Editing SN 1987A (section)

==Condensation of warm dust in the ejecta==
[[File:Images of the Warm Dust in the SN 1987A debris.png|thumb|left|Images of the SN 1987A debris obtained with the instruments T-ReCS at the 8-m Gemini telescope and VISIR at one of the four VLT. Dates are indicated. An HST image is inserted at the bottom right (credits Patrice Bouchet, CEA-Saclay)]]

Soon after the SN 1987A outburst, three major groups embarked in a photometric monitoring of the supernova: the [[South African Astronomical Observatory]] (SAAO),<ref name="MNRAS1">
{{cite journal
 |last1=Menzies |first1=J.W.
 |display-authors=etal
 |year=1987
 |title=Spectroscopic and photometric observations of SN 1987a - The first 50 days
 |journal=[[Monthly Notices of the Royal Astronomical Society]]
 |volume=227 |pages=39P–49P
 |bibcode=1987MNRAS.227P..39M
 |doi=10.1093/mnras/227.1.39P
 |doi-access=free
}}</ref><ref name="MNRAS2">
{{cite journal
 |last1=Catchpole |first1=R.M.
 |display-authors=etal
 |year=1987
 |title=Spectroscopic and photometric observations of SN 1987a. II - Days 51 to 134
 |journal=[[Monthly Notices of the Royal Astronomical Society]]
 |volume=229 |pages=15P–25P
 |bibcode=1987MNRAS.229P..15C
 |doi=10.1093/mnras/229.1.15P
 |doi-access=free
}}</ref> the [[Cerro Tololo Inter-American Observatory]] (CTIO),<ref name="CTIO">
{{cite journal
 |last1=Elias |first1=J.H.
 |display-authors=etal
 |year=1988
 |title=Line identifications in the infrared spectrum of SN 1987A
 |journal=[[The Astrophysical Journal]]
 |volume=331 |pages=L9
 |bibcode=1988ApJ...331L...9E
 |doi=10.1086/185225
}}</ref><ref name="Proceedings Astronomical Society of Australia">
{{cite journal
 |last1=Terndrup |first1=D.M.
 |display-authors=etal
 |year=1988
 |title=Optical and infrared observations of SN 1987A from Cerro Tololo
 |journal=[[Astronomical Society of Australia]]
 |volume=7 |issue=4 |pages=412–423
 |bibcode=1988PASA....7..412T
 |doi=10.1017/S1323358000022566
 |s2cid=117801292
 }}</ref> and the [[European Southern Observatory]] (ESO).<ref name=AA>
{{cite journal
 |last1=Bouchet |first1=P.
 |display-authors=etal
 |year=1987
 |title=Infrared photometry of SN 1987A
 |journal=[[Astronomy and Astrophysics]]
 |volume=177 |pages=L9
 |bibcode=1987A&A...177L...9B
}}</ref><ref name=ESO>
{{cite conference
 |last1=Bouchet |first1=P.
 |display-authors=etal
 |year=1987
 |chapter=Infrared photometry of SN 1987A - The first four months
 |title=ESO Workshop on the SN 1987A, Garching, Federal Republic of Germany
 |conference=European Southern Observatory Conference and Workshop, July 6–8, 1987
 |publisher=European Southern Observatory
 |volume=177 |pages=79
 |bibcode=1987ESOC...26...79B
}}</ref> In particular, the ESO team reported an [[infrared excess]] which became apparent beginning less than one month after the explosion (March 11, 1987).  Three possible interpretations for it were discussed in this work: the infrared echo hypothesis was discarded, and [[thermal emission]] from dust that could have condensed in the ejecta was favoured (in which case the estimated temperature at that epoch was ~ 1250 K, and the dust mass was approximately {{solar mass|{{val|6.6|e=-7}}}}). The possibility that the IR excess could be produced by optically thick [[free-free emission]] seemed unlikely because the luminosity in UV photons needed to keep the envelope ionized was much larger than what was available, but it was not ruled out in view of the eventuality of electron scattering, which had not been considered.{{citation needed|date=February 2021}}

