MAST Preval et al. STIS-FUSE White Dwarf Spectral Atlas

A Comprehensive UV Spectral Linelist of White Dwarf G191-B2B

Preval et al. 2013, MNRAS, 436, 659

Introduction

Data Format

Data Access And Interactive Plot Tool


Fig. 1: Co-added spectrum from 48 FUSE observations (LWRS, MDRS, and HIRS).	Fig. 2: Co-added spectrum from 98 STIS observations (E140H, E230H gratings).

Introduction

A team led by Simon Preval have created one of the most complete UV linelists of a white dwarf. Co-adding over 150 spectra from both HST STIS and FUSE, the team was able to identify nearly 950 absorption lines with equivalent widths as small as a few mÅ. They were able to identify every observed feature in the coadded FUSE spectrum, and nearly every feature in the coadded STIS spectrum. In addition to line identification, the team was able to measure abundances for 9 elements (C, N, O, Al, Si, P, S, Fe, Ni).

For full details of the data reduction, line identification, and analysis, we refer the reader to the original paper. At MAST, we provide the complete linelist, as well as the spectra (individual and coadded versions), as a High Level Science Product. The linelist is provided as an ASCII text table, while the spectra are in FITS format, as explained in the Data Format section below. An interactive plotting tool for users to explore these high quality white dwarf spectra is provided as links in the Atlas table below. Note that the HST STIS spectra did not have additional dispersion corrections as suggested by Ayres (2010) applied, but a future release may include versions of the spectra with these corrections.

Data Format

HST FITS

The FITS headers and data format of the HST HLSP files are summarized in this table (show / hide).

HST Individual Epoch Files
Primary Header (HDU0)
*Header Keywords*
TELESCOP	string	Telescope designation ("HST")
INSTRUME	string	Instrument used ("STIS")
TARGNAME	string	Name of target
OBSID	string	MAST Dataset ID of original observation
DATE-OBS	string	Time at start of observation (YYYY-MM-DDTHH:MM:SS)
EXPTIME	float	Total exposure time (seconds)
EXPSTART	float	Start of observation (MJD)
EXPEND	float	End of observation (MJD)
GRATING	string	Grating setting used
RA_TARG	float	Right Ascension (degrees)
DEC_TARG	float	Declination (degrees)
RADESYS	string	Astrometric reference system
EQUINOX	float	Equinox of the coordinates
HLSPLEAD	string	HLSP lead contact
PR_INV_L	string	Principle investigator last name
PR_INV_F	string	Principle investigator first name
WAVEUNIT	string	Wavelength unit of measure
WAVEMIN	string	Minimum wavelength in spectrum
WAVEMAX	string	Maximum wavelength in spectrum
AIRORVAC	string	Are wavelengths measured in air or vacuum? (One of "AIR" or "VAC")
First Extension (HDU1)
*Binary FITS Table (3 Columns)*
WAVE	float	Wavelength in Å
FLUX	float	Flux in ergs/cm^2/s/Å
ERROR	float	1-sigma flux uncertainty in ergs/cm^2/s/Å

HST Coadd Files
Primary Header (HDU0)
*Header Keywords*
TELESCOP	string	Telescope designation ("HST")
INSTRUME	string	Instrument used ("STIS")
TARGNAME	string	Name of target
GRATING	string	Grating setting used
RA_TARG	float	Right Ascension (degrees)
DEC_TARG	float	Declination (degrees)
RADESYS	string	Astrometric reference system
EQUINOX	float	Equinox of the coordinates
HLSPLEAD	string	HLSP lead contact
PR_INV_L	string	Principle investigator last name
PR_INV_F	string	Principle investigator first name
WAVEUNIT	string	Wavelength unit of measure
WAVEMIN	string	Minimum wavelength in spectrum
WAVEMAX	string	Maximum wavelength in spectrum
AIRORVAC	string	Are wavelengths measured in air or vacuum? (One of "AIR" or "VAC")
First Extension (HDU1)
*Binary FITS Table (5 Columns)*
WAVE	float	Wavelength in Å
FLUX	float	Flux in ergs/cm^2/s/Å
ERROR	float	1-sigma flux uncertainty in ergs/cm^2/s/Å
TIME_EL	float	Exposure time per wavelength bin in seconds
SIGNOI	float	Signal-to-noise per wavelength bin

(show / hide)

FUSE FITS

The FITS headers and data format of the FUSE HLSP files are summarized in this table (show / hide).

