The spectrum of ρ Cassiopeiae.

Abstract

view Abstract Citations (2) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The spectrum of ρ Cassiopeiae. Beardsley, Wallace R. Abstract The unprecedented decrease in light of the F8 supergiant p Cassiopeiae in 1946 was accompanied by marked changes in its spectrum. One striking feature was the appearance of many lines of o-volt excitation potential not previously present in the spectrum, which are, in fact, normally observed only in M-type supergiant stars. Radial velocity measures and intensity estimates for a number of these lines have been made for a series of 30 plates with a dispersion of 26 A/mm at H~ taken at the McDonald Observatory at intervals since the star's return to normal brightness in 1947. The spectra studied were obtained by a number of members of the Yerkes and McDonald staffs. Radial velocity results for sharp, unblended lines are as follows: No. of No. of Lines Measures Av. Vel. Ioniz. Pot. Sci 2 25 -69.6km/sec 6.7 volts Vi 6 8o -63.4 6.7 Tii 6 69 -6o.o 6.8 Coi 3 63 -5i.8 7.8 Fei 6 100 -55.2 7.9 A correlation between velocity and ionization potential is indicated which corresponds to that which Keen an found between Ti and Fe in the infrared spectrum of p Cas.1 No marked variation in average velocity per plate for these lines has been found for the interval between minimum light and the present time. In addition, a plate taken during minimum light gave the same average velocity. Eye estimates of line intensity reveal, however, considerable changes. The lines retained the minimum phase intensity through 1948. In 1949 and 1950 a general decrease in intensity occurred and the lines disappeared or became very weak. This was followed in 1951 by a moderate increase in strength of many lines which have then remained to the present time. Probable emission H~, H~, and X4226 of Ca I also appeared during the post-minimum phase. The continued existence to the present time of many of these unusual lines in the spectrum of p Cas, and the apparent dependence of the radial velocity of these lines upon ionization potential would appear to support the hypothesis that these lines are formed in a low-excitation shell rather than by the absorption of light by an otherwise invisible eclipsing star. I.Ap. J. 106, 295, 1947. Yerkes Observatory, Williams Bay, Wis. Publication: The Astronomical Journal Pub Date: March 1953 DOI: 10.1086/106807 Bibcode: 1953AJ.....58...34B full text sources ADS | data products SIMBAD (1)