A STELLAR SPECTRAL FLUX LIBRARY BY A.J. PICKLES (1998)
(PASP 110, 863)
This library of wide spectral coverage, consists of 131 flux calibrated
stellar spectra, encompassing all normal spectral types and luminosity
classes at solar abundance, and metal-weak and metal-rich F-K dwarf
and G-K giant components. Each spectrum in the library is a combination of
several sources overlapping in wavelength coverage. The creator of the
library has followed precise criteria to combine sources and to assemble
the most reliable spectra. As part of the selection criteria prior to
combination, all input sources were checked aginst the SIMBAD database
and against the colors and line strengths as derived by the observed
spectra themselves to make sure they had similar spectral types.
In the following, the list of the above mentioned input sources is given,
numbered following Table 1 in the original paper.
1) Sviderskiene (1988)
2) Heck et al. (1984)
3) Gunn and Stryker (1983)
4) Kiehling (1987)
5) Jacobi, Hunter and Christian (1984)
6) Silva and Cornell (1992)
7) Pickles (1985)
8) Pickles and van der Kruit (1990)
9) Serote Roos, Boisson and Joly (1996)
10) Danks and Dennefeld (1994)
11) Lancon and Rocca-Volmerange (1992)
12) Dallier, Boisson and Joly (1996)
13) Kleinmann and Hall (1986)
14) Cohen et al. (1995, 1996a, 1996b)
15) Fluks et al. (1994)
Table 1 of Pickles (1998) precisely identifies what of the above sources
entered the combination to create the complete set of spectral types.
The output wavelength grid was chosen to be 1150-25000 Angstrom,
with a sampling interval of 5 Angstrom per pixel and resolution of
~500 Angstrom. In the end, two separate libraries were created, UVILIB and
UVKLIB, that cover the spectral range 1150-10620 Angstrom, and 1150-25000
Angstrom, respectively. In fact, only half of all spectral types in the
library (mainly later types of solar abundance) have longer spectral coverages
available.
The following quick-look table gives an idea of the spectra available.
Spectra are ordered by progressive number, according to the spectral type
(decreasing effective temperature) and luminosity class. The same ordering
sequence is valid for both the UVILIB and the UVKLIB libraries, where the suffix
"uk" differentiates between two spectra of the same spectral type but with
different wavelength coverage (see ahead the section on the CDBS/HST Pickles
library).
Table 1: Pickles library spectra:
spectrum id no. spectral types
and luminosity class
1-45 O5-M6 V
46-59 B2-K3 IV
60-105 O8-M10 III
106-113 B2-M3 II
114-131 B0-M2 I
Some reasons why it is worth to use this library may be summarized as follows:
1) it provides an uniform and complete flux library of observed spectra
representing normal stellar types, and
2) each spectrum was put together after selecting the best spectra in each
wavelength interval, grouping them by spectral type, luminosity class and
abundance (and color and line strength), to produce a final product with
an uniform grid.
THE HST/CDBS VERSION OF THE PICKLES LIBRARY
The library installed in CDBS and distributed within STSDAS is from
http://cdsarc.u-strasbg.fr/viz-bin/ftp-index?J/PASP/110/863.
This library is divided in 2 independent subdirectories, according to
spectral coverage, and exactly reproducing the structure of the original
library by Pickles. Subdirectory dat_uvi groups all spectra derived
from all ultraviolet, optical and near infrared sources, in the wavelength
range 1150-10620 Angstrom. This library has complete spectral coverage for
all components over this wavelength range, and is (in the original library)
referred to as UVILIB. Subdirectory dat_uvk groups all spectra that were
derived by combining the UVILIB spectra with additional infrared data to a
long wavelength limit of 25000 Angstrom. This is originally referred to as
UVKLIB. Within each subdirectory each spectrum is given in STSDAS table
format: the first column gives the wavelength for the given spectral range,
and the second column gives the flux. Fluxes are tabulated in units of
erg/s/cm^2/A and were calculated by normalizing the original fluxes in the
Pickles V band to a 0 magnitude in vegamag. In the vegamag system, Vega has
magnitude zero in all passbands.
For the UVILIB spectra, the names of the files are given as pickles_ttt.fits
where "pickles", for Pickles, is the library identifier and "ttt" is a number
ranging from 1 to 131. For the UVKLIB spectra, the names have the format
pickles_uk_ttt.fits, following the same nomenclature, and with the suffix
"uk" provided as to distinguish them from the shorter wavelength library.
The complete list of stars of different spectral type and luminosity class
together with the corresponding Pickles file is presented in Table 2.
The effective temperature information is extracted from Table 2 of Pickles
(1998). A "w" or an "r" preceding the spectral type indicates a
"weak" or "rich" metallicity in respect to solar.
Table 2: Spectral type and Effective temperature corresponding to the Pickles
spectra in the library.
FILENAME SPTYPE EFF TEMP.
