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Title: Very Deep inside the SN 1987A Core Ejecta: Molecular Structures Seen in 3D

Abstract

Most massive stars end their lives in core-collapse supernova explosions and enrich the interstellar medium with explosively nucleosynthesized elements. Following core collapse, the explosion is subject to instabilities as the shock propagates outward through the progenitor star. Observations of the composition and structure of the innermost regions of a core-collapse supernova provide a direct probe of the instabilities and nucleosynthetic products. SN 1987A in the Large Magellanic Cloud is one of very few supernovae for which the inner ejecta can be spatially resolved but are not yet strongly affected by interaction with the surroundings. Our observations of SN 1987A with the Atacama Large Millimeter/submillimeter Array are of the highest resolution to date and reveal the detailed morphology of cold molecular gas in the innermost regions of the remnant. The 3D distributions of carbon and silicon monoxide (CO and SiO) emission differ, but both have a central deficit, or torus-like distribution, possibly a result of radioactive heating during the first weeks (“nickel heating”). The size scales of the clumpy distribution are compared quantitatively to models, demonstrating how progenitor and explosion physics can be constrained.

Authors:
;  [1]; ;  [2]; ;  [3]; ;  [4];  [5];  [6]; ; ;  [7];  [8];  [9];  [10];  [11];  [12];  [13];  [14] more »; « less
  1. Departamento de Astronomía y Astrofísica, Universidad de Valencia, C/Dr. Moliner 50, E-46100 Burjassot (Spain)
  2. Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904 (United States)
  3. Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Straße 1, D-85748 Garching (Germany)
  4. Department of Astronomy, The Oskar Klein Centre, Stockholm University, Alba Nova University Centre, SE-106 91 Stockholm (Sweden)
  5. ESO, Karl-Schwarzschild-Straße 2, D-85748 Garching (Germany)
  6. Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States)
  7. School of Physics and Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff CF24 3AA (United Kingdom)
  8. Dunlap Institute for Astronomy and Astrophysics, University of Toronto, Toronto, ON M5S 3H4 (Canada)
  9. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  10. KTH, Department of Physics, and the Oskar Klein Centre, AlbaNova, SE-106 91 Stockholm (Sweden)
  11. Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States)
  12. Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong (China)
  13. Department of Physics, University of Texas at Arlington, 108 Science Hall, Box 19059, Arlington, TX 76019 (United States)
  14. Department of Physics, University of Oxford, Oxford OX1 3RH (United Kingdom)
Publication Date:
OSTI Identifier:
22654450
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 842; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CARBON; CARBON MONOXIDE; DISTRIBUTION; EMISSION; EXPLOSIONS; HEATING; HYDRODYNAMICS; INSTABILITY; INTERACTIONS; MAGELLANIC CLOUDS; MOLECULAR STRUCTURE; NICKEL; NUCLEOSYNTHESIS; RESOLUTION; SILICON; SILICON OXIDES; SUPERNOVA REMNANTS; SUPERNOVAE

