COMMISSION 27 OF THE I. A. U.
          INFORMATION BULLETIN ON VARIABLE STARS
                       Number 3315

                                           Konkoly Observatory
                                           Budapest
                                           5 April 1989

                                           HU ISSN 0374 - 0676


       CW Leo = IRC+10216 HAS RETURNED TO A HIGH LIGHT LEVEL


The dust-enshrouded variable carbon star CW Leo, best known as the infrared
source IRC+10216 has been monitored in photographic red R(0.64) and infrared
I(0.81) bands with the Schmidt telescope of the Radioastrophysical observatory.
In addition to the Mira-type light variation a conspicuous long-term secondary
variation was found. Due to the secondary variation the star faded by two
magnitudes during 1974-1978 and remained at such a low light level up to 1986
(Alksnis et al., 1987). Further observations have shown that the star
gradually brightened and in the season 1988/89 again reached the high light
level in the photographic infrared.

According to all our I(0.81) observations the light curve elements for the
periodic component are:

                     Max J.D.=2441738+635d*E

The corresponding light curve for the periodic component is shown in Figure 1,
and for the secondary component in Figure 2.


                               [FIGURE 1]

 Figure 1. The curve of the periodic component of the light variation in
 photographic infrared I(0.81). Observed values (I) corrected for the 
 secondary variation DeltaI(t) and averaged over 0.05 phase intervals 
 (filled circles) or single observations (open circles) vs. phase 
 calculated according to the elements given in the text.

                               [FIGURE 2]

 Figure 2. The curve of the secondary component of the light variation in 
 I(0.81): deviation in mag of individual observed I(0.81) values from the 
 curve of the periodic component (Fig.1) vs. time


Similarly, in the red region, the secondary component of the light variation
shows the brightening, although the high light level as observed about 15 years
ago the star has not yet reached.

Possibly, during the last 15 years CW Leo has gone through a full cycle of the
secondary variation. It seems important to study this object in other
wavelength regions at this stage of high light level.


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

Reference:

Alksnis, A., Alksne, Z., Ozolina, V., Zacs, L. 1987, Investigations of the
   Sun and red stars, No. 26, p. 31. [BIBCODE 1987ISKZ...26...31A ]