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ALMA observations of Molecules in Supernova 1987A
Line survey Chemistry, mixing and isotopologues High angular resolution images Clumps and torus Evolution of ring dust (c.f. ejecta dust – Phil Cigan’s talk) Mikako Matsuura (Cardiff University) P. Cigan, F. Abellan, R. Indebetouw, J. Kamenetzky, D. McCray, J. Larsson, C. Fransson, M. J. Barlow, V. Bujarrabal, R. Chevalier, E. Dwek, H. Gomez, S. Woosley, et al.
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ALMA (Atacama Large millimetre and sub-millimetre array)
High sensitivities (RMS~33 mJy in less than hour at 200 GHz) High angular resolutions (0.05 arcsec – 0.3 arcsec) SN 1987A Ejecta ~0.9 arcsec Ring
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ALMA detections of molecules in 2012
Cold ( K) ‘molecular gas’ in the ejecta after 25 years 12CO J=2-1 12CO J=1-0 28SiO 29SiO CO FWHM~ 2300 km s-1 (Kamenetzky et al. 2013)
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Contents Molecules Evolution of ring dust Line survey
What kind of molecules have formed in the ejecta? What is the chemical processes? Chemistry, mixing and isotopologues High angular resolution images Using molecular lines to prove dynamics of the ejecta Clumps and torus Evolution of ring dust Does the interaction of blast winds destroy dust in the ring?
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ALMA molecular survey in 2014/2015
SiO CO SiO CO+SiO Synchrotron Matsuura et al. (2017)
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Estimating temperature and density by modelling molecular lines
SiO T=20–170 K Mass: 1x10-3 – 2x10-5 M n(Hcorr): 106 cm-3 Only small fraction of Si (0.2 M) is in SiO (most Si in silicate dust?) CO T=20–50 K Mass: 0.5–9x10-3 M n(Hcorr): 105–106 cm-3 Cold & Relatively high density gas
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First detections of SO and HCO+ from SNe
29SiO SO + 29SiO HCO+ + SO2 SO HCO+? Matsuura et al. (2017)
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How to form HCO+? Reactions
H2++H2 -> H3++H & H3+ + CO -> H2 + HCO+ C+H2 -> CH + H & CH + O -> HCO++ e-
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Explosive nucleosynthesis without mixing
Elemental mass fraction No mixing = no HCO+ Interior Mass (M) Explosive nucleosynthesis for SN 1987A (Woosley in preparation)
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Explosive nucleosynthesis with mixing between zones
HCO+ formation H C O Elemental mass fraction Explosive nucleosynthesis for SN 1987A (Woosley in preparation) Interior Mass (M)
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Isotopologues 28SiO At millimeter and submillimeter wavelengths, isotope shifts are larger than the SN expansion velocity (~2000 km s-1) 29SiO 30SiO
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Constraints on SN nucleosynthesis: isotope ratio
28SiO CO 28SiO 29SiO+SO 29SiO+SO ALMA 28SiO / 29SiO >13 Matsuura et al. (2017)
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Si isotope ratios SN 1987A could be slightly offset from presolar grains sequence Low metallicity effects Neutron-rich isotopes are poorer at lower metallicity Measurements in presolar grains 28Si/30Si 44Ca decay fro 44 Ti 28Si/29Si Matsuura et al. (2017)
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Si isotope ratios Models slightly under-predict 29Si and 30Si slightly, with respect to 28Si SN 1987A (~30% of solar Z) (Woosley) 28Si/30Si Solar metallicity models Sukhbold et al. (2016) 28Si/29Si Matsuura et al. (2017)
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Clumps – footprints of Rayleigh-Taylor instabilities at the time of explosion
t=350 sec t=9000 sec 3D simulation of instability at the time of SN explosion (Hammer et al. 2010; Wongwathanarat et al. 2015) Carbon/Oxygen/Nickel
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Contents Molecules Evolution of ring dust Line survey
What kind of molecules have formed in the ejecta? What is the chemical processes? Chemistry, mixing and isotopologues High angular resolution images Using molecular lines to prove dynamics of the ejecta Clumps and torus Evolution of ring dust Does the interaction of blast winds destroy dust in the ring?
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Blast wave has passed the circumstellar ring
Feb 2008 June 2014 Material outside of the ring is illuminated by shocks Destruction of ring (Fransson et al. 2015)
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Warm ring dust in SN 1987A Dust Gemini mid-IR resolved image (green)
Warm dust in the ring Red-supergiant origin (red) (green) Bouchet et al. (2006) Warm ring dust Cold ejecta dust In 2000s, new telescopes have been built, and dust is detected with mid-infrared observations with Gemini and Spitzer Space Telescope. There is a famous ring bright in optical, and mid infrared image, which traces the thermal emission of dust, is found in red surrounding the ring. This ring itself is believed to be formed before the supernova explosion, when the star was red-supergiant phase. So that mid-infrared emission traces dust colliding into the ring, and heated by shocks. This is the spectral energy distribution of supernova 1987A before Herschel launch. Red and green shows the Spitzer observations. A model fit to this was like this blue line, and the flux drops sharply towards the longer wavelength. Herschel detection limits are here, so that the prediction was that supernova 1987A would not be detected with Herschel, which was launched in But fortunately and unexpectedly, we detected SN 1987A at far-infrared wavelength with Herschel. --- Blue dashed line shows the model spectrum to fit the Spitzer data. This model can predict the dust emission in Herschel wavelength range, And the expected flux was much lower than the Herschel detection limit. Ejecta Ring (red supergiant origin)
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Summary Molecular line survey High resolution images Ring dust
Cold ( K) molecules in the ejecta, with high density gas (Ncoll~106 cm-3) Finding of HCO+ & SO Detection of HCO+ suggests mixing at the time of explosion High resolution images Clumps: tracing the instabilities at the time of explosions Ring dust Cold dust in post-shocked region?
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