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SN 1988Z
Event type	Supernova
	IIn
Constellation	Leo
Right ascension	10h 51m 50.10s
Declination	+16° 00′ 00.5″
Epoch	J2000
Redshift	0.0225
Host	MCG +03-28-22
Peak apparent magnitude	16.80 (B)
	[edit on Wikidata]

SN 1988Z was a prototypical^[2] type IIn supernova event in the equatorial constellation of Leo. The apparent host is an irregular galaxy with the designation MCG +03-28-22.^[1] It has a redshift of z equal to 0.0225.^[1] This was a very luminous supernova that faded unusually slowly and has remained detectable three decades after the event. It is one of the most radio and X-ray luminous supernova ever detected, and it has been extensively studied.^[3]^[4]

Observations

This event was discovered independently, both by C. Pollas at the Côte d'Azur Observatory on a photographic plate taken December 12, 1988, and by G. Candeo at the Asiago Astrophysical Observatory from a plate taken December 14.^[5] The supernova was already past maximum when it was discovered. A spectrum taken December 17 showed this was most likely a type II supernova.^[6]

Light curves for SN 1988Z in three photometric bands, Blue, Visual and Red, adapted from Turatto *et al.*^[7]

This supernova displayed a number of unusual characteristics. It was unusually bright at maximum and showed very slow fading. There were strong, narrow emission lines caused by thick circumstellar material. Unlike a typical type II supernova, no P Cygni profiles or absorption lines were observed.^[8] Emission lines of neutral helium were also visible. The spectral lines displayed a complex structure that evolved over time. Decline in the Hydrogen-alpha line strength was unusually slow and lacked an explanation in terms of radioactive decay. The overall picture suggested interaction between the supernova ejecta and a dense circumstellar medium.^[7]

A year after the event, radio emission from the supernova was detected using the Very Large Array. The host galaxy shows a redshift of z equal to 0.022, making this the most distant radio supernova detected at that time. It was also one of the most luminous radio supernova discovered. The radio properties indicated a very massive progenitor star in the range of 20–30 M_☉. In the late evolutionary stages of the star, it underwent a high rate of mass loss on the order of 10⁻⁴ M_☉·yr⁻¹, which created a dense circumstellar cocoon.^[9] In 1996, X-ray emission from the supernova was detected by ROSAT, making it the most distant supernova to be detected in this band. The estimated X-ray luminosity was 10⁴¹ erg·s⁻¹, which is consistent with a supernova event within dense circumstellar material.^[10]

Most studies now favor a model of a very massive progenitor that ejected up to 10 M_☉ at a rate of around 10⁻³ M_☉·yr⁻¹ for a period of about 10,000 years prior to the explosion. The mass loss rate ramped up during the final millennium prior to core collapse.^[3]

References

^ ^a ^b ^c ^d ^e ^f ^g Barbon, R.; Buondi, V.; Cappellaro, E.; Turatto, M. (2008), "VizieR Online Data Catalog: Asiago Supernova Catalogue (Version 2008-Mar)", VizieR On-line Data Catalog, Bibcode:2008yCat.2283....0B.
^ Ransome, C. L.; et al. (October 2021), "A systematic reclassification of Type IIn supernovae", Monthly Notices of the Royal Astronomical Society, 506 (4): 4715–4734, arXiv:2107.02179, Bibcode:2021MNRAS.506.4715R, doi:10.1093/mnras/stab1938.
^ ^a ^b Smith, Nathan; et al. (April 2017), "Endurance of SN 2005ip after a decade: X-rays, radio and Hα like SN 1988Z require long-lived pre-supernova mass-loss", Monthly Notices of the Royal Astronomical Society, 466 (3): 3021–3034, arXiv:1612.02011, Bibcode:2017MNRAS.466.3021S, doi:10.1093/mnras/stw3204.
^ Schlegel, Eric M.; Petre, Robert (July 2006), "A Chandra ACIS Observation of the X-Ray-luminous SN 1988Z", The Astrophysical Journal, 646 (1): 378–384, arXiv:astro-ph/0604106, Bibcode:2006ApJ...646..378S, doi:10.1086/504890.
^ Pollas, C.; et al. (December 15, 1988), Marsden, Brian G. (ed.), "Supernova 1988Z in MCG +03-28-022", IAU Circulars, 4691, Central Bureau for Astronomical Telegrams, retrieved 2024-01-08.
^ Heathcote, S.; et al. (December 1988), Marsden, B. G. (ed.), "Supernova 1988Z in MCG +03-28-022", IAU Circular, 4693: 1, Bibcode:1988IAUC.4693....1H.
^ ^a ^b Turatto, M.; et al. (May 1993), "The type II supernova 1988Z in MCG +03-28-022 : increasing evidence of interaction of supernova ejecta with a circumstellar wind", Monthly Notices of the Royal Astronomical Society, 262: 128–140, Bibcode:1993MNRAS.262..128T, doi:10.1093/mnras/262.1.128.
^ Stathakis, Raylee A.; Sadler, Elaine M. (June 1991), "What was supernova 1988Z?", Monthly Notices of the Royal Astronomical Society, 250 (4): 786, Bibcode:1991MNRAS.250..786S, doi:10.1093/mnras/250.4.786.
^ van Dyk, Schuyler D.; et al. (December 1993), "SN 1988Z: The Most Distant Radio Supernova", The Astrophysical Journal, 419: L69 – L72, Bibcode:1993ApJ...419L..69V, doi:10.1086/187139.
^ Fabian, A. C.; Terlevich, R. (May 1996), "X-ray detection of Supernova 1988Z with the ROSAT High Resolution Imager", Monthly Notices of the Royal Astronomical Society, 280 (1): L5 – L8, Bibcode:1996MNRAS.280L...5F, doi:10.1093/mnras/280.1.L5.