FUSE Individual Epoch Files
Primary Header (HDU0)
*Header Keywords*
TELESCOP	string	Telescope designation ("FUSE")
INSTRUME	string	Instrument used ("FUV")
INSTMODE	string	Instrument mode used ("HIST")
APERTURE	string	Aperture used ("LWRS","MDRS", or "HIRS")
TARGNAME	string	Name of target
OBSID	string	MAST Dataset ID of original observation
DATE-OBS	string	Time at start of observation (YYYY-MM-DDTHH:MM:SS)
EXPTIME	float	Total exposure time (seconds)
EXPSTART	float	Start of observation (MJD)
EXPEND	float	End of observation (MJD)
RA_TARG	float	Right Ascension (degrees)
DEC_TARG	float	Declination (degrees)
RADESYS	string	Astrometric reference system
EQUINOX	float	Equinox of the coordinates
HLSPLEAD	string	HLSP lead contact
PR_INV_L	string	Principle investigator last name
PR_INV_F	string	Principle investigator first name
WAVEUNIT	string	Wavelength unit of measure
WAVEMIN	string	Minimum wavelength in spectrum
WAVEMAX	string	Maximum wavelength in spectrum
AIRORVAC	string	Are wavelengths measured in air or vacuum? (One of "AIR" or "VAC")
First Extension (HDU1)
*Binary FITS Table (3 Columns)*
WAVE	float	Wavelength in Å
FLUX	float	Flux in ergs/cm^2/s/Å
ERROR	float	1-sigma flux uncertainty in ergs/cm^2/s/Å

FUSE Coadd Files
Primary Header (HDU0)
*Header Keywords*
TELESCOP	string	Telescope designation ("FUSE")
INSTRUME	string	Instrument used ("FUV")
INSTMODE	string	Instrument mode used ("HIST")
APERTURE	string	Aperture used ("LWRS","MDRS", or "HIRS")
TARGNAME	string	Name of target
RA_TARG	float	Right Ascension (degrees)
DEC_TARG	float	Declination (degrees)
RADESYS	string	Astrometric reference system
EQUINOX	float	Equinox of the coordinates
HLSPLEAD	string	HLSP lead contact
PR_INV_L	string	Principle investigator last name
PR_INV_F	string	Principle investigator first name
WAVEUNIT	string	Wavelength unit of measure
WAVEMIN	string	Minimum wavelength in spectrum
WAVEMAX	string	Maximum wavelength in spectrum
AIRORVAC	string	Are wavelengths measured in air or vacuum? (One of "AIR" or "VAC")
First Extension (HDU1)
*Binary FITS Table (5 Columns)*
WAVE	float	Wavelength in Å
FLUX	float	Flux in ergs/cm^2/s/Å
ERROR	float	1-sigma flux uncertainty in ergs/cm^2/s/Å
TIME_EL	float	Exposure time per wavelength bin in seconds
SIGNOI	float	Signal-to-noise per wavelength bin

(show / hide)

Linelist ASCII Tables

The columns of the ASCII linelist files are summarized in this table (show / hide).

Data Access And Interactive Plot Tool

Use the "plotter" links to visit the interactive plot tool and preview spectra (zoom, etc). Expand the table by clicking on the "Show Individual Spectra Rows" to see any of the spectra that went into the coadds. You can also download files through your browser or download a tarball (~77 MB) containing all of the FITS files and linelist catalogs.

^†The FUSE coadd spectrum has not been corrected for shifts in the individual segments. This has resulted in several line velocities deviating from the accepted values of Preval et al. (2013), who found the photospheric and two ISM components to have velocities of 23.8, 19.4, and 8.64 km/s respectively. According to Dobbie et al. (2005), the uncertainties in the absolute velocity uncertainty of FUSE spectra can be as large as 20km/s, which is in agreement with the largest velocity we found of > 30 km/s (see Table B1 in Preval et al. 2013).