Massive star's dying blast caught by rapid-response telescopes

July 26, 2017, Arizona State University
The RATIR camera captured the fading afterglow (arrow) of the June 2016 gamma-ray burster in this sequence running from June 26-Aug. 20, 2016. Credit: Nathaniel Butler/ASU

In June 2016, an international team of 31 astronomers, led by the University of Maryland's Eleanora Troja and including Arizona State University's Nathaniel Butler, caught a massive star as it died in a titanic explosion deep in space.

The blast of the dying star released in about 40 seconds as much energy as the Sun releases over its entire lifetime, all focused into a tight beam of gamma rays aimed by chance toward Earth.

The team's findings, reported in the scientific journal Nature, provide strong evidence for one of two competing models for how gamma-ray bursters (GRBs) produce their energy.

"These are the brightest explosions in the universe," says Butler, an associate professor in ASU's School of Earth and Space Exploration. "And we were able to measure this one's development and decay almost from the initial blast."

Quick reflexes

The gamma-ray blast on June 25, 2016, was detected by two NASA satellites that monitor the sky for such events, the Fermi Gamma-ray Space Telescope and the Swift Gamma-Ray Burst Mission.

The satellite observatories detected the burst of gamma rays, identified where in the sky it came from, and sent its celestial position within seconds to automated telescopes on the ground.

The MASTER-IRC telescope at the Teide Observatory in the Canary Islands observed it first, within a minute of the satellite notification. The telescope is part of Russia's MASTER network of robotic telescopes at the Teide Observatory. It made optical light observations while the initial phase was still active, gathering data on the amount of polarized optical light relative to the total light produced.

After the Sun set over this facility eight and a half hours later, the RATIR camera in which ASU is involved began observing. RATIR stands for Reionization And Transients InfraRed camera; it is mounted on a 1.5-meter (60-inch) robotically controlled telescope located on San Pedro Mártir Peak, at Mexico's National Astronomical Observatory in Baja California. Butler is the principal investigator for the fully-automated camera.

This image shows the most common type of gamma-ray burst, thought to occur when a massive star collapses, forms a black hole, and blasts particle jets outward at nearly the speed of light. An international team led by University of Maryland astronomers has constructed a detailed description of a similar gamma-ray burst event, named GRB160625B. Their analysis has revealed key details about the initial 'prompt' phase of gamma-ray bursts and the evolution of the large jets of matter and energy that form as a result. Credit: NASA's Goddard Space Flight Center

Butler explains, "At best, it takes a minute or two for our telescope to slew to the burst's position. In this case, we had to wait for it to rise over the horizon. This means the gamma-ray burst itself had ended, and we were observing what's called the afterglow. This is the fading explosion as the radiation shocks up the interstellar medium around the star that exploded."

He says, "The RATIR camera lets us take simultaneous images in six colors, two optical and four near-infrared. Over the past five years, RATIR has imaged 155 ."

Mystery beams of energy

While gamma-ray bursters have been known for about fifty years, astronomers are still mostly in the dark about how they erupt.

"Despite a long history of observations," Butler says, "the emission mechanism driving gamma-ray bursters remains largely mysterious."

Gamma-ray bursts are detected approximately once per day and are brief, but intense, flashes of gamma radiation. They come from all different directions in the sky, and they last from tens of milliseconds to about a minute, making it hard to observe them in detail.

Astronomers believe most of these explosions are associated with supernovas. These occur when a massive star reaches the end of its normal existence and blows up in a colossal explosion. A supernova throws off some of the star's outer layers, while its core and remaining layers collapse in a few seconds into a neutron star or, in the case of highly , a black hole.

Continued RATIR observations over weeks following the June 2016 outburst showed that the were shot out in a beam about two degrees wide, or roughly four times the apparent size of the Moon. It was sheer chance that Earth happened to lie within the beam.

Beaming effects, Butler says, may result from the spin of the black hole produced after the supernova explosion, as it releases material along its poles.

