Red supergiants as potential type IIn supernova progenitors

Spatially resolved 4.6 μm CO emission aroung VY CMa and betelgeuse

Nathan Smith, Kenneth H. Hinkle, Nils Ryde

Research output: Contribution to journalArticle

106 Citations (Scopus)

Abstract

We present high-resolution 4.6 μm 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, 12CO emission within 3″ (12 km s-1) follows a mildly clumpy but otherwise spherical shell, smaller than its 55″ shell in K I λ7699. In stark contrast, 4.6 μm CO emission around VY CMa is coincident with bright K I in its clumpy asymmetric reflection nebula, within 5″ (40 km s-1) of the star. Our CO data reveal redshifted features not seen in K I spectra of VY CMa, indicating a more isotropic distribution of gas punctuated by randomly distributed asymmetric clumps. The relative CO and K I distribution in Betelgeuse arises from ionization effects within a steady wind, whereas in VY CMa, K I is emitted from skins of CO cloudlets resulting from episodic mass ejections 500-1000 yr ago. In both cases, CO and K I 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.

Original languageEnglish (US)
Pages (from-to)3558-3573
Number of pages16
JournalAstronomical Journal
Volume137
Issue number3
DOIs
StatePublished - 2009
Externally publishedYes

Fingerprint

supernovae
shell
reflection nebulae
stellar envelopes
skin
ionization
spherical shells
clumps
ejection
gas
stars
requirements
high resolution
gases
distribution
loss
effect

Keywords

  • Circumstellar matter
  • Stars: evolution
  • Stars: mass loss
  • Stars: winds, outflows

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Red supergiants as potential type IIn supernova progenitors : Spatially resolved 4.6 μm CO emission aroung VY CMa and betelgeuse. / Smith, Nathan; Hinkle, Kenneth H.; Ryde, Nils.

In: Astronomical Journal, Vol. 137, No. 3, 2009, p. 3558-3573.

Research output: Contribution to journalArticle

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AB - We present high-resolution 4.6 μm 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, 12CO emission within 3″ (12 km s-1) follows a mildly clumpy but otherwise spherical shell, smaller than its 55″ shell in K I λ7699. In stark contrast, 4.6 μm CO emission around VY CMa is coincident with bright K I in its clumpy asymmetric reflection nebula, within 5″ (40 km s-1) of the star. Our CO data reveal redshifted features not seen in K I spectra of VY CMa, indicating a more isotropic distribution of gas punctuated by randomly distributed asymmetric clumps. The relative CO and K I distribution in Betelgeuse arises from ionization effects within a steady wind, whereas in VY CMa, K I is emitted from skins of CO cloudlets resulting from episodic mass ejections 500-1000 yr ago. In both cases, CO and K I 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.

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