The Present Spectral Characteristics of Sixteen Old Novae.
Abstract
Spectra of sixteen old novae have been observed with a small-dispersion spectro- graph. Observations have been made in the fields of two others in an effort to identify them by their spectra. Visual magnitudes of the observed objects range from io.o to 16.5. Charts of all the fields are given for the benefit of other observers. Most of the objects have a strong continuous spectrum extending well into the violet, in which neither absorption nor emission lines can be seen. They have therefore been classified as 0 Con, since the extension into the violet corresponds to that of 0-type stars, or possibly of early B stars. When emission lines have been observed, the stars have been classified as 0 Em. In the search for Nova B Cassiopeiae (1572), Baade observed an interesting faint blue star on a color plate of the region. Its photographic magnitude is 17.0, its spectrum Aon. As the mean absolute magnitude for stars of this type is roughly + 1.0, the dis- tance modulus, uncorrected for space absorption, is i6.o, thus indicating a distance of the order of i6,ooo parsecs in a direction 125° from that of the galactic center. It is not assumed that this star is the nova. Spectral types of four stars observed in the field of Nova Vulpeculae (1670) indicate that this nova has not yet been rediscovered. One of these objects is the faint variable star found by W. H. Steavenson. With the exception of T Coronae, all the novae observed are blue and probably correspond in temperature with the 0 or early B stars. T Coronae may also be blue if it is the companion of a red star. The density of Nova Persei (1901) ill its present state is of the order of 220 0. The corresponding value for Nova Aquilae (1918) is 70 0. For eleven novae whose distances are not so reliably known, a mean density has been determined by using Mmax = - 7.0, the mean M of galactic novae at maximum, from which their present mean M is ob- tained by adding the mean of their amplitudes. The resulting mean density of this group is 6o 0
- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 1938
- DOI:
- 10.1086/143980
- Bibcode:
- 1938ApJ....88..228H