
Contains no data. The header contains information about basic stellar parameters.
A binary table extension with columns for wavelength (in Angstroms), uncorrected flux, scattered light corrected flux, scattered light & slit off-center corrected flux, and scattered light, slit off-center & dust corrected (fully corrected) flux (fluxes are in erg/s/cm2/Angstrom). Flux errors are also included as separate columns.
A binary table extension with columns for wavelength (in Angstroms), uncorrected count rate, scattered light corrected count rate, scattered light & slit off-center corrected count rate, and scattered light, slit off-center & dust corrected (fully corrected) count rate. Uncertainties are also included as separate columns.
Flux (Log Wavelength Scale):
This binary table extension contains the same information as HDU 2, but rebinned such that the wavelengths are spaced on a uniform log scale with log Delta lambda = 0.0002.
Count Rate (Log Wavelength Scale):
This binary table extension contains the same information as the HDU 3, but rebinned such that the wavelengths are spaced on a uniform log scale with log Δλ = 0.0002.
Spectra are available in the MAST Portal (web-based, cross-mission search interface) and Astroquery (Python package to search for and download files from Python scripts you write), and via the direct download table below. Set the Provenance Name filter to LOWLIB in the Portal Advanced Search to find all or individual spectra. Each observation in the Portal contains a single source's spectra. The spectra can also be retrieved programmatically by using the astroquery—mast module. See the code example below for retrieving and downloading all files. The metadata and spectra files can also be accessed via direct download below.
from astroquery.mast import Observations all_obs = Observations.query_criteria(provenance_name="lowlib") data_products = Observations.get_product_list(all_obs) Observations.download_products(data_products)
A web-based interface for cross-mission searches of data at MAST or the Virtual Observatory
Search for and retrieve LOWLIB data products programmatically.
|hlsp_lowlib_hst_stis_all_g230lb-g430l-g750l_v1.0_metadata.csv||448 KB||Metadata file|
|165 MB||Preview images|