RED SUPERGIANTS AS POTENTIAL TYPE IIn SUPERNOVA PROGENITORS: SPATIALLY RESOLVED 4.6 μm CO EMISSION AROUND VY CMa AND BETELGEUSE

By N. Smith, K. Hinkle, N. Ryde. 2008

155 citations recorded by the source corpus.

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.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/ae7235153d676b5b0465ef283f37649cc01bd32d

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In Astronomy and Astrophysics

1. N. Smith
2. A. Filippenko
3. S. Smartt
4. Stan Woosley
5. Ryan Chornock
6. Weidong Li
7. J. Silverman
8. S. Valenti

Citations in the corpus

• SPECTRAL EVOLUTION OF THE EXTRAORDINARY TYPE IIn SUPERNOVA 2006gy (2009, methodology): “The effective value of RBB begins to fall, not because the radius is actually decreasing, but because the CDS is fragmented and is becoming progressively more transparent (Smith et al. 2008a).”
• Luminous blue variables are antisocial: their isolation implies that they are kicked mass gainers in binary evolution (2014, background): “Besides massive LBVs exploding as SNe IIn, there are also examples where SNe IIn may result from: (1) extreme RSGs with strong clumpy winds (Smith et al. 2009a,b), (2) electroncapture SNe (ecSNe) from 8-10 M⊙ super-AGB stars (such as the class of SNe IIn-P and possibly the Crab Nebula; Mauerhan et…”
• Observed Fractions of Core-Collapse Supernova Types and Initial Masses of their Single and Binary Progenitor Stars (2010, background): “…even among the subclass, with the faintest SNe IIn like SN 2005ip looking basically like an SN II-L with strong narrow emission lines (Smith et al. 2009b), whereas the CSM is opaque and qualitatively changes the SN in more luminous SNe IIn such as SN 2006tf and SN 2006gy (Smith et al. 2008b).”
• Light-curve modelling of superluminous supernova 2006gy: collision between supernova ejecta and a dense circumstellar medium (2012, background): “Because of the high NIR luminosities, Smith et al. (2008) and Miller et al. (2010) suggest that the late-time luminosity is due to light echoes.”
• Mass Loss: Its Effect on the Evolution and Fate of High-Mass Stars (2014, background): “…recently, pre-SN eruptive mass loss and connections to LBVs were mostly hypothetical, limited to (reasonable) conjectures supported by the circumstantial evidence that something must deposit a large mass of outflowing H-rich CSM so close to the star (Chugai et al. 2004, Smith et al. 2008, 2010b).”
• Type II-Plateau supernova radiation: dependences on progenitor and explosion properties (2013, background): “If it were to explode, rather than producing a type II-P, the resulting SN would probably be a Type IIn, or a II-L.”
• Unifying Type II Supernova Light Curves with Dense Circumstellar Material (2016, background): “Even for the extremely dense wind of the most luminous known RSG (VY CMa, Smith et al. 2009) the estimated mass loss rate is 1 − 2 × 10−3M yr−1.”
• Carnegie Supernova Project: Observations of Type IIn supernovae ⋆ (2013, background): “This was discussedby Smith et al. (2008), where they present SN 2006tf.”
• The Unprecedented Third Outburst of SN 2009ip: A Luminous Blue Variable Becomes a Supernova (2012, background): “While LBVs provide the only known precedent for the eruptive pre-SN mass loss needed to make luminous SNe IIn (e.g., Smith et al. 2010a, 2008a), this suggestion has been controversial because it directly contradicts current expectations of standard stellar evolution models (Heger et al. 2003;…”