view Abstract Citations (75) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS An Analysis of W Virginis. Abt, Helmut A. Abstract A study has been made of the population II cepheid, W Virginis, from high-dispersion spectra obtained by Sanford and Abt and from photoelectric colors and magnitudes obtained by Whitford and Code, Eggen, and Gordon and Kron. The radial velocity-curve by Sanford has been integrated for three different choices of a velocfty, each giving a total displacement of the order of 35 X 106 krn. Layers of gas rise and fall in about twice the period of light-variation. During nearly half the period two layers of gas can be seen, one rising while the other is falling. Hydrogen emission lines are formed in the lower layer when it is first seen to rise. The light- and color-curves have been used to obtain relative radII. A comparison with displacements from the radial gives a maximum radius that is smaller than the total displacement of the atmosphere. Curves of growth were constructed for 17 of the plates. Excitation temperatures for Fe I and for lines of high excitation potential of Mg n show that when two layers are seen, their temperatures differ by ()o . Ionization temperatures calculated from the degree of ionization of Fe I and the continuous opacity agree with the effective temperatures from the colors and with the Mg II excitation temperatures. Relative to Fe, Ba and Ca have normal abundances, but the Sr and Sc abundances are small by factors of 5 and 3, respectively. Several lines of evidence indicate that the layers of gas are geometrically thin and transparent. A model of a shock wave traveling through an extended atmosphere was found to give too much material between the compressed regions following the shock fronts and too high temperatures. A model of shells of gas thrown off at maximum expansion of the photosphere explains the failure of Baade's method for finding the total radius. If these shells have to coffi4e, they cannot be uniform but must consist of many condensations. Publication: The Astrophysical Journal Supplement Series Pub Date: April 1954 DOI: 10.1086/190003 Bibcode: 1954ApJS....1...63A full text sources ADS | data products SIMBAD (4)