COMMISSION 27 OF THE I. A. U.
          INFORMATION BULLETIN ON VARIABLE STARS
                       Number 3396

                                         Konkoly Observatory
                                         Budapest
                                         15 November 1989

                                         HU ISSN 0374 - 0676


       ON THE VARIABILITY OF THE DUSTY CARBON STAR LP And


The infrared object IRC+40540 = AFGL 3116 = IRAS 23320+4316 = NSV 14623
(Schmitz, Mead and Gezari, 1987), a carbon star of spectral type C8,3.5
extremely reddened due to circumstellar dust shell (Cohen, 1979) was
suspected to be variable in the course of the "Two-micron Sky Survey"
(Neugebauer and Leighton, 1969), its infrared variations confirmed by Lockwood
(1974) and time scale of variability 500-1000 days found by Strecker and Ney
(1974). The object is named LP And in the General Catalogue of Variable Stars
(1985).

To improve knowledge of the character of variability of LP And, the star was
monitored photographically with the Schmidt telescope of the Radioastrophysical
Observatory at Baldone using Kodak IN plates and red filter KC 19. During
1984-1989 30 estimates of I(0.81) magnitudes were made and a mean cycle length
of approximately 625 days was found. If early observations in K-passband
published by Neugebauer and Leighton (1969), Strecker and Ney (1974), Grasdalen
et al. (1983) and Cohen (1984) are also taken into consideration, a mean cycle
length of 614 days is obtained.

In Figure 1 (bottom) a mean light curve in photographic infrared I(0.81) for LP
And is given according to the elements:

Max. J.D. = 2446340+614*E    (1)

The amplitude of the mean light curve in I(0.81) is 1.5 mag. However the first
observation made in 1978 shows the object 1 mag brighter than expected.

At the top of Figure 1 the K-magnitudes published by the authors cited are
plotted versus phase based on elements (1). It seems that the range in K is
nearly similar to that in I(0.81).

Thus the object LP And = AFGL 3116 belongs to the group of carbon stars with
thick circumstellar shells and very long periods, whose other known members are
CW Leo = IRC+10216 (P=635d, Alksnis, 1989), RW LMi = CIT 6 (P=605d, Alksnis and
Khozov, 1987), as well as AFGL 971 (P~=610d) and AFGL 1235 (P~=590d) (Le
Bertre, 1988).

                                [FIGURE 1]

 Figure 1. Mean light curves of LP And in K- (top) and in I(0.81)- (bottom)
 passbands: individual observed magnitudes plotted versus phase according to
 (1). K-magnitudes by authors cited are signed with different symbols: open
 circles - Neugebauer and Leighton; filled circles - Strecker and Ney; + signs
 - Grasdalen et al., x - Cohen (1984); dots are 104-magnitudes by Lockwood minus
 6.1 mag.


A. ALKSNIS
Radioastrophysical Observatory
Latvian Academy of Sciences
226524, Riga, Turgeneva 19
Latvia, U.S.S.R.

References:

Alksnis, A. 1989, IBVS, No. 3315.
Alksnis, A., Khozov, V.G. 1987, Investigations of Sun and red stars, 27, 55. [BIBCODE 1987ISKZ...27...55A ]
Cohen, M. 1979, MNRAS, 186, 837. [BIBCODE 1979MNRAS.186..837C ]
Cohen, M. 1984, MNRAS, 206, 137. [BIBCODE 1984MNRAS.206..137C ]
General Catalogue of Variable Stars, Fourth Edition. Ed. Kholopov, P.N.,
   Vol. I, 1985.
Grasdalen, G.L., Gehrz, R.D., Hackwell, J.A., Castelaz, M., Gullixson, C.
   1983, Ap.J. Suppl., 53, 413. [BIBCODE 1983ApJS...53..413G ]
Le Bertre, T. 1988, Astron. Astrophys., 203, 85. [BIBCODE 1988A&A...203...85L ]
Lockwood, G.W. 1974, Ap.J., 192, 113. [BIBCODE 1974ApJ...192..113L ]
Neugebauer, G., Leighton, R.B. 1969. Two-Micron Sky Survey. [BIBCODE 1969tmss.book.....N ]
Schmitz, M., Mead, J.M., Gezari, D.Y. 1987, Infrared Source Cross-Index,
   First Edition, NASA RP-1182. [BIBCODE 1987isci.book.....G ]
Strecker, D.W., Ney, E.P. 1974, A.J., 79, 797. [BIBCODE 1974AJ.....79..797S ]