Magnetic focus

"We think the gamma-ray emission is due to highly energetic electrons, propelled outward like a fireball," Butler says. Magnetic fields must also be present, he adds, and theories differ as to how the fields are produced and to what extent the flow of magnetic energy outward is important.

A key diagnostic is measuring the radiation's polarization, he explains. This, astronomers think, is largely controlled by the strength of the magnetic fields that focus the radiation. Butler says, "Measuring the strength of magnetic fields by their polarization effects can tell us about the mechanisms that accelerate particles such as electrons up to very high energies and cause them to radiate at gamma-ray energies."

In the case of the June 2016 blast, the scientists were able to measure polarization using MASTER within minutes, an unprecedented early discovery. The large amount of polarization the team observed indicates that powerful magnetic fields were confining and directing it. This lends support for the magnetic origin model for gamma-ray bursters.

While gamma-ray bursters have many more mysteries to be unfolded, Butler says, "this is the first strong evidence that the early shocks generated by these bursts are magnetically driven."

Explore further: Fermi and Swift see 'shockingly bright' burst

More information: E. Troja et al, Significant and variable linear polarization during the prompt optical flash of GRB 160625B, Nature (2017). DOI: 10.1038/nature23289

Related Stories

Fermi and Swift see 'shockingly bright' burst

May 3, 2013

A record-setting blast of gamma rays from a dying star in a distant galaxy has wowed astronomers around the world. The eruption, which is classified as a gamma-ray burst, or GRB, and designated GRB 130427A, produced the highest-energy ...

Birth of black hole kills the radio star

December 20, 2013

Astronomers led by a Curtin University researcher have discovered a new population of exploding stars that "switch off" their radio transmissions before collapsing into a Black Hole.

Glimpsing the infrastructure of a gamma-ray burst jet

December 4, 2013

(Phys.org) —A new study using observations from a novel instrument provides the best look to date at magnetic fields at the heart of gamma-ray bursts, the most energetic explosions in the universe. An international team ...

Recommended for you

New space industry emerges: on-orbit servicing

November 17, 2018

Imagine an airport where thousands of planes, empty of fuel, are left abandoned on the tarmac. That is what has been happening for decades with satellites that circle the Earth.

SpaceX gets nod to put 12,000 satellites in orbit

November 16, 2018

SpaceX got the green light this week from US authorities to put a constellation of nearly 12,000 satellites into orbit in order to boost cheap, wireless internet access by the 2020s.

Electric blue thrusters propelling BepiColombo to Mercury

November 16, 2018

In mid-December, twin discs will begin glowing blue on the underside of a minibus-sized spacecraft in deep space. At that moment Europe and Japan's BepiColombo mission will have just come a crucial step closer to Mercury.

Overflowing crater lakes carved canyons across Mars

November 16, 2018

Today, most of the water on Mars is locked away in frozen ice caps. But billions of years ago it flowed freely across the surface, forming rushing rivers that emptied into craters, forming lakes and seas. New research led ...

12 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

starfart
4.5 / 5 (2) Jul 26, 2017
Why does this article refer to gamma ray bursts [grb] as 'bursters'? That could be erroneously construed to imply the objects involved are capable of repeating their performance. So far as is known of the mechanisms involved, they are not. Almost nobody in the field refers to them as 'bursters', reserving that term for variable behavior (in x-rays) with certain binaries. The term as applied to grb's was abandoned by the turn of the century.
rossim22
1 / 5 (2) Jul 26, 2017
If supernova explosions are 'magnetically driven' then doesn't that illuminate the flaws in standard models of solar dynamics?

No need for a gravitational collapse from lack of fuel?
Jeffhans1
5 / 5 (1) Jul 26, 2017
If supernova explosions are 'magnetically driven' then doesn't that illuminate the flaws in standard models of solar dynamics?

No need for a gravitational collapse from lack of fuel?


I believe in this case, they are indicating that the special nature of the gamma ray burst events versus a more conventional supernova, is the presence of the extremely high magnetic fields.
Based on some research, this indicates that the electrons have become excessively massive and are transferring orders of magnitude more energy than is normal for them to carry.
Shootist
1 / 5 (1) Jul 26, 2017
If supernova explosions are 'magnetically driven' then doesn't that illuminate the flaws in standard models of solar dynamics?

