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Is Betelgeuse About To Explode? – Forbes

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Rogelio Bernal Andreo

When you take a look at the stars in the night sky, they generally appear the same regardless of time. Only a small number of stars ever appear to change on human timescales, as most stars burn through their fuel very stably, with almost no variation in their continuous brightness. The few stars that do appear to change are either intrinsically variable, members of multi-star systems, or go through an enormous evolutionary change.

When very massive stars get close to the end of their lives, they start varying by tremendous amounts, and do so with significant irregularity. At a critical moment, most of these stars will run out of the nuclear fuel holding up their cores against collapse, and the resulting implosion leads to a runaway cataclysm: a core-collapse supernova. Could Betelgeuse, whose variability intensified in a novel way over the last few days, be about to explode? Here’s what astronomers know so far.

A. Dupree (CfA), R. Gilliland (STScI), NASA

The last time our species witnessed a supernova from within our own galaxy with the naked human eye, the year was 1604. A new point of light in the sky suddenly appeared, brightened, and briefly outshone every single star before slowly fading away. This wasn’t the first such event, as prior supernovae had illuminated Earth’s skies like this in 1572, 1054, and 1006, among others.

But all of those supernovae occurred from stars that were thousands of light-years away, with Kepler’s 1604 explosion being traced back to a stellar remnant located some 20,000 light-years across the Milky Way. Of all the stars we see in the night sky, one bright member stands out as the most fascinating possibility as our galaxy’s next supernova: Betelgeuse, one of our sky’s 10 brightest stars, located a mere 640 light-years away.

ESO/L. Calçada

Betelgeuse, best known as the bright red “shoulder” star in the constellation of Orion, is one of the most remarkable objects in all of astronomy. It is a red supergiant star: red because of its low surface temperatures, supergiant because its radius is so enormous that — if it were to replace the Sun in our Solar System — it would engulf the orbits of Mercury, Venus, Earth, Mars, the asteroid belt, and possibly even Jupiter! In terms of physical size, it’s approximately 900 times the radius, and 700 million times the volume, of our Sun.

Betelgeuse is so large and so close that it was the first star beyond our Sun to ever be resolved as more than a point source. But perhaps its most fascinating property is that Betelgeuse is a pulsating, variable star, meaning that its diameter and brightness both change with time.

NRAO/AUI and J. Lim, C. Carilli, S.M. White, A.J. Beasley, and R.G. Marson

At approximately 20 times the mass of our Sun, there’s little doubt that Betelgeuse is headed on it was to becoming a supernova. Betelgeuse was likely formed in the great Orion molecular cloud complex very recently on cosmic scales: within the last 10 million years. It has already finished burning through all the hydrogen fuel in its core, and has gone onto the next element, helium, which it fuses into carbon.

Perhaps ironically, the core of Betelgeuse is now much smaller than when it was fusing hydrogen, as it contracted and heated up tremendously in order to begin fusing helium. The outer layers, with this increased radiation pressure, expanded and cooled tremendously. At a surface temperature of only 3500 K, barely half the temperature of our Sun’s photosphere, only 13% of Betelgeuse’s energy output is detectable to human eyes. If we could see the entire electromagnetic spectrum from our perspective, Betelgeuse would outshine every star in the Universe except our Sun.

NASA / WISE

We aren’t sure whether Betelgeuse is exclusively fusing helium in its core, or whether the interior has contracted even further and is now fusing carbon. While the helium fusion phase lasts for timescales of ~100,000 years, carbon fusion lasts for merely hundreds. Unfortunately, the only signature that would give us a surefire view of what processes are occurring in the core — neutrino emissions — are too faint to be seen from 640 light-years away.

All we can observe, when it comes to Betelgeuse at the present, is what’s occurring in its outermost layers. When we look there, what we see is remarkable: it’s constantly losing mass, pulsing, having its outermost layers expelled, and changing over time in both its apparent brightness and redness.

ESO/P. Kervella

Recently, in just the past few weeks, its brightness has dropped tremendously, knocking it out of the top 10 brightest stars for the first time in many years. This dimming has led many to suspect that a supernova may be imminent, but this is extremely unlikely. The story is simple, straightforward, but not known by most people, with the exception of professional astronomers.

The key takeaway is this: what’s occurring in the outer layers of a supergiant star is largely unrelated to what processes are occurring in the inner core of a supergiant star. When you examine variable stars in general, you might think that the pulsing/variability that you see is because some process that’s changing in the core is propagating to the surface, but that’s not usually the case. Instead, there are huge convective cells in the outer layers of the star, and changes there are more than capable of causing this dimming.

