The G292.0 + 1.8 supernova remnant contains a pulsar that moves at more than a million miles per hour, as seen in Chandra’s image along with an optical image from the Digitized Sky Survey. Pulsars are fast-rotating neutron stars that can form when massive stars run out of fuel, collapse, and explode. Sometimes these explosions produce a “kick”, which caused this pulsar to pass through the remnants of the supernova explosion. Additional images show a close-up of this Chandra X-ray pulsar, which he observed 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-rays: NASA / CXC / SAO / L. Xi et al .; Optical: Palomar DSS2
- A pulsar runs through the debris of an exploded star at a speed of over a million miles per hour.
- To measure this, the researchers compared images from NASA’s G292.0 + 1.8 X-ray Chandra Observatory taken in 2006 and 2016.
- Pulsars can form when massive stars run out of fuel, collapse and explode, leaving behind a dense, rapidly rotating object.
- This result may help to explain how some pulsars accelerate at such remarkably high speeds.
The G292.0 + 1.8 supernova remnant contains a pulsar that moves at more than a million miles per hour. This image includes data from NASA’s Chandra X-ray Observatory (red, orange, yellow, and blue), which was used to make this discovery. X-rays were combined with an optical image from the Digitized Sky Survey, a terrestrial survey of the entire sky.
Pulsars are fast-rotating neutron stars that can form when massive stars run out of fuel, collapse, and explode. Sometimes these explosions produce a “kick”, which is what caused this pulsar to escape through the remnants of the supernova explosion. An insert shows a close-up look at this X-ray pulsar by Chandra.
To make this discovery, the researchers compared Chandra’s images of G292.0 + 1.8 taken in 2006 and 2016. A couple of additional images show the change in the position of the pulsar over the 10-year period. The change in the position of the source is small because the pulsar is about 20,000 light-years from Earth, but it traveled about 120 billion miles (190 billion km) during that period. The researchers were able to measure this by combining Chandra’s high-resolution images with a careful technique of checking the coordinates of the pulsar and other X-ray sources using accurate positions from the Gaia satellite.
Press Positions, 2006 & 2016. Credit: X-ray: NASA / CXC / SAO / L. Xi et al.
The team estimated that the pulsar moves at least 1.4 million miles per hour from the center of the supernova remnant to the lower left. This speed is about 30% higher than a previous estimate of the speed of the pulsar which was 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 exploded about 2,000 years ago from Earth, rather than 3,000 years ago as previously estimated. This new estimate of the age 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.
Various civilizations around the world were recording supernova explosions at the time, opening the possibility that G292.0 + 1.8 could be observed directly. However, G292.0 + 1.8 is below the horizon for most northern hemisphere civilizations that could have observed it, and there are no recorded examples of a supernova observed in the southern hemisphere in the direction of G292.0 + 1.8.
A close-up view of the center of Chandra’s image of G292 + 1.8. The direction of movement of the pulsar (arrow) and the position of the center of the explosion (green oval) are shown as a function of the movement of the residue seen in the optical data. The position of the pulsar is extrapolated 3,000 years ago and the triangle represents the uncertainty in the angle of the extrapolation. The agreement of the extrapolated position with the center of the explosion gives an age of about 2,000 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 to the center of the pulsar explosion in motion. This asymmetry in the debris in the upper right of the explosion resulted in the pulsar being struck in the lower left, for conservation of momentum. Credit: X-ray: NASA / CXC / SAO / L. Xi et al .; Optical: Palomar DSS2
In addition to learning more about the age of G292.0 + 1.8, the research team also examined how the supernova struck its powerful blow. There are two main possibilities, both implying that the material is not ejected by the supernova uniformly in all directions. One possibility is that the neutrinos produced in the explosion will be expelled from the explosion asymmetrically, and the other is that the residue from the explosion will be expelled asymmetrically. If the material has a preferred direction, the pulsar will be launched in the opposite direction due to the principle of physics called conservation of momentum.
The amount of neutrino asymmetry required to explain the high velocity in the latter result would be extreme, supporting the explanation that the asymmetry in the debris from the explosion gave its impulse to the pulsar.
The energy given to the pulsar by this explosion was gigantic. Although only about 10 miles in diameter, the mass of the pulsar is 500,000 times that of the Earth and travels 20 times faster than the speed of the Earth orbiting the Sun.
The latest work by Xi Long and Paul Plucinksky (Center for Astrophysics | Harvard and Smithsonian) on G292.0 + 1.8 was presented at the 240th meeting of the American Astronomical Society in Pasadena, CA. The results are also discussed in an article that has been accepted for publication in The Astrophysical Journal. The other authors of the article are Daniel Patnaude and Terrance Gaetz, both of the Center for Astrophysics.
Reference: “The Proper Motion of the Pulsar J1124-5916 in the Galactic Supernova Remnant 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 Smithsonian Astrophysical Observatory’s Chandra X-ray Center oversees scientific operations from Cambridge, Massachusetts, and flight operations from Burlington, Massachusetts.