COMMISSION 27 OF THE I. A. U.
	 INFORMATION BULLETIN ON VARIABLE STARS
		     Number 2654

				   Konkoly Observatory
				   Budapest
				   17 January 1985


				   HU ISSN 0374 - 0676


	        PHOTOMETRY OF HD 23838


The star HD 23838(= HR 1176) is included in the list of F, G & K stars
having Ca H and K emission compiled by Eggen (1978). It is also included in the
catalogue of emission line stars compiled by Bidelman (1954). It is thought
to be a dwarf star of spectral type G0. Young (1939) has given a range of
40 km s^-1 for its radial velocity while Abt (1969) found a range of 24 km s^-1.
This made us suspect that HD 23838 could be an RS CVn type binary. To verify
this, we have monitored this system photoelectrically as a part of our long
term photometric program on RS CVn and related binaries.
We observed this system on 10 nights during 1980-81 and 1981-82 observing
seasons using the 1.22m reflecting telescope of the Japal-Rangapur Observatory.
HD 23728 and HD 23477 were used as comparison and check stars, respectively.
The photometric equipment, method of observation and the reduction techniques
employed for deriving Delta m (var-comp) have been described in a previous paper on
UV Piscium (Vivekananda Rao and Sarma 1983). The r.m.s. of Delta m (check-comp)
was found to be ~0.02m which indicates that the comparison is constant in
brightness during the period of our observations. The values of Delta m (var-comp)
along with the times of observations (HJD) are available with us. As no orbital
period for this system is available in the literature, we have plotted in
Figure 1 the observed Delta m (var-comp) versus HJD in UBV passbands.

                          [FIGURE 1]

  Figure 1: Photometric observations of HD 23838 in UBV passbands.

From these figures it is evident that curing each of the nights the system
HD 23838 does not show any systematic or abrupt variability except for small
scatter which is comparable to that of the Delta m (check-comparison) values. It is
also found that on all the nights the mean magnitudes of the system in each of
the UBV passbands remained constant within the observational uncertainties.

  Spectroscopic observations of HD 23838 were made by Raghavendra Rao (1983)
during the 1981-82 and 1982-83 observing seasons on 13 nights. No detectable
Ca II H, K emission feature was found on any of these nights. This is quite
surprising in view of its classification as Ca II emission line star both by
Bidelman (1954) and Eggen (1978). It is conceivable that the star may be in low
activity phase of its stellar activity cycle during our observation period.
Further spectroscopic observations are required to check this suggestion.

  Hence based on the presently available photometric and spectroscopic
information it appears very unlikely that HD 23838 belongs to the RS CVn group.




		       P. VIVEKANANDA RAO, M.B.K. SARMA,
		       Center of Advanced Study in Astronomy,
		       Osmania University, Hyderabad 500 007,
		       India

		       P.C. AGRAWAL and M.V.K. APPARAO,
		       Tata Institute of Fundamental Research,
		       Colaba, Bombay 400 005, India





References:

Abt, H.A. 1969, Astrophys.J.Suppl.  19, 425. [BIBCODE 1970ApJS...19..387A ]
Bidelman,W.P. 1954,  Astrophys.J.Suppl., 1, 175. [BIBCODE 1954ApJS....1..175B ]
Eggen, O.J. 1978, Inf.Bull.Var.Stars. No. 1426.
Raghavendra Rao, C. 1983, Private Communication.
Vivekananda Rao, P. and Sarma, M.B.K. 1983, J.Astrophys.Astr., 4, 161. [BIBCODE 1983JApA....4..161V ]
Young, R.K. 1939, Pub.David Dunlap Obs., 1, 71. [BIBCODE 1939PDDO....1...69Y ]