However, none of these three groups had sufficiently convincing proofs to claim for a dusty ejecta on the basis of an IR excess alone.{{citation needed|date=February 2021}}
[[File:Model of the dust distribution.png|thumb|right|Distribution of the dust inside the SN 1987A ejecta, as from the Lucy et al.'s model built at ESO<ref name="LucyModel">
{{Cite book
 |last1=Lucy |first1=L.
 |title=Structure and Dynamics of the Interstellar medium
 |chapter=Dust condensation in the ejecta of SN 1987A
 |display-authors=etal
 |year=1989
 |journal=<!-- Bypass citation bot-->
 |editor1=Guillermo Tenorio-Tagle |editor2=Mariano Moles |editor3=Jorge Melnick
 |publisher=[[Springer-Verlag]]
 |series=[[Lecture Notes in Physics]]
 |volume=350 |pages=164–179
 |bibcode=1989LNP...350..164L
 |doi=10.1007/BFb0114861
 |isbn=978-3-540-51956-0
|s2cid=222246187
 }}</ref>
]]
An independent Australian team advanced several arguments in favour of an echo interpretation.<ref name="Infrared Echo">
{{Cite journal
 |last1=Roche |first1=P.F.
 |display-authors=etal
 |year=1989
 |title=Old cold dust heated by supernova 1987A
 |journal=[[Nature (journal)|Nature]]
 |volume=337 |issue=6207|pages=533–535
 |bibcode=1989Natur.337..533R
 |doi=10.1038/337533a0
 |s2cid=4308604
}}</ref>  This seemingly straightforward interpretation of the nature of the IR emission was challenged by the ESO group<ref name="IAUC1">
{{Cite journal
 |last1=Bouchet |first1=P.
 |last2=Danziger |first2=J.
 |last3=Lucy |first3=L.
 |year=1989
 |title=Supernova 1987A in the Large Magellanic Cloud
 |journal=[[IAU Circular]]
 |issue=4933|pages=1
 |bibcode=1989IAUC.4933....1B
}}</ref> and definitively ruled out after presenting optical evidence for the presence of dust in the SN ejecta.<ref name="IAUC2">
{{Cite journal
 |last1=Danziger |first1=I. J.
 |last2=Gouiffes |first2=C.
 |last3=Bouchet |first3=P.
 |last4=Lucy |first4=L. B.
 |year=1989
 |title=Supernova 1987A in the Large Magellanic Cloud
 |journal=[[IAU Circular]]
 |issue=4746 |pages=1
 |bibcode=1989IAUC.4746....1D
}}</ref>
To discriminate between the two interpretations, they considered the implication of the presence of an echoing dust cloud on the optical light curve, and on the existence of diffuse optical emission around the SN.<ref name="Nature Felten Dwek">
{{Cite journal
 |last1=Felten |first1=J.E.
 |last2=Dwek |first2=E.
 |year=1989
 |title=Infrared and optical evidence for a dust cloud behind supernova 1987A
 |journal=[[Nature (journal)|Nature]]
 |volume=339 |issue=6220 |pages=123
 |bibcode=1989Natur.339..123F
 |doi=10.1038/339123a0
 |s2cid=4243200
}}</ref>  They concluded that the expected optical echo from the cloud should be resolvable, and could be very bright with an integrated visual brightness of [[apparent magnitude|magnitude]] 10.3 around day 650. However, further optical observations, as expressed in SN light curve, showed no [[inflection point|inflection]] in the light curve at the predicted level. Finally, the ESO team presented a convincing clumpy model for dust condensation in the ejecta.<ref name="LucyModel" /><ref name=SUPE>
{{cite conference
 |last1=Lucy |first1=L.
 |display-authors=etal
 |year=1991
 |title=Dust Condensation in the Ejecta of Supernova 1987A - Part Two
 |conference=Supernovae. The Tenth Santa Cruz Workshop in Astronomy and Astrophysics, Held July 9–21, 1989, Lick Observatory.
 |editor-last1=Woosley |editor-first1=S.E.
 |publisher=[[Springer Verlag]] |place=New York
 |pages=82
 |bibcode=1991supe.conf...82L
 |isbn=978-0387970714
}}</ref>

Although it had been thought more than 50 years ago that dust could form in the ejecta of a core-collapse supernova,<ref name="Annales d'Astrophysique">
{{Cite journal
 |last1=Cernuschi |first1=F.
 |last2=Marsicano |first2=F.
 |last3=Codina |first3=S.
 |year=1967
 |title=Contribution to the theory on the formation of cosmic grains
 |journal=[[Annales d'Astrophysique]]
 |volume=30 |pages=1039
 |bibcode=1967AnAp...30.1039C
}}</ref> which in particular could explain the origin of the dust seen in young galaxies,<ref name="Science Advances">
{{Cite journal
 |last1=Liu |first1=N.
 |display-authors=etal
 |year=2018
 |title=Late formation of silicon carbide in type II supernovae
 |journal=[[Science Advances]]
 |volume=4 |issue=1 |pages=1054
 |arxiv=1801.06463 |bibcode=2018SciA....4.1054L
 |doi=10.1126/sciadv.aao1054
 |pmid=29376119
 |pmc=5777395
}}</ref> that was the first time that such a condensation was observed. If SN 1987A is a typical representative of its class then the derived mass of the warm dust formed in the debris of core collapse supernovae is not sufficient to account for all the dust observed in the early universe. However, a much larger reservoir of ~0.25 solar mass of colder dust (at ~26 K) in the ejecta of SN 1987A was found<ref name="herschel">
{{cite journal
 |last1=Matsuura |first1=M.
 |display-authors=etal
 |year=2011
 |title=Herschel Detects a Massive Dust Reservoir in Supernova 1987A
 |journal=[[Science (journal)|Science]]
 |volume=333 |issue=6047 |pages=1258–1261
 |arxiv=1107.1477|bibcode=2011Sci...333.1258M
 |doi=10.1126/science.1205983
 |pmid=21737700
 |s2cid=46458836
}}</ref> with the infrared [[Herschel Space Observatory|Herschel Space Telescope]] in 2011 and confirmed with the [[Atacama Large Millimeter Array]] (ALMA) in 2014.<ref name="alma">
{{cite journal
 |last1=Indebetouw |first1=R.
 |display-authors=etal
 |year=2014
 |title=Dust Production and Particle Acceleration in Supernova 1987A Revealed with ALMA
 |journal=[[The Astrophysical Journal]]
 |volume=782 |issue=1 |pages=L2
 |bibcode=2014ApJ...782L...2I
 |doi=10.1088/2041-8205/782/1/L2|arxiv=1312.4086|s2cid=33224959
}}</ref>