Observations with NASA’s Chandra, Swift and Rossi X-ray observatories, Fermi Gamma-ray Space Telescope and ESA’s XMM-Newton have revealed that a slowly rotating neutron star with an ordinary surface magnetic field is giving off bursts of X-rays and gamma rays. This discovery may indicate the presence of an internal magnetic field much more intense than the surface magnetic field, with implications for how the most powerful magnets in the cosmos evolve.
The neutron star, SGR 0418+5729, was discovered on June 5, 2009, when the Fermi Gamma-ray Space Telescope detected bursts of gamma-rays from this object. Follow-up observations four days later with the Rossi X-Ray Timing Explorer (RXTE) showed that, in addition to sporadic X-ray bursts, the neutron star exhibits persistent X-ray emission with regular pulsations that indicate that the star has a rotational period of 9.1 seconds. RXTE was able to monitor this activity for about 100 days. This behavior is similar to a class of neutron stars called magnetars, which have strong to extreme magnetic fields 20 to 1000 times above the average of the galactic radio pulsars.
As neutron stars rotate, the radiation of low frequency electromagnetic waves -- or winds of high-energy particles -- carry energy away from the star, causing the rotation rate of the star to gradually decrease. Careful monitoring of SGR 0418 was possible because Chandra and XMM-Newton were able to measure its pulsation period even though it faded by a factor of 10 after the initial detection. What sets SGR 0418 apart from other magnetars is that careful monitoring over a span of 490 days has revealed no detectable decrease in its rotation rate.
The lack of rotational slowing implies that the radiation of low frequency waves must be weak, and hence the surface magnetic field must be much weaker than normal. But this raises another question: Where does the energy come from to power bursts and the persistent X-ray emission from the source?
The generally accepted answer for magnetars is that the energy to power the X-ray and gamma-ray emission comes from an internal magnetic field that has been twisted and amplified in the turbulent interior of the neutron star. Theoretical studies indicate that if the internal field becomes about ten or more times stronger than the surface field, the decay or untwisting of the field can lead to the production of steady and bursting X-ray emission through the heating of the neutron star crust or the acceleration of particles.
A crucial question is how large an imbalance can be maintained between the surface and interior fields. SGR 0418 represents an important test case. The observations already imply an imbalance of between 50 and 100. If further observations by Chandra push the surface magnetic field limit lower, then theorists may have to dig deeper for an explanation of this enigmatic object.
This discovery is the result of an international teamwork from CSIC-IEEC, INAF, University of Padua, MSSL-UCL, CEA-Saclay, Sabanci University and NASA’s Marshall Space Flight Center in Huntsville, Ala. These results appear in the Oct. 14 issue of Science Express, which provides electronic publication of selected science papers in advance of print.
The Marshall Center manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass.
For More Information visit http://www.nasa.gov/mission_pages/chandra/news/10-137.html
- Fermi Telescope Caps First Year With Glimpse of Space-Time - November 8th, 2009 [November 8th, 2009]
- Antarctic Airborne Science Mission Nears Mid-Point - November 8th, 2009 [November 8th, 2009]
- NASA Awards Education Research Grants to Minority Universities - November 8th, 2009 [November 8th, 2009]
- New Celestial Map Gives Directions for GPS - November 8th, 2009 [November 8th, 2009]
