An artist's impression of the binary star system PSR J1023+0038. The
extremely dense, rapidly-spinning neutron star, just 10-15 km in size,
is in a close orbit with a more normal companion star. The strong
gravity of the neutron star pulls gas from its companion, which spirals
in towards the neutron star, forming a disk. Some fraction of that gas
gets accelerated outwards in energetic, oppositely-directed jets, which
give off the radio waves that can be seen by Earth’s radio telescopes.
Credit: ICRAR. Click here for a full resolution version and here (labeled)
A super-dense star formed in the aftermath of a supernova explosion is
shooting out powerful jets of material into space, research suggests.
In a study published today, a team of scientists in the Australia and
the Netherlands discovered powerful jets blasting out of a double star
system known as PSR J1023+0038.
It was previously thought that the only objects in the Universe capable of forming such powerful jets were black holes.
PSR J1023+0038 contains an extremely dense type of star astronomers call
a neutron star, in a close orbit with another, more normal star nearby.
It was first identified as a neutron star in 2009 but it was only when
the research team observed the star with the Very Large Array radio
telescope in the United States in 2013 and 2014 that they realised the
star was producing much stronger jets than expected.
Astronomer James Miller-Jones, from the International Centre for Radio
Astronomy Research (ICRAR), says neutron stars can be thought of as
stellar corpses.
“They’re formed when a massive star runs out of fuel and undergoes a
supernova, and the central parts of the star collapse under their own
gravity,” he says.
“These things are typically about one and a half times the mass of the
Sun and yet they’re only 10-15km across, so they’re incredibly dense.”
ASTRON astronomer Adam Deller, who led the research, says neutron stars
and black holes are sometimes found in orbit with a nearby “companion”
star.
“Gas can then flow from the companion star to the neutron star or black
hole, producing spectacular displays when some of the material is
blasted out in powerful jets at close to the speed of light,” he says.
“From what we had seen previously, black holes were previously
considered the undisputed kings of forming powerful jets, even when they
were only fed by a little bit of material from their companion star.”
“In comparison, neutron stars seemed to make relatively puny jet, which
only became bright enough to see when the neutron star was gobbling gas
from their companion at a very high rate.”
Dr Deller says when the team looked at PSR J1023+0038 it was only
consuming a trickle of material and should have been producing a very
feeble jet.
“But our observations suggest its jets are nearly as strong as you’d expect from a black hole,” he says.
Dr Miller-Jones says PSR J1023+0038 is a “transitional” neutron star,
spending years at a time powered mainly by the rotation of the neutron
star but transitioning occasionally into an active gathering state, when
it gets much brighter.
“Two other transitional systems are now known and both of these have also been shown to exhibit powerful jets,” he says.
“This is casting neutron stars in a new light and showing that in fact
they can sometimes launch jets to rival those coming from black holes.”
The research was published today in the Astrophysical Journal.
More Information
ICRAR is a joint venture between Curtin University and The University of
Western Australia with support and funding from the State Government of
Western Australia.
Original publication details:
‘Radio Imaging Observations of PSR J1023+0038 in an LMXB State’ published in the Astrophysical Journal on 4/8/2015. Available online at http://arxiv.org/pdf/1412.5155.pdf
Contact Details:
Dr James Miller-Jones, ICRAR/Curtin University
Ph: +61 8 9266 9141 | E:James.Miller-Jones@icrar.org | M: +61 488 484 825
Dr Adam Deller, ASTRON
Ph: +31 610 906 427 | E: deller@astron.nl
Pete Wheeler, ICRAR Media Contact
Ph: +61 8 6488 7758 | E: Pete.Wheeler@icrar.org | M: +61 423 982 018
