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The Type II supernovae 2006V and 2006au: two SN 1987A-like events
Stockholm University, Faculty of Science, Department of Astronomy.
Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
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2012 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 537, 140- p.Article in journal (Refereed) Published
Abstract [en]

Context. Supernova 1987A revealed that a blue supergiant (BSG) star can end its life as a core-collapse supernova (SN). SN 1987A and other similar objects exhibit properties that distinguish them from ordinary Type II Plateau (IIP) SNe, whose progenitors are believed to be red supergiants (RSGs). Similarities among 1987A-like events include a long rise to maximum, early luminosity fainter than that of normal Type IIP SNe, and radioactivity acting as the primary source powering the light curves. Aims: We present and analyze two SNe monitored by the Carnegie Supernova Project that are reminiscent of SN 1987A. Methods: Optical and near-infrared (NIR) light curves, and optical spectroscopy of SNe 2006V and 2006au are presented. These observations are compared to those of SN 1987A, and are used to estimate properties of their progenitors. Results: Both objects exhibit a slow rise to maximum and light curve evolution similar to that of SN 1987A. At the earliest epochs, SN 2006au also displays an initial dip which we interpret as the signature of the adiabatic cooling phase that ensues shock break-out. SNe 2006V and 2006au are both found to be bluer, hotter and brighter than SN 1987A. Spectra of SNe 2006V and 2006au are similar to those of SN 1987A and other normal Type II objects, although both consistently exhibit expansion velocities higher than SN 1987A. Semi-analytic models are fit to the UVOIR light curve of each object from which physical properties of the progenitors are estimated. This yields ejecta mass estimates of Mej ≈ 20 M&sun;, explosion energies of E ≈ 2-3 × 1051 erg s-1, and progenitor radii of R ≈ 75-100 R&sun; for both SNe. Conclusions: The progenitors of SNe 2006V and 2006au were most likely BSGs with a larger explosion energy as compared to that of SN 1987A. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile (ESO Programme 076.A-0156). This paper includes data gathered with the 6.5-m Magellan Telescopes located at Las Campanas Observatory, Chile.Tables 1-6 are available in electronic form at

Place, publisher, year, edition, pages
2012. Vol. 537, 140- p.
Keyword [en]
supernovae: general, supernovae: individual: SN 2006V, supernovae: individual: SN 2006au, supernovae: individual: SN 1987A
National Category
Natural Sciences
URN: urn:nbn:se:su:diva-83518DOI: 10.1051/0004-6361/201118091OAI: diva2:576108
Available from: 2012-12-12 Created: 2012-12-12 Last updated: 2014-10-20Bibliographically approved
In thesis
1. Observations of rare supernovae and their environments
Open this publication in new window or tab >>Observations of rare supernovae and their environments
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Supernovae (SNe) are the final stage in the life of massive stars. Their explosion unbinds the progenitor star revealing its inner layers. The SN ejecta interact with the circumstellar material (CSM), providing further information on the progenitor star.

In this work we present the study of rare SN subtypes, aiming to investigate their observational and physical properties and those of their progenitor stars.These studies include the analysis of SN samples as well as that of single objects.Two main SN classes are discussed: radioactively-powered events and SNe interacting with their CSM.

Within the first group, we investigated the rare (~1% of core-collapse SNe) family of SN 1987A-like events. These SNe are found to be the explosion of compact, hydrogen-rich blue supergiant (BSG) stars, and to occur mainly in moderately low metallicity environs. We also studied a sample of 20 stripped-envelope (SE) SNe, which are also powered by the decay of radioactive 56Ni. These SNe are the result of the core-collapse of massive, hydrogen or even helium-poor stars stripped of their outer envelopes by line-driven winds and/or by the accretion onto companion stars.We investigated the differences among the early-time light curves of the subtypes forming the SE SN group (IIb, Ib, Ic, Ic-BL) and found that in all of them the 56Ni is strongly mixed out in the ejecta. This result suggests that the difference between helium-poor and helium-rich SNe is due to an actual lack of helium in SNe Ic and Ic-BL rather than to a different degree of 56Ni mixing.

Our work on CSM-interacting SNe include the study of a sample of SNe IIn, i.e. core-collapse SNe interacting with hydrogen-rich CSM, and the analysis of SN 2008J, a particularly rare event which we interpreted as the interaction of a thermonuclear SN Ia with a thick hydrogen-rich CSM. Spectral analysis of the SN IIn sample suggests that these SNe are likely to be the explosion of luminous blue variable stars (LBVs), although other channels are not excluded.

Place, publisher, year, edition, pages
Stockholm: Department of Astronomy, Stockholm University, 2014. 80 p.
Supernova, stellar evolution, metallicity, circumstellar interaction
National Category
Astronomy, Astrophysics and Cosmology
Research subject
urn:nbn:se:su:diva-108286 (URN)978-91-7649-030-3 (ISBN)
Public defence
2014-12-19, sal FB52, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (English)

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 5: Submitted.

Available from: 2014-11-27 Created: 2014-10-17 Last updated: 2014-11-20Bibliographically approved

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Taddia, FrancescoSollerman, JesperErgon, MattiasFransson, Claes
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