Artist's illustration of Supernova 1987A
Portrait of a Dramatic Stellar Crib*
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 [1]
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 [2],
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.
"SN 1987A is a special place since it hasn't mixed with the surrounding environment, so what we see there was made there," said Indebetouw. "The
new ALMA results, which are the first of their kind, reveal a supernova
remnant chock full of material that simply did not exist a few decades
ago."
Supernovae, however, can both create and destroy dust grains.
As the shockwave from the initial explosion radiated out into space,
it produced bright glowing rings of material, as seen in earlier
observations with the NASA/ESA Hubble Space Telescope. After hitting
this envelope of gas, which was sloughed off by the progenitor red giant
star as it neared the end of its life, a portion of this powerful
explosion rebounded back towards the centre of the remnant. "At some point, this rebound shockwave will slam into these billowing clumps of freshly minted dust," said Indebetouw. "It's
likely that some fraction of the dust will be blasted apart at that
point. It's hard to predict exactly how much — maybe only a little,
possibly a half or two thirds." If a good fraction survives and
makes it into interstellar space, it could account for the copious dust
astronomers detect in the early Universe
.
"Really early galaxies are incredibly dusty and this dust plays a major role in the evolution of galaxies," said Mikako Matsuura of University College London, UK. "Today
we know dust can be created in several ways, but in the early Universe
most of it must have come from supernovae. We finally have direct
evidence to support that theory."
Notes
[1] Cosmic dust consist of silicate and
graphite grains — minerals also abundant on Earth. The soot from a
candle is very similar to cosmic graphite dust, although the size of the
grains in the soot are ten or more times bigger than typical grain
sizes of cosmic graphite grains.
[2] Light from this supernova arrived at Earth in 1987, as is reflected in the name.
More information
The Atacama Large Millimeter/submillimeter
Array (ALMA), an international astronomy facility, is a partnership of
Europe, North America and East Asia in cooperation with the Republic of
Chile. ALMA is funded in Europe by the European Southern Observatory
(ESO), in North America by the U.S. National Science Foundation (NSF) in
cooperation with the National Research Council of Canada (NRC) and the
National Science Council of Taiwan (NSC) and in East Asia by the
National Institutes of Natural Sciences (NINS) of Japan in cooperation
with the Academia Sinica (AS) in Taiwan. ALMA construction and
operations are led on behalf of Europe by ESO, on behalf of North
America by the National Radio Astronomy Observatory (NRAO), which is
managed by Associated Universities, Inc. (AUI) and on behalf of East
Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint
ALMA Observatory (JAO) provides the unified leadership and management
of the construction, commissioning and operation of ALMA.
This research was presented in a paper “Dust Production and Particle
Acceleration in Supernova 1987A Revealed with ALMA”, by R. Indebetouw et
al., to appear in the Astrophysical Journal Letters.
The team is composed of R. Indebetouw (National Radio Astronomy
Observatory (NRAO); University of Virginia, Charlottesville, USA), M.
Matsuura (University College London, United Kingdom [UCL]), E. Dwek
(NASA Goddard Space Flight Center, Greenbelt, USA), G. Zanardo
(International Centre for Radio Astronomy Research, University of
Western Australia, Crawley, Australia [ICRAR]), M.J. Barlow (UCL), M.
Baes (Sterrenkundig Obst Gent, Gent, Belgium), P. Bouchet (CEA-Saclay,
Gif-sur-Yvette, France), D.N. Burrows (The Pennsylvania State
University, University Park, USA), R. Chevalier (University of Virginia,
Charlottesville, USA), G.C. Clayton (Louisiana State University, Baton
Rouge,USA), C. Fransson (Stockholm University, Sweden), B. Gaensler
(Australian Research Council Centre of Excellence for All-sky
Astrophysics [CAASTRO]; Sydney Institute for Astronomy, The University
of Sydney, Australia), R. Kirshner (Harvard-Smithsonian Center for
Astrophysics, Cambridge, USA), M.Lakicevic (Lennard-Jones Laboratories,
Keele University, UK), K.S. Long (Space Telescope Science Institute,
Baltimore, USA [STScI]), P. Lundqvist (Stockholm University, Sweden), I.
MartÃ-Vidal (Chalmers University of Technology, Onsala Space
Observatory, Onsala, Sweden), J. Marcaide (Universidad de Valencia,
Burjassot, Spain), R. McCray (University of Colorado at Boulder, USA),
M. Meixner (STScI; The Johns Hopkins University, Baltimore, USA), C.-Y.
Ng (The University of Hong Kong, Hong Kong), S. Park (University of
Texas at Arlington, Arlington, USA), G. Sonneborn (STScI), L.
Staveley-Smith (ICRAR; CAASTRO), C. Vlahakis (Joint ALMA
Observatory/European Southern Observatory, Santiago, Chile) and J. van
Loon (Lennard-Jones Laboratories, Keele University, UK).
ESO is the foremost intergovernmental astronomy organisation in
Europe and the world’s most productive ground-based astronomical
observatory by far. It is supported by 15 countries: Austria, Belgium,
Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy,
the Netherlands, Portugal, Spain, Sweden, Switzerland and the United
Kingdom. ESO carries out an ambitious programme focused on the design,
construction and operation of powerful ground-based observing facilities
enabling astronomers to make important scientific discoveries. ESO also
plays a leading role in promoting and organising cooperation in
astronomical research. ESO operates three unique world-class observing
sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO
operates the Very Large Telescope, the world’s most advanced
visible-light astronomical observatory and two survey telescopes. VISTA
works in the infrared and is the world’s largest survey telescope and
the VLT Survey Telescope is the largest telescope designed to
exclusively survey the skies in visible light. ESO is the European
partner of a revolutionary astronomical telescope ALMA, the largest
astronomical project in existence. ESO is currently planning the
39-metre European Extremely Large optical/near-infrared Telescope, the
E-ELT, which will become "the world’s biggest eye on the sky".
Links
Contacts
Remy IndebetouwNational Radio Astronomy Observatory (NRAO) and the University of Virginia
Charlottesville, USA
Tel: +1 434 924 4895/+1 434 244 6883
Email: remy@virginia.edu
Mikako Matsuura
University College London
London, United Kingdom
Tel: +44 (0)20 7679 4348
Email: mikako.matsuura@ucl.ac.uk
Richard Hook
ESO, Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org
Charles E. Blue
National Radio Astronomy Observatory, Public Information Officer
Charlottesville, USA
Tel: +1 434 296 0314
Email: cblue@nrao.edu
