Featured Research

from universities, journals, and other organizations

Astronomers get first peek into core of supernova, using NuSTAR telescope

February 19, 2014
University of California - Berkeley
Astronomers have peered for the first time into the heart of an exploding star in the final minutes of its existence. The feat by the high-energy X-ray satellite NuSTAR provides details of the physics of the core explosion inaccessible until now, says team member Steven Boggs of UC Berkeley. NuSTAR mapped radioactive titanium in the Cassiopeia A supernova remnant, which has expanded outward and become visible from Earth since the central star exploded in 1671.

Astronomers for the first time have peered into the heart of an exploding star in the final minutes of its existence. Superimposed images of the Cas A supernova remnant taken by NASA’s Chandra and NuSTAR orbiting telescopes. Red and green are X-ray emissions detected by Chandra of heated iron and silicon/magnesium, respectively, while blue shows NuSTAR’s map of the distribution of titanium produced in the core of the explosion 340 years ago.
Credit: NASA/NuSTAR image

Astronomers for the first time have peered into the heart of an exploding star in the final minutes of its existence.

Related Articles

The feat is one of the primary goals of NASA's NuSTAR mission, launched in June 2012 to measure high-energy X-ray emissions from exploding stars, or supernovae, and black holes, including the massive black hole at the center of our Milky Way Galaxy.

The NuSTAR team reported in this week's issue of the journal Nature the first map of titanium thrown out from the core of a star that exploded in 1671. That explosion produced the beautiful supernova remnant known as Cassiopeia A (Cas A).

The well-known supernova remnant has been photographed by many optical, infrared and X-ray telescopes in the past, but these revealed only how the star's debris collided in a shock wave with the surrounding gas and dust and heated it up. NuSTAR has produced the first map of high-energy X-ray emissions from material created in the actual core of the exploding star: the radioactive isotope titanium-44, which was produced in the star's core as it collapsed to a neutron star or black hole. The energy released in the core collapse supernova blew off the star's outer layers, and the debris from this explosion has been expanding outward ever since at 5,000 kilometers per second.

"This has been a holy grail observation for high energy astrophysics for decades," said coauthor and NuSTAR investigator Steven Boggs, UC Berkeley professor and chair of physics. "For the first time we are able to image the radioactive emission in a supernova remnant, which lets us probe the fundamental physics of the nuclear explosion at the heart of the supernova like we have never been able to do before."

"Supernovae produce and eject into the cosmos most of the elements are important to life as we know it," said UC Berkeley professor of astronomy Alex Filippenko, who was not part of the NuSTAR team. "These results are exciting because for the first time we are getting information about the innards of these explosions, where the elements are actually produced."

Boggs says that the information will help astronomers build three-dimensional computer models of exploding stars, and eventually understand some of the mysterious characteristics of supernovae, such as jets of material ejected by some. Previous observations of Cas A by the Chandra X-ray telescope, for example, showed jets of silicon emerging from the star.

"Stars are spherical balls of gas, and so you might think that when they end their lives and explode, that explosion would look like a uniform ball expanding out with great power," said Fiona Harrison, the principal investigator of NuSTAR at the California Institute of Technology. "Our new results show how the explosion's heart, or engine, is distorted, possibly because the inner regions literally slosh around before detonating."

Expanding supernova remnant

Cas A is about 11,000 light years from Earth and the most studied nearby supernova remnant. In the 343 years since the star exploded, the debris from the explosion has expanded to about 10 light years across, essentially magnifying the pattern of the explosion so that it can be seen from Earth.

Earlier observations of the shock-heated iron in the debris cloud led some astronomers to think that the explosion was symmetric, that is, equally powerful in all directions. Boggs noted, however, that the origins of the iron are so unclear that its distribution may not reflect the explosion pattern from the core.

"We don't know whether the iron was produced in the supernova explosion, whether it was part of the star when it originally formed, if it is just in the surrounding material, or even if the iron we see represents the actual distribution of iron itself, because we wouldn't see it if it were not heated in the shock," he said.

The new map of titanium-44, which does not match the distribution of iron in the remnant, strongly suggests that there is cold iron in the interior that Chandra does not see. Iron and titanium are produced in the same place in the star, said UC Berkeley research physicist Andreas Zoglauer, so they should be similarly distributed in the explosive debris.

"The surprising thing, which we suspected all along, is that the iron does not match titanium at all, so the iron we see is not mapping the distribution of elements produced in the core of the explosion," Boggs said.

