Abstract
We have identified lines from the 0-3, 0-4, 0-5, 0-6, 0-7, 1-3, 1-4, 1-7, and 1-8 bands of the (MgH)-Mg-24 B' (2)Sigma(+)-X (2)Sigma(+) transition in sunspot umbral spectra. Lines of the 0-7 and 1-8 bands in the uncluttered 7500 Angstrom region are the most obvious, but B' (2)Sigma(+) -X (2)Sigma(+) lines have been tracked as far to the blue as 5300 Angstrom. In combination with weak lines of the 0-7 bands of the (MgH)-Mg-25 and (MgH)-Mg-26 isotopes, the solar isotope ratio Mg-24:Mg-25:Mg-26 has been measured as 76:12:12, in agreement with the much better determined terrestrial ratio 79:10:11. The intensity distribution of bands with nu " from 4 to 8 has been measured and found to show no anomalies; the excitation temperature of 3100 K agrees well with a value of 3200 K determined from SiO in a sunspot spectrum. The lines of the MgH B' (2)Sigma(+)-X (2)Sigma(+) transition are much more cleanly separated and much less blended than lines from the stronger A (2)Pi-X (2)Sigma(+) transition. The B' (2)Sigma(+)-X (2)Sigma(+) lines should prove useful in isotopic abundance analyses for stars where the A (2)Pi-X (2)Sigma(+) transition is too strong to yield useful results.
| Original language | English |
|---|---|
| Pages (from-to) | 454-461 |
| Number of pages | 8 |
| Journal | The Astrophysical Journal |
| Volume | 524 |
| Issue number | 1 |
| Publication status | Published - 10 Oct 1999 |
Keywords
- molecular data
- Sun : abundances
- sunspots
- METAL-RICH STARS
- SPECTRUM
- POOR