Astronomy

What happens when a star gets hit by a supernova?

What happens when a star gets hit by a supernova?

This may sound like a strange question, but say that two stars are relatively next to one another in a binary star system, what would happen to one of the stars if the other went supernova? Would it explode as well, or would it survive the blast?


Remember that although a supernova expels a huge amount of matter, this matter travels outwards in all directions and only a tiny fraction of it impacts on the binary partner. In the case of a core collapse supernova, the vast majority of the energy released is in the form of neutrinos, which will generally fly straight through the binary partner without impact.

In a type 1a supernova, most of the released energy is kinetic. However, as the exploding star is completely disrupted, this "kicks" the other star out of the system (think of swinging a ball on a string in a circle around you, and you suddenly relax your grip on the string), so it's not hanging around for the shock wave. Since this is travelling at 5,000-20,000 km/s, it will eventually (within a few hours) catch up with the escaping star, but will have become substantially attenuated by then.

In addition to Glorfindel's answer, it's worth noting that where the remnant partner of a high-mass X-ray binary is a black hole, it's likely that the progenitor star was also high-mass and collapsed directly to singularity, without a significant explosion. As Felix Mirabel and Irapuan Rodrigues note in Formation of a Black Hole in the Dark: "The observations suggest that high-mass stellar black holes may form promptly, when massive stars disappear silently."

You might also be interested in the answers to these questions on our sibling site [Physics.SE]:

What happens to the neighboring star of a type Ia supernova?

Regarding binary systems (with pulsars)


There are certain cases where the remaining star survives; this happened to high-mass X-ray binary star systems, pairs which consist of a neutron star or black hole (the remnant of a supernova) and a massive star. The X-rays are produced when some of the material ejected by the star is captured by the supernova remnant.

The most famous of these is Cygnus X-1, the first object widely accepted to be a black hole. The massive star in this pair has the same name as one of our moderators.


Supernovas that happened in galaxies far, far away have left the most bizarre evidence on Earth

When stars go supernova, that usually happens too many millions of light years away to actually have any impact on us Earthlings…right?

Not all cosmic catastrophes happen in places that are so far away. We often think of phenomena like this as so distant, that by the time their light reaches Earth, our telescopes see them as they were long before even the most primitive humans emerged. Radiocarbon (carbon-14) found in tree rings is now thought to be revealing evidence of climate disruption caused by at least four supernovas. One of these events, which happened in the Vela constellation, was the death of a star only about 815 light years away.

More Supernova

Compare that with Betelgeuse, which is only 642.5 light years from us. Scary.

“It is the gamma and X-rays, which are very intense for such relatively close supernovas, that are of most concern,” researcher Robert Brakenridge, who led a study recently published in the International Journal of Astrobiology, told SYFY WIRE. “Upper atmosphere is fragile in this regard. Its composition affects our climate, and ozone that protects us from solar UV rays it would be destroyed, though temporarily, by this radiation. So not only are trace amounts of radiocarbon changed other atmospheric effects are also expected.”

Radiocarbon is rare on Earth and doesn’t even come from here. The carbon isotope forms when our atmosphere, which is made mostly of oxygen and 14N, the stable isotope of nitrogen, is showered with cosmic rays that include gamma rays. Carbon-14 forms when gamma rays interact with the 14N. Some of that radiocarbon will manage to get through. Because trees breathe in carbon dioxide, some of the carbon in those CO2 molecules will end up being radiocarbon, but the amount is usually consistent from year to year.

What Brakenridge noticed was a spike in radiocarbon which showed up in tree rings for what appeared to be several years. That could possibly be an indicator of supernova effects on Earth, and there were traces believed to be from one frightfully recent supernova.

Betelgeuse. Credit: ESO, ESA/Hubble, M. Kornmesser

The Vela event was that supernova. It is thought to have happened when a star in the Vela constellation burst sometime between 11,300 years ago and 8,400 years ago. That is hardly the blink of an eye for the universe. Just the visible light from this phenomenon was brighter than the full moon, and it bombarded our planet with two types of radiation. Ionizing radiation—which includes the gamma and X-rays from the stellar explosion—brings in enough energy to knock out electrons and break molecular bonds when it passes through anything, and that includes air. UV radiation is non-ionizing radiation that only has enough energy to excite atoms and molecules.

