The thing about a supernova is that you never know when it might occur. Supernovae are triggered either by a collision with another star or when the interior of a massive star becomes depleted of nuclear fuel and begins a rapid collapse. Neither of these show any major optical changes before the explosion, so we are left to scan the sky in the hopes of catching one in its early stages. But that could soon change.
For the second type of supernova, known as core-collapse supernova, there is an early warning. As the core of the star collapses, the rapid collision of nuclei triggers a tremendous production of both gamma rays and neutrinos. The gamma-ray photons collide strongly with nuclei, which generates much of the pressure that eventually rips the star apart. But the neutrinos only interact weakly with nuclei, so most of them stream out of the star unimpeded. As a result, while the gamma-ray photons are starting to trigger the supernova, the neutrinos are already on their way to deep space.
This means that when a core-collapse supernova occurs, we experience a burst of neutrinos before the star begins to brighten as a supernova. We have seen this happen once before, when neutrino observatories detected a few events just before SN 1987a occurred. In that case, this was only realized long after the fact. It actually helped us understand how neutrinos are generated during a supernova, but we couldn’t use it as an early warning system. By the time the neutrino detections were recognized, the supernova had already occurred.
A simulated localization of a supernovae neutrino source. Credit: CGTN
But the Jiangmen Underground Neutrino Observatory (JUNO) hopes to change that. In a new paper on the arXiv, the authors discuss how JUNO should be able to recognize neutrino events in near real-time. Given the time delay of optical supernovae, this could be fast enough to localize the neutrino source quickly enough to alert other observatories. These observatories could then focus their attention on a particular region of the sky to catch a supernova in the act. Based on the design of JUNO, the authors estimate there would be about a false alarm roughly once a year, but for real events, the system should be able to detect the neutrinos of the initial core collapse for a 30 solar-mass star more than a million light-years away. Even more impressive, the system could also detect the much fainter burst of neutrinos that occurs in the pre-supernova stage for a 30 solar-mass star up to 3,000 light years away. So if Betelgeuse ever does go supernova in the near future, JUNO could tell us in plenty of time to grab our binoculars.
JUNO is still under construction but hopes to come online by the end of this year or so.
Reference: Abusleme, Angel, et al. “Real-time Monitoring for the Next Core-Collapse Supernova in JUNO.” arXiv preprint arXiv:2309.07109 (2023).
The post A New Observatory Will Spot Core-Collapse Supernovae Before They Explode appeared first on Universe Today.
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How Do Lava Worlds Become Earth-Like, Living Planets?
Earth was once entirely molten. Planetary scientists call this phase in a planet’s evolution a magma ocean, and Earth may have had more than one magma ocean phase. Earth cooled and, over 4.5 billion years, became the vibrant, life-supporting world it is today.
Can the same thing happen to exo-lava worlds? Can studying them shed light on Earth’s transition?
Planet-hunters like the Kepler Spacecraft and TESS have found thousands of worlds around other stars. Many of these worlds orbit their stars very closely, so close that they’re heated to extreme temperatures. A lot of these planets are gas giants, but a significant number are rocky, and the extreme heat keeps them molten, or at least partially molten. At least half of these super-heated rocky worlds are capable of maintaining magma on their surfaces.
There’s nothing like a lava world in our Solar System. The closest is Jupiter’s moon Io. But it’s volcanically active, which isn’t the same as a magma ocean. Studying lava worlds gives scientists a glimpse into Earth’s molten past, and luckily, they’re not hard to find.
A new study looked at hot rocky super-Earths, how their magma oceans affect our observations, and how they also influence their evolutionary paths.
The study is “Fizzy Super-Earths: Impacts of Magma Composition on the Bulk Density and Structure of Lava Worlds,” and it was published in The Astrophysical Journal. The lead author is Kiersten Boley, a graduate student in astronomy at The Ohio State University.
“When planets initially form, particularly for rocky terrestrial planets, they go through a magma ocean stage as they’re cooling down,” said Boley. “So lava worlds can give us some insight into what may have happened in the evolution of nearly any terrestrial planet.”
“Being able to trap a lot of volatile elements within their mantles could have greater implications for habitability.”
Kiersten Boley, lead author, Ohio State University.
The team used exoplanet modelling software to simulate Super-Earths that orbit their stars very closely. These planets are called ultra-short period (USP) planets. They simulated multiple evolutionary pathways for a planet similar to Earth but with surface temperatures between 2600 and 3860 F (1426 and 2126 C.) Within this range, a planet’s solid mantle would melt into magma depending largely on its composition.
Their work produced three classes of magma oceans, each with different mantle structures: a mantle magma ocean, a surface magma ocean, and one consisting of a surface magma ocean, a solid rock layer, and a basal magma ocean.
This figure from the study shows the three types of mantle structures in the simulations. The researchers found that the mantle may be a mantle magma ocean, a surface magma ocean and solid rock layer, or a MOSMO structure (i.e., Surface Magma Ocean (MO)–Solid Rock Layer (S)–Basal Magma Ocean (MO)). Image Credit: Boley et al. 2023.
The research shows that mantle magma ocean planets are less common than the other two, but not by much. But when it comes to evolutionary pathways that might lead to habitable planets, it’s the planet’s composition that’s more important than its mantle structure. In lava worlds without atmospheres, the composition dictates how effective the magma is at trapping volatiles. That’s critical when it comes to life as we know it.
For a planet to one day express life, it needs an atmosphere with critical components like carbon and oxygen. Earth life is based on carbon, and oxygen is key to complex life here on Earth. So a magma planet with ample carbon and oxygen in its magma could eventually off-gas these critical materials into a planet’s burgeoning atmosphere if it held onto one.
Water, as we all know, is also critical to life, and some of the simulated planets had massive reserves of water. According to the study, a basal magma planet four times more massive than Earth—a
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Day Has Returned, but India’s Lander and Rover have Failed to Wake Up
It looks like India’s Chandrayaan-3 succumbed to the cold, and its mission is over. The frigid lunar night lasted about two weeks, and a new day has dawned. With that day came hopes of a sunlit revival for the lander and the rover, but the India Space Research Organization (ISRO) says the chances of the spacecraft awakening in the Sun are diminishing by the hour.
The lunar night that wrapped its cold arms around the lander and rover lasted 14 days, and so will the current lunar day. When the day dawned last Friday, ISRO began trying to communicate with the lander. There’s been no response so far, as both explorers may be forever entombed about 600km (373 mi) from the Moon’s south pole.
Even though things don’t look good for the mission, it’s still a success. It’s the first spacecraft to land in the Moon