view Abstract Citations (4) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Spectrophotometry of RS Ophiuchi (nova Ophiuchi no. Wilson, O. C. ; Williams, E. G. Abstract From one good plate taken with the three-prism violet spectrograph on August 30, 1933, the apparent color temperature of RS Ophiuchi is found to be 4000° K. Contours of the hydrogen emission bandshave been determined from several plates covering the period August i6-September ii, ~ On the assumption that the red sides of the bands present the true unmodified shapes, the following facts emerge: a) The contours are roughly exponential in form. The earlier ones can be represented approximately by the formula 1= e-(u/u~, where n-~ r+k(uo/u)-k and k =0.125. The value u0 decreases rapidly with time at first, then more slowly, ftnally attaining a more or less constant value; k also decreases and may be considered to vanish for the later contours. b) In addition to a sharp absorption component present on the short-wave-length sides of the band maxima in the early stages, there appears to be a general deficiency of intensity over the violet halves of the bands relative to that of the red halves. The sup- position that this is due to the complete suppression of the continuous spectrum under the violet sides is not in entire agreement with the facts, but there may be complicating factors. This hypothesis would require a large velocity range among the atoms directly in front of the star, and leaves no room for the monochromatic hydrogen absorption components or for the sharp nebular lines. It is suggested that the latter arise in a quies- cent shell around the star left over from its previous outburst. The Balmer decrement has been obtained from two accordant plates, and is found to be appreciably faster than the mean of those found by Plaskett and by Berman for planetary and diffuse nebulae. The observed decrement is brought into good agreement with the latter by applying the differential factors necessary to reduce a true tempera- ture of 35,0000 to an apparent one of 40000. From several spectrograms it appears that the ratio of the area of Hy to the intensity in the underlying continuous spectrum did not vary greatly between August i6 and September 2, 1933. Zanstra's method gives a photo-electric temperature of 35,000°, calculated from the measures on plate V4o4, August i8. If this is a real measure of the temperature, it fol- lows from the preceding paragraph that, while the star decreased in brightness by about two magnitudes from August i6 to September 2, its temperature remained constant. This conclusion would imply that the fading of the star was due to a shrinkage in the radiating surface. From the measured intensity of the K line, with an approximate allowance for a probable stellar blend, a distance of 95o parsecs is deduced. This is shown to be fairly consistent with the recent results of Stebbins and Huffer on the assumption that the difference between the photo-electric and apparent temperatures is due to space redden- ing Publication: The Astrophysical Journal Pub Date: December 1934 DOI: 10.1086/143609 Bibcode: 1934ApJ....80..344W full text sources ADS | Related Materials (1) Reprint: 1934CMWCI.501....1W