J/A+A/328/175 K & M giants equivalent widths (Aoki+ 1997)
High resolution infrared spectroscopy of CN and NH lines:
nitrogen abundance in oxygen-rich giants through K to late M
Aoki W., Tsuji T.
<Astron. Astrophys. 328, 175 (1997)>
=1997A&A...328..175A 1997A&A...328..175A (SIMBAD/NED BibCode)
ADC_Keywords: Stars, giant ; Spectra, infrared ; Equivalent widths
Keywords: stars: abundances - stars: atmospheres - stars: late-type -
stars: AGB and post AGB
Abstract:
The analyses of high resolution infrared spectra have been done for CN
lines in oxygen-rich cool evolved stars including 2 K giants, 20 M
giants and 1 S-type star. Since CN lines analyzed in the present work
are weak and resolved well, they are appropriate for quantitative
analyses. CN lines of {DELTA}v=-2 and -1 sequences (red system) which
are in the K- and the H-window regions, respectively, give the
consistent nitrogen abundance for each star. The analyses of NH lines
in the L-window region have been done for 5 late M giants for which CN
lines have been also analyzed. Although the triplet structure of NH
lines cannot be fully resolved, they are preferable because
determination of nitrogen abundance is almost independent of other
elemental abundances while nitrogen abundance based on CN depends on
carbon abundance. The nitrogen abundances derived from NH for late M
giants agree well with those from CN for which we adopt 7.75eV as the
dissociation energy in the analysis. The results show that the
nitrogen abundances in late M giants are larger than those in early M
giants while decrease of the carbon abundance was found in late M
giants by our previous work (Tsuji, 1991A&A...245..203T 1991A&A...245..203T). These
variations of abundances can not be explained by the first dredge-up
model but require additional processing by the CN cycle and mixing
after the first dredge-up. However, there is no obvious evidence of
other processes such as the 3α-process and subsequent hot bottom
burning in our program stars. Such variation of the carbon and
nitrogen abundances is not well understood by the present evolutionary
models of low-mass and intermediate-mass stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tab10ab 56 1463 CN lines in K- and H-windows region in K and
early M giants
tab10cd 56 1300 CN lines in K- and H-windows region in late M giants
tab10e 62 115 NH lines in L-window region in late M type giants
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Byte-by-byte Description of file: tab10ab tab10cd
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name Star name
12 A1 --- Window [HK] Window
14- 23 A10 --- Line Line
25- 32 F8.3 cm-1 WN Wavenumber
34- 39 F6.3 --- log(gf) log of oscillation strength
41- 49 F9.3 cm-1 LEP Lower excitation potential
51- 56 F6.3 [0.1nm] log(EW) ? Equivalent width
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Byte-by-byte Description of file: tab10e
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Bytes Format Units Label Explanations
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1- 7 A7 ---- Name Star name
9- 15 A7 ---- Line Line
17- 24 F8.3 cm-1 WN Wavenumber
26- 34 F9.3 cm-1 LEP Lower excitation potential
36- 41 F6.3 --- log(gf)1 log of oscillation strength (1)
43- 48 F6.3 --- log(gf)2 log of oscillation strength (1)
50- 55 F6.3 --- log(gf)3 log of oscillation strength (1)
57- 62 F6.3 [0.1nm] log(EW) ? Equivalent width
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Note (1): The equivalent widths are measured for two or three components of
the triplet structure together with the 3 gf values given.
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Acknowledgements: Wako Aoki
(End) Patricia Bauer [CDS] 22-Sep-1997