- a[{” attribute=””>pulsar is racing through the debris of an exploded star at a speed of over a million miles per hour.
- To measure this, researchers compared NASA Chandra X-ray Observatory images of G292.0+1.8 taken in 2006 and 2016.
- Pulsars can form when massive stars run out of fuel, collapse, and explode — leaving behind a rapidly spinning dense object.
- This result may help explain how some pulsars are accelerated to such remarkably high speeds.
The G292.0 + 1.8 supernova remnant contains a pulsar moving at over a million miles per hour. This image contains data from NASA’s Chandra X-ray Observatory (red, orange, yellow, and blue), which was used to make this discovery. X-rays are combined with an optical image from the Digital Sky Survey, a ground-based survey of the entire sky.
Pulsars are spinning fast neutron stars They can form when massive stars run out of fuel, collapse and explode. These explosions sometimes produce a “kick” that causes a pulsar to race through the remnants of a supernova explosion. The inset shows a close-up of this pulsar in X-rays of Chandra.
To make this discovery, the researchers compared Chandra images of G292.0 + 1.8 taken in 2006 and 2016. A pair of complementary images show the change in the pulsar’s position over 10 years. The source’s change of location is negligible because the pulsar is about 20,000 light-years away from Earth, but it has traveled about 120 billion miles (190 billion km) during this time. The researchers were able to measure this by combining high-resolution Chandra images with micro-technology to verify the coordinates of the pulsar and other X-ray sources using precise positions from the Gaia satellite.
Pulsar sites, 2006 and 2016. Credit: X-ray: NASA/CXC/SAO/L. Shi et al.
The team calculated that the pulsar was moving 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 the previous estimate of the pulsar’s velocity, which was based on an indirect method, by measuring the pulsar’s distance from the center of the explosion.
The newly determined velocity of the pulsar suggests that G292.0 + 1.8 and the pulsar may be much smaller than astronomers previously thought. The researchers estimate that G292.0 + 1.8 could have erupted about 2,000 years ago, as seen from Earth, rather than 3,000 years ago as previously calculated. This new estimate of G292.0 + 1.8’s age is based on extrapolating the pulsar’s location in time to coincide with the center of the explosion.
Many civilizations around the world recorded supernova explosions at that time, opening the possibility of direct observation of G292.0 + 1.8. However, G292.0 + 1.8 is below the horizon for most of the civilizations in the northern hemisphere that I have observed, and there are no recorded examples of a supernova observed in the southern hemisphere towards G292.0 + 1.8.
Close-up of the Chandra image center of the G292 + 1.8. The direction of motion of the pulsar (arrow) and the position of the blast center (green oval) are shown based on the motion of debris seen in the optical data. The position of the pulsar was extrapolated 3000 years ago and the triangle represents the uncertainty in the induction angle. The similarity of the site of the induction to the epicenter of the explosion gives an age of approximately 2,000 years for the pulsar and G292 + 1.8. The center of gravity (junction) of the X-ray elements detected in the debris (Si, S, Ar, Ca) is located opposite the center of the explosion of a moving pulsar. The asymmetry in the debris in the upper right corner of the explosion pushed the pulsar lower left, maintaining momentum. Credit: X-ray: NASA/CXC/SAO/L. Shi et al.; Optical: Palomar DSS2
In addition to learning more about G292.0 + 1.8’s age, the research team also studied how the pulsar’s supernova gave its powerful boost. There are two main possibilities, both of which indicate that the material was not ejected evenly in all directions from the supernova. One possibility is that neutrinos The explosion output from the explosion is ejected asymmetrically, the other is that the debris from the explosion is ejected asymmetrically. If matter had a preferred orientation, the pulsar would be pushed in the opposite direction due to a physical principle called conservation of momentum.
The amount of neutrino asymmetry needed to account for the high speed in this last result would be extreme, supporting the interpretation that the asymmetry in the debris from the explosion gave the pulsar its kick.
The energy transferred to the pulsar from this explosion was enormous. Although the pulsar is only about 10 miles in diameter, the pulsar has a mass of 500,000 times the mass of Earth, and it travels 20 times faster than Earth in orbit around the Sun.
The latest work by Xi Long and Paul Plucinksky (Astrophysics Center | 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 accepted for publication in The Astrophysical Journal. The other authors of the paper are Daniel Patno and Terence Gaetz, both of whom work at the Center for Astrophysics.
Reference: “Correct motion of 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, Astrophysical Journal†
arXiv: 2205.07951
NASA’s Marshall Space Flight Center manages the Chandra program. The Chandra X-ray Center at the Smithsonian Astrophysical Observatory controls science operations from Cambridge, Massachusetts, and flight operations from Burlington, Massachusetts.
