Detalles de publicación
PP 07002
The 2004-2006 outburst and environment of V1647 Ori
(1) IAC, (2) Konkoly Observatory, Hungary, (3) University of Sidney, Australia, (4) Baja Astronomical Observatory, Hungary, (5) University of Szeged, Hungary
We studied the brightness and spectral evolution
of the young eruptive star V1647~Ori during its recent outburst in
the period February 2004--May 2006. The main results, derived
from combining our {\it V\/}, {\it R\/}$_\mathrm{C}$, {\it
I\/}$_\mathrm{C}$, {\it J\/}, {\it H\/}, {\it K\/}$_s$
photometric, as well as optical and near-infrared spectroscopic
observations with published results are as follows. The brightness
of V1647~Ori stayed more than 4\,mag above the pre-outburst level
until October 2005 when it started a rapid fading. In the high
state we found a periodic component in the optical light curves
with a period of 56 days. The time delay between the brightness
variations of the star and a nebular position corresponds to an
angle of $61\degr\pm14\degr$ between the axis of the nebula and
the line of sight. The overall appearance of the infrared and
optical spectra did not change in the period March~2004 --
March~2005, though steady decrease of HI emission line fluxes
could be observed. We show that the periodic variations of the
H$\alpha$ equivalent width, suggested by several authors, could
be caused by variation of the continuum with the 56 days period.
In May 2006, in the quiescent phase, the HeI 1.083 $\mu$m line was
in emission, contrary to its deep blueshifted absorption observed
during the outburst. The $J-H$ and $H-K_s$ color maps of the
infrared nebula reveal an envelope around the star whose largest
extension is about 18\arcsec (0.03\,pc). The color distribution
of the infrared nebula suggests reddening of the scattered light
inside a thick circumstellar disk. Comparison of the {\it K\/}$_s$
and H$\alpha$
images of McNeil's Nebula shows that HH\,22A, the Spitzer infrared source
and the bright clump C
of the nebula may be unrelated objects. We show that the observed
properties of V1647~Ori could be interpreted in the framework of
the thermal instability models of Bell et al. (1994). We speculate
that V1647~Ori might belong to a new class of young eruptive
stars, defined by relatively short timescales, recurrent
outbursts, modest increase in bolometric luminosity and accretion
rate, and an evolutionary state earlier than that of typical
EXors.
of the young eruptive star V1647~Ori during its recent outburst in
the period February 2004--May 2006. The main results, derived
from combining our {\it V\/}, {\it R\/}$_\mathrm{C}$, {\it
I\/}$_\mathrm{C}$, {\it J\/}, {\it H\/}, {\it K\/}$_s$
photometric, as well as optical and near-infrared spectroscopic
observations with published results are as follows. The brightness
of V1647~Ori stayed more than 4\,mag above the pre-outburst level
until October 2005 when it started a rapid fading. In the high
state we found a periodic component in the optical light curves
with a period of 56 days. The time delay between the brightness
variations of the star and a nebular position corresponds to an
angle of $61\degr\pm14\degr$ between the axis of the nebula and
the line of sight. The overall appearance of the infrared and
optical spectra did not change in the period March~2004 --
March~2005, though steady decrease of HI emission line fluxes
could be observed. We show that the periodic variations of the
H$\alpha$ equivalent width, suggested by several authors, could
be caused by variation of the continuum with the 56 days period.
In May 2006, in the quiescent phase, the HeI 1.083 $\mu$m line was
in emission, contrary to its deep blueshifted absorption observed
during the outburst. The $J-H$ and $H-K_s$ color maps of the
infrared nebula reveal an envelope around the star whose largest
extension is about 18\arcsec (0.03\,pc). The color distribution
of the infrared nebula suggests reddening of the scattered light
inside a thick circumstellar disk. Comparison of the {\it K\/}$_s$
and H$\alpha$
images of McNeil's Nebula shows that HH\,22A, the Spitzer infrared source
and the bright clump C
of the nebula may be unrelated objects. We show that the observed
properties of V1647~Ori could be interpreted in the framework of
the thermal instability models of Bell et al. (1994). We speculate
that V1647~Ori might belong to a new class of young eruptive
stars, defined by relatively short timescales, recurrent
outbursts, modest increase in bolometric luminosity and accretion
rate, and an evolutionary state earlier than that of typical
EXors.