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.