[vsnet-alert 12112] LkHA 188 G4 outburst (ATEL)

[Taichi Kato]

   This object would be of high interest.  The relatively low reddening
in this dark cloud would be also interesting.  The spetrum reported
for LkHA 188 G4 was K7-M0 (em), at V=18.9.

Please use the designation LkHA188G4 in reporting VSNET format.

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ATEL #2801							     ATEL #2801

Title:		A possible new FUor star in NGC 7000
Author:	E. Semkov, S. Peneva (Institute of Astronomy, Sofia, Bulgaria)
Queries:	esemkov at astro.bas.bg
Posted:	17 Aug 2010;  23:55  UT
Subjects:	Optical, Variables

We report the discovery of a strong outburst in the region of NGC 7000/IC
5070. A source of the outburst seems to be a T Tauri star located in the
dark clouds between North American and Pelican Nebulae. The first designation
of this object LkHA 188 G4 is given by Cohen and Kuhi (1979). The star
is a member of a small group of H alpha emission stars around LkHA 188.
The object is included in the Catalog of emission-line stars of the Orion
population (Herbig et al. 1988) with the designation HBC 722. According
to SIMBAD Astronomical Database the coordinates of the star are:   <br
/>   (J2000) 20 58 17.03 +43 53 43.4   <br />   The results from our photometric
observations indicate that for a period of about three months (from 13
May 2010 to 16 August 2010) the star brightness increased by 3.3 mag. (R).
At the same time the star has become considerably bluer. The V-R index
decreased from 0.65 mag. (May) to 0.45 mag. (August). The photometric data
from the period 6-16 August 2010 suggest that the star brightness rises
continuously by approximately 0.04 mag. per day. Our photometric observations
from 16 August 2010 give the following magnitudes:   <br />   R=13.33 and
V=13.77   <br />   The magnitudes calibration of our data was carried out
with respect to five stars from USNO-B1.0 Catalog.    <br />   Having in
mind the rapid increase in brightness, we assume that the observed outburst
is from FUor type. Such a rapid increase in brightness is observed in cases
of FU Ori and V1057 Cyg. But an outburst from EXor type or an object similar
to V1647 Ori are also possible. We encourage those observers interested
in FUor and EXor variables to start a photometric and spectroscopic following
of HBC 722. The multicolor photometric observations and high resolution
spectroscopy are very important for the exact determination of the outburst
type.     

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Password Certification:  E. Semkov  (esemkov at astro.bas.bg)
http://www.astronomerstelegram.org/?read=2801
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