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Nils Ryde

Nils Ryde

Professor

Nils Ryde

Red supergiants as potential Type IIn supernova progenitors: Spatially Resolved 4.6 Mum CO Emission Around VY CMa and Betelgeuse

Author

  • Nathan Smith
  • Kenneth H. Hinkle
  • Nils Ryde

Summary, in English

We present high-resolution 4.6 mu m CO spectra of the circumstellar environments of two red supergiants (RSGs) that are potential supernova (SN) progenitors: Betelgeuse and VY Canis Majoris (VY CMa). Around Betelgeuse, (CO)-C-12 emission within +/-3 '' (+/-12 km s(-1)) follows a mildly clumpy but otherwise spherical shell, smaller than its similar to 55 '' shell in KI lambda 7699. In stark contrast, 4.6 mu m CO emission around VY CMa is coincident with bright KI in its clumpy asymmetric reflection nebula, within +/-5 '' (+/-40 km s(-1)) of the star. Our CO data reveal redshifted features not seen in KI spectra of VY CMa, indicating a more isotropic distribution of gas punctuated by randomly distributed asymmetric clumps. The relative CO and KI distribution in Betelgeuse arises from ionization effects within a steady wind, whereas in VY CMa, KI is emitted from skins of CO cloudlets resulting from episodic mass ejections 500-1000 yr ago. In both cases, CO and KI trace potential pre-SN circumstellar matter: we conclude that an extreme RSG like VY CMa might produce a Type IIn event like SN 1988Z if it were to explode in its current state, but Betelgeuse will not. VY CMa demonstrates that luminous blue variables are not necessarily the only progenitors of SNe IIn, but it underscores the requirement that SNe IIn suffer enhanced episodic mass loss shortly before exploding.

Department/s

  • Lund Observatory - Undergoing reorganization

Publishing year

2009

Language

English

Pages

3558-3573

Publication/Series

The Astronomical Journal

Volume

137

Issue

3

Document type

Journal article review

Publisher

IOP Publishing

Topic

  • Astronomy, Astrophysics and Cosmology

Keywords

  • stars: mass loss
  • circumstellar matter
  • stars: evolution
  • outflows
  • stars: winds

Status

Published

Project

  • VR-projektbidrag: Infraröd spektroskopi - ett nytt fönster mot galaktisk astronomi

ISBN/ISSN/Other

  • ISSN: 1538-3881