Seventeen years after the initial stellar explosion, astronomers were able to locate the surviving companion to a supernova. Photo by Hubble/NASA/ESA

April 27 (UPI) -- The Hubble Space Telescope has captured the best evidence yet that double-star systems host supernovas.

Seventeen years after astronomers first spotted a supernova 40 million light-years away in the galaxy NGC 7424, a Hubble photograph revealed a second star, the supernova's surviving companion.

"We know that the majority of massive stars are in binary pairs," Stuart Ryder, researcher at the Australian Astronomical Observatory in Sydney, said in a news release. "Many of these binary pairs will interact and transfer gas from one star to the other when their orbits bring them close together."

The companion in Hubble's image was more than just a spectator to the action 17 years ago. The companion is a cosmic criminal, guilty of theft. Millions of years before its companion exploded a fire death, the star was creating instability in the primary star by siphoning off hydrogen from its stellar envelope, the layer that shuttles energy from the core to the star's atmosphere.

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As a result of millions of years of theft, the primary star demise, dubbed SN 2001ig, was classified as a Type IIb stripped-envelope supernova, an explosion characterized by a lack of hydrogen.

Most scientists thought Type IIb stripped-envelope supernovas originated in single star systems, their out envelopes blown away by strong stellar winds. But over the years, astronomers have struggled to find the primary stars responsible for such explosions.

"That was especially bizarre because astronomers expected that they would be the most massive and the brightest progenitor stars," said Ori Fox of the Space Telescope Science Institute in Baltimore. "Also, the sheer number of stripped-envelope supernovas is greater than predicted."

Astronomers now think as many as half of all Type IIb stripped-envelope supernovas may originate in binary star systems.

The revelation might not have happened if SN 2001ig occurred just a little farther away. The stellar system sits right on the edge of Hubble's photographic limits. The companion is so faint, it likely would be invisible to Hubble if it was a few more light-years away. A bit of luck allowed for the breakthrough.

"We were finally able to catch the stellar thief, confirming our suspicions that one had to be there," said Alex Filippenko, astronomer at the University of California, Berkeley.

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RELATED Hubble captures glow of giant galaxy cluster</s>If you were flying through space, irrespective of how you were doing it, it would be sensible to keep away from some objects, like black holes or massive stars on the verge of going supernova. These latter events, among the most energetic that occur in space, happen when a massive star runs out of fuel and collapses under the effect of its own gravity, and the afterglow from the explosion lasts for weeks or even months.

And yet, thanks to Hubble Space Telescope, we now know that one star survived the supernova explosion of its companion star, in an event that took place in a binary star system 40 million light-years away.

The supernova itself was observed 17 years ago in a galaxy called NGC 7424, and the event was named SN 2001ig. Its surviving companion, however, was observed with certainty only in 2016. Soon after the event in 2001, astronomers used the European Southern Observatory’s Very Large Telescope, and the Gemini South Observatory, both in Chile, which first hinted at the presence of another star among the supernova’s remnants.

It was only when the afterglow from SN 2001ig faded that Hubble, with its high resolution and ultraviolet capability, could actually find and photograph the survivor. Before the explosion, the two stars in the binary system took about one year to orbit each other.

“We know that the majority of massive stars are in binary pairs. Many of these binary pairs will interact and transfer gas from one star to the other when their orbits bring them close together,” Stuart Ryder from the Australian Astronomical Observatory in Sydney, and lead author of a recent study on the Hubble observation, said in a statement Thursday.

This transfer of gas was especially noticeable in this binary pair. In the years preceding the supernova, the surviving star had sucked away almost all the hydrogen from its companion, dooming it to a loss of fuel. Much before going supernova, the primary star had already become unstable due to this, and periodically blew off hydrogen in fits and spurts.

SN 2001ig is classified as a Type IIb stripped-envelope supernova, because the primary star had been stripped of most of its hydrogen in its stellar envelope — that part of a star which is responsible for moving energy from the core to the atmosphere. This type of supernova was first identified as such in 1987.

There are two theories to explain how stars lose their stellar envelopes. One holds stellar winds responsible for blowing off the envelope, and the other — like in the case of SN 2001ig — lose them due to the actions of a companion in a binary system.

With the launch of NASA’s James Webb Space Telescope, astronomers would find it easier to observe these supernovae and to confirm — or revise or abandon — their theories about how they come about.

Hubble is a partnership between NASA and the European Space Agency.

The research paper discussing SN 2001ig and its surviving, thieving companion, is titled “Ultraviolet Detection of the Binary Companion to the Type IIb SN 2001ig,” and was published in the Astrophysical Journal.</s>This amazing discovery is the first solid proof of a binary star system, NASA reveals.

