COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 1918 Konkoly Observatory Budapest 1981 February 3 HU ISSN 0374-0676 HONDA'S VARIABLE IN CYGNUS: A NEW LONG PERIOD VARIABLE Following Honda's discovery of a probable nova in Cygnus on 1980 November 29 (Honda, 1980), a spectroscopic program was initiated at the Kavalur Observatory. The spectra reveal that this star is not a nova but a long period variable of type M4e. The spectrograms were obtained between 1980 December 8 and 1981 January 5. An image tube spectrograph was used at the Cassegrain focus of the 102cm reflector at the Kavalur Observatory. Most of the spectra were recorded at a low dispersion of 400A/mm since a spectroscopic programme on the recent supernovae in NCC 6946 and 1316 was in progress (Prabhu, 1981). However, one spectrogram was obtained at a higher dispersion of 65A/mm on 1981 January 4.61 UT to facilitate detailed analysis. This spectrogram covers the wavelength region of 4200A- 6200A while the lower dispersion spectrograms cover 4200A-8400A. Even as the first spectrum was recorded, the prominent molecular bands and the sharp emission lines of hydrogen showed this star to be a red variable and not a nova. Subsequent observations at higher dispersion allow us to classify the spectrum. A density plot of this spectrogram in the region of 4800A-6200A appears in the figure. The plot is digitally averaged over ten sampling intervals of 8 microm each. The narrow emission line of Hbeta and the absorption bands of TiO have been labelled in the figure. The identifications have been made following Merrill (1940), Merill, Deutsch. and Keenan (1962) and Keenan and McNeil (1976). The prominence of TiO bands and the absence of ZrO bands show that this variable has a spectral type of M. The 5736A band of VO a characteristic of stars later than M6, is not visible in the spectrum. The TiO alpha System at 5759A (0,2) and 5810A (1,3) are clearly visible and hence the spectrum cannot be of type earlier than M3. The strengths of the above bands and also the bands at 5448A (0,1) and 5497A (1,2) belonging to the same system indicate a spectral type of M4. Though the region between Hbeta to Hgamma has a lower exposure on our spectrogram, a few more features could definitely be identified by us as also the Balmer emission lines seen in our spectrograms appear in Tables I and II. Table I Emission Lines 6563A Halpha 4861A Hbeta 4303A Hgamma 4101A Hdelta [FIGURE 1] Spectrum of the variable in the region 4800A-6200A on Jan. 4.61 UT Table II Absorption Bands of TiO 5167 alpha(0,0) 5448 alpha(0,1) 5759 alpha(0,2) 5810 alpha(1,3) 4955 alpha(1,0) 4999 alpha(2,1) 5497 alpha(1,2) 4761 alpha(2,0) 4804 alpha(3,1) 4584 alpha(3,0) 6158 gamma'(0,0) 5838 gamma'(1,0) 7054 gamma(0,0) 7589 gamma(0,2) 8206 gamma(0,3) 6651 gamma(1,0) 7125 gamma(1,2) The identifications between 6200A and 8400A have been made on the low dispersion spectrograms. The sharpness of the emission lines of Hbeta and Hgamma indicates that the variable was already in its post-maximum phase. Waagen (1980) finds from the Harvard photographic plates that this object has varied in brightness from a mag >14 to mag ~ 10 between 1938 and 1951. Continuous photoelectric observations of this variable are necessary in order to ascertain its period and the range of light variations. T.P. PRABHU M. V. MEKKADEN Indian Institute of Astrophysics Bangalore 560034 India References: Honda, M., 1980, I.A.U. Circular No. 3546 [BIBCODE 1980IAUC.3546....1K ] Keenan, F.C., McNeil, R.C., 1976, An Atlas of Spectra of the Cooler Stars: Types G,K,M,S, and C The Ohio State University Press. [BIBCODE 1976aasc.book.....K ] Merrill, P.W., 1940, Spectra of Long Period Variable Stars, University of Chicago Press. [BIBCODE 1940QB895.M395..... ] Merrill, P.W., Deutsch, A.J., Keenan, P.C., 1962, Astrophys.J. 136, 21 [BIBCODE 1962ApJ...136...21M ] Prabhu, T.P., 1981, in press Waagen, E., 1980, I.A.U. Circular No. 3553. [BIBCODE 1980IAUC.3553....3M ]