AAVSO / Lautaro Vergara

In fact, if you look beyond the previous decade and instead go back to the past century, you’ll find that Betelgeuse has been this dim many, many times in the past. If you look beyond the photosphere of the star itself, you’ll find that there are enormous radio emissions that reveal the presence of expelled gas out beyond where the orbit of Neptune is around the Sun.

Similar dimming events have occurred before, reducing the brightness of Betelgeuse below even what it currently is at. But to see a dimming event occur this rapidly and this severely really hasn’t been seen before over the past century at all. It’s unlikely to be a signature of an imminent supernova, but we have to remember that since the advent of modern astronomy, we’ve never seen a star up close in the lead-up to a supernova. Whether there’s a detonation about to happen or not, something fascinating is truly occurring.

Bernd Freytag with Susanne Höfner & Sofie Liljegren

What’s not up for debate is how truly remarkable the processes at play are here. On our Sun alone, the sized of the convective cells that we find are larger than the continent of North America, with sunspots frequently exceeding the size of Earth. On the surface of a red supergiant — thousands of times larger than our Sun — there might only be a handful of convective cells altogether, causing it to look like, according to astronomer Emily Levesque, a “wacky, giant, boiling amoeba-star,” as simulated above.

Our actual astronomical maps of Betelgeuse cannot yet attain that kind of resolution, but can still reveal the following properties of Betelgeuse:

  • its irregular shape,
  • its uneven, non-uniform temperature,
  • localized hot spots,
  • and even faint plumes of illuminated ejecta near the photosphere itself.

ALMA (ESO/NAOJ/NRAO)/E. O’Gorman/P. Kervella

The opportunity to study a red supergiant up close, one that’s about to go supernova relatively soon (at least, on astronomical timescales), has never occurred like this before. At only 640 light-years distant, Betelgeuse could have gone supernova at any time since the 14th century and that signal would not yet have arrived here on Earth.

When that supernova does occur, however, we’re in for a real treat. The runaway fusion reaction that occurs in the final few instants of the star’s life will generate neutrinos that should lead to millions of detectable events here our terrestrial neutrino detectors. The star will brighten to the point where it will rival or possibly even exceed the brightness of the full Moon, casting brilliant shadows at night and being clearly visible during the day for more than a year.

Wikimedia Commons user HeNRyKus / Celestia

Unfortunately, though, the key question of exactly when Betelgeuse is going to go supernova is one that we’re not any closer to having an answer to. Until we can measure the processes occurring in the star’s core, which would require a neutrino telescope far more powerful than all the neutrino observatories on Earth combined, we cannot know which elements are being fused inside of it.

Right now, our best models are consistent with helium-burning rather than any of the heavier elements, indicating that we have at least hundreds of years — and possibly hundreds of thousands — until the inevitable supernova finally detonates. If you haven’t checked out the constellation of Orion recently, though, take a good look and notice how much dimmer red Betelgeuse is than blue Rigel, a severe departure from its past decade of appearances. A supernova may not be imminent, but is sure is fascinating to watch and hope!

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Las Vegas Aces Rookie Kate Martin Suffers Ankle Injury in Game Against Chicago Sky

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Las Vegas Aces rookie Kate Martin had to be helped off the floor and taken to the locker room after suffering an apparent ankle injury in the first quarter of Tuesday night’s game against the Chicago Sky.

Late in the first quarter, Martin was pushing the ball up the court when she appeared to twist her ankle and lost her balance. The rookie was in serious pain, lying on the floor before eventually being helped off. Her entire team came out in support, and although she managed to put some pressure on the leg, she was taken to the locker room for further evaluation.

Martin returned to the team’s bench late in the second quarter but was ruled out for the remainder of the game.

“Kate Martin is awesome. Kate Martin picks up things so quickly, she’s an amazing sponge,” Aces guard Kelsey Plum said of the rookie during the preseason. “I think (coach) Becky (Hammon) nicknamed her Kate ‘Money’ Martin. I think that’s gonna stick. And when I say ‘money,’ it’s not just about scoring and stuff, she’s just in the right place at the right time. She just makes people better. And that’s what Becky values, that’s what our coaching staff values and that’s why she’s gonna be a great asset to our team.”

