(CN) – New images of a fast-moving “neutron” star shed light on a 25-year-old mystery of how planets form in the aftermath of a supernova, the cosmic explosion of a star many times larger than the sun.
While such a blast should destroy any nearby – in cosmic terms – celestial bodies, the first planets to be discovered outside the exploded star system were orbiting the remnant of the supernova: a small, super-dense neutron star.
British researchers may have an explanation for where these incredibly rare “planets in the dark” came from, after observing Geminga, a type of neutron star known as a “pulsar.” Their findings will be presented Thursday at the National Astronomy Meeting at the University of Hull in the United Kingdom.
Pulsars can be detected because their gravitational pull affects the times of arrival of radio pulses – which frequently pass Earth. By studying Geminga – located about 800 light years away in the Gemini constellation – the team hoped to determine how neutron stars gather the materials necessary to form companion planets.
“Astronomers thought they’d found a planet there in 1997, but later discounted it because of glitches in the timing,” said study co-author Jane Greaves, an astronomer at the University of Cardiff. “So it was much later when I went through our sparse data and tried to make an image.”
The team observed Geminga using the James Clerk Maxwell Telescope (JCMT) in Hawaii, which can detect light that barely gets through Earth’s atmosphere and is invisible to the human eye. The scientists then compared the image created by the new data with the older image of the pulsar.
“What we saw was very faint,” said Wayne Holland, an astronomer at the U.K. Astronomy Technology Centre in Scotland and co-author of the new findings. “To be sure, we went back to it in 2013 with the new camera our Edinburgh-based team had built, SCUBA-2, which we also put on JCMT. Combining the two sets of data helped to ensure we weren’t just seeing some faint artifacts.”
The images show a signal toward the pulsar and an arc around it.
“This seems to be like a bow-wave – Geminga is moving incredibly fast through our galaxy, much faster than the speed of sound in interstellar gas,” Greaves said. “We think material gets caught up in the bow-wave, and then some solid particles drift in towards the pulsar.”
Greaves calculates these particles add up to at least a few times the mass of Earth, which could be enough to form planets. However, the team cautions that more data is needed to tackle this cosmic quandary.
“Our image is quite fuzzy, so we’ve applied for time on the international Atacama Large Millimetre Array – ALMA – to get more detail,” Greaves said. “We’re certainly hoping to see this space-grit orbiting nicely around the pulsar, rather than some distant blob of galactic background!”