Featured Research

from universities, journals, and other organizations

Dozens Of Newly Discovered Pulsars Probed By NASA's Fermi Gamma-ray Space Telescope

Date:
July 7, 2009
Source:
NASA/Goddard Space Flight Center
Summary:
With NASA's Fermi Gamma-ray Space Telescope, astronomers now are getting their best look at those whirling stellar cinders known as pulsars. Astronomers have analyzed gamma-rays from two dozen pulsars, including 16 discovered by Fermi.

The Vela pulsar, which spins 11 times a second, is the brightest persistent source of gamma rays in the sky.
Credit: NASA/DOE/Fermi LAT Collaboration

With NASA's Fermi Gamma-ray Space Telescope, astronomers now are getting their best look at those whirling stellar cinders known as pulsars. In two studies published in the July 2 edition of Science Express, international teams have analyzed gamma-rays from two dozen pulsars, including 16 discovered by Fermi. Fermi is the first spacecraft able to identify pulsars by their gamma-ray emission alone.

A pulsar is the rapidly spinning and highly magnetized core left behind when a massive star explodes. Most of the 1,800 cataloged pulsars were found through their periodic radio emissions. Astronomers believe these pulses are caused by narrow, lighthouse-like radio beams emanating from the pulsar's magnetic poles.

"Fermi has truly unprecedented power for discovering and studying gamma-ray pulsars," said Paul Ray of the Naval Research Laboratory in Washington. "Since the demise of the Compton Gamma Ray Observatory a decade ago, we've wondered about the nature of unidentified gamma-ray sources it detected in our galaxy. These studies from Fermi lift the veil on many of them."

The Vela pulsar, which spins 11 times a second, is the brightest persistent source of gamma rays in the sky. Yet gamma rays -- the most energetic form of light -- are few and far between. Even Fermi's Large Area Telescope sees only about one gamma-ray photon from Vela every two minutes.

"That's about one photon for every thousand Vela rotations," said Marcus Ziegler, a member of the team reporting on the new pulsars at the University of California, Santa Cruz. "From the faintest pulsar we studied, we see only two gamma-ray photons a day."

Radio telescopes on Earth can detect a pulsar easily only if one of the narrow radio beams happens to swing our way. If not, the pulsar can remain hidden.

A pulsar's radio beams represent only a few parts per million of its total power, whereas its gamma rays account for 10 percent or more. Somehow, pulsars are able to accelerate particles to speeds near that of light. These particles emit a broad beam of gamma rays as they arc along curved magnetic field lines.

The new pulsars were discovered as part of a comprehensive search for periodic gamma-ray fluctuations using five months of Fermi Large Area Telescope data and new computational techniques.

"Before launch, some predicted Fermi might uncover a handful of new pulsars during its mission," Ziegler added. "To discover 16 in its first five months of operation is really beyond our wildest dreams."

Like spinning tops, pulsars slow down as they lose energy. Eventually, they spin too slowly to power their characteristic emissions and become undetectable.

But pair a slowed dormant pulsar with a normal star, and a stream of stellar matter from the companion can spill onto the pulsar and increase its spin. At rotation periods between 100 and 1,000 times a second, ancient pulsars can resume the activity of their youth. In the second study, Fermi scientists examined gamma rays from eight of these "born-again" pulsars, all of which were previously discovered at radio wavelengths.

"Before Fermi launched, it wasn't clear that pulsars with millisecond periods could emit gamma rays at all," said Lucas Guillemot at the Center for Nuclear Studies in Gradignan, near Bordeaux, France. "Now we know they do. It's also clear that, despite their differences, both normal and millisecond pulsars share similar mechanisms for emitting gamma rays."

NASA's Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership, developed in collaboration with the U.S. Department of Energy, along with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden, and the U.S.


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. "Dozens Of Newly Discovered Pulsars Probed By NASA's Fermi Gamma-ray Space Telescope." ScienceDaily. ScienceDaily, 7 July 2009. <www.sciencedaily.com/releases/2009/07/090706112910.htm>.
NASA/Goddard Space Flight Center. (2009, July 7). Dozens Of Newly Discovered Pulsars Probed By NASA's Fermi Gamma-ray Space Telescope. ScienceDaily. Retrieved September 18, 2014 from www.sciencedaily.com/releases/2009/07/090706112910.htm
NASA/Goddard Space Flight Center. "Dozens Of Newly Discovered Pulsars Probed By NASA's Fermi Gamma-ray Space Telescope." ScienceDaily. www.sciencedaily.com/releases/2009/07/090706112910.htm (accessed September 18, 2014).

Share This



More Space & Time News

Thursday, September 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Boeing, SpaceX to Send Astronauts to Space Station

Boeing, SpaceX to Send Astronauts to Space Station

AFP (Sep. 17, 2014) — NASA selected Boeing and SpaceX on Tuesday to build America's next spacecraft to carry astronauts to the International Space Station (ISS) by 2017, opening the way to a new chapter in human spaceflight. Duration: 01:13 Video provided by AFP
Powered by NewsLook.com
East Coast Treated To Rare Meteor Sighting

East Coast Treated To Rare Meteor Sighting

Newsy (Sep. 16, 2014) — Numerous residents along the East Coast reported seeing a bright meteor flash through the sky Sunday night. Video provided by Newsy
Powered by NewsLook.com
Space Race Pits Bezos Vs Musk

Space Race Pits Bezos Vs Musk

Reuters - Business Video Online (Sep. 16, 2014) — Amazon CEO Jeff Bezos' startup will team up with Boeing and Lockheed to develop rocket engines as Elon Musk races to have his rockets certified. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
NASA Picks Boeing and SpaceX to Ferry Astronauts

NASA Picks Boeing and SpaceX to Ferry Astronauts

AP (Sep. 16, 2014) — NASA is a giant step closer to launching Americans again from U.S. soil. It has announced it has picked Boeing and SpaceX to transport astronauts to the International Space Station in the next few years. (Sept. 16) Video provided by AP
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:
from the past week

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