A spectrophotometric study of recent eclipses of 32 Cygni.

Abstract

view Abstract Citations (1) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A spectrophotometric study of recent eclipses of 32 Cygni. Wellmann, P. Abstract A spectrophotometric study of the 1949 and 1952 eclipses of 32 Cygni has been made from plates taken at the David Dunlap Observatory, the University of Michigan Observatory and the Hamburg-Bergedorf Observatory. Lines of the following spectra have been investigated: Caii, Srii, Till, Cai, Fei, and Cri. The study of other lines is in progress. The manner in which the intensity of the K line changes during ingress and egress has been used to establish the time of third contact 1949 (Nov. 9.8 UT), second contact 1952 (Dec. 20.8) and mid-eclipse 1952 (Dec. 27.3). These data point to a period of 1148d which is sensibly longer than the period of I 140d8 hitherto accepted. The intensity ratio of the continua for the two components has been derived by comparing the depth of corresponding lines in the composite spectrum and in the K spectrum during totality. The result is that the two stars are nearly equal in brightness at X3900, whereas near H7 the B star contributes only 10 per cent to the brightness of the whole system. If K~ Ib is assumed as the spectral type of the primary, B2 is derived for the secondary from these data, and the difference of visual absolute magnitude between the two stars is found to be about ~ magnitudes. The increase of chromospheric line intensities with time at the ingress of 1952 begins farther from totality for the lines of ionized metals than for the lines of neutral atoms which show a steep rise of intensity only during a short interval before totality. Resonance lines and lines of low excitation develop stronger chromospheric components than do high excitation lines. The increase of the chromospheric absorption in H~ and H~ is faster than in the neighboring lines before 1952 Dec. 17.0 and slower after that time. This indicates the disappearance of the Balmer lines of the B spectrum, that is, the beginning of the partial phase. The hydrogen line intensities in the K spectrum point to a high luminosity for the primary. They have been used to derive the Balmer line intensities in the B-type spectrum. The results again indicate a B2 V spectrum for the secondary. The intensity ratio between the Caii and Cai lines, and the comparison of the chromospheric line intensities expressed as equivalent width in the continuum of the B star give evidence of a low temperature about 3300-44000K, and of a low electron density at the base of the chromosphere of 32 Cygni. These results allow a preliminary calculation of elements for this system. From the intensity ratio iB/ix and the temperatures of 20,0000 and 32000, derived from the spectral types, the ratio of the radii is found to be I :90. From the duration of totality, 13d0, and the most probable value of the partial phase, 4d0, the following are deduced: radius of the K star 353 O, radius of the B star 3.9 O, inclination of the system 72?5 O. The eclipse is therefore nearly grazing. David Dunlap Observatory, Richmond Hill, Ont. Publication: The Astronomical Journal Pub Date: 1953 DOI: 10.1086/106932 Bibcode: 1953AJ.....58R.233W full text sources ADS | data products SIMBAD (1)