He and his UC Berkeley colleagues also launch balloon-borne high-energy X-ray and gamma-ray detectors to record the radioactive decay of other elements, including iron, in supernovae to learn more about the nuclear reactions that take place during these brief, catastrophic explosions.

"The radioactive nuclei act as a probe of supernova explosions and allow us to see directly into densities and temperatures where nuclear processes are going that we don't have access to in terrestrial laboratories," Boggs said.

NuSTAR continues to observe radioactive titanium-44 emissions from a handful of other supernova remnants to determine if the pattern holds for other supernovae as well. These supernova remnants must be close enough to Earth for the debris structure to be seen, yet young enough for radioactive elements like titanium -- which has a 60-day half-life -- to still be emitting high-energy X-rays.

This work was supported under NASA No. NNG08FD60C, and made use of data from the Nuclear Spectroscopic Telescope Array (NuSTAR) mission, a project led by Caltech, managed by the Jet Propulsion Laboratory, and funded by the National Aeronautics and Space Administration.

NuSTAR mission instrument manager William Craig of UC Berkeley's Space Sciences Laboratory is also a coauthor of the Nature paper. Zoglauer conducted computer simulations of NuSTAR's detectors before launch, and continues to monitor the radioactive background in the detectors to correct observations.

Story Source:

The above story is based on materials provided by University of California - Berkeley. The original article was written by Robert Sanders. Note: Materials may be edited for content and length.

Journal Reference:

  1. B. W. Grefenstette, F. A. Harrison, S. E. Boggs, S. P. Reynolds, C. L. Fryer, K. K. Madsen, D. R. Wik, A. Zoglauer, C. I. Ellinger, D. M. Alexander, H. An, D. Barret, F. E. Christensen, W. W. Craig, K. Forster, P. Giommi, C. J. Hailey, A. Hornstrup, V. M. Kaspi, T. Kitaguchi, J. E. Koglin, P. H. Mao, H. Miyasaka, K. Mori, M. Perri, M. J. Pivovaroff, S. Puccetti, V. Rana, D. Stern, N. J. Westergaard, W. W. Zhang. Asymmetries in core-collapse supernovae from maps of radioactive 44Ti in Cassiopeia A. Nature, 2014; 506 (7488): 339 DOI: 10.1038/nature12997

Cite This Page:

University of California - Berkeley. "Astronomers get first peek into core of supernova, using NuSTAR telescope." ScienceDaily. ScienceDaily, 19 February 2014. <www.sciencedaily.com/releases/2014/02/140219133333.htm>.
University of California - Berkeley. (2014, February 19). Astronomers get first peek into core of supernova, using NuSTAR telescope. ScienceDaily. Retrieved April 1, 2015 from www.sciencedaily.com/releases/2014/02/140219133333.htm
University of California - Berkeley. "Astronomers get first peek into core of supernova, using NuSTAR telescope." ScienceDaily. www.sciencedaily.com/releases/2014/02/140219133333.htm (accessed April 1, 2015).

Share This

More From ScienceDaily

More Space & Time News

Wednesday, April 1, 2015

Featured Research

from universities, journals, and other organizations

Featured Videos

from AP, Reuters, AFP, and other news services

The Universe Could Be Full Of Tatooine Sunsets

The Universe Could Be Full Of Tatooine Sunsets

Newsy (Mar. 30, 2015) University of Utah researchers say mathematical simulations show small, rocky planets, like Tatooine from "Star Wars," can form in dual-star systems. Video provided by Newsy
Powered by NewsLook.com
What NASA Wants To Learn From Its 'Year In Space' Tests

What NASA Wants To Learn From Its 'Year In Space' Tests

Newsy (Mar. 28, 2015) Astronaut Scott Kelly and cosmonaut Mikhail Kornienko will spend a year in space running tests on human physiology and psychology. Video provided by Newsy
Powered by NewsLook.com
Raw: Astronauts Arrive at ISS for 1-Year Mission

Raw: Astronauts Arrive at ISS for 1-Year Mission

AP (Mar. 28, 2015) The capsule carrying a Russian and an American who are to spend a year away from Earth docked Saturday with the International Space Station. (March 28) Video provided by AP
Powered by NewsLook.com
Crew Starts One-Year Space Mission

Crew Starts One-Year Space Mission

Reuters - News Video Online (Mar. 28, 2015) Russian-U.S. crew arrives safely at the International Space Station for the start of a ground-breaking year-long stay. Paul Chapman reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.


Breaking News:

Strange & Offbeat Stories

Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News


Free Subscriptions

Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile

Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?

Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins