Cigan, P, Matsuura, M, Gomez, HL, Indebetouw, R, Abellan, F, Gabler, M, Richards, A, Alp, D, Davis, TA, Janka, H-T, Spyromilio, J, Barlow, MJ, Burrows, D, Dwek, E, Fransson, C, Gaensler, B, Larsson, J, Bouchet, P, Lundqvist, P, Marcaide, JM, Ng, C-Y, Park, S, Roche, P, van Loon, JT, Wheeler, JC and Zanardo, G (2019) High Angular Resolution ALMA Images of Dust and Molecules in the SN 1987A Ejecta. Astrophysical Journal, 886 (1). ISSN 0004-637X

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We present high angular resolution (similar to 80 mas) ALMA continuum images of the SN.1987A system, together with CO J = 2 -> 1, J = 6 -> 5, and SiO J = 5 -> 4 to J = 7 -> 6 images, which clearly resolve the ejecta (dust continuum and molecules) and ring (synchrotron continuum) components. Dust in the ejecta is asymmetric and clumpy, and overall the dust fills the spatial void seen in H alpha images, filling that region with material from heavier elements. The dust clumps generally fill the space where CO J = 6 -> 5 is fainter, tentatively indicating that these dust clumps and CO are locationally and chemically linked. In these regions, carbonaceous dust grains might have formed after dissociation of CO. The dust grains would have cooled by radiation, and subsequent collisions of grains with gas would also cool the gas, suppressing the CO J = 6 -> 5 intensity. The data show a dust peak spatially coincident with the molecular hole seen in previous ALMA CO J = 2 -> 1 and SiO J = 5 -> 4 images. That dust peak, combined with CO and SiO line spectra, suggests that the dust and gas could be at higher temperatures than the surrounding material, though higher density cannot be totally excluded. One of the possibilities is that a compact source provides additional heat at that location. Fits to the far-infrared-millimeter spectral energy distribution give ejecta dust temperatures of 18-23 K. We revise the ejecta dust mass to M-dust = 0.2-0.4 M-circle dot for carbon or silicate grains, or a maximum of <0.7 M-circle dot for a mixture of grain species, using the predicted nucleosynthesis yields as an upper limit.

Item Type: Article
Additional Information: © 2019 IOP, American Astronomical Society. This is the final published version of the article (version of record). It first appeared online via IOP Science at - please refer to any applicable terms of use of the publisher.
Subjects: Q Science > QB Astronomy > QB799 Stars
Divisions: Faculty of Natural Sciences > School of Chemical and Physical Sciences
Related URLs:
Depositing User: Symplectic
Date Deposited: 17 Dec 2019 17:07
Last Modified: 17 Dec 2019 17:11

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