- NASA Invites Reporters to Tranquility Node Ceremony at Kennedy - November 8th, 2009 [November 8th, 2009]
- Happy Halloween - November 8th, 2009 [November 8th, 2009]
- NASA's Fermi Telescope Detects Gamma-Ray From "Star Factories" in Other Galaxies - November 8th, 2009 [November 8th, 2009]
- NASA Announces Advisory Council Chairs and Committee Structure - November 8th, 2009 [November 8th, 2009]
- NASA and X Prize Announce Winners of Lunar Lander Challenge - November 8th, 2009 [November 8th, 2009]
- MESSENGER Spacecraft Reveals More Hidden Territory on Mercury - November 8th, 2009 [November 8th, 2009]
- Successful Flight Through Enceladus Plume - November 8th, 2009 [November 8th, 2009]
- Education Secretary Hosts DC Students for Talk with Space Station - November 8th, 2009 [November 8th, 2009]
- Operation Ice Bridge Studies Antarctic Sea Ice - November 8th, 2009 [November 8th, 2009]
- NASA West Point Welcomes Home One of Their Heroes - November 8th, 2009 [November 8th, 2009]
- NASA Spitzer Observes a Chaotic Planetary System - November 8th, 2009 [November 8th, 2009]
- X-38 Crew Return Vehicle Finds New Home - November 8th, 2009 [November 8th, 2009]
- Frost-Covered Phoenix Lander Seen in Winter Images - November 8th, 2009 [November 8th, 2009]
- Have some faith He is doing his best - November 8th, 2009 [November 8th, 2009]
- The Cross - November 8th, 2009 [November 8th, 2009]
- Spring Bloom in New Zealand Waters - November 8th, 2009 [November 8th, 2009]
- NASA Hubble image showcases star birth in M83, the Southern Pinwheel - November 8th, 2009 [November 8th, 2009]
- Take Me Out to the Ballpark - On Mars! - November 8th, 2009 [November 8th, 2009]
- Poisk Poised for Live NASA TV Space Station Docking - November 8th, 2009 [November 8th, 2009]
- Ceremony Reset for ESA Handover of Tranquility to NASA - November 8th, 2009 [November 8th, 2009]
- NASA Reproduces a Building Block of Life in Laboratory - November 8th, 2009 [November 8th, 2009]
- Now Online: Aeronautics Goes E-Book - December 12th, 2009 [December 12th, 2009]
- Water on the Moon, Drought on Earth: NASA Experts Available for Radio And Podcast Interviews During Major Science Meeting - December 12th, 2009 [December 12th, 2009]
- Launch of NASA's Wise Spacecraft Delayed Until Dec. 14 - December 12th, 2009 [December 12th, 2009]
- Connecticut Students Set for Cosmic Conversation with Space Station Commander - December 12th, 2009 [December 12th, 2009]
- Magnetic Dance of Titan and Saturn To Be Main Attraction during Flyby - December 12th, 2009 [December 12th, 2009]
- Hubble's Deepest View of Universe Unveils Never-Before-Seen Galaxies - December 13th, 2009 [December 13th, 2009]
- Earth's Moon - December 13th, 2009 [December 13th, 2009]
- How do you Make a Helicopter Safer to Fly? You Crash One. - December 13th, 2009 [December 13th, 2009]
- Physicist Earns Title as Kennedy's Best - December 13th, 2009 [December 13th, 2009]
- Hubble Unveils Never-Before-Seen Galaxies - December 13th, 2009 [December 13th, 2009]
- Saturn's Mysterious Hexagon Emerges from Winter Darkness - December 13th, 2009 [December 13th, 2009]
- Fermi Sees Brightest-Ever Blazar Flare - December 13th, 2009 [December 13th, 2009]
- Magnetic Power Revealed in Gamma-Ray Burst Jet - December 13th, 2009 [December 13th, 2009]
- Just 5 Questions: Aerosols - December 13th, 2009 [December 13th, 2009]
- Hometown Heroes 2009: Astronaut & Terrible Towel Return to Pittsburgh - December 13th, 2009 [December 13th, 2009]
- Garver Honors Four for Saving the Life of a Fifth at NASA Langley - December 13th, 2009 [December 13th, 2009]
- Administrator Bolden Speaks at AAIA-WIA Luncheon - December 13th, 2009 [December 13th, 2009]
- Best (Meteor) Shower of 2009 - No Towel Required - December 13th, 2009 [December 13th, 2009]