NASA’s Hubble Space Telescope has detected a space crime, Outer Places reports. The telescope caught a glimpse of a “stellar thief,” a star that had been siphoning hydrogen from a nearby supernova, quite possibly leading to its neighbor’s extinction.

NASA provides the whole back story in a recent news release, explaining that the supernova, called SN 2001ig, was first sighted 17 years ago, when the light from its explosion eventually reached Earth. It’s swindling companion, however, was only recently observed, once the glare from the explosion started fading away and exposed a suspect presence near the dying star.

This cosmic murder mystery has a deep significance for the astronomers who uncovered it. This is the first time anyone has found actual proof that some massive stars, just like the one that was killed off in the supernova, can occur in binary star systems, where they coexist next to a companion star.

This first-ever documented binary star system was discovered by Hubble in “a galaxy far, far away,” lying at a distance of 40 million light-years from Earth, in the Grus constellation, also known as the Crane. The galaxy’s name is NGC 7424.

The Hubble photo that tied it all together “is the most compelling evidence that some supernovas originate in double-star systems,” NASA revealed in the news release.

The fortuitous discovery is also detailed in study published last month in the Astrophysical Journal.

“We know that the majority of massive stars are in binary pairs,” said lead study author Stuart Ryder, from the Australian Astronomical Observatory (AAO) in Sydney, Australia.

“Many of these binary pairs will interact and transfer gas from one star to the other when their orbits bring them close together,” he explained in the news release.

This was also the case with SN 2001ig and its stellar companion. SN 2001ig is a rare type of supernova, categorized as a Type IIb stripped-envelope supernova, which means that most of the hydrogen in is “stellar envelope” — the region of the star which transports materials from its core to its atmosphere — had already been depleted before the explosion.

The reason was none other than its thieving companion, which had been stealing hydrogen from SN 2001ig for millions of years, long before its unsuspecting victim went supernova.

With its neighbor constantly mooching off hydrogen, SN 2001ig eventually became unstable and started “to episodically blow off a cocoon and shells of hydrogen gas before the catastrophe,” states the NASA news release.

Similar occurrences are common in the universe, since “the sheer number of stripped-envelope supernovas is greater than predicted,” says study co-author Ori Fox of the Space Telescope Science Institute in Baltimore.

But Hubble was the first to ever capture evidence that binary star systems, long-time predicted, really exist.

“We were finally able to catch the stellar thief, confirming our suspicions that one had to be there,” said study co-author Alex Filippenko of the University of California, Berkeley, who was the first to discover Type IIb stripped-envelope supernovae in 1987.</s>NASA’s Hubble Space Telescope has captured the first image of a surviving companion to a supernova, the most compelling evidence that some supernovas originate in double-star systems. A supernova is an astronomical event that occurs during the last evolutionary stages of a massive star’s life.

Seventeen years ago, astronomers had witnessed a supernova go off 40 million light-years away in the galaxy called NGC 7424, located in the southern constellation Grus, the Crane, NASA said. The image of the companion star was seen in the fading afterglow of that supernova, called SN 2001ig. “We know that the majority of massive stars are in binary pairs,” said Stuart Ryder from the Australian Astronomical Observatory (AAO). “Many of these binary pairs will interact and transfer gas from one star to the other when their orbits bring them close together,” said Ryder, lead author of the study published in the Astrophysical Journal.

The companion to the supernova’s progenitor star was no innocent bystander to the explosion, researchers said. It siphoned off almost all of the hydrogen from the doomed star’s stellar envelope, the region that transports energy from the star’s core to its atmosphere, they said. Millions of years before the primary star went supernova, the companion’s thievery created an instability in the primary star, causing it to episodically blow off a cocoon and shells of hydrogen gas before the catastrophe.

SN 2001ig is categorised as a Type IIb stripped-envelope supernova. This type of supernova is unusual because most, but not all, of the hydrogen is gone prior to the explosion. This type of exploding star was first identified in 1987 by Alex Filippenko of the University of California, Berkeley. Looking for a binary companion after a supernova explosion is no easy task. First, it has to be at a relatively close distance to Earth for Hubble to see such a faint star. SN 2001ig and its companion are about at that limit. Within that distance range, not many supernovas go off. Even more importantly, astronomers have to know the exact position through very precise measurements.

