Featured Research

from universities, journals, and other organizations

NASA Satellite Pins Down Timer In Stellar Ticking Time Bomb

Date:
April 30, 2008
Source:
NASA/Goddard Space Flight Center
Summary:
Astronomers have discovered a timing mechanism that allows them to predict exactly when a superdense star will unleash incredibly powerful explosions. The explosions occur on a neutron star, which is a city-sized remnant of a giant star that exploded in a supernova. But despite the neutron star’s small size, it contains more material than our sun.

A thermonuclear explosion as it engulfs an entire neutron star.
Credit: NASA

Using NASA’s Rossi X-ray Timing Explorer (RXTE) satellite, a team of four astronomers has discovered a timing mechanism that tells them exactly when a superdense star will let loose incredibly powerful explosions.

Related Articles


"We found a clock that ticks slower and slower, and when it slows down too much, boom! The bomb explodes," says team leader Diego Altamirano of the University of Amsterdam in the Netherlands.

The explosions occur on a neutron star, which is a city-sized remnant of a giant star that exploded in a supernova. But despite the neutron star’s small size, it contains more material than our sun. The neutron star is not alone in space. It has a companion star, and the two objects orbit each other every 3.8 hours. This double-star system is known as 4U 1636-53 for its sky coordinates in the Southern Hemisphere.

The system acts like a ticking time bomb. The neutron star has incredibly strong gravity, so it sucks in some of the gas from the companion star’s atmosphere. The gas spirals onto the neutron star, slowly building up on its surface until it heats up to a critical temperature. Suddenly, the gas at one small spot on the neutron star’s surface ignites a powerful explosion, and the flame quickly spreads around the entire star. The resulting explosion appears as a bright flash of X-rays that can be detected by satellites.

The neutron star in 4U 1636-53 produces about 7 to 10 bursts per day. These explosions are mind-boggling to contemplate. They release more energy in just 10 to 100 seconds than our sun radiates in an entire week. The energy is equivalent to 100 hydrogen bombs exploding simultaneously over each postage-stamp-size patch of the neutron star’s surface. It’s a good thing for us that this neutron star is 20,000 light-years from Earth, which is far enough away that the explosions pose no danger to humans or our planet. Fortunately for the neutron star, the explosion takes place only on its surface and in its atmosphere, so the neutron star survives the blast.

Scientists have observed thousands of similar X-ray bursts from about 80 different neutron stars. But until now, they had no way to predict when they would occur.

The key to this discovery is RXTE, which makes extremely precise timing measurements of objects that emit X-rays in a rapidly flickering pattern. As gas gradually builds up on the neutron star’s surface, the atoms that make up the gas slam together to form heavier atoms in a process known as fusion. Sometimes, the fusion occurs in a stable and almost perfectly repetitive fashion, producing a nearly regular X-ray signal known as a quasi-periodic oscillation (or QPO for short). Think of the QPO as a clock that ticks with near-perfect precision.

Scientists expect that the QPO clock should tick about once every two minutes (120 seconds). This is what Altamirano’s team found when the astronomers observed the system with RXTE. But the team also found that the QPO clock starts ticking slower and slower as gas builds up on its surface. Whenever it slows down to one cycle every 125 seconds, the neutron star lets loose a powerful explosion.

"We can predict when these explosions are happening. We have a clock that tells us when the bomb will explode!" says Altamirano.

"It's an exciting discovery," adds Tod Strohmayer of NASA’s Goddard Space Flight Center in Greenbelt, Md. Strohmayer is an expert in neutron stars who was not involved in this study. He notes that the ticking of the QPO clock depends on the size and weight of the neutron star. "It gives us a new tool to study these fascinating objects," he says.


Story Source:

The above story is based on materials provided by NASA/Goddard Space Flight Center. Note: Materials may be edited for content and length.


Cite This Page:

NASA/Goddard Space Flight Center. "NASA Satellite Pins Down Timer In Stellar Ticking Time Bomb." ScienceDaily. ScienceDaily, 30 April 2008. <www.sciencedaily.com/releases/2008/04/080430112525.htm>.
NASA/Goddard Space Flight Center. (2008, April 30). NASA Satellite Pins Down Timer In Stellar Ticking Time Bomb. ScienceDaily. Retrieved January 29, 2015 from www.sciencedaily.com/releases/2008/04/080430112525.htm
NASA/Goddard Space Flight Center. "NASA Satellite Pins Down Timer In Stellar Ticking Time Bomb." ScienceDaily. www.sciencedaily.com/releases/2008/04/080430112525.htm (accessed January 29, 2015).

Share This


More From ScienceDaily



More Space & Time News

Thursday, January 29, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Asteroid's Moon Spotted During Earth Flyby

Asteroid's Moon Spotted During Earth Flyby

Rumble (Jan. 27, 2015) Scientists working with NASA&apos;s Deep Space Network antenna at Goldstone, California discovered an unexpected moon while observing asteroid 2004 BL86 during its recent flyby past Earth. Credit to &apos;NASA JPL&apos;. Video provided by Rumble
Powered by NewsLook.com
Water Fleas Prepare for Space Voyage

Water Fleas Prepare for Space Voyage

Reuters - Innovations Video Online (Jan. 26, 2015) Scientists are preparing a group of water fleas for a unique voyage into space. The aquatic crustaceans, known as Daphnia, can be used as a miniature model for biomedical research, and their reproductive and swimming behaviour will be tested for signs of stress while on board the International Space Station. Jim Drury went to meet the team. Video provided by Reuters
Powered by NewsLook.com
Mars Rover Opportunity Celebrates 11-Year Anniversary

Mars Rover Opportunity Celebrates 11-Year Anniversary

Rumble (Jan. 26, 2015) Eleven years ago NASA&apos;s Opportunity rover touched down on Mars for what was only supposed to be a 90-day mission. Since then it has traveled 25.9 miles (41.7 kilometers), further than any other off-Earth surface vehicle has ever driven. Credit to &apos;NASA&apos;. Video provided by Rumble
Powered by NewsLook.com
NASA's On Course To Take Pluto's Best Photo Ever

NASA's On Course To Take Pluto's Best Photo Ever

Newsy (Jan. 25, 2015) NASA&apos;s New Horizons probe is en route to snap a picture of Pluto this summer, but making sure it doesn&apos;t miss its one chance to do so starts now. Video provided by Newsy
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.

Save/Print:
Share:

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



Save/Print:
Share:

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