Brightening of LBV HDE 269006 = R71 (LMC)

[Olivier Thizy]

alert from AAVSO on thie LBV in the Large Magellan Cloud:

AAVSO Special Notice #291

Brightening of LBV HDE 269006 = R71
July 26, 2012

The luminous blue variable (LBV) HDE 269006 = R71 in the Large
Magellanic Cloud is brightening and is currently at V magnitude
8.3.

Observations in the AAVSO International Database going back to
1987 show HDE 269006 at visual magnitude ~10.8 until 2006, when it
began to brighten, reaching magnitude ~8.5 in late 2009. It then
declined to ~magnitude 9 by late 2012, where it has been since
then.

All observations of this LBV are welcome. In particular,
VBRI photometry would be very valuable in the coming seasons to
correlate with the spectra being obtained now and multiwavelength
observations sure to be obtained in the future, and to document
the optical behavior of HDE 269006 at this time in its history.

According to IAU Central Bureau Electronic Telegram 3192 (Daniel
W. E. Green, Ed.), "R. Gamen, Instituto de Astrofisica de La
Plata, CONICET, Universidad Nacional de la Plata; N. Walborn,
Space Telescope Science Institute; N. Morrell, Las Campanas
Observatory, Carnegie Observatories; R. Barba, Instituto de
Ciencias Astronomicas y de la Tierra, CONICET, San Juan; and E.
Fernandez Lajus, Instituto de Astrofisica de La Plata, CONICET,
Universidad Nacional de la Plata, write that the luminous blue
variable HDE 269006 (= R71) in the Large Magellanic Cloud
continues to brighten in the visual since their last report in
2009 (IAUC 9082), when it was at magnitude V = 9. Differential
photometry from images obtained in Apr. 2012 shows that R71 has
brightened by 0.6 mag in V since Apr. 2010 and is currently at V
approximately 8.3. This unprecedented rise in its light curve is
accompanied by spectacular variations in its optical spectrum.
In Aug. 2009, it resembled a (peculiar) early-F supergiant, while
currently R71 displays early-G supergiant characteristics, on the
basis of ionization ratios of absorption lines such as Fe I/Fe II
as well as the strength and width of the Ca II H and K absorption
lines. Concurrently, H-alpha has transformed from a P-Cyg profile
into a centrally reversed, symmetrical broad emission
(alternatively, an absorption line with symmetrical emission
wings), while the Ca II infrared triplet (849.8-, 854.2-, and
866.2-nm) emission has declined and strong forbidden [Ca II]
729.1- and 732.4-nm emission lines have appeared -- along with
weaker ones of [O I-II], [N II], and [S II]. This is the first
report of [Ca II] emission in an apparent S Dor event to their
knowledge and suggests comparison with the red transients
(Humphreys et al. 2011, Ap.J. 743, 118). R71 is previously known
to have an unusually strong dust signature in the infrared
(Bonanos et al. 2009, A.J. 138, 1003, and references therein).
Further monitoring is indicated to determine the nature and
outcome of the current event." [extensive quotation from CBET
3192 by permission of D. Green]

Coordinates: 05 02 07.39 -71 20 13.1 (2000.0)

Charts for this star may be created using the AAVSO Variable Star
Plotter (http://www.aavso.org/vsp). Be sure to use the name
HD 269006 (do not use HDE 269006).

Please report your observations to the AAVSO International
Datbase as HD 269006.

This AAVSO Special Notice was compiled by Elizabeth O. Waagen.