“Our distant ancestors saw that supernova. It is reasonable to wonder if they experienced, and adapted to, the environmental changes,” Brakenridge said.

What happened post-supernova then could possibly tell us the effects of something like Betelgeuse exploding so close to Earth. Brakenridge, who had previously studied the effects of the Vela event through ice cores, believes that the ozone layer was severely (though temporarily) eaten away. With only a thin veil of ozone, Earth’s exposure to intense solar UV rays increased way past what any SPF could possibly protect against. There is still some irony in this. Even with all the UV suddenly flooding in, ozone depletion and the blockage of visible light (thought to have been caused by ionizing radiation from the supernova), made Earth cooler and darker.

“It is still likely that the environmental changes which occurred during the Vela supernova are still visible in paleoenvironmental records,” Brakenridge said. “It seems that the supernova probably caused short-lived atmospheric cooling. This event happened close enough to have left geological traces, such as evidence of an increased transfer of nitrogen, behind.”

Another hypothesized effect of the supernova is a surge in atmospheric nitrogen dioxide (NO2), an influx of nitrogen that made it possible for photosynthetic algae to bloom in places where nitrogen was previously scarce.

Some scientists argue that the source of the abnormal amounts of radiocarbon concentrated in tree rings could also be solar flares or coronal mass ejections, but there is no easy way to tell. There has been research that showed spikes in carbon-14 only come from gamma photons and not particles, and other research shows that there are not just spikes in the carbon isotope but beryllium-10 (10Be), another isotope from space. That could change the supernova theory. Brakenridge acknowledges that finding both of those isotopes at the same site could instead be an indicator of a monster solar flare that releases cosmic rays and charged particles.

“Some work suggests the effects of a solar superflare rather than supernova gamma photons,” he said. “Much more data is needed, and also better theoretical understanding and modeling of the predicted effects.”

In the meantime, you don’t need to build a doom shelter for Betelegeuse anytime soon. Stick to the masks and hand sanitizer.


What Happens After a Supernova?

Depending on the size of the star before it explodes as a supernova, the core of the star either shrinks back into a tiny neutron star or becomes a black hole. If the star is only a few times bigger than the sun, the core becomes a tiny neutron star. If the star is much bigger than the sun, the chances of it becoming a black hole are much greater.

A supernova lasts between one to two years. This type of explosion usually happens because the core of the star has collapsed in on itself. The collapse happens in about less than a second, then the outer layers of the star are blown off in a mighty explosion. The pieces of the star that are flung off during the shock wave help form new stars.

In a galaxy that is close to the size of the Milky Way, supernovas occur roughly every 50 years. Scientists predict, however, that a supernova happens around every second across the universe based on how many galaxies have been observed.

There are two ways that a supernova happens. A Type I supernova occurs when a star accumulates too much matter from nearby stars. Eventually, this leads to a nuclear reaction. A Type II supernova occurs after a star runs out of nuclear fuel and the force of its own gravity becomes too much.


What happens to the neighboring star of a type Ia supernova?

Supernovae of type "Ia" are those without helium present, but with evidence of silicon present in the spectrum. The most accepted theory is that this type of supernova is the result of mass accretion on a carbon-oxygen white dwarf from a companion star, usually a red giant. This can happen in very close binary star systems. Both stars have the same age and models indicate that they almost always have a similar mass. But usually one of the stars is more massive than the other and the more massive star evolves faster (leave the main sequence) before the lower mass star does. A star with less than 8-9 solar masses evolves at the end of its life into a white dwarf, binary systems would consist of a white dwarf and a red giant which has greatly expanded its outer layers.

During the explosion an amount of carbon undergoes fusion that a normal star would take centuries to use up. This enormous release of energy creates a powerful shockwave that destroys the star, ejecting all its mass at speeds of around 10,000 km / s. The energy released in the explosion also causes an extreme increase in brightness, so these supernovae become the brightest of all, emitting around 10^44 J (1 foe). Normally there are no traces of the star that caused the cataclysm, but only traces of superheated gas and dust that is rapidly expanding.


