J/ApJS/99/173 Synthetic UV spectra of massive stars (Leitherer+ 1995)
Atlas of synthetic ultraviolet spectra of massive star populations Leitherer C., Robert C., Heckman T.M. <Astrophys. J. Suppl. Ser. 99, 173 (1995)> =1995ApJS...99..173L
ADC_Keywords: Stars, early-type ; Spectra, ultraviolet Keywords: atlases - stars: early-type - stars: mass-loss - stars: Wolf-Rayet - ultraviolet: stars Abstract: An atlas of synthetic ultraviolet spectra of a population of massive stars is presented. The spectra are based on a stellar library of IUE high-dispersion spectra of O and Wolf-Rayet stars, coupled to an evolutionary synthesis code. Later spectral types are included via low-dispersion spectra. Line profiles of N V lambda 1240, Si IV lambda 1400, C IV lambda 1550, He II lambda 1640, and N IV lambda 1720 have been computed for star-formation histories and initial mass functions typically found in starburst regions. It is found that the lines are sensitive indicators for the presence or absence of massive stars. C IV lambda 1550 is the strongest stellar line in the ultraviolet spectrum of a typical starburst. If O stars with zero-age main-sequence masses above 50M☉ are present, C IV always shows a P Cygni profile. In the absence of such stars, only a blue-shifted absorption is present. During later epochs of the starburst, when late-O/early-B stars dominate, an unshifted photospheric absorption appears. Si IV lambda 1400 shows a conspicuous wind profile when luminous O supergiants are present. A strong P Cygni profile is found only for an instantaneous burst observed at 3 to 5Myr, which has a top-heavy IMF. The velocity of the blueshifted absorption is strongly correlated with the age and the upper cutoff mass (or slope) of the IMF. N V lambda 1240 traces the most massive stars and behaves rather similar to Si IV lambda 1400. Its usefulness as an indicator of very massive stars is limited due to the strong blending effect of the nearby Ly-alpha line. Nevertheless, strong N V lambda 1240 emission in a starburst suggests the presence of stars with masses in excess of 60M☉. He II lambda 1640 and N IV lambda 1720 are produced by very hot and luminous O and Wolf-Rayet stars. Both lines can have weak absorption or emission in a typical starburst but are predicted to be observable only under rare circumstances, such as in an instantaneous burst at t~3Myr. The profiles presented in the atlas can be compared to high-quality ultraviolet observations of galaxies with active star formation in order to constrain the massive star population. The atlas is published in its entirety in computer-readable form in the AAS CD-ROM series, Vol. 5. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file models.all 44 123840 *Spectra for 144 models
Note on models.all: There are 8 combinations of cut-off masses and IMF exponents for each of the 9 timesteps so that there are 2 x 9 x 8 =144 files for the two star formation laws (burst and continuous).
Byte-by-byte Description of file: models.all
Bytes Format Units Label Explanations
1 A1 --- Form [bc] b: burst star formation c: continuous star formation 3- 6 F4.2 --- IMF [1.50-3.75] IMF exponents (1.50, 2.35, 3.00 or 3.75) 8- 10 I3 solMass Mass [30-100] Upper cut-off mass (30, 40, 60, 80 or 100 M☉) 12- 14 F3.1 Myr Age [1.0-9.0] Age, in intervals of 1.0 Myr 16- 23 F8.3 0.1nm Lambda [1205.5-1849.75] Wavelength 26- 33 F8.5 [uW/nm] log(Lum) Luminosity per wavelength interval (erg/s/A) 36- 44 F9.7 --- Spectrum Normalized spectrum, which is plotted in the figures in the printed paper.
Origin: AAS CD-ROM series, Volume 5, 1995 Lee Brotzman [ADS] 29-Aug-95
(End) [CDS] 01-Feb-1996
|The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line|