G292.0+1.8
Credit: X-ray: NASA/CXC/SAO/L. Xi et al.; Optical: Palomar DSS2
The G292.0+1.8 supernova remnant contains a pulsar moving at over a million miles per hour. This image features data from NASA's Chandra X-ray Observatory (red, orange, yellow, and blue), which was used to make this discovery, as discussed in our latest press release. The X-rays were combined with an optical image from the Digitized Sky Survey, a ground-based survey of the entire sky.
Pulsars
are rapidly spinning neutron stars that can form when massive stars run
out of fuel, collapse and explode. Sometimes these explosions produce a
"kick," which is what sent this pulsar racing through the remains of
the supernova explosion. An inset shows a close-up look at this pulsar
in X-rays from Chandra.
To make this discovery, the researchers compared Chandra images of G292.0+1.8 taken in 2006 and 2016. A pair of supplemental images
show the change in position of the pulsar over the 10-year span. The
shift in the source's position is small because the pulsar is about
20,000 light-years from Earth, but it traveled about 120 billion miles over this 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 by using precise
positions from the Gaia satellite.
Credit: X-ray: NASA/CXC/SAO/L. Xi et al.
The team calculated the pulsar is 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 a previous estimate of the pulsar's
speed that was based on an indirect method, by measuring how far the
pulsar is from the center of the explosion.
The newly determined speed of the pulsar indicates that G292.0+1.8
and its pulsar may be significantly younger than astronomers previously
thought. The researchers estimate that G292.0+1.8 would have exploded
about 2,000 years ago as seen from Earth, rather than 3,000 years ago as
previously calculated. This new estimate of the age of G292.0+1.8 is
based on extrapolating the position of the pulsar backwards in time so
that it coincides with the center of the explosion.
Several civilizations around the globe were recording supernova
explosions at that time, opening the possibility that G292.0+1.8 was
directly observed. However, G292.0+1.8 is below the horizon for most
northern hemisphere civilizations that might have observed it, and there
are no recorded examples of a supernova being observed in the southern
hemisphere in the direction of G292.0+1.8.
In addition to learning more about the age of G292.0+1.8, the
research team also examined how the supernova gave the pulsar its
powerful kick. There are two main possibilities, both involving material
not being ejected by the supernova evenly in all directions. One
possibility is that neutrinos
produced in 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 because of the principle
of physics called the conservation of momentum.
The amount of asymmetry of neutrinos required to explain the high
speed in this latest result would be extreme, supporting the explanation
that asymmetry in the explosion debris gave the pulsar its kick.
The energy imparted to the pulsar from this explosion was gigantic.
Although only about 10 miles across, the pulsar's mass is 500,000 times
that of the Earth and it is traveling 20 times faster than Earth's speed
orbiting the Sun.
The latest work by Xi Long and Paul Plucinksky (Center for
Astrophysics | Harvard & Smithsonian) on G292.0+1.8 was presented at
the 240th meeting of the American Astronomical Society meeting in
Pasadena, CA. The results are also discussed in a paper that has been
accepted for publication in The Astrophysical Journal and is available online. The other authors of the paper are Daniel Patnaude and Terrance Gaetz, both from the Center for Astrophysics.
NASA's Marshall Space Flight Center manages the Chandra program. The
Smithsonian Astrophysical Observatory's Chandra X-ray Center controls
science operations from Cambridge, Massachusetts, and flight operations
from Burlington, Massachusetts.
Fast Facts for G292.0+1.8:
Scale: Main image is about 11.4 arcmin (66 light-years) across.
Category: Supernovas & Supernova Remnants
Coordinates (J2000): RA 11h 24m 36.00s | Dec -59° 16´ 00.00"
Constellation: Centaurus
Observation Date: 6 pointings between 13 Sep and 16 Oct 2006 and 9 pointings between 4 Oct and 13 Nov 2016
Obs. ID: 6677-6680, 8221, 8447, 18028, 18029, 19893, 19894, 19897-19899
Instrument: ACIS
References: Xi L. et al, 2022, ApJ, Accepted; arXiv: 2205.07951
Color Code: X-ray: (red: 0.50-1.2keV, orange/yellow: 1.2-2.2 keV, blue: 2.2-8.0 keV); Optical: red and blue
Distance Estimate: About 20,000 light-years
