Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Astronomers see right into heart of exploding star

08.10.2014

An international team of astronomers has been able to see into the heart of an exploding star, by combining data from telescopes that are hundreds or even thousands of kilometres apart. Their results are published at 18:00 hours on Oct 8 2014 in the journal Nature.

Highly-detailed images produced using radio telescopes from across Europe and America have pinpointed the locations where a stellar explosion (called a nova), emitted gamma rays (extremely high energy radiation). The discovery revealed how the gamma-ray emissions are produced, something which mystified astronomers when they were first observed in 2012.


Artist's impressions of the gas ejected in the nova explosion with the binary star system at the center.

Credit: Bill Saxton, NRAO/AUI/NSF

"We not only found where the gamma rays came from, but also got a look at a previously-unseen scenario that may be common in other nova explosions," said Laura Chomiuk, of Michigan State University.

Tim O'Brien of The University of Manchester's Jodrell Bank Observatory, one of the international team of astronomers who worked on the study, explains, "A nova occurs when gas from a companion star falls onto the surface of a white dwarf star in a binary system. This triggers a thermonuclear explosion on the surface of the star which blasts the gas into space at speeds of millions of miles per hour".

"When it explodes it brightens hugely, leading in some cases to the appearance of a new star in the sky, hence the term nova. These explosions are unpredictable, so when one goes off, the pressure is on for us to try and get as many of the world's telescopes as possible to take a look before it fades away. For this nova, our international team was primed and ready to go and we really came up trumps."

Astronomers did not expect this nova scenario to produce high-energy gamma rays. However, in June of 2012, NASA's Fermi spacecraft detected gamma rays coming from a nova called V959 Mon, some 6500 light-years from Earth.

At the same time, observations with the Karl G. Jansky Very Large Array (VLA) of telescopes in the USA indicated that radio waves coming from the nova were probably the result of subatomic particles moving at nearly the speed of light interacting with magnetic fields. The high-energy gamma-ray emission, the astronomers noted, also required such fast-moving particles.

Later observations from the telescopes of the European VLBI network (EVN) and the Very Long Baseline Array (VLBA) in the USA revealed two distinct knots of radio emission. These knots then were seen to move away from each other.

This observation, along with studies made with the e-MERLIN telescope array in the UK, and further VLA observations in 2014, provided the scientists with information that allowed them to put together a picture of how the radio knots, and the gamma rays, were produced.

In the first stage of this scenario, the white dwarf and its companion give up some of their orbital energy to boost some of the explosion material, making the ejected material move outward faster in the plane of their orbit. Later, the white dwarf blows off a faster wind of particles moving mostly outward along the poles of the orbital plane. When the faster-moving polar flow hits the slower-moving material, the shock accelerates particles to the speeds needed to produce the gamma rays, and the knots of radio emission.

"By watching this system over time and seeing how the pattern of radio emission changed, then tracing the movements of the knots, we saw the exact behaviour expected from this scenario," Chomiuk said.

A technique called radio interferometry, in which data from various radio telescopes are combined to obtain a sharper image, played a fundamental role in this result. By connecting together radio telescopes across tens, hundreds and even thousands of kilometres, the scientists were able to zoom in to get a much sharper view of the heart of this exploding star.

Gamma rays from several nova explosions have now been detected so it may be that the phenomenon is relatively common, but perhaps seen only when the nova is sufficiently close to Earth.

Because this type of ejection is also seen in other binary-star (two stars orbiting each other) systems, the new insights may help astronomers understand how those systems develop. The phase in which matter ejected from one star engulfs its companion occurs in all close binary stars, and is poorly understood.

"We may be able to use novae as a 'testbed' for improving our understanding of this critical stage of binary evolution," Chomiuk said.

###

Media enquiries to:

Katie Brewin
Media Relations Officer
The University of Manchester
Tel: 0161 275 8387
Email: atie.brewin@manchester.ac.uk

Notes to editors:

The paper: Binary orbits as the driver of gamma-ray emission and mass ejection in classical novae is by L. Chomiuk, J. D. Linford, J. Yang, T. J. O'Brien, Z. Paragi, A. J. Mioduszewski, R. J. Beswick, C. C. Cheung, K. Mukai, T. Nelson, V. A. R. M. Ribeiro, M. P. Rupen, J. L. Sokoloski, J. Weston, Y. Zheng, M. F. Bode, S. Eyres, N. Roy, G. B. Taylor, published in Nature and available online 18:00 hrs (London time) October 08 2014

Images: Artist's impressions of the gas ejected in the nova explosion with the binary star system at the centre are available on request. Picture:Credit: Bill Saxton, NRAO/AUI/NSF

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

e-MERLIN is operated by The University of Manchester for the UK's Science and Technology Facilities Council (STFC).

The European VLBI Network is a collaboration of the major radio astronomical institutes in Europe, Asia and South Africa and performs high angular resolution observations of cosmic radio sources.

The Joint Institute for VLBI in Europe (JIVE) is a scientific foundation based in the Netherlands with a mandate to support the operations of the European VLBI Network.

Katie Brewin | Eurek Alert!
Further information:
http://www.manchester.ac.uk

More articles from Physics and Astronomy:

nachricht A better way to weigh millions of solitary stars
15.12.2017 | Vanderbilt University

nachricht A chip for environmental and health monitoring
15.12.2017 | Friedrich-Alexander-Universität Erlangen-Nürnberg

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First-of-its-kind chemical oscillator offers new level of molecular control

DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.

Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Engineers program tiny robots to move, think like insects

15.12.2017 | Power and Electrical Engineering

One in 5 materials chemistry papers may be wrong, study suggests

15.12.2017 | Materials Sciences

New antbird species discovered in Peru by LSU ornithologists

15.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>