Citation Formats

Abellán, F. J., Marcaide, J. M., Indebetouw, R., Chevalier, R., Gabler, M., Janka, H.-Th., Fransson, C., Lundqvist, P., Spyromilio, J., Burrows, D. N., Cigan, P., Gomez, H. L., Matsuura, M., Gaensler, B. M., Kirshner, R., Larsson, J., McCray, R., Ng, C.-Y., Park, S., Roche, P., E-mail: francisco.abellan@uv.es, and and others. Very Deep inside the SN 1987A Core Ejecta: Molecular Structures Seen in 3D. United States: N. p., 2017. Web. doi:10.3847/2041-8213/AA784C.
Abellán, F. J., Marcaide, J. M., Indebetouw, R., Chevalier, R., Gabler, M., Janka, H.-Th., Fransson, C., Lundqvist, P., Spyromilio, J., Burrows, D. N., Cigan, P., Gomez, H. L., Matsuura, M., Gaensler, B. M., Kirshner, R., Larsson, J., McCray, R., Ng, C.-Y., Park, S., Roche, P., E-mail: francisco.abellan@uv.es, & and others. Very Deep inside the SN 1987A Core Ejecta: Molecular Structures Seen in 3D. United States. doi:10.3847/2041-8213/AA784C.
Abellán, F. J., Marcaide, J. M., Indebetouw, R., Chevalier, R., Gabler, M., Janka, H.-Th., Fransson, C., Lundqvist, P., Spyromilio, J., Burrows, D. N., Cigan, P., Gomez, H. L., Matsuura, M., Gaensler, B. M., Kirshner, R., Larsson, J., McCray, R., Ng, C.-Y., Park, S., Roche, P., E-mail: francisco.abellan@uv.es, and and others. Tue . "Very Deep inside the SN 1987A Core Ejecta: Molecular Structures Seen in 3D". United States. doi:10.3847/2041-8213/AA784C.
@article{osti_22654450,
title = {Very Deep inside the SN 1987A Core Ejecta: Molecular Structures Seen in 3D},
author = {Abellán, F. J. and Marcaide, J. M. and Indebetouw, R. and Chevalier, R. and Gabler, M. and Janka, H.-Th. and Fransson, C. and Lundqvist, P. and Spyromilio, J. and Burrows, D. N. and Cigan, P. and Gomez, H. L. and Matsuura, M. and Gaensler, B. M. and Kirshner, R. and Larsson, J. and McCray, R. and Ng, C.-Y. and Park, S. and Roche, P., E-mail: francisco.abellan@uv.es and and others},
abstractNote = {Most massive stars end their lives in core-collapse supernova explosions and enrich the interstellar medium with explosively nucleosynthesized elements. Following core collapse, the explosion is subject to instabilities as the shock propagates outward through the progenitor star. Observations of the composition and structure of the innermost regions of a core-collapse supernova provide a direct probe of the instabilities and nucleosynthetic products. SN 1987A in the Large Magellanic Cloud is one of very few supernovae for which the inner ejecta can be spatially resolved but are not yet strongly affected by interaction with the surroundings. Our observations of SN 1987A with the Atacama Large Millimeter/submillimeter Array are of the highest resolution to date and reveal the detailed morphology of cold molecular gas in the innermost regions of the remnant. The 3D distributions of carbon and silicon monoxide (CO and SiO) emission differ, but both have a central deficit, or torus-like distribution, possibly a result of radioactive heating during the first weeks (“nickel heating”). The size scales of the clumpy distribution are compared quantitatively to models, demonstrating how progenitor and explosion physics can be constrained.},
doi = {10.3847/2041-8213/AA784C},
journal = {Astrophysical Journal Letters},
number = 2,
volume = 842,
place = {United States},
year = {Tue Jun 20 00:00:00 EDT 2017},
month = {Tue Jun 20 00:00:00 EDT 2017}
}
  • Carbon monoxide has been observed in the ejecta of SN 1987A. The molecular formation and destruction mechanisms in the ejecta environment are explored to determine how the CO and other molecules may be formed. In the absence of grains the first molecules must be formed either through negative ion reactions or through radiative association. The molecules are destroyed by interactions with the radiation field, by fast electron impact, and most effectively by charge transfer reactions with He(+) ions. The CO masses inferred from the observations of vibrational emission can be reproduced by a partially mixed model of the element distributionmore » or by a fully mixed model with rapid charge transfer of He(+) to metal atoms. 23 refs.« less
  • Mixing of matter in the ejecta is suggested by hydrodynamical calculations for SN 1987A. The X-ray flux calculated including mixing reproduces well the observed X-ray light curve and spectra. The effects of mixing on the gamma-ray lines have been estimated. The line fluxes at times less than 1.5 yr after the explosion strongly depend on mixing, and are greatly increased for values of the mixed mass larger than 4 solar masses. The peak advances to an earlier time and its flux is also greatly enhanced. If 5 solar masses are adopted for the mixed mass, as suggested from the X-raymore » calculations, the 847 keV line will reach its peak around 1.1 yr after the explosion with flux of 0.00086 photons/sq cm per s. If the mixed mass is less than 4 solar masses, the mixing effect becomes less prominent. The gamma-ray lines expected from SN 1987A should be observable. The way in which gamma-ray line observations can be used to diagnose properties of the ejecta is discussed. 23 references.« less
  • Formation of dust grains in the ejecta of SN 1987A is investigated on the basis of a theory of homogeneous nucleation and grain growth. The formation of dust grains in the gas ejected from a heavy element-rich mantle is considered, including the effects of latent heat released during grain growth and of radiation from the photosphere. It is shown that dust grains can condense in the heavy-element-rich mantle, and that the time of formation strongly depends on the temperature structure in the ejecta. Moreover, the formation of dust grains is retarded by the strong SN radiation field and the effectmore » of latent heat deposited during grain growth. 41 refs.« less
  • A model for the formation of CO in the expanding ejecta of SN 1987A suggests that the 4.6-micron and 2.3 micron emissions noted in the SN spectrum may originate from the inner metal-rich regions of the ejecta. Also reported are the assignment of a 2.26-micron excess feature in the high-resolution IR spectra to the v = 2 to 0 overtone of CO(+) and the possible identification of a 2.95-micron feature with the v = 2 to 0 transition of electronically excited CO. The results suggest that the regions in which CO formation takes place must be ionized to a substantiallymore » lower degree than regions which dominate the line emission of heavier metals. 60 refs.« less
  • Earlier light curve models for SN 1987A have been improved by adopting more realistic presupernova models and adopting a postexplosion elemental distribution consistent with X-ray and gamma-ray observations. The light curve shape is sensitive to the distributions of abundance and expansion velocity in the ejecta. It is found that the prepeak smooth rise and the broad peak of the light curve, respectively, are well modeled by assuming some mixing of Ni-56 into the hydrogen-rich envelope and of hydrogen into the core. The existence of the hydrogen recombination front is responsible for the formation of the plateaulike peak. For explosion energy,more » good agreement with the observed light curve is obtained for E/M(env) = (1.1 + or - 0./3) x 10 to the 50th ergs/solar mass. Further improvements on the early light curve, the dependence of the light curve on the distribution of Ni-56 and hydrogen, and the relation with other type II supernovae are discussed. 72 refs.« less