Do You Want Some REAL Fireworks?

Today is the Fourth of July, a national holiday in the U.S. where we celebrate the signing of the Declaration of Independence (we didn’t actually win our independence until 1783, depending on how you look at it).

It’s traditional to celebrate with fireworks, which I’ve always enjoyed (though some people are making the case that we should be aware of people—and pets—who don’t). But as an astronomer, my idea of fireworks is maybe somewhat more expansive than most folks …

Like, the explosion of an entire star. Called a supernova, they’re among the most violent events the Universe has to offer. The amount of energy they emit can be equal to the total amount of energy the Sun emits over its entire lifetime. The closest example is the Crab Nebula, seen above. Want a fun little bit of cosmic trivia to astound your friends? The light from this explosion reached Earth in the year 1054 … on July 4.

Anyway, the good news is that these ridiculously huge events tend to happen very far away. But what if one were a lot closer? Well, if it got close enough, we’d be in trouble. I wrote a chapter in my book Death From the Skies! about that.

But I also talked to science communicator Rose Eveleth about what would happen if a supernova were too close for comfort on her podcast Meanwhile in the Future. Also appearing is my friend and astrophysicist Katie Mack.

That was fun. She starts off each episode with a little vignette talking about some event in the future, then uses that as a springboard to talk about the science of an event. Clever.

I wrote more about the Crab in a recent post, and it turned out to be a little more poetic than I expected. But hopefully, it’ll give you an impression of the cosmic forces out there, ones which craft the Universe we live in.

If you’re celebrating July Fourth today, have fun! But remember, have some perspective. The fireworks you’re watching could be a lot, lot bigger.


How Supernova’s Gamma Ray Burst Would Destroy Earth’s Ozone Layer

An engineer explained what would most likely happen to Earth if it gets hit by a gamma-ray burst (GRB) produced by an exploding star. According to the engineer, half of Earth’s ozone layer would get destroyed during such an event.

GRBs are known to be extremely energetic explosions. According to scientific reports, these explosions are caused by supernova events. Due to the immense power carried by GRBs, they are often referred to as one of the greatest cosmic threats to Earth.

But, since Earth is currently not near any star that’s in danger of going supernova soon, the planet will most likely not get completely destroyed if it gets hit by a distant GRB. According to retired engineer Duncan Caincross from New Zealand, a GRB from a faraway supernova could destroy half of the Earth’s ozone layer.

Although this would leave large parts of the world exposed to the radiation from space, it won’t cause an extinction-level event. Caincross noted that eventually, the ozone layer would rebuild itself and return to normal.

“Some people think that a GRB could destroy the Ozone layer - and they may be correct - but that will only affect one hemisphere - and by the time that the depleted zone has spread the chemical reaction will have run its course and the ozone layer will be rebuilding,” Cairncross explained on Quora.

“Removing the ozone layer would not be an extinction-level event - some vulnerable species would go - but most would survive to repopulate once the ozone layer rebuilt itself,” he continued.

However, Cairncross noted that if Earth gets hit by a much stronger GRB from a nearby star or supernova event, the outcome would be very different. As noted by the retired engineer, the blast would obliterate the entire ozone layer.

In addition, the extreme heat from the energy of the blast would be enough to cause Earth’s oceans to boil. Depending on how powerful the GRB is, mass extinctions across various species could occur in just a matter of minutes. Eventually, the effects of the GRB would render the planet completely uninhabitable.

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. Photo: NASA's Goddard Space Flight Center


What happens when a star’s fuel runs out?

When stars run out of fuel they begin to collapse rapidly under their own weight. Some stars that are large enough naturally end their lives by exploding in a supernova.

Throughout their lives, stars are fighting against the crushing force of their own gravity. Inside, nuclear reactions fuse together smaller elements, like hydrogen, to create bigger ones and release energy. Stars must burn through fuel and release energy to prevent them from collapsing in on themselves, but this cannot go on forever. Eventually the star will run out of its essential fuel entirely, resulting in its explosive end.

The compression of a star many times larger than our Sun can be so much that a rebounding shockwave is created. This can cause a final expansion that releases the layers of a star in a supernova.