Las Vegas selected Martin in the second round of the 2024 WNBA Draft. She was coming off the best season of her collegiate career at Iowa, where she averaged 13.1 points, 6.8 rebounds, and 2.3 assists per game during the 2023-24 campaign. Martin’s integration into the Aces organization has been seamless, with her quickly earning the respect and admiration of her teammates and coaches.

The team and fans alike are hoping for a speedy recovery for Martin, whose contributions have been vital to the Aces’ performance this season.

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Asteroid Apophis will visit Earth in 2029, and this European satellite will be along for the ride

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The European Space Agency is fast-tracking a new mission called Ramses, which will fly to near-Earth asteroid 99942 Apophis and join the space rock in 2029 when it comes very close to our planet — closer even than the region where geosynchronous satellites sit.

Ramses is short for Rapid Apophis Mission for Space Safety and, as its name suggests, is the next phase in humanity’s efforts to learn more about near-Earth asteroids (NEOs) and how we might deflect them should one ever be discovered on a collision course with planet Earth.

In order to launch in time to rendezvous with Apophis in February 2029, scientists at the European Space Agency have been given permission to start planning Ramses even before the multinational space agency officially adopts the mission. The sanctioning and appropriation of funding for the Ramses mission will hopefully take place at ESA’s Ministerial Council meeting (involving representatives from each of ESA’s member states) in November of 2025. To arrive at Apophis in February 2029, launch would have to take place in April 2028, the agency says.

This is a big deal because large asteroids don’t come this close to Earth very often. It is thus scientifically precious that, on April 13, 2029, Apophis will pass within 19,794 miles (31,860 kilometers) of Earth. For comparison, geosynchronous orbit is 22,236 miles (35,786 km) above Earth’s surface. Such close fly-bys by asteroids hundreds of meters across (Apophis is about 1,230 feet, or 375 meters, across) only occur on average once every 5,000 to 10,000 years. Miss this one, and we’ve got a long time to wait for the next.

When Apophis was discovered in 2004, it was for a short time the most dangerous asteroid known, being classified as having the potential to impact with Earth possibly in 2029, 2036, or 2068. Should an asteroid of its size strike Earth, it could gouge out a crater several kilometers across and devastate a country with shock waves, flash heating and earth tremors. If it crashed down in the ocean, it could send a towering tsunami to devastate coastlines in multiple countries.

Over time, as our knowledge of Apophis’ orbit became more refined, however, the risk of impact  greatly went down. Radar observations of the asteroid in March of 2021 reduced the uncertainty in Apophis’ orbit from hundreds of kilometers to just a few kilometers, finally removing any lingering worries about an impact — at least for the next 100 years. (Beyond 100 years, asteroid orbits can become too unpredictable to plot with any accuracy, but there’s currently no suggestion that an impact will occur after 100 years.) So, Earth is expected to be perfectly safe in 2029 when Apophis comes through. Still, scientists want to see how Apophis responds by coming so close to Earth and entering our planet’s gravitational field.

“There is still so much we have yet to learn about asteroids but, until now, we have had to travel deep into the solar system to study them and perform experiments ourselves to interact with their surface,” said Patrick Michel, who is the Director of Research at CNRS at Observatoire de la Côte d’Azur in Nice, France, in a statement. “Nature is bringing one to us and conducting the experiment itself. All we need to do is watch as Apophis is stretched and squeezed by strong tidal forces that may trigger landslides and other disturbances and reveal new material from beneath the surface.”

The Goldstone radar’s imagery of asteroid 99942 Apophis as it made its closest approach to Earth, in March 2021. (Image credit: NASA/JPL–Caltech/NSF/AUI/GBO)

By arriving at Apophis before the asteroid’s close encounter with Earth, and sticking with it throughout the flyby and beyond, Ramses will be in prime position to conduct before-and-after surveys to see how Apophis reacts to Earth. By looking for disturbances Earth’s gravitational tidal forces trigger on the asteroid’s surface, Ramses will be able to learn about Apophis’ internal structure, density, porosity and composition, all of which are characteristics that we would need to first understand before considering how best to deflect a similar asteroid were one ever found to be on a collision course with our world.

Besides assisting in protecting Earth, learning about Apophis will give scientists further insights into how similar asteroids formed in the early solar system, and, in the process, how  planets (including Earth) formed out of the same material.

