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SN1972E was a supernova in the galaxy NGC 5253 that was discovered 13 May 1972 with an apparent B magnitude of about 8.5, shortly after it had reached its maximum brightness. In terms of apparent brightness, it was the second-brightest supernova of any kind (fainter only than SN 1987A) of the 20th century. It was observed for nearly 700 days, and it became the prototype object for the development of theoretical understanding of Type Ia supernovae.

SN 1972E

Event type	Supernova
SNIa
Constellation	Centaurus
Other designations	SN 1972E, AAVSO 1334-31
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Background

The supernova was discovered by Charles Kowal,[1] about 56 arc seconds west and 85 arc seconds south of the center of NGC 5253.[2] The position in the periphery of the galaxy aided observation, minimizing interference by background objects.[3] Well-positioned for Southern Hemisphere observers, it was quite observable from Northern Hemisphere observatories as well. Attempts made to observe it in X-rays with Uhuru and OSO 7[4][5] and to detect gamma rays from it via Cherenkov radiation showers[6] gave at best equivocal results.

Photometric and spectroscopic measurements were made in the visible and near infrared by many observers, extending to about 700 days after maximum light.[7] Interstellar absorption lines of ionized calcium due to gas both in our galaxy and NGC 5253 were observed,[8] allowing an estimate of the interstellar extinction.

The extended length of the observed light curve found a remarkably uniform 0.01 magnitudes per day decline starting about 60 days after discovery. Translated into other units, this is almost exactly a 77-day half-life, which is the half-life of ⁵⁶Co. In the standard model for Type Ia supernovae, approximately a solar mass of ⁵⁶Ni is formed and ejected from a white dwarf which accretes mass from a binary companion and is raised over the Chandrasekhar limit and explodes. This ⁵⁶Ni decays with a half-life of about 6 days to ⁵⁶Co, and the decay of the cobalt provides the energy radiated away by the supernova remnant. The model also produces an estimate for the luminosity of such a supernova. The observations of SN1972e, both peak brightness and fade rate, were in general agreement with these predictions, and led to rapid acceptance of this degenerate-explosion model.[9]

See also

• List of supernovae that are of historical significance

References

Further reading

• Kirshner, R. P. & Oke, J. B. Supernova 1972e in NGC 5253. Astrophysical Journal. 200. Sept. 1975, pt. 1, p. 574-581 (SAO/NASA Astrophysics Data System)
• Riess, Adam G. et al. Using Type IA Supernova Light Curve Shapes to Measure the Hubble Constant. Astrophysical Journal Letters. 438. Jan. 1995. *: Self Published version.

External links

• Light curves and spectra on the Open Supernova Catalog
• First images (1972). Photo comparisons of NGC 5253 in June 1959 then in May 1972 showing first images of the actual SN 1972e explosion near NGC 5253 (Palomar Observatory blog).
• SIMBAD, SN 1972E
• SN 1972E in NGC 5253 Department of Physics and Astronomy at the University of Oklahoma.

На других языках

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[de] SN 1972E

SN 1972E war eine am 13. Mai 1972 in der Galaxie NGC 5253 entdeckte Supernova. Die kurz nach Erreichen des Helligkeitsmaximums gemessene scheinbare Helligkeit lag bei 8,5 mag. In Bezug auf ihre Helligkeit war das nach SN 1987A die zweithellste entdeckte Supernova ihrer Art im zwanzigsten Jahrhundert. Sie wurde fast 700 Tage lang beobachtet und wurde zum prototypischen Objekt in der Entwicklung des theoretischen Verständnisses von Supernovae vom Typ Ia.

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- [en] SN 1972E

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