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TOPIC: Nova Monocerotis 2012

Blobrana

L

Posts: 131433

Date: Mar 16 10:04 2015

Nova V959 Mon	Permalink

Title: The Distance to Nova V959 Mon from VLA Imaging Author: J.D. Linford, V.A.R.M. Ribeiro, L. Chomiuk, T. Nelson, J.L. Sokoloski, M.P. Rupen, K. Mukai, T.J. O'Brien, A.J. Mioduszewski, J. Weston Determining reliable distances to classical novae is a challenging but crucial step in deriving their ejected masses and explosion energetics. Here we combine radio expansion measurements from the Karl G. Jansky Very Large Array with velocities derived from optical spectra to estimate an expansion parallax for nova V959 Mon, the first nova discovered through its gamma-ray emission. We spatially resolve the nova at frequencies of 4.5-36.5 GHz in nine different imaging epochs. The first five epochs cover the expansion of the ejecta from 2012 October to 2013 January, while the final four epochs span 2014 February to 2014 May. These observations correspond to days 126 through 199 and days 615 through 703 after the first detection of the nova. The images clearly show a non-spherical ejecta geometry. Utilising ejecta velocities derived from 3D modelling of optical spectroscopy, the radio expansion implies a distance between 0.9 ± 0.2 and 2.2 ± 0.4 kpc, with a most probable distance of 1.4 ± 0.4 kpc. This distance implies a gamma-ray luminosity much less than the prototype gamma-ray-detected nova, V407 Cyg, possibly due to the lack of a red giant companion in the V959 Mon system. V959 Mon also has a much lower gamma-ray luminosity than other classical novae detected in gamma-rays to date, indicating a range of at least a factor of 10 in the gamma-ray luminosities for these explosions. Read more (1911kb, PDF) __________________

Blobrana

L

Posts: 131433

Date: Apr 12 06:25 2013

RE: Nova Monocerotis 2012	Permalink

Title: The 7.1 hour X-ray-UV-NIR period of the gamma-ray classical Nova Monocerotis 2012 Authors: K.L. Page (1), J.P Osborne (1), R.M. Wagner (2), A.P. Beardmore (1), S.N. Shore (3), S. Starrfield (4), C.E. Woodward (5) ((1) University of Leicester, (2) Ohio State University, (3) Universita di Pisa, (4) Arizona State University, (5) University of Minnesota) Nova Mon 2012 is the third gamma-ray transient identified with a thermonuclear runaway on a white dwarf, that is, a nova event. Swift monitoring has revealed the distinct evolution of the harder and super-soft X-ray spectral components, while Swift-UV and V and I-band photometry show a gradual decline with subtle changes of slope. During the super-soft emission phase, a coherent 7.1 hr modulation was found in the soft X-ray, UV, optical and near-IR data, varying in phase across all wavebands. Assuming this period to be orbital, the system has a near-main sequence secondary, with little appreciable stellar wind. This distinguishes it from the first GeV nova, V407 Cyg, where the gamma-rays were proposed to form through shock-accelerated particles as the ejecta interacted with the red giant wind. We favour a model in which the gamma-rays arise from the shock of the ejecta with material close to the white dwarf in the orbital plane. This suggests that classical novae may commonly be GeV sources. We ascribe the orbital modulation to a raised section of an accretion disk passing through the line of sight, periodically blocking and reflecting much of the emission. The disk must, therefore, have reformed by day 150 after outburst. Read more (134kb, PDF) __________________

Blobrana

L

Posts: 131433

Date: Aug 22 01:35 2012

	Permalink
A magnitude 9.4 nova was discovered in the constellation Monocerotis on the 9th August, 2012, by S. Fujikawa (Japan) Position (J2000): R.A. 06 39 38.74 \| Dec. +05° 53' 52.0'' __________________

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