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Title: Reappearance of Mcneil's nebula (V1647 Orionis) and its outburst environment

We present a detailed study of McNeil's nebula (V1647 Ori) in its ongoing outburst phase starting from 2008 September to 2013 March. Our 124 nights of photometric observations were carried out in optical V, R, I, and near-infrared J, H, K bands, and 59 nights of medium-resolution spectroscopic observations were done in the 5200-9000 Å wavelength range. All observations were carried out with the 2 m Himalayan Chandra Telescope and 2 m IUCAA Girawali Telescope. Our observations show that over the past four and a half years, V1647 Ori and region C near the Herbig-Haro object HH 22A have been undergoing a slow dimming at a rate of ∼0.04 mag yr{sup –1} and ∼0.05 mag yr{sup –1}, respectively, in R band, which is six times slower than the rate during a similar stage of V1647 Ori in the 2003 outburst. We detected change in flux distribution over the reflection nebula, implying changes in circumstellar matter distribution between the 2003 and 2008 outbursts. Apart from steady wind of velocity ∼350 km s{sup –1}, we detected two episodic magnetic reconnection driven winds. Forbidden [O I] λ6300 and [Fe II] λ7155 lines were also detected, implying shock regions probably from jets. We triedmore » to explain the outburst timescales of V1647 Ori using the standard models of the FUors kind of outburst and found that pure thermal instability models like Bell and Lin cannot explain the variations in timescales. In the framework of various instability models we conclude that one possible reason for the sudden ending of the 2003 outburst in 2005 November was a low-density region or gap in the inner region (∼1 AU) of the disk.« less
Authors:
; ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6]
  1. Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005 (India)
  2. Indian Institute of Astrophysics, Koramangala, Bangalore 560 034 (India)
  3. National Centre for Radio Astrophysics, Tata Institute of Fundamental Research, Pune 411 007 (India)
  4. Inter-University Centre for Astronomy and Astrophysics, Pune 411 007 (India)
  5. National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan)
  6. Max-Planck-Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany)
Publication Date:
OSTI Identifier:
22341955
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 778; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; DENSITY; DISTRIBUTION; HERBIG-HARO OBJECTS; INSTABILITY; MAGNETIC RECONNECTION; NEBULAE; REFLECTION; RESOLUTION; SPECTRA; STARS; TELESCOPES; VELOCITY; WAVELENGTHS