[vsnet-alert 5138] Delta Sco: a new extremely bright Gamma Cas-type star in outburst

[Taichi Kato <tkato>]

Delta Sco: a new extremely bright Gamma Cas-type star in outburst

   The following messages are from Sebastian Otero.  Delta Sco has now
become one of the brightest gamma Cas stars (active Be stars) among
historically recorded outbursts of this class.  The phenomenon is apparently
ongoing, and the object may attain the 1-st magnitude brightness.
   Please watch closely and report your observations!

Subject: [vsnet-be 2] (fwd) Delta Sco - GCAS???

The bright B0.5IV  star DELTA SCORPII is probably brighter than normal.
It looks like 2.2 instead of 2.3.  
I searched for photometric data in the past and there are several 
measurements in the range 2.31 - 2.33.  But there is one isolate 2.21 
(Hogg A.R., 1958, "Photometric observations of 244 bright stars") that 
makes me suspicious. It's been some weeks since I noticed this probable 
little brightening but I hadn't paid much attention. In addition, the 
Hipparcos Catalogue gives a brighter value of 2.29.
Several suitable comparison stars may be used in estimating:

GAMMA CEN:  2.16
ALPHA LUP and EPSILON CEN:  ~2.30*
KAPPA SCO:   2.40*
ETA OPH:       2.43

(These 3 stars are BCEP variables but the amplitude is very small)

Of course, the variability is too small for being followed visually, but 
it would be interesting to do some photometry in order to confirm this 
probable brightening. Could it be a possible GCAS variable? The 
behaviour is similar to that of ALPHA ARAE and ETA CENTAURI. Could a new 
spectrum taken right now show emission lines?

I hope someone can measure it. I just have my eyes...

Sebastian Otero.

Subject: [vsnet-be 3] SPECTROSCOPIC CONFIRMATION of Delta Scorpii variability

WE HAVE A NEW VARIABLE STAR CONFIRMED.

And it's one of the brightest.

Spectroscopic observations show that the H Alpha line is in emission.
DELTA SCORPII IS A NEW GCAS star.

This confirmation came from Spain and it will be reported to the IAU.

Sebastian Otero.

  Recent observations:

  YYYYMMDD(UT)   mag  observer
  20000626.901    22  (S. Otero)
  20000630.028    22  (S. Otero)
  20000704.078    22  (S. Otero)
  20000716.928    21  (S. Otero)
  20000717.123    21  (S. Otero)
  20000718.949    21  (S. Otero)
  20000720.018    20  (S. Otero)

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