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We've finally figured out what happens when a star explodes

What happens when a star explodes? Surprisingly, the same thing that happens when gas explodes here on Earth.

For explosions to occur, there needs to be a build-up of pressure. Alexei Poludnenko at the University of Connecticut and his team wanted to find out is how this can happen in explosions that occur in open, unconfined spaces, such as type Ia supernova, which is when a small, very dense star called a white dwarf detonates.

Poludnenko and his colleagues wondered whether there were similarities between these stellar events and unconfined explosions on Earth, such as the accidental blast that occurred at the Buncefield fuel storage facility in the UK in 2005.

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“In Buncefield there was a fuel leak and there was a fuel-air vapour cloud formed above ground,” says Poludnenko. What was unclear is how this kind of vapour cloud could hold together long enough for an explosion to occur – the same problem as the exploding stars.

Read more: There aren’t enough space explosions to explain strange radio bursts

To investigate, the researchers ignited a mixture of hydrogen and air in a lab facility and measured the pressure of the resulting explosion with sensors, while also tracking the speed of the flames using a high-speed camera. They also compared this to a computer simulation of a type Ia supernova.

They found that igniting the gas mix created fast turbulence, stirring up the flames and making the burning much more vigorous, says Poludnenko. Once the burning is fast enough, this creates pressure so quickly that it doesn’t have time to dissipate, eventually causing a detonation.

The same process seems to be behind supernova explosions, says Poludnenko. “We also see in the simulations that this happens in a star, it’s the same mechanism.”


Astronomers think they saw a star exploding out of a giant gas bubble

A supernova starting in a cocoon of gas. NASA

It appeared as a flash of light on the arm of a distant spiral galaxy. It outshone neighboring stars, an attention-grabbing display of brilliance that peaked after 2.2 days in the sky. Then it was gone, dimming slowly into the background even as researchers raced to focus more telescopes on the ephemeral event.

It was too fast for a typical supernova, which tend to gradually build and recede as a star enters that last phase of its life, exploding in an astronomical fireworks show that can persist for months. Astronomers had noticed about a dozen other events like this in the past, a class of stellar phenomenon all their own: fast-evolving, luminous transients or FELTs.

No one was sure what they were. A star that tried and failed to go supernova would be fast, but also much fainter. The afterglow of a gamma ray burst? Possible, but gamma ray bursts are rare, and this didn’t quite fit. Two neutron stars slamming into each other? Also too faint. Something driven by a black hole drawing in surrounding matter? Possible, but the contortions to make the scenario fit the data made it unlikely.

Then, in 2015, the Kepler space telescope noticed this latest FELT on the arm of a distant galaxy. Snapping an image of that segment of the sky every 30 minutes, it provided a more detailed view of the rapid rise and fall of the FELT than had been seen before.

Scientists published those observations in a Nature Astronomy study this week, and think they might know at least part of the mechanism behind the phenomenon. It was a supernova, but one that had been hidden in a cocoon of gas for days before emerging—a dazzling, short-lived butterfly.

What kind of supernova are astronomers talking about? A handy guide. NASA

The star likely cast off its gaseous shell a few months to a year before its core exploded, explains Armin Rest, an astronomer at the Space Telescope Science Institute and lead author of the paper.

“The shell that gets ejected is normally the lighter elements like hydrogen and helium. It’s also relatively cool,” Rest says. “The ejecta from the supernova is more from the core of the star—it’s already richer in heavier elements. Then the supernova produces even more heavier elements, and heats it up by tens of thousands of degrees Kelvin.”

Ultimately, Rest explains, you wind up with really fast—and really hot—heavy elements slamming into relatively cool and light elements. The collision is violent and sudden, like a car hitting a wall. Light and heat rapidly spew out into space and then quickly die down, with the energy from the stellar vehicle sputtering out quickly after the collision.

The scenario matches the light curve Rest observed incredibly well. The cloud of gas initially hides the supernova’s light, so when the material from the stellar explosion finally meets the shell of its gassy cocoon, telescopes catch a sudden flash of light. But there isn’t much more material left of the star by that point, so it swiftly fades from view.

That doesn’t leave astronomers like Rest much time to focus powerful slow, ground-based telescopes on the event. Because of Kepler’s current requirements, items seen in the space telescope are only visible here on Earth for a few short hours every day.

