COMMISSION 27 OF THE I.A.U.
                 INFORMATION BULLETIN ON VARIABLE STARS
                             Number 2996

                                                        Konkoly Observatory
                                                        Budapest
                                                        13 March 1987

                                                        HU ISSN 0374 - 0676


                   INFRARED PHOTOMETRY OF BRUN 276

We have secured JHKLM photometry, on the San Pedro Martir photometric 
system (cf. Tapia et al.), of the T Tauri star Brun 276,
embedded in the Orion Nebula, with the 2.1 m telescope of Observatorio
Astronomico Nacional, UNAM at San Pedro Martir, B.C.N, Mexico, on
January 29, 1987 (U.T.). These data have been combined with Walker's
(1969) UVB photometry, and "R,I"-magnitudes estimated from a red paper
copy of the PSS, and from a glass infrared plate taken also with the
Palomar Schmidt by Haro in 1959, respectively. These R, I- magnitudes
were derived following the procedure outlined by Liller and Liller
(1975). The results are summarized in Table 1 (the probable errors are
listed in the last row of this Table).


        Table I: MULTICOLOR PHOTOMETRY OF BRUN 276

   U      B       V      R     I     J      H      K      L    M
 17.78  18.77  18.04   16    15    14.15  13.50  12.75  10.7   8.8
                        0.6   0.6   0.1    0.1    0.1    0.4   0.4

   The previous data (cf. Mendoza et al.) placed Brun 276 below the
main sequence (M_bol=~10). Now, the infrared observations can be used to
derive a photometric luminosity (cf. Mendoza 1966, 1968, and Imhoff and
Mendoza 1974). However, this luminosity will be a lower limit of the
total luminosity, because of (1), Brun 276 can be brighter (see below);
and (2), the observed fluxes have been used uncorrected by the effects
of interstellar extinction (spectral type unknown), if any. On the other
hand, since Brun 276 is not an IRAS source, it is possible to have a
good approximation of this photometric luminosity assuming that fluxes
beyond 30 microns are negligible. This way, the results yield a
photometric luminosity around 3 solar luminosities. Therefore, the warm
circumstellar envelope, indicated by the infrared photometry listed in
Table I raises Brun 276 slightly above the main sequence on the HR
diagram, as do other T Tauri stars (loc. cit.).
   One of us (EEM) also obtained uvbyH-beta photometry of Brun 276
on November 8, 1986 (U.T.) which confirms the variability of this
object, and the emission in the hydrogen line H-beta. This photometry
yields V = 15.5, roughly the brigthness of the star at the time that
Brun made his catalogue (cf. Brun 1935).
   We would like to thank to Prof. Haro for facilitating us his
IR-plate, and Mssrs. Chaidez, and Sanchez for their help at the 2.1m
telescope.


                  E.N. MENDOZA, and L.F. RODRIGUEZ

                      Instituto de Astronomia
                 Universidad Nacional Autonoma de Mexico
                         P.O. Box 20-15a
                           01000 MEXICO


References:

Brun, A.                        (1935) Pub. Obs. Lyon, Vol. 1, No. 12. [BIBCODE 1935POLyo...1...12B ]
Imhoff, C.L., and Mendoza, E.E. (1974) Rev. Mex. Astron. Astrof., 1, 25. [BIBCODE 1974RMxAA...1...25I ]
Liller, M.H., and Liller, W.    (1975) Ap. J. 199, L133. [BIBCODE 1975ApJ...199L.133L ]
Mendoza, E.E.                   (1966) Ap. J. 143, 1010. [BIBCODE 1966ApJ...143.1010M ]
Mendoza, E.E.                   (1968) Ap. J. 151, 977 [BIBCODE 1968ApJ...151..977M ]
Mendoza, E.E., Firmani, C., and Haro, G. (1985) IAU I.B.V.S., No. 2817.
Tapia, M., Neri, L., and Roth, M. (1986) Rev. Mex. Astron. Astrof. 13, 115 [BIBCODE 1986RMxAA..13..115T ]
Walker, M.F.                   (1969) Ap. J. 155, 447. [BIBCODE 1969ApJ...155..447W ]