Astronomers find X-ray pulsar in record-fast orbit
Scientists found a pair of stars orbiting one another at record speed.
The duo orbit each other once every 38 minutes, the shortestknown orbital period for its specific class of pulsar binary systems, UPI reported.
The unusual pair, named J17062, was discovered while interrogating the first batch of data recorded by the Neutron star Interior Composition Explorer mission, or NICER mission.
According to researchers, the system is made up of a rapidly spinning, superdense neutron star called an accreting millisecond X-ray pulsar and a hydrogen-poor white dwarf.
Tod Strohmayer, an astrophysicist at NASA’S Goddard Space Flight Center, said, “It’s not possible for a hydrogen-rich star, like our Sun, to be the pulsar’s companion.
“You can’t fit a star like that into an orbit so small.”
Neutron stars are the extremely hot, superdense stellar cores sometimes left over after supernovae.
The stars are so hot, they emanate X-rays. Their violent spin and its accretion from its companion causes intense beams of X-rays to pulse from their poles.
NICER data showed J17062 pulses 163 times per second, which means the pulsar is spinning at a speed of 9,800 revolutions per minute.
Though J17062 boasts a record orbit, its spin rate is average. Some pulsar spin some 700 revolutions per second, several orders of magnitude greater than J17062 spin rate.
The hotspots that produce the neutron star’s polar pulses are created by the accretion of material from its companion, the hydrogen-poor white dwarf.
Stolen material is pulled into an accretion disk, much like a black hole.
Because the pulsar has an intense magnetic field, the material in the accretion disk are pulled into the stellar core unevenly, creating hotspots.
Over time, the pulsar will accrue more material than it can handle. The excess mass will eventually trigger a thermonuclear reaction, a massive release of energy in the form of X-rays. NICER can detect such releases, but has yet to measure an outburst from J17062.
While the pulsar’s donor star is rather puny, it still has a small effect on the orbital path of J17062. That the slight perturbation can be measured is a testament to the sensitivity of NICER’S instruments.
Strohmayer said, “The distance between us and the pulsar is not constant.
“It’s varying by this orbital motion. When the pulsar is closer, the X-ray emission takes a little less time to reach us than when it’s further away.
“This time delay is small, only about eight milliseconds for J17062’s orbit, but it’s well within the capabilities of a sensitive pulsar machine like NICER.”
Strohmayer and his colleagues detailed their investigation of J17062 in a new paper, published in the Astrophysical Journal. The California rocket company Spacex has conducted what is arguably its most important launch to date.
Flying out of Florida, the firm’s Falcon-9 vehicle lifted a standard telecommunications satellite for Bangladesh into orbit, bbc.com wrote.
But the booster incorporated everything Spacex has so far learnt about reusability.
This ‘Block 5’ version of the Falcon is designed to launch and land at least 10 times without any servicing.
Earlier iterations of the rocket have not flown more than twice and required some level of refurbishment between missions.
Spacex CEO Elon Musk said, “It’s taken us 16 years of extreme effort, many iterations and thousands of small but important development changes to get to where we think this is even possible. Crazy hard.”
Block 5 will now become the mainstay of Spacex’s operations. What is more, the vehicle has been built to the ‘over-engineered’ and fault-tolerant standards demanded for human use.
The first astronauts to ride the rocket should do so within the year.
Friday’s mission lifted clear of the pad at the Kennedy Space Center at 16:14 local time (21:14 BST).
Separation of the first and second stages took place just over two minutes later, with the upper-stage and the Bangabandhu-1 satellite continuing to orbit — and the booster returning to Earth to make a controlled landing.
This well-practiced procedure saw the first-stage put itself experienced minimal wear and tear during its flight and can be reused with no parts exchange.
If this is shown to be the case, rocketry really will have entered a new era.
Musk said, “The key to Block 5 is that it is designed to do 10 or more flights with no scheduled refurbishment between each flight.
“The only thing that needs to change is you reload propellant and you fly again. There would be moderate scheduled maintenance at 10, but we believe Block 5s are capable of on the order of 100 flights before being retired.”
The entrepreneur said the company would have perhaps 30 vehicles it would use in rotation. should make it more robust.
The goal is to be able to get the rocket back on its pad for another flight within weeks rather than months. And to demonstrate the capability of the Block 5 booster, Musk said that the company would even try to do a couple of 24-hour, backto-back missions at some point next year.
“That I think would be truly remarkable, to launch the same orbital class rocket twice in one day.”
The Spacex boss explained that the old booster represented about 60 percent of the cost of a mission.
If he can reuse the new Block 5s 10 times or more, then this would have a dramatic impact