In 2002, shortly after SN 2001ig exploded, scientists pinpointed the precise location of the supernova with the European Southern Observatory’s Very Large Telescope (VLT) in Chile. In 2004, they then followed up with the Gemini South Observatory in Chile. This observation first hinted at the presence of a surviving binary companion. Knowing the exact coordinates, Ryder and his team were able to focus Hubble on that location 12 years later, as the supernova’s glow faded. With Hubble’s exquisite resolution and ultraviolet capability, they were able to find and photograph the surviving companion – something only Hubble could do.

For all the latest Technology News, download Indian Express App</s>Seventeen years ago, astronomers witnessed a supernova go off 40 million light-years away in the galaxy called NGC 7424, located in the southern constellation Grus, the Crane. Now, in the fading afterglow of that explosion, NASA’s Hubble Space Telescope has captured the first image of a surviving companion to a supernova. This picture is the most compelling evidence that some supernovas originate in double-star systems.

“We know that the majority of massive stars are in binary pairs,” said Stuart Ryder from the Australian Astronomical Observatory (AAO) in Sydney, Australia, and lead author of the study. “Many of these binary pairs will interact and transfer gas from one star to the other when their orbits bring them close together.”

The companion to the supernova’s progenitor star was no innocent bystander to the explosion. It siphoned off almost all of the hydrogen from the doomed star’s stellar envelope, the region that transports energy from the star’s core to its atmosphere. Millions of years before the primary star went supernova, the companion’s thievery created an instability in the primary star, causing it to episodically blow off a cocoon and shells of hydrogen gas before the catastrophe.

The supernova, called SN 2001ig, is categorized as a Type IIb stripped-envelope supernova. This type of supernova is unusual because most, but not all, of the hydrogen is gone prior to the explosion. This type of exploding star was first identified in 1987 by team member Alex Filippenko of the University of California, Berkeley.

How stripped-envelope supernovas lose that outer envelope is not entirely clear. They were originally thought to come from single stars with very fast winds that pushed off the outer envelopes. The problem was that when astronomers started looking for the primary stars from which supernovas were spawned, they couldn’t find them for many stripped-envelope supernovas.

“That was especially bizarre, because astronomers expected that they would be the most massive and the brightest progenitor stars,” explained team member Ori Fox of the Space Telescope Science Institute in Baltimore. “Also, the sheer number of stripped-envelope supernovas is greater than predicted.” That fact led scientists to theorize that many of the primary stars were in lower-mass binary systems, and they set out to prove it.

Looking for a binary companion after a supernova explosion is no easy task. First, it has to be at a relatively close distance to Earth for Hubble to see such a faint star. SN 2001ig and its companion are about at that limit. Within that distance range, not many supernovas go off. Even more importantly, astronomers have to know the exact position through very precise measurements.

In 2002, shortly after SN 2001ig exploded, scientists pinpointed the precise location of the supernova with the European Southern Observatory’s Very Large Telescope (VLT) in Cerro Paranal, Chile. In 2004, they then followed up with the Gemini South Observatory in Cerro Pachón, Chile. This observation first hinted at the presence of a surviving binary companion.

Knowing the exact coordinates, Ryder and his team were able to focus Hubble on that location 12 years later, as the supernova’s glow faded. With Hubble’s exquisite resolution and ultraviolet capability, they were able to find and photograph the surviving companion—something only Hubble could do.

Prior to the supernova explosion, the orbit of the two stars around each other took about a year.

When the primary star exploded, it had far less impact on the surviving companion than might be thought. Imagine an avocado pit—representing the dense core of the companion star—embedded in a gelatin dessert—representing the star’s gaseous envelope. As a shock wave passes through, the gelatin might temporarily stretch and wobble, but the avocado pit would remain intact.

In 2014, Fox and his team used Hubble to detect the companion of another Type IIb supernova, SN 1993J. However, they captured a spectrum, not an image. The case of SN 2001ig is the first time a surviving companion has been photographed. “We were finally able to catch the stellar thief, confirming our suspicions that one had to be there,” said Filippenko.

Perhaps as many as half of all stripped-envelope supernovas have companions—the other half lose their outer envelopes via stellar winds. Ryder and his team have the ultimate goal of precisely determining how many supernovas with stripped envelopes have companions.

Their next endeavor is to look at completely stripped-envelope supernovas, as opposed to SN 2001ig and SN 1993J, which were only about 90 percent stripped. These completely stripped-envelope supernovas don’t have much shock interaction with gas in the surrounding stellar environment, since their outer envelopes were lost long before the explosion. Without shock interaction, they fade much faster. This means that the team will only have to wait two or three years to look for surviving companions.

