ALMA and ATCA Astronomers dissect the remnants of a supernova

Simulated still showing components of Supernova Remnant 1987A. 

Credit: The International Centre for Radio Astronomy Research (ICRAR)

In research published today in the Astrophysical Journal, an Australian led team of astronomers has used radio telescopes in Australia and Chile to see inside the remains of a supernova.

The supernova, known as SN1987A, was first seen by observers in the Southern Hemisphere in 1987 when a giant star suddenly exploded at the edge of a nearby dwarf galaxy called the Large Magellanic Cloud.

In the two and a half decades since then the remnant of Supernova 1987A has continued to be a focus for researchers the world over, providing a wealth of information about one of the Universe's most extreme events.

PhD Candidate Giovanna Zanardo at The University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR) led the team that used the Atacama Large Millimetre/submillimeter Array (ALMA) in Chile's Atacama Desert and the Australia Telescope Compact Array (ATCA) in New South Wales to observe the remnant at wavelengths spanning the radio to the far infrared.

"By combining observations from the two telescopes we've been able to distinguish radiation being emitted by the supernova's expanding shock wave from the radiation caused by dust forming in the inner regions of the remnant," said Zanardo.

A panel of images showing different views of Supernova 1987A. 

Left Panel: SNR1987A as seen by the Hubble Space Telescope in 2010. 

Middle Panel: SNR1987A as seen by the ATCA in New South Wales and the ALMA in Chile. 

Right Panel: A computer generated visualisation of the remnant showing the possible location of a Pulsar. 

Credit: ATCA & ALMA Observations & data - G. Zanardo et al. / HST Image: NASA, ESA, K. France (University of Colorado, Boulder), P. Challis and R. Kirshner (Harvard-Smithsonian Center for Astrophysics)

"This is important because it means we're able to separate out the different types of emission we're seeing and look for signs of a new object which may have formed when the star's core collapsed. It's like doing a forensic investigation into the death of a star."

"Our observations with the ATCA and ALMA radio telescopes have shown signs of something never seen before, located at the centre or the remnant. It could be a pulsar wind nebula, driven by the spinning neutron star, or pulsar, which astronomers have been searching for since 1987."

"It's amazing that only now, with large telescopes like ALMA and the upgraded ATCA, we can peek through the bulk of debris ejected when the star exploded and see what's hiding underneath."

More research published recently in the Astrophysical Journal also attempts to shine a light on another long-standing mystery surrounding the supernova remnant.

Since 1992 the radio emission from one side of the remnant has appeared 'brighter' than the other.

More information: 'Spectral and Morphological Analysis of the Remnant of Supernova 1987a with ALMA & ATCA' G. Zanardo, L. Staveley-Smith, R. Indebetouw et al. Astrophysical Journal November 10th, 2014: arxiv.org/abs/1409.7811 and iopscience.iop.org/0004-637X/796/2/82

'Multi-dimensional simulations of the expanding supernova remnant SN 1987a' T.M Potter, L Staveley-Smith, B. Reville et al. Astrophysical Journal October 20th, 20144: arxiv.org/abs/1409.4068 and iopscience.iop.org/0004-637X/794/2/174

Carbon monoxide predicts 'red and dead' future of gas guzzler galaxy

This image shows radio waves emitted from ALESS65 as observed by the Australia Telescope Compact Array (ATCA). 

Credit: Huynh et al.

Astronomers have studied the carbon monoxide in a galaxy over 12 billion light years from Earth and discovered that it's running out of gas, quite literally, and headed for a 'red and dead' future.

The galaxy, known as ALESS65, was observed by the Atacama Large Millimeter Array (ALMA) in 2011 and is one of less than 20 known distant galaxies to contain carbon monoxide.

Dr Minh Huynh from The University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR) led the team on their search for galactic carbon monoxide in work published today in the Monthly Notices of the Royal Astronomical Society.

"We're familiar with carbon monoxide here on Earth as the deadly gas that can cause suffocation, but in galaxies it plays an important role in the lifecycle of stars," said Huynh.

"Out of the galaxies that we know contain carbon monoxide, less than 20 are as far away from Earth as ALESS65. Out of the billions of galaxies out there, the detections are very rare!"

Huynh, who grew up in Perth, said that at first astronomers didn't think there could be massive 'red and dead' galaxies in the distant Universe, so studying galaxies heading towards that fate is important to solve the puzzle of their existence.

This is NGC5044, a "red and dead" galaxy like ALESS65 will become in about 25 million years. 

NB:The X-Rays are shown in blue and the visible light is shown in yellow. 

Credit: X-ray: NASA /CXC /Stanford Univ /N.Werner et al; Optical: DSS

Using the Australia Telescope Compact Array (ATCA) radio telescope in NSW, Australia, Huynh and the team worked out how much carbon monoxide they could see in ALESS65 and extrapolated that out into how much fuel the galaxy has left, how much gas it has.

"All galaxies have a certain amount of fuel to make new stars," said Huynh.

"Our galaxy, the Milky Way, has about five billion years before it runs out of fuel and becomes 'red and dead', but ALESS65 is a gas guzzler and only has 10s of millions of years left, very fast in astronomical terms."

The Atacama Compact Array (ACA) forming part of the ALMA observatory. 

Credit: ALMA, ESO

The team also combined their observations of the galaxy with the original data from ALMA to work out how similar ALESS65 is to galaxies nearer to Earth.

Arp220, a nearby ‘Ultraluminous Infrared Galaxy’ similar to what ALESS65 would look like if it were closer to Earth. 

Credit: NASA, ESA, and the Hubble Team

"We were able to work out the strength of the UV radiation in ALESS65; it's similar to some 'starbursting' galaxies in the local universe, but the stars in ALESS65 are forming in much larger areas when compared to local galaxies," said Huynh.

The team will now turn their attentions to the search for carbon monoxide in another galaxy near to ALESS65, named ALESS61.

"Finding and studying carbon monoxide in more galaxies will tell us even more about how stars formed in the early days of the Universe and help solve the mystery of far away 'red and dead' galaxies" said Huynh.

More information: "Detection of molecular gas in an ALMA [CII]-identified Submillimetre Galaxy at z=4.44" Huynh et al. Monthly Notices of the Royal Astronomical Society, Published 9th of July 2014. mnrasl.oxfordjournals.org/look… 0.1093/mnrasl/slu077 . On Arxiv: arxiv.org/abs/1407.0463