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IAUC 4775: V834 Cen; 1988 VP4

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IAUC number 

                                                  Circular No. 4775
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM     EASYLINK 62794505
MARSDEN or GREEN@CFA.BITNET    MARSDEN or GREEN@CFAPS2.SPAN


V834 CENTAURI
     K. Beuermann and H.-C. Thomas, Max-Planck-Institut (MPI) fur
Physik und Astrophysik, Garching; and A. Schwope, Technische
Universitat, Berlin, write:  "The AM-Her binary V834 Cen has for the
first time entered a low state, at V = 17.  Spectrophotometry
with the European Southern Observatory/MPI 2.2-m telescope on Jan.
26 and 29 reveals the TiO features of the dM5 secondary and the blue
continuum of the white dwarf with only faint H-alpha emission.  Zeeman
absorption troughs of H-alpha and H-beta indicate an effective field
strength of 22 +/- 2 MG.  Orbital light variation of 0.3 mag full
amplitude is still present with maximum light near phase 0.0 (high
state photometric minimum).  The absence of cyclotron lines suggests
that a higher photospheric temperature of the white dwarf near the
previous accretion spot is responsible for this variation.  Estimates
for radiative cooling or horizontal redistribution of heat by magnetic
instabilities both predict time scales on the order of several months.
Further observations (especially photometry) are urged."


1988 VP4
     Ephemeris extension (cf. IAUC 4707) from orbital elements on
MPC 14200:

     1989 ET      R.A. (1950) Decl.     Delta      r       V
     May   4    15 47.56    -56 13.6    0.370    1.306    15.1
           9    15 31.39    -52 14.2
          14    15 19.47    -48 25.6    0.435    1.404    15.3
          19    15 10.83    -44 53.4
          24    15 04.74    -41 40.8    0.519    1.501    15.7
          29    15 00.70    -38 49.1
     June  3    14 58.32    -36 18.2    0.623    1.597    16.3
           8    14 57.33    -34 07.3
          13    14 57.51    -32 14.9    0.746    1.690    16.9
          18    14 58.65    -30 39.3
          23    15 00.61    -29 18.4    0.886    1.781    17.4
          28    15 03.26    -28 10.5
     July  3    15 06.51    -27 13.9    1.041    1.869    17.9
           8    15 10.28    -26 27.0
          13    15 14.50    -25 48.6    1.208    1.955    18.4


1989 April 27                  (4775)             Daniel W. E. Green

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