In the future, they also hope to use the James Webb Space Telescope to continue their search.

Publication: Stuart D. Ryder, et al., “Ultraviolet Detection of the Binary Companion to the Type IIb SN 2001ig,” ApJ, 2018; doi:10.3847/1538-4357/aaaf1e</s>NASA’s Hubble Space Telescope has captured the first image of a surviving companion to a supernova, a compelling evidence that some supernovas originate in double-star systems, the US space agency said. Seventeen years ago, astronomers had witnessed a supernova go off 40 million light-years away in the galaxy called NGC 7424, located in the southern constellation Grus, the Crane, the NASA statement said.

The image of the companion star was seen in the fading afterglow of that supernova, called SN 2001ig.

SN 2001ig is categorised as a Type IIb stripped-envelope supernova. This type of supernova is unusual because most, but not all, of the hydrogen is gone prior to the explosion.

According to the study, published in the Astrophysical Journal, the supernova’s companion star was not just an innocent bystander to the explosion. Instead, it was most likely the instigator, as it siphoned off almost all of the hydrogen from the doomed star’s stellar envelope, the region that transports energy from the star’s core to its atmosphere.

Millions of years before the primary star went supernova, the companion’s thievery created an instability in the primary star, causing it to episodically blow off a cocoon and shells of hydrogen gas before the catastrophe.

Originally, these type of exploding star were thought to come from single stars with very fast winds that pushed off the outer envelopes.

However, when astronomers started looking for the primary stars from which supernovas were spawned, they could not find them for many stripped-envelope supernovas.

“That was especially bizarre, because astronomers expected that they would be the most massive and the brightest progenitor stars,” said Ori Fox, an astronomer at the Space Telescope Science Institute in Baltimore, US.

“Also, the sheer number of stripped-envelope supernovas is greater than predicted.”

This fact led astronomers to hypothesise that Type IIb stripped-envelope supernovae may instead be a result of co-orbiting pairs of binary stars.

“We know that the majority of massive stars are in binary pairs,” said lead author Stuart Ryder, an astronomer at the Australian Astronomical Observatory (AAO) in Sydney.

“Many of these binary pairs will interact and transfer gas from one star to the other when their orbits bring them close together,” he noted.</s>SN 2001ig is categorised as a Type IIb stripped-envelope supernova. This type of supernova is unusual because most, but not all, of the hydrogen is gone prior to the explosion

Washington: NASA's Hubble Space Telescope has captured the first image of a surviving companion to a supernova, a compelling evidence that some supernovas originate in double-star systems, the US space agency said. Seventeen years ago, astronomers had witnessed a supernova go off 40 million light-years away in the galaxy called NGC 7424, located in the southern constellation Grus, the Crane, the NASA statement said.

The image of the companion star was seen in the fading afterglow of that supernova, called SN 2001ig.

SN 2001ig is categorised as a Type IIb stripped-envelope supernova. This type of supernova is unusual because most, but not all, of the hydrogen is gone prior to the explosion.

According to the study, published in the Astrophysical Journal, the supernova's companion star was not just an innocent bystander to the explosion. Instead, it was most likely the instigator, as it siphoned off almost all of the hydrogen from the doomed star's stellar envelope, the region that transports energy from the star's core to its atmosphere.

Millions of years before the primary star went supernova, the companion's thievery created an instability in the primary star, causing it to episodically blow off a cocoon and shells of hydrogen gas before the catastrophe.

Originally, these type of exploding star were thought to come from single stars with very fast winds that pushed off the outer envelopes.

However, when astronomers started looking for the primary stars from which supernovas were spawned, they could not find them for many stripped-envelope supernovas.

"That was especially bizarre, because astronomers expected that they would be the most massive and the brightest progenitor stars," said Ori Fox, an astronomer at the Space Telescope Science Institute in Baltimore, US.

"Also, the sheer number of stripped-envelope supernovas is greater than predicted."

This fact led astronomers to hypothesise that Type IIb stripped-envelope supernovae may instead be a result of co-orbiting pairs of binary stars.

"We know that the majority of massive stars are in binary pairs," said lead author Stuart Ryder, an astronomer at the Australian Astronomical Observatory (AAO) in Sydney.

"Many of these binary pairs will interact and transfer gas from one star to the other when their orbits bring them close together," he noted.

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A photograph from the Hubble Space Telescope reveals a companion star that survived the explosion of a supernova in galaxy NGC 7424. This brings strong evidence to a theory according to which Type IIb "stripped-envelope" supernovae are due to stellar companions capturing hydrogen from the progenitor star's envelope before its explosion.