- NASA Making Government More Accessible With Cutting-Edge Use Of New Media - December 13th, 2009 [December 13th, 2009]
- Scarce Water, Our Quiet Sun and Space Rocks Among NASA News Highlights at American Geophysical Union Meeting - December 13th, 2009 [December 13th, 2009]
- Press Credentials Deadlines Set for Next Space Shuttle Flight - December 13th, 2009 [December 13th, 2009]
- Reddish Dust and Ice Migration Darken Saturn's Moon Iapetus - December 13th, 2009 [December 13th, 2009]
- Galaxy Collision Switches on Black Hole - December 13th, 2009 [December 13th, 2009]
- I’m watching the launch of NASA’s WISE spacecraft - December 13th, 2009 [December 13th, 2009]
- SOFIA Aloft - December 13th, 2009 [December 13th, 2009]
- Guide to the International Space Station Laboratory Racks Interactive - December 14th, 2009 [December 14th, 2009]
- Freezing WISE's Hydrogen - December 14th, 2009 [December 14th, 2009]
- Local High School Wins Invention Challenge - December 14th, 2009 [December 14th, 2009]
- WISE Ready to Soar Into Space - December 14th, 2009 [December 14th, 2009]
- NASA Data Reveal Major Groundwater Loss in California's Heartland - December 15th, 2009 [December 15th, 2009]
- NASA Looks for Safer Icing Forecast For Pilots - December 15th, 2009 [December 15th, 2009]
- Challenges of Living and Working Aboard the Space Station: NASA Astronaut Nicole Stott Available for TV Interviews - December 15th, 2009 [December 15th, 2009]
- NASA Astronaut, Food Scientist Available for Interviews about Holiday Feasts in Space - December 15th, 2009 [December 15th, 2009]
- NASA Launches Web Site for Teenagers That Want More Class - December 15th, 2009 [December 15th, 2009]
- A Unique Geography -- and Soot and Dust -- Conspire Against Himalayan Glaciers - December 15th, 2009 [December 15th, 2009]
- New Study Turns Up the Heat on Soot's Role in Himalayan Warming - December 15th, 2009 [December 15th, 2009]
- NASA's WISE Eye on the Universe Begins All-Sky Survey Mission - December 15th, 2009 [December 15th, 2009]
- NASA Offers Sound Clips for Radio, Online Newscasters - December 17th, 2009 [December 17th, 2009]
- NASA Gets Up-Close Look at Far Corner of the Globe - December 17th, 2009 [December 17th, 2009]
- Orion Launch Abort System Attitude Control Motor Test-fired - December 17th, 2009 [December 17th, 2009]
- Hubble Finds Smallest Kuiper Belt Object Ever Seen - December 17th, 2009 [December 17th, 2009]
- The Dark Side of Carbon - December 17th, 2009 [December 17th, 2009]
- R97UYEA6HD8W - December 17th, 2009 [December 17th, 2009]
- NASA's AIM Satellite and Models are Unlocking the Secrets of Mysterious "Night-Shining" Clouds - December 17th, 2009 [December 17th, 2009]
- Classroom Learning Takes Off with NASA-Funded Education Projects - December 17th, 2009 [December 17th, 2009]
- NASA Buys Additional Space Shuttle Reusable Solid Rocket Motors - December 17th, 2009 [December 17th, 2009]
- Searching for New Vaccines and Studying Butterflies in Space; NASA Offers TV Interviews about Latest Space Station Science Research - December 17th, 2009 [December 17th, 2009]
- NASA Partners with Saudi Arabia on Moon and Asteroid Research - December 17th, 2009 [December 17th, 2009]
- New Results from a Terra-ific Decade in Orbit - December 17th, 2009 [December 17th, 2009]
- Deposits in Martian Trough Point to Complex Hydrological Past - December 17th, 2009 [December 17th, 2009]
- NASA Outlines Recent Greenhouse Gas Research - December 17th, 2009 [December 17th, 2009]
- Unexpected Wheel-Test Results - December 17th, 2009 [December 17th, 2009]
- Solar Storms and Radiation Exposure on Commercial Flights - December 17th, 2009 [December 17th, 2009]
- Global Digital Elevation Model - December 17th, 2009 [December 17th, 2009]
- Hubble's Festive View of a Grand Star-Forming Region - December 17th, 2009 [December 17th, 2009]