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Nova multiwavelength light curves: predicting UV precursor flashes and pre-maximum halts

Hillman, Y. and Prialnik, D. and Kovetz, A. and Shara, M. M. and Neill, J. D. (2014) Nova multiwavelength light curves: predicting UV precursor flashes and pre-maximum halts. Monthly Notices of the Royal Astronomical Society, 437 (2). pp. 1962-1975. ISSN 0035-8711.

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The dramatic brightenings of classical novae have yielded rich data sets of detailed light curves. Modelling these light curves is a challenge for any theory of classical novae. We have used our extended grid of nova outburst calculations to predict the luminosities of erupting novae expected in three electromagnetic bands – the visual, the near UV and the X-ray. Our models predict and explain many features of novae before eruption, as well as detailed characterizations of nova outbursts and post-nova declines. The evolutionary time-scales of eruption features vary by orders of magnitude, and depend on the basic nova parameters: white dwarf mass, luminosity and accretion rate. However, all light curves are found to share common features. Some of these features are unique to only one electromagnetic passband, while others show up in two, or in all three of the analysed bands. One extraordinary feature, common to all of our low-mass white dwarfs (0.65 M_⊙) novae, is that all exhibit a sharp rise followed by a more gradual decline in the near-UV luminosity, prior to the eruption in the visual luminosity. This is because the expansion of the outer layers lags behind the rise in bolometric luminosity. These predicted precursor-UV-flashes last between a few hours and a few days, and the predicted luminosity increase is between ∼0.5 and ∼3 mag. These flashes should be easily observable if a nova event is detected early and its time coverage is dense. Many observed novae exhibit a pre-maximum halt, and this feature is found in all three electromagnetic bands of many, but not all, of our nova models. We explain the presence or absence of pre-maximum halts as due to changes in the convective energy transfer regime. Finally we note cases where the maximum visual magnitude reaches as high as −8.5 mag for low-mass white dwarfs. This re-emphasizes the fact that white dwarf mass is not always the determining factor in setting a nova's peak luminosity.

Item Type:Article
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Neill, J. D.0000-0002-0466-1119
Additional Information:© 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2013 October 18. Received 2013 October 17. In original form 2013 August 6. This work was supported by Grant No.2010220 of the United States – Israel Binational Science Foundation. MS gratefully acknowledges ongoing support from Hilary and Ethel Lipsitz, and very helpful conversations with J. Mikolajewska concerning symbiotic novae. A very helpful referee report by Mike Bode is also gratefully acknowledged.
Group:Space Astrophysics Laboratory
Funding AgencyGrant Number
Binational Science Foundation (USA-Israel)2010220
Hilary and Ethel LipsitzUNSPECIFIED
Subject Keywords:methods: data analysis; methods: numerical; binaries: close; novae, cataclysmic variables; white dwarfs.
Issue or Number:2
Record Number:CaltechAUTHORS:20140326-132742017
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Official Citation:Y. Hillman, D. Prialnik, A. Kovetz, M. M. Shara, and J. D. Neill Nova multiwavelength light curves: predicting UV precursor flashes and pre-maximum halts MNRAS (January 11, 2014) Vol. 437 1962-1975 first published online November 19, 2013 doi:10.1093/mnras/stt2027
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:44533
Deposited By: Ruth Sustaita
Deposited On:26 Mar 2014 20:44
Last Modified:03 Oct 2019 06:19

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