Spectrographic Studies in the Red
Abstract
I. The spectrum of the companion of the Andromeda nebi4ci (M 32) has been photo- graphed to about X 7600. Attempts have been made to find the forbidden Ca~ lines 42S_32D (XX 7291, 7324) in emission, but the low-dispersion spectra obtained give no certain evidence for the presence of these lines. The D lines of sodium are considerably stronger in the spectrum of the nebula than in that of the sun, but otherwise the two spectra are very similar. II. A number of stars, both giants and dwarfs, with H and K bright, have been pho~ tographed in a higher dispersion to the same limit, X 7600. These spectra also show no trace of the forbidden Ca~ lines, although this result might have been expected because of the bright-line spectrum. III. A number of representative M-type giants and dwarfs have been observed for the purpose of trying to find new luminosity effects in the orange and red. Several interesting differences between the spectra of giants and dwarfs have been found in these regions. The spectra of the M dwarfs have in general a much smoother appearance than those of M giants, notably because of the presence of stronger titanium oxide bands in giant spectra. Three bands of calcium hydride (CaH)-corresponding to the band-heads XX 6389, 6382, XX 6921, 6903, and XX 7035, 7028-have been found in the spectra of M-type dwarfs but are hardly visible in the spectra of giants. These bands seem to give a valuable new luminosity criterion for M stars. Very good evidence has also been found for the presence in M dwarf spectra of bands of magnesium hydride with heads at XX 5211, 4845. These bands seem to contribute to the smooth appearance in the M dwarf spectra of the TiO bands with heads at XX 5167, 4955, and 4762, and appear also to be responsi- ble for a general depression of the radiation-curve in this region. Tue Ca lines XX 6162, 6122, and 6102 are remarkably strong in late-type dwarfs but faint or invisible in the giants. This result is in agreement with that found by Miss Burwell for stars of types K and M
- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 1934
- DOI:
- 10.1086/143595
- Bibcode:
- 1934ApJ....80..171O