Even Stars Doomed to Die as Supernovae can Have Planets

90 percent of all exoplanets discovered to date (there are now more than 5000 of them) orbit around stars the same size or smaller than our sun. Giant stars seem to lack planetary companions, and this fact has serious implications for how we understand solar system formation. But is the dearth of planets around large stars a true reflection of nature, or is there some bias inherent in how we look for exoplanets that is causing us to miss them? The recent discovery of two gas giants orbiting a giant star called µ2 Scorpii suggests it might be the latter.

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Supernova Remnant Cassiopeia A is Lopsided

Coloured image of Cassiopeia A based on data from the space telescopes Hubble, Spitzer and Chandra. Image Credit: NASA/JPL-Caltech [via Wikimedia]

Cassiopeia A is the remnant of a supernova that exploded 11,000 light-years away. The light from the exploding star likely reached Earth around 1670 (only a couple of years before Newton invented the reflecting telescope.) But there are no records of it because the optical light didn’t reach Earth.

The Cass A nebula ripples with energy and light from the ancient explosion and is one of the most-studied objects in deep space. It’s an expanding gas shell blasted into space when its progenitor star exploded.

But Cass A isn’t expanding evenly, and astronomers think they know why.

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Astronomers Watch a Star Die and Then Explode as a Supernova

Artist's impression of a supernova. Credit: NASA

It’s another first for astronomy.

For the first time, a team of astronomers have imaged in real-time as a red supergiant star reached the end of its life. They watched as the star convulsed in its death throes before finally exploding as a supernova.

And their observations contradict previous thinking into how red supergiants behave before they blow up.

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Nearby Supernovae Were Essential to Life on Earth

Illustration of the Milky Way seen from Earth where supernova accelerates cosmic rays to high energies. Some of these cosmic ray particles enterers the Earth’s atmosphere, where they produce shower structures of secondary particles. A surprising result is that changes in cosmic rays through Earth's history have influenced life on Earth. Credit: H. Svensmark/DTU Space

It’s almost impossible to comprehend a supernova explosion’s violent, destructive power. An exploding supernova can outshine its host galaxy for a few weeks or even months. That seems almost impossible when considering that a galaxy can contain hundreds of billions of stars. Any planet too close to a supernova would be completely sterilized by all the energy released, its atmosphere would be stripped away, and it may even be shredded into pieces.

But like many things in nature, it all comes down to dose.

A certain amount of supernova activity might be necessary for life to exist.

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Quick Action Let Hubble Watch the Earliest Stages of an Unfolding Supernova Detonation

Astronomers recently witnessed supernova SN 2020fqv explode inside the interacting Butterfly galaxies, located about 60 million light-years away in the constellation Virgo. Researchers quickly trained NASA's Hubble Space Telescope on the aftermath. Along with other space- and ground-based telescopes, Hubble delivered a ringside seat to the first moments of the ill-fated star's demise, giving a comprehensive view of a supernova in the very earliest stage of exploding. Hubble probed the material very close to the supernova that was ejected by the star in the last year of its life. These observations allowed researchers to understand what was happening to the star just before it died, and may provide astronomers with an early warning system for other stars on the brink of death. Credits: NASA, ESA, Ryan Foley (UC Santa Cruz); Image Processing: Joseph DePasquale (STScI)

If it weren’t for supernova remnants we wouldn’t have much knowledge of supernovae themselves. If a supernova explosion is the end of a star’s life, then we can also thank forensic astrophysics for much of our knowledge. The massive exploding stars leave behind brilliant and mesmerizing evidence of their catastrophic ends, and much of what we know about supernovae comes from studying the remnants rather than the explosions themselves. Supernova remnants like the Crab Nebula and SN 1604 (Kepler’s Supernova) are some of our most-studied objects.

Observing an active supernova in the grip of its own destruction can be difficult. But it looks like the Hubble Space Telescope is up to the task.

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A Black Hole or Neutron Star Fell Into Another Star and Triggered a Supernova

Artist's conception of the ring of material surrounding a star shortly after engulfing a dense companion. Credit: Bill Saxton, NRAO/AUI/NSF

What happens when you slam a neutron star (or black hole, take your pick) into a companion star? A supernova, that’s what. And for the first time ever, astronomers think they’ve spotted one.

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Astronomers saw the Same Supernova Three Times Thanks to Gravitational Lensing. And in Twenty Years They Think They’ll see it one More Time

It is hard for humans to wrap their heads around the fact that there are galaxies so far away that the light coming from them can be warped in a way that they actually experience a type of time delay.  But that is exactly what is happening with extreme forms of gravitational lensing, such as those that give us the beautiful images of Einstein rings.  In fact, the time dilation around some of these galaxies can be so extreme that the light from a single event, such as a supernova, can actually show up on Earth at dramatically different times.  That is exactly what a team led by Dr. Steven Rodney at the University of South Carolina and Dr. Gabriel Brammer of the University of Copenhagen has found. Except three copies of this supernova have already appeared – and the team thinks it will show up again one more time, 20 years from now.

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Supernova Observed by Astronomers in 1181 Could Have Been a Rare Type 1ax That Leaves Behind a “Zombie Star” Remnant

Artistic impression of a star going supernova, casting its chemically enriched contents into the universe. Credit: NASA/Swift/Skyworks Digital/Dana Berry

In 1181 CE, Chinese and Japanese astronomers noticed a “guest star” as bright as Saturn briefly appearing in their night sky. In the thousand years since, astronomers have not been able to pinpoint the origins of that event. New observations have revealed that the “guest star” was a supernova, and a strange one at that. It was a supernova that did not destroy the star, but left behind a zombie that is still shining.

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Shrapnel From Relatively Recent Supernovae Found in the Earth’s Crust

A Japanese oil exploration company recently dug up some samples from the Pacific Ocean floor and donated them to researchers.  Those researchers, led by Dr. Anton Wallner at the Australian National University, then found the first ever evidence of a plutonium radioactive isotope that originally came from outer space.  Now scientists are trying to understand what could have created that isotope, and another intriguing extraterrestrial one, and what that might have meant for Earth’s cosmic neighborhood a few million years ago.

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