The rest of the supernova G292.0 + 1.8 contains a pulsar moving at over a million miles per hour, as seen in the Chandra image along with an optical image from the Digitized Sky Survey. Pulsars are fast-spinning neutron stars that can form when massive stars run out of fuel, collapse, and explode. Sometimes these explosions cause a “kick” that sends this pulsar to run through the remnants of the supernova explosion. Additional images show a close-up view of this X-ray pulsar from Chandra, who observed it in both 2006 and 2016 to measure this remarkable speed. The red crosses on each panel show the position of the pulsar in 2006. Credit: X-ray: NASA / CXC / SAO / L. Xi et al .; Optics: Palomar DSS2
- A pulsar races through the wreckage of an exploding star at a speed of over a million miles per hour.
- To measure this, the researchers compared images of G292.0 + 1.8 from NASA’s Chandra X-ray Observatory taken in 2006 and 2016.
- Pulsars can form when massive stars run out of fuel, collapse and explode – leaving behind a rapidly rotating dense object.
- This result may help explain how some pulsars accelerate to such remarkably high speeds.
The rest of the supernova G292.0 + 1.8 contains a pulsar moving at over a million miles per hour. This image includes data from NASA’s Chandra X-ray Observatory (red, orange, yellow and blue) that were used to make this discovery. The X-rays were combined with an optical image from the Digitized Sky Survey, a ground-based study of the entire sky.
Pulsars are fast-spinning neutron stars that can form when massive stars run out of fuel, collapse, and explode. Sometimes these explosions cause a “kick”, which is what makes this pulsar run through the remnants of a supernova explosion. An insert shows a close look at this pulsar in X-rays from Chandra.
To make this finding, the researchers compared Chandra’s G292.0 + 1.8 images taken in 2006 and 2016. A couple of additional images show the change in pulsar position over a 10-year period. The change in the position of the source is small, as the pulsar is about 20,000 light-years from Earth, but has traveled about 120 billion miles (190 billion km) in that period. The researchers were able to measure this by combining Chandra’s high-resolution images with careful technique to check the coordinates of the pulsar and other X-ray sources using accurate positions from the Gaia satellite.
Pulsar Positions, 2006 & 2016. Credit: X-ray: NASA / CXC / SAO / L. Xi et al.
The team estimated that the pulsar was moving at least 1.4 million miles per hour from the center of the supernova remnant in the lower left corner. This speed is about 30% higher than the previous estimate of the pulsar speed, which is based on an indirect method, measuring how far the pulsar is from the center of the explosion.
The newly determined pulsar speed indicates that G292.0 + 1.8 and its pulsar may be significantly younger than astronomers previously thought. Researchers estimate that G292.0 + 1.8 would have exploded about 2,000 years ago, as seen from Earth, not 3,000 years ago, as previously calculated. This new age estimate of G292.0 + 1.8 is based on extrapolating the position of the pulsar back in time so that it coincides with the center of the explosion.
Several civilizations around the world recorded supernova explosions at the time, allowing G292.0 + 1.8 to be observed directly. However, G292.0 + 1.8 is below the horizon for most northern hemisphere civilizations that may have observed it, and there are no recorded examples of supernovae observed in the southern hemisphere in the G292.0 + 1.8 direction.
Close-up view of the center of Chandra’s image on the G292 + 1.8. The direction of movement of the pulsar (arrow) and the position of the center of the explosion (green oval) are indicated based on the movement of debris observed in the optical data. The position of the pulsar was extrapolated 3,000 years ago, and the triangle depicts the uncertainty in the angle of extrapolation. The alignment of the extrapolated position with the center of the explosion gives an age of about 2000 years for the pulsar and G292 + 1.8. The center of mass (cross) of the elements detected by X-rays in the debris (Si, S, Ar, Ca) is on the opposite side of the center of the explosion from the moving pulsar. This asymmetry in the debris in the upper right corner of the explosion led to a pulsar rhythm in the lower left corner by maintaining momentum. Credit: X-ray: NASA / CXC / SAO / L. Xi et al .; Optics: Palomar DSS2
In addition to learning more about the age of G292.0 + 1.8, the research team also studied how the supernova gave the pulsar its powerful impact. There are two main options, both involving material that is not ejected from the supernova evenly in all directions. One possibility is that neutrinos produced during the explosion are ejected from the explosion asymmetrically, and the other is that the debris from the explosion is ejected asymmetrically. If the material has a preferred direction, the pulsar will be kicked in the opposite direction due to the principle of physics called momentum conservation.
The amount of neutrino asymmetry required to explain the high velocity in this latter result would be extreme, supporting the explanation that the asymmetry in the debris of the explosion struck the pulsar.
The energy given to the pulsar by this explosion was gigantic. Although only about 10 miles in diameter, the pulsar’s mass is 500,000 times that of Earth, and it moves 20 times faster than the speed of the Earth orbiting the Sun.
Xi Long and Paul Plucinksky’s latest work (Center for Astrophysics | Harvard & Smithsonian) on G292.0 + 1.8 was presented at the 240th meeting of the American Astronomical Society in Pasadena, California. The results are also discussed in a paper that has been accepted for publication in The Astrophysical Journal. The other authors of the article are Daniel Patnaud and Terence Gaetz, both from the Center for Astrophysics.
Reference: “The correct motion of the pulsar J1124-5916 in the remnant of the galactic supernova G292.0 + 1.8” by Xi Long, Daniel J. Patnaude, Paul P. Plucinsky and Terrance J. Gaetz, Accepted, The Astrophysical Journal.arXiv: 2205.07951
NASA’s Marshall Space Flight Center manages the Chandra program. The Chandra X-ray Center of the Smithsonian Astrophysical Observatory oversees scientific operations from Cambridge, Massachusetts, and flights from Burlington, Massachusetts.
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