No need for a gravitational collapse from lack of fuel?


I believe in this case, they are indicating that the special nature of the gamma ray burst events versus a more conventional supernova, is the presence of the extremely high magnetic fields.
Based on some research, this indicates that the electrons have become excessively massive and are transferring orders of magnitude more energy than is normal for them to carry.


massive electrons? Does that indicate perhaps Muon or Kaon?
wduckss
1 / 5 (7) Jul 27, 2017
"Newly formed black holes of stellar mass launch collimated outflows (jets) of ionized matter that approach the speed of light." from "Nature" http://www.nature...ack=true

The authors claim (almost) that the black holes = massive stars. Stars with fast and very fast rotation have radiant emission exclusively on poles (identical to fast-rotating galaxies). Fast rotating stars have 0.00003% (Harvard spectral classification) of the total number of stars (200 to 400 billion) in the Milky Way.
Black hole = fiction, Rotation = all present reality. I hope it will, and "Nature" to get into the world of reality and leave the writing fairy tales.
Shootist
4 / 5 (2) Jul 27, 2017
"Newly formed black holes of stellar mass launch collimated outflows (jets) of ionized matter that approach the speed of light." from "Nature" http://www.nature...ack=true

The authors claim (almost) that the black holes = massive stars. Stars with fast and very fast rotation have radiant emission exclusively on poles (identical to fast-rotating galaxies). Fast rotating stars have 0.00003% (Harvard spectral classification) of the total number of stars (200 to 400 billion) in the Milky Way.
Black hole = fiction, Rotation = all present reality. I hope it will, and "Nature" to get into the world of reality and leave the writing fairy tales.


Ah, yet more fake news.
billpress11
not rated yet Jul 27, 2017
Could theses gamma ray burst be the result of matter antimatter annihilation?
Shootist
5 / 5 (1) Jul 27, 2017
Could theses gamma ray burst be the result of matter antimatter annihilation?


My understanding is that GRBs are of a much higher energy level than those produced by MAMA
cantdrive85
1 / 5 (4) Jul 27, 2017
Continued RATIR observations over weeks following the June 2016 outburst showed that the gamma rays were shot out in a beam...Beaming effects, Butler says, may result from the spin of the black hole

The plasma ignoramus displays his, ignorance.
"We think the gamma-ray emission is due to highly energetic electrons, propelled outward like a fireball," Butler says. Magnetic fields must also be present, he adds, and theories differ as to how the fields produced. and to what extent the flow of magnetic energy outward is important.

This guy seems unfamiliar with the fact that electric currents create magnetic fields (and beams). BTW, magnetic energy doesn't flow, electrical energy will flow and create magnetic fields. I bet he likes to think of himself as being a scientist. Laughable!
"Students using astrophysical textbooks remain essentially ignorant of even the existence of plasma concepts...." Hannes Alfven
bertbarnes48
5 / 5 (1) Jul 27, 2017
If supernova explosions are 'magnetically driven' then doesn't that illuminate the flaws in standard models of solar dynamics?

No need for a gravitational collapse from lack of fuel?


I believe in this case, they are indicating that the special nature of the gamma ray burst events versus a more conventional supernova, is the presence of the extremely high magnetic fields.
Based on some research, this indicates that the electrons have become excessively massive and are transferring orders of magnitude more energy than is normal for them to carry.


massive electrons? Does that indicate perhaps Muon or Kaon?

Indicates that any object (electron in this case) that has mass will increase mass as it approaches the speed of light and will have infinite mass at the speed of light.
Shootist
not rated yet Jul 27, 2017
Indicates that any object (electron in this case) that has mass will increase mass as it approaches the speed of light and will have infinite mass at the speed of light.


At some point then you're looking at cosmic rays
Da Schneib
not rated yet Jul 27, 2017
I don't think we'll get enough information to figure out what GRBs are until we have the ability to image with high sensitivity continuously over a wide field and we get lucky and catch one.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.