REAPPEARANCE OF McNEIL'S NEBULA (V1647 ORIONIS) AND ITS OUTBURST ENVIRONMENT

Abstract

We present a detailed study of McNeil's nebula (V1647 Ori) in its ongoing outburst phase starting from September 2008 to March 2013. Our 124 nights of photometric observations were carried out in optical V, R, I and near-infrared (NIR) J, H, K bands, and 59 nights of medium resolution spectroscopic observations were done in 5200 -9000Å wavelength range. All observations were carried out with 2-m Himalayan Chandra Telescope (HCT) and 2-m IUCAA Girawali Telescope. Our observations show that over last four and a half years, V1647 Ori and the region C near Herbig-Haro object, HH 22A, have been undergoing a slow dimming at a rate of ∼ 0.04 mag yr −1 and ∼ 0.05 mag yr −1 respectively in R-band, which is 6 times slower than the rate during similar stage of V1647 Ori in 2003 outburst. We detected change in flux distribution over the reflection nebula implying changes in circumstellar matter distribution between 2003 and 2008 outbursts. Apart from steady wind of velocity ∼ 350 km s −1 we detected two episodic magnetic reconnection driven winds. Forbidden [O I] 6300Å and [Fe II] 7155Å lines were also detected implying shock regions probably from jets. We tried to explain the outburst timescales of V1647 Ori using the standard models of FUors kind of outburst and found that pure thermal instability models like Bell & Lin (1994) cannot explain the variations in timescales. In the framework of various instability models we conclude that one possible reason for sudden ending of 2003 outburst in 2005 November was due to a low density region or gap in the inner region (∼ 1 AU) of the disc.

V899 Mon: An Outbursting Protostar With a Peculiar Light Curve, and Its Transition Phases

“…The green squares measured during the 2013 -2015 period of second outburst show small movements along the reddening vector. Such short period, small amplitude fluctuations during the outburst phase are also seen in other FUor/EXor objects (Audard et al 2014;Semkov et al 2013;Ninan et al 2013). Unlike the quiescence in 2011, these short variations in second outburst could be due to small dust clump occultations or minor fluctuations in the accretion.…”

“…Few other outburst sources like V1647 Ori, V582 Aur and V2492 Cyg have also shown such a sudden brief transition to quiescent phase after reaching peak of first outburst (Ninan et al 2013;Semkov et al 2013;Kóspál et al 2013). V582 Aur and V2492 Cyg's light curves were very unstable, but V1647 Ori's light curve was very similar to V899 Mon in terms of the stability during the phase transitions.…”

Indian Astronomical Observatory, Leh-Hanle

“…A detailed study of the post-outburst phase of McNeil's nebula (illuminated by the young stellar object V1647 Orionis) confirmed that V1647 Ori is a pre-main-sequence star of the EX Or type (Ojha et al, 2006). The object is continuously observed for understanding the evolution of the system (Ninan et al, 2013).…”

V346 Nor: The Post-outburst Life of a Peculiar Young Eruptive Star

“…Apart from the clearly repetitive outbursts of EX Lupitype objects (EXors), there are other young eruptive stars that showed multiple outbursts. V1647 Ori is an embedded object that was in outburst between 2004 and 2006, then again between 2008 and 2018, and photographic plates suggest an outburst in 1966 as well (Aspin et al 2006;Acosta-Pulido et al 2007;Ninan et al 2013;Giannini et al 2018). It is not a bona fide FUor, because its light curves and spectra show a mix of characteristics from both FUors and EXors.…”