(K)
pickles_uk_1 O5V 39810.7
pickles_uk_2 O9V 35481.4
pickles_uk_3 B0V 28183.8
pickles_uk_4 B1V 22387.2
pickles_uk_5 B3V 19054.6
pickles_uk_6 B5-7V 14125.4
pickles_uk_7 B8V 11749.0
pickles_uk_9 A0V 9549.93
pickles_uk_10 A2V 8912.51
pickles_uk_11 A3V 8790.23
pickles_uk_12 A5V 8491.80
pickles_uk_14 F0V 7211.08
pickles_uk_15 F2V 6776.42
pickles_uk_16 F5V 6531.31
pickles_uk_20 F8V 6039.48
pickles_uk_23 G0V 5807.64
pickles_uk_26 G2V 5636.38
pickles_uk_27 G5V 5584.70
pickles_uk_30 G8V 5333.35
pickles_uk_31 K0V 5188.00
pickles_uk_33 K2V 4886.52
pickles_uk_36 K5V 4187.94
pickles_uk_37 K7V 3999.45
pickles_uk_38 M0V 3801.89
pickles_uk_40 M2V 3548.13
pickles_uk_43 M4V 3111.72
pickles_uk_44 M5V 2951.21
pickles_uk_46 B2IV 19952.6
pickles_uk_47 B6IV 12589.3
pickles_uk_48 A0IV 9727.47
pickles_uk_49 A4-7IV 7943.28
pickles_uk_50 F0-2IV 7030.72
pickles_uk_51 F5IV 6561.45
pickles_uk_52 F8IV 6151.77
pickles_uk_53 G0IV 5929.25
pickles_uk_54 G2IV 5688.53
pickles_uk_55 G5IV 5597.57
pickles_uk_56 G8IV 5308.84
pickles_uk_57 K0IV 5011.87
pickles_uk_58 K1IV 4786.30
pickles_uk_59 K3IV 4570.88
pickles_uk_60 O8III 31622.8
pickles_uk_61 B1-2III 19952.6
pickles_uk_63 B5III 14791.1
pickles_uk_64 B9III 11091.8
pickles_uk_65 A0III 9571.94
pickles_uk_67 A5III 8452.79
pickles_uk_69 F0III 7585.78
pickles_uk_71 F5III 6531.31
pickles_uk_72 G0III 5610.48
pickles_uk_73 G5III 5164.16
pickles_uk_76 G8III 5011.87
pickles_uk_78 K0III 4852.89
pickles_uk_87 K3III 4365.16
pickles_uk_93 K5III 4008.67
pickles_uk_95 M0III 3819.44
pickles_uk_100 M5III 3419.79
pickles_uk_105 M10III 2500.35
pickles_uk_106 B2II 15995.6
pickles_uk_107 B5II 12589.3
pickles_uk_108 F0II 7943.28
pickles_uk_109 F2II 7328.25
pickles_uk_110 G5II 5248.07
pickles_uk_111 K0-1II 5011.87
pickles_uk_112 K3-4II 4255.98
pickles_uk_113 M3II 3411.93
pickles_uk_114 B0I 26001.6
pickles_uk_117 B5I 13396.8
pickles_uk_118 B8I 11194.4
pickles_uk_119 A0I 9727.47
pickles_uk_121 F0I 7691.30
pickles_uk_122 F5I 6637.43
pickles_uk_123 F8I 6095.37
pickles_uk_124 G0I 5508.08
pickles_uk_126 G5I 5046.61
pickles_uk_127 G8I 4591.98
pickles_uk_128 K2I 4255.98
pickles_uk_130 K4I 3990.25
pickles_uk_131 M2I 3451.44
A similar list applies for the UKVKLIB library. For these spectra the names
have the format "pickles_uk_ttt.fits". A reduced form of Table 2 can also
be found in the library installed in CDBS and is named pickles.fits for the
spectra in dat_uvi, and pickles_uk.fits for the spectra in dat_uvk directory.
A "w" or an "r" preceding the spectral type indicates a "weak" or "rich"
metallicity in respect to solar.
USE OF THE PICKLES STAR SPECTRA WITH SYNPHOT
Use of these spectra should be exactly similar to other libraries already
available in synphot. The desired spectrum is provided in input in any of
the synphot tasks as appropriate with no particular syntax. For examples on
how to use spectra from the synphot atlas library, please refer to the
Synphot Data User's Guide
(http://www.stsci.edu/hst/HST_overview/documents/synphot/hst_synphot_cover.html).
APPENDIX
Below is an example of a standard header file for the spectrum
pickles_uk_51.fits. This spectrum corresponds to a star of spectral type
F5IV and covers a range in wavelength of 1150 to 25000 Angstrom
as can be assumed by the suffix "uk", which indicates a spectrum of the
UVKLIB library.
1 SIMPLE b T Fits standard
2 BITPIX i 16 Bits per pixel
3 NAXIS i 0 Number of axes
4 EXTEND b T File may contain extensions
5 DATE t '2007-01-11T21:02:21' Date FITS file was generated
6 IRAF-TLM t '16:02:37 (11/01/2007)' Time of last modification
7 COMMENT t FITS (Flexible Image Transport System) format is defined in 'Astronomy
8 COMMENT t and Astrophysics', volume 376, page 359; bibcode: 2001A&A...376..359H
9 ORIGIN t 'STScI-STSDAS/TABLES' Tables version 2002-02-22
10 FILENAME t 'pickles_uk_51.fits' name of file
11 NEXTEND i 1 number of extensions in file
12 COMMENT1 t spectral type: F5IV
13 COMMENT2 t metallicity: solar
14 COMMENT3 t original filename: ukf5iv.dat
15 HISTORY t File created by F.R.Boffi.
16 HISTORY t SEDs from Pickles UVKLIB Library (1998, PASP 110, 863).
17 HISTORY t Wavelength is in Angstrom.
18 HISTORY t Fluxes are tabulated in units of erg/s/cm2/A
19 HISTORY t and were calculated by normalizing the original fluxes
20 HISTORY t in the Pickles V band to a 0 magnitude in vegamag.
21 HISTORY t In the vegamag system, Vega has magnitude zero in all passbands.
22 HISTORY t Please refer to the SYNPHOT manual for further information.
