sn1987a

Today is the anniversary of the discovery of the first modern supernova, currently named SN1987A, located in the Tarantala Nebula in the Large Magellanic Cloud.  It was independently discovered by both  Ian Shelton and Oscar Duhalde of the Las Campanas Observatory in Chile on the night of February 23/24, 1987, and within the same 24 hours independently by Albert Jones in New Zealand. Two weeks later, between March 4–12, 1987 it was observed from space by Astron, a large ultraviolet space telescope. The supernova has yet to receive an official name.  

While plenty of modern scientific words can be dated accurately, the older a word is (in general) the harder it is to pin down a date.  The word supernova however, defies this logic.  Late October 1604 (and some sources give the date 6 November 1604) a new and bright object appeared in the sky.  German astronomer and mathematician Johannes Kepler (born 27 December 1571-15 November 1630) noticed the ‘new’ object and unsure what exactly it was, simply named it stella nova, from the Latin words for new star.  It wasn’t until the 1930s that astronomers Walter Baade and Fritz Zwicky started using the term super-nova and by 1938 the hyphen was dropped and the word became supernova.  The first reliably recorded supernova was noted by Pliny in AD 185.  Notable supernovae (note the plural maintains the Latin form and does not take the -s that English mostly uses) occurred in 1054, noted mainly by Chinese and Arabic astronomers, and the supernova of 1572 noted extensively by Tycho Brahe.

Time-lapse animation of SN1987A from 1994 to 2009, video compilation courtesy Mark Macdonald, via Larsson, J. et al. (2011). “X-ray illumination of the ejecta of supernova 1987A”. Nature 474 (7352): 484–486., used with permission under a Creative Commons 3.0 license.  

ALMA spots supernova dust factory

Striking new observations with the Atacama Large Millimeter/submillimeter Array (ALMA) telescope capture, for the first time, the remains of a recent supernova brimming with freshly formed dust. If enough of this dust makes the perilous transition into interstellar space, it could explain how many galaxies acquired their dusty, dusky appearance.

Galaxies can be remarkably dusty places and supernovae are thought to be a primary source of that dust, especially in the early Universe. But direct evidence of a supernova’s dust‐making capabilities has been slim up to now, and could not account for the copious amount of dust detected in young, distant galaxies. But now observations with ALMA are changing that.

“We have found a remarkably large dust mass concentrated in the central part of the ejecta from a relatively young and nearby supernova,” said Remy Indebetouw, an astronomer at the National Radio Astronomy Observatory (NRAO) and the University of Virginia, both in Charlottesville, USA. “This is the first time we’ve been able to really image where the dust has formed, which is important in understanding the evolution of galaxies.”

An international team of astronomers used ALMA to observe the glowing remains of Supernova 1987A, which is in the Large Magellanic Cloud, a dwarf galaxy orbiting the Milky Way about 160,000 light‐years from Earth. SN 1987A is the closest observed supernova explosion since Johannes Kepler’s observation of a supernova inside the Milky Way in 1604.

Astronomers predicted that as the gas cooled after the explosion, large amounts of dust would form as atoms of oxygen, carbon, and silicon bonded together in the cold central regions of the remnant. However, earlier observations of SN 1987A with infrared telescopes, made during the first 500 days after the explosion, detected only a small amount of hot dust.

With ALMA’s unprecedented resolution and sensitivity, the research team was able to image the far more abundant cold dust, which glows brightly in millimetre and submillimetre light. The astronomers estimate that the remnant now contains about 25 percent the mass of the Sun in newly formed dust. They also found that significant amounts of carbon monoxide and silicon monoxide have formed.

Image credit: ALMA (ESO/NAOJ/NRAO)/A. Angelich. Visible light image: the NASA/ESA Hubble Space Telescope. X-Ray image: The NASA Chandra X-Ray Observatory

Image of the Day: Supernova Ring in Satellite Galaxy of Milky Way

A NASA/ESA Hubble Space Telescope image of a gaseous ring surrounding the supernova 1987A, which exploded on February 23, 1987 in the Large Magellanic Cloud, an irregular satellite galaxy of the Milky Way. The image, taken with the European Space Agency’s Faint Object Camera (FOC), reveals clumpy structure in the ring which indicates that the material is not uniformly distributed.