The astronomers managed to get one good image of the supernova at its peak, but cloudy skies marred their view when they went back for another look the next night. “The next time we got images was 14 days later, and if you look at the light curve after 14 days it’s nearly gone,” Rest says.

That’s one of the hazards of studying FELTs. There are still plenty of unanswered questions about how they form, and a razor-thin timeline. Researchers are still trying to figure out what could possibly cause that eruption of gas from the star in the first place. The mechanisms behind these events remain elusive, but observations like this one can help pin them down.

“The beautiful thing with this event is that we have this extraordinarily light curve, and what that allows us to do is create a simulation, theoretical models, and we can predict what kind of light curve we will see,” Rest says.

He and his colleagues worked with collaborators in Berkeley to create those simulations. “Now we can constrain what kind of shell there is. How far away from the star is it? How thick is the shell? How much mass is in the shell? Having these parameters allows us to say, ‘ok, whatever event happened, it had to produce a light curve like that.’ In the future this will help us constrain the ‘burp,’ or eruption that actually caused the shell to be ejected.”

Astronomers will keep looking for events like this, using Kepler for as long as its fuel holds out and the next generation space telescope TESS after that. They’ve just got to watch the steady stars and galaxies and jump into action as soon as one of these explosions happens to intersect with their field of view—and hope for clear skies. They’ll only get the astronomical equivalent of a moment with it before it fades forever. Don’t blink.


Titanium bubbles found after star explosion could help solve mystery of supernovas

CNN — Titanium bubbles found in a supernova could hold the secrets as to why some giant stars explode, a new study suggests.

When stars explode, they release their elements into space. Telescopes like the one at NASA’s Chandra X-ray Observatory can help find which ones Cassiopeia A released when it exploded.

Cassiopeia A is a giant bubble of hot, expanding gas, and it’s the youngest known remnant from a supernova explosion, dating back 340 years ago, in our Milky Way galaxy. The light from this supernova first reached Earth in the 1670s.

Researchers have studied Cassiopeia A for years because it’s relatively nearby — astronomically speaking — and provides insight into the evolution of the universe.

Heavy elements & star explosions

While stars with masses more than 10 times our sun are known to explode once they run out of fuel, scientists don’t exactly know why it happens. Past explosions have led to the release of heavy elements throughout the universe, like gold and titanium, that are found on Earth.

“Scientists think most of the titanium that is used in our daily lives — such as in electronics or jewelry — is produced in a massive star’s explosion,” said lead study author Toshiki Sato, an assistant professor in the department of physics at Rikkyo University in Tokyo, in a statement. “However, until now scientists have never been able to capture the moment just after stable titanium is made.”

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Massive stars run on nuclear power generated by reactions that happen at their core. When this fuel runs out, the star’s center collapses, forming a black hole or a dense object called a neutron star.

If the object becomes a neutron star, a shock wave ripples out from the star, creating new elements as nuclear reactions occur.

When scientists have conducted computer modeling of the phenomenon, they found that the energy burns up fast and causes the shock wave to stall. This would stop a supernova explosion from happening.

New simulations

New computer models suggest a missing element that could allow the supernova to continue: neutrinos.

The explosion that created the Cassiopeia A supernova was likely driven by neutrinos, according to the new study.

Data from NASA’s Chandra observatory, which looks at space using X-ray emissions, produced structures shaped like fingers that pointed away from the supernova. These structures had titanium and chromium, along with iron that was previously detected by the telescope.

“We have never seen this signature of titanium bubbles in a supernova remnant before, a result that was only possible with Chandra’s incredibly sharp images,” co-author Keiichi Maeda, an associate professor in the department of astronomy at Kyoto University in Japan, said. “Our result is an important step in solving the problem of how these stars explode as supernovae.”

This means that fragments of titanium were created deep within the star as the supernova happened. The amount of stable titanium produced by this particular explosion is greater than Earth’s total mass, the researchers said.

The findings also support the theory that explosions driven by neutrinos could be used to explain other massive star explosions.

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Watch the video: How to detect a supernova - Samantha Kuula (September 2021).