Event type | Supernova |
---|---|
SNIa | |
Constellation | Centaurus |
Other designations | SN 1972E, AAVSO 1334-31 |
SN 1972E 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.
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]
A supernova is a powerful and luminous explosion of a star. A supernova occurs during the last evolutionary stages of a massive star, or when a white dwarf is triggered into runaway nuclear fusion. The original object, called the progenitor, either collapses to a neutron star or black hole, or is completely destroyed to form a diffuse nebula. The peak optical luminosity of a supernova can be comparable to that of an entire galaxy before fading over several weeks or months.
SN 1987A was a type II supernova in the Large Magellanic Cloud, a dwarf satellite galaxy of the Milky Way. It occurred approximately 51.4 kiloparsecs from Earth and was the closest observed supernova since Kepler's Supernova in 1604. Light and neutrinos from the explosion reached Earth on February 23, 1987 and was designated "SN 1987A" as the first supernova discovered that year. Its brightness peaked in May of that year, with an apparent magnitude of about 3.
Messier 83 or M83, also known as the Southern Pinwheel Galaxy and NGC 5236, is a barred spiral galaxy approximately 15 million light-years away in the constellation borders of Hydra and Centaurus. Nicolas-Louis de Lacaille discovered M83 on 17 February 1752 at the Cape of Good Hope. Charles Messier added it to his catalogue of nebulous objects in March 1781.
Messier 61 is an intermediate barred spiral galaxy in the Virgo Cluster of galaxies. It was first discovered by Barnaba Oriani on May 5, 1779, six days before Charles Messier discovered the same galaxy. Messier had observed it on the same night as Oriani but had mistaken it for a comet. Its distance has been estimated to be 45.61 million light years from the Milky Way Galaxy. It is a member of the M61 Group of galaxies, which is a member of the Virgo II Groups, a series of galaxies and galaxy clusters strung out from the southern edge of the Virgo Supercluster.
Centaurus A is a galaxy in the constellation of Centaurus. It was discovered in 1826 by Scottish astronomer James Dunlop from his home in Parramatta, in New South Wales, Australia. There is considerable debate in the literature regarding the galaxy's fundamental properties such as its Hubble type and distance. It is the closest radio galaxy to Earth, as well as the closest BL Lac object, so its active galactic nucleus has been extensively studied by professional astronomers. The galaxy is also the fifth-brightest in the sky, making it an ideal amateur astronomy target. It is only visible from the southern hemisphere and low northern latitudes.
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NGC 1309 is a spiral galaxy located approximately 120 million light-years away, appearing in the constellation Eridanus. It is about 75,000 light-years across, and is about 3/4s the width of the Milky Way. Its shape is classified as SA(s)bc, meaning that it has moderately wound spiral arms and no ring. Bright blue areas of star formation can be seen in the spiral arms, while the yellowish central nucleus contains older-population stars. NGC 1309 is one of over 200 members of the Eridanus Group of galaxies.
NGC 5253 is an irregular galaxy in the constellation Centaurus. It was discovered by William Herschel on 15 March 1787.
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NGC 4639 is a barred spiral galaxy located in the equatorial constellation of Virgo. It was discovered by German-born astronomer William Herschel on April 12, 1784. John L. E. Dreyer described it as "pretty bright, small, extended, mottled but not resolved, 12th magnitude star 1 arcmin to southeast". This is a relatively nearby galaxy, lying approximately 72 million light-years away from the Milky Way. It is a companion to NGC 4654, and the two appear to have interacted roughly 500 million years ago. NGC 4639 is a member of the Virgo Cluster.
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SN 1895B was a supernova event in the irregular dwarf galaxy NGC 5253, positioned 16″ east and 23″ north of the galactic center. It is among the closest known extragalactic supernova events. The supernova was discovered by Williamina Fleming on December 12, 1895 after noticing an unusual spectrum on a photographic plate taken July 18, 1895, and was initially given the variable star designation Z Centauri. The light curve is consistent with an event that began ~15 days before the discovery plate was taken, and this indicates the supernova reached a peak visual magnitude of up to 8.49±0.03.
SN 2014J was a type-Ia supernova in Messier 82 discovered in mid-January 2014. It was the closest type-Ia supernova discovered for 42 years, and no subsequent supernova has been closer as of 2023. The supernova was discovered by chance during an undergraduate teaching session at the University of London Observatory. It peaked on 31 January 2014, reaching an apparent magnitude of 10.5. SN 2014J was the subject of an intense observing campaign by professional astronomers and was bright enough to be seen by amateur astronomers.
NGC 3191 is a barred spiral galaxy in the constellation Ursa Major. It was discovered on 5 February 1788 by William Herschel. It is located at a distance of about 400 million light years from Earth, which, given its apparent dimensions, means that NGC 3191 is about 115,000 light years across.
NGC 4070 is an elliptical galaxy located 340 million light-years away in the constellation Coma Berenices. NGC 4070 was discovered by astronomer William Herschel on April 27, 1785. It was rediscovered by John Herschel on April 29, 1832 and was listed as NGC 4059. The galaxy is a member of the NGC 4065 Group.
NGC 4076 is a spiral galaxy located 290 million light-years away in the constellation Coma Berenices. The galaxy was discovered by astronomer William Herschel on April 27, 1785 and is a member of the NGC 4065 Group.
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