(NASA)  In February 1987, light from the brightest stellar explosion seen in modern times reached Earth - supernova SN1987A. This Hubble Space Telescope image from the sharp Advanced Camera for Surveys taken in November 2003 shows the explosion site over 16 years later. The snap shot indicates that the supernova blast wave continues to impact a pre-existing, one light-year wide ring of material, and the nascent central supernova remnant continues to expand. Like pearls on a cosmic necklace, bright hot spots produced as the blast wave heats material up to millions of degrees began to appear on the ring in the mid 1990s and have been followed across the spectrum by astronomers ever since. Supernova SN1987A lies in the Large Magellanic Cloud, a neighboring galaxy some 170,000 light-years away. That really does mean that the explosive event - the core collapse and detonation of a star about 20 times as massive as the Sun - occurred 170,000 years before February 1987.

A backup to something else I was going to draw but quit on, the Supernova Remnant SN1987A, located 168,000 lightyears from Earth in the Nearby Galaxy known as the Large Magellanic Cloud, close to the edge of the Tarantula nebula.

This star was seen to explode on 23rd February 1987, and is still currently the last Supernova that occurred that could be seen with the Naked eye, seen only in the Southern Hemisphere.

The star that exploded was a Blue Supergiant known as “Sanduleak -69° 202”, and was the first supernova to have it’s progenitor star identified.

Currently, there are expanding rings of hot material at the site of the explosion, and though an extremely dense mass is detected here, no expected stellar remnant such as a Neutron star or Pulsar has yet been found there, leading some to speculate the core may have collapsed into a Black Hole.

Citation number over time for the infamous Supernova 1987A, in 2 year chunks. Not surprisingly, there are no references in 1984-1985. Also perhaps not surprisingly, the number of papers about SN 1987A peaks in 1988-1989, showing that researchers took a while to gather and publish their results. Interestingly, citation rate has remained pretty constant since the mid-1990s. 

NuSTAR Provides Explosive Evidence For Supernova Asymmetry

New results from the NASA NuSTAR telescope show that a supernova close to our galaxy experienced a single-sided explosion.

A team of scientists including Lawrence Livermore National Laboratory researchers found that X-ray emissions taken with the Nuclear Spectroscopic Telescope Array (NuSTAR) show that the Supernova 1987A explosion was highly asymmetric. The results appear in the May 8 edition of the journal, Science.

NuSTAR observations, including those of 1987A, provide strong and compelling observational evidence that supernovae are not symmetric.

Supernova 1987A in the Large Magellanic Cloud provides a unique opportunity to study a nearby (170,000 light years) core collapse supernova explosion (CCSN) and its subsequent evolution into a supernova remnant.

SN1987A has validated some basic scientific assumptions about CCSNs. A neutrino flash confirmed that the overall explosion is driven by the collapse of the central core to a neutron star. Direct gamma-ray detection of cobalt isotopes and the correlation between the exponential decay of the optical light curve and lifetime of these isotopes confirmed that the light curve is powered by radioactive decay.

“Even with all we have previously learned about SN1987A, NuSTAR has taught us some new things,” said Michael Pivovaroff, one of the LLNL scientists and co-author of the paper. “Our observations confirmed the tremendous speeds at which the exploding material is moving and helped us constrain geometrical models that show just how lopsided the supernova explosion was.”

In core-collapse supernovae, an isotope of titanium (?? Ti) is produced in the innermost ejecta, in the layer of material directly on top of the newly formed remnant. The radioactive decay of this isotope provides a direct probe of the supernova engine. NuSTAR measurements confirm that heavy elements are moving at speeds of about 3,000 kilometers per second, several times higher than expected from spherically symmetric models.

There has been growing evidence for asymmetries in supernovae explosions over the past decades, including in SN1987A from the extensive evidence for mixing and polarized optical emission. NuSTAR observations of the spatial distribution of ?? Ti in the Cassiopeia A supernova remnant shows direct evidence of asymmetry. And these observations indicate even more asymmetry for SN1987A.

Subsequent X-ray observations have revealed expanding, brightening ejecta (a supernova remnant). To date, there is no evidence yet for a compact central object that formed form the core of the exploding star.

NuSTAR observed SN1987A for multiple periods between September 2012 and July 2014 with a total exposure of 2,283 kiloseconds (a kilosecond is 1,000 seconds).

Image Credit: Ott/Caltech (simulation), Drasco/Calpoly San Luis Obsipo [visualization])

Ground-breaking findings reveal new insights into the death of stars.

An international team of space researchers are now one step closer to discovering what happened when Supernova SN1987A exploded 28 years ago. The findings were recently published in the international journal Science and are based on observations using two sensitive mirror systems designed at DTU…

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