J/ApJ/513/168 HST observations of carbon in spiral galaxies (Garnett+, 1999)
Carbon in spiral galaxies from Hubble space telescope spectroscopy
Garnett D.R., Shields G.A., Peimbert M., Torres-Peimbert S., Skillman
E.D., Dufour R.J., Terlevich E., Terlevich R.J.
<Astrophys. J. 513, 168 (1999)>
=1999ApJ...513..168G 1999ApJ...513..168G
ADC_Keywords: Abundances ; Galaxies, spectra ; Spectra, ultraviolet
Mission_Name: HST
Keywords: galaxies: abundances - galaxies: evolution -
galaxies: individual (M101, NGC 2403) - galaxies: ISM -
galaxies: spiral
Abstract:
We present measurements of the gas-phase abundance ratio C/O in six H
II regions in the spiral galaxies M101 and NGC 2403, based on
ultraviolet spectroscopy using the Faint Object Spectrograph on the
Hubble Space Telescope. The ratios of C to O increase systematically
with O/H in both galaxies, from log(C/O){~=}-0.8 at log(O/H){~=}-4.0
to log(C/O){~=}-0.1 at log(O/H){~=}-3.4. C/N shows no correlation with
O/H. The rate of increase of C/O is somewhat uncertain because of
uncertainty as to the appropriate UV reddening law and uncertainty in
the metallicity dependence on grain depletions. However, the trend of
increasing C/O with O/H is clear, confirming and extending the trend
in C/O indicated previously from observations of irregular galaxies.
Our data indicate that the radial gradients in C/H across spiral
galaxies are steeper than the gradients in O/H. Comparing the data to
chemical-evolution models for spiral galaxies shows that models in
which the massive star yields do not vary with metallicity predict
radial C/O gradients that are much flatter than the observed
gradients.
Description:
All six regions were scanned over the full wavelength region from 1600
to 6900 Å with the four medium-resolution gratings G190H, G270H,
G400H, and G570H, observed through the 0.86'' square (C-1) upper
aperture.
Objects:
-----------------------------------------
RA (2000) DE Designation(s)
-----------------------------------------
14 04 29.02 +54 23 48.8 M101-NGC 5471
14 03 01.16 +54 14 27.0 M101-NGC 5455
14 03 41.62 +54 19 04.4 M101-NGC 5461
07 36 28.63 +65 33 49.0 NGC 2403-VS9
07 36 52.13 +65 36 48.5 NGC 2403-VS38
07 37 06.82 +65 36 38.7 NGC 2403-VS44
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 99 152 Spectra for M101 and NGC 2403 HII regions
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See also:
J/AJ/104/92 : HII Regions Properties in M101 (Scowen+ 1992)
J/A+AS/91/285 : HII galaxies spectrophotometric catalogue (Terlevich+, 1991)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Name H II region name
11- 18 A8 --- Ion Ion
20- 23 I4 0.1nm Wave Wavelength of Ion
30 A1 --- l_Flux Indicates a lower limit in Flux
31- 35 F5.3 --- Flux Observed flux relative to Hβ
37- 41 F5.3 --- e_Flux ? Uncertainty (1σ) in Flux
45 A1 --- l_F3.1 Indicates a lower limit in F3.1
46- 50 F5.3 --- F3.1 Extinction Corrected flux (R=3.1) relative
to Hβ
53- 57 F5.3 --- e_F3.1 ? Uncertainty (1σ) in F3.1
60 A1 --- l_F5 Indicates a lower limit in F5
61- 65 F5.3 --- F5 Extinction Corrected flux (R=5) relative
to Hβ
69- 73 F5.3 --- e_F5 ? Uncertainty (1σ) in F5
76- 79 F4.2 mag A3.1 Extinction (R=3.1) at Hβ
81- 84 F4.2 mag e_A3.1 Uncertainty in A3.1
90- 93 F4.2 mag A5 Extinction (R=5) at Hβ
96- 99 F4.2 mag e_A5 Uncertainty in A5
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History:
From ApJ electronic edition
(End) Greg Schwarz [AAS] 02-Mar-2000