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IAUC 5048: VY Aqr; eta Cen

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                                                  Circular No. 5048
Central Bureau for Astronomical Telegrams
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

     U. Munari, A. Bianchini and R. Claudi, Asiago and Padua
Observatories, report: "We obtained low- and medium-resolution spectra
of VY Aqr in outburst at the Asiago 1.8-m telescope (Boller and Chivens
+ CCD, range 320-760 nm) on July 4.9-5.1 UT.  The spectra show an early
A-type continuum with little developed Balmer discontinuity.  The
higher Balmer lines are in pure absorption, H alpha has an emission
component, and H beta shows a single peaked and broad central emission.
The FWHM and profile of the Balmer absorption lines are typical of
A0-A4 dwarfs.  No other emission lines are visible.  There is a marked
resemblance to the spectra at the 1987 outburst (cf. IAUC 4415)."
     T. Augusteijn and M. Della Valle, European Southern Observatory,
report: "Preliminary analysis of 37 CCD spectra (range 380-700 nm,
dispersion 59 A/mm) obtained on July 4.4 and 5.4 UT with the ESO
1.52-m telescope at La Silla, shows shallow absorptions (FWZI about
4000 km/s) due to Balmer lines and He I (402.6, 447.1, 501.5 and 587.5
nm), superimposed on a fairly strong continuum.  The H lines appear
variously filled in with emissions.  Radial-velocity variations of the
H beta emission line suggest an orbital period of 0.060 day, consistent
with the superhump period of 0.064 day reported by Ritter (A. Ap.
Suppl., in press)."

     E. Janot-Pacheco and N. V. Leister, Instituto Astronomico e
Geofisico, Universidade Sao Paulo; and C. A. P. C. O. Torres, G. R.
Quast and R. P. Campos, Laboratorio Nacional de Astrofisica (LNA),
Itajuba, communicate: "High-resolution (> 40 000), high-signal-to-noise
ratio (> 300), spectroscopic observations of the Be star eta Cen,
obtained on Mar. 12 and June 8 and 9 with a CCD detector on the coude
spectrograph of the LNA 1.60-m telescope, have shown the presence of
subfeatures (< 1 percent of the continuum) moving rapidly from blue to
red across the He I 667.8-nm line profile.  Nonradial pulsation (NRP)
is the most likely explanation for this kind of variation, which has
also been observed in, for instance, some bright Be stars and rapidly
rotating early-type pulsators.  Assuming sectorial-mode pulsation,
preliminary analysis of the data indicates that the average spacing and
acceleration of the subfeatures is consistent with p-modes of NRPs of
low-to-moderate azimuthal order.  On June 10 the H alpha line showed
strong emission with a marked central reversal."

1990 July 5                    (5048)              Brian G. Marsden

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