One way we already know Earth will affect Apophis is by changing its orbit. Currently, Apophis is categorized as an Aten-type asteroid, which is what we call the class of near-Earth objects that have a shorter orbit around the sun than Earth does. Apophis currently gets as far as 0.92 astronomical units (137.6 million km, or 85.5 million miles) from the sun. However, our planet will give Apophis a gravitational nudge that will enlarge its orbit to 1.1 astronomical units (164.6 million km, or 102 million miles), such that its orbital period becomes longer than Earth’s.

It will then be classed as an Apollo-type asteroid.

Ramses won’t be alone in tracking Apophis. NASA has repurposed their OSIRIS-REx mission, which returned a sample from another near-Earth asteroid, 101955 Bennu, in 2023. However, the spacecraft, renamed OSIRIS-APEX (Apophis Explorer), won’t arrive at the asteroid until April 23, 2029, ten days after the close encounter with Earth. OSIRIS-APEX will initially perform a flyby of Apophis at a distance of about 2,500 miles (4,000 km) from the object, then return in June that year to settle into orbit around Apophis for an 18-month mission.

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Furthermore, the European Space Agency still plans on launching its Hera spacecraft in October 2024 to follow-up on the DART mission to the double asteroid Didymos and Dimorphos. DART impacted the latter in a test of kinetic impactor capabilities for potentially changing a hazardous asteroid’s orbit around our planet. Hera will survey the binary asteroid system and observe the crater made by DART’s sacrifice to gain a better understanding of Dimorphos’ structure and composition post-impact, so that we can place the results in context.

The more near-Earth asteroids like Dimorphos and Apophis that we study, the greater that context becomes. Perhaps, one day, the understanding that we have gained from these missions will indeed save our planet.

 

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McMaster Astronomy grad student takes a star turn in Killarney Provincial Park

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Astronomy PhD candidate Veronika Dornan served as the astronomer in residence at Killarney Provincial Park. She’ll be back again in October when the nights are longer (and bug free). Dornan has delivered dozens of talks and shows at the W.J. McCallion Planetarium and in the community. (Photos by Veronika Dornan)

Veronika Dornan followed up the April 8 total solar eclipse with another awe-inspiring celestial moment.

This time, the astronomy PhD candidate wasn’t cheering alongside thousands of people at McMaster — she was alone with a telescope in the heart of Killarney Provincial Park just before midnight.

Dornan had the park’s telescope pointed at one of the hundreds of globular star clusters that make up the Milky Way. She was seeing light from thousands of stars that had travelled more than 10,000 years to reach the Earth.

This time there was no cheering: All she could say was a quiet “wow”.

Dornan drove five hours north to spend a week at Killarney Park as the astronomer in residence. part of an outreach program run by the park in collaboration with the Allan I. Carswell Observatory at York University.

Dornan applied because the program combines her two favourite things — astronomy and the great outdoors. While she’s a lifelong camper, hiker and canoeist, it was her first trip to Killarney.

Bruce Waters, who’s taught astronomy to the public since 1981 and co-founded Stars over Killarney, warned Dornan that once she went to the park, she wouldn’t want to go anywhere else.

The park lived up to the hype. Everywhere she looked was like a painting, something “a certain Group of Seven had already thought many times over.”

The dome telescopes at Killarney Provincial Park.

She spent her days hiking the Granite Ridge, Crack and Chikanishing trails and kayaking on George Lake.  At night, she went stargazing with campers — or at least tried to. The weather didn’t cooperate most evenings — instead of looking through the park’s two domed telescopes, Dornan improvised and gave talks in the amphitheatre beneath cloudy skies.

Dornan has delivered dozens of talks over the years in McMaster’s W.J. McCallion Planetarium and out in the community, but “it’s a bit more complicated when you’re talking about the stars while at the same time fighting for your life against swarms of bugs.”

When the campers called it a night and the clouds parted, Dornan spent hours observing the stars. “I seriously messed up my sleep schedule.”

She also gave astrophotography a try during her residency, capturing images of the Ring Nebula and the Great Hercules Cluster.

A star cluster image by Veronika Dornan

“People assume astronomers take their own photos. I needed quite a lot of guidance for how to take the images. It took a while to fiddle with the image properties, but I got my images.”

Dornan’s been invited back for another week-long residency in bug-free October, when longer nights offer more opportunities to explore and photograph the final frontier.

She’s aiming to defend her PhD thesis early next summer, then build a career that continues to combine research and outreach.

“Research leads to new discoveries which gives you exciting things to talk about. And if you’re not connecting with the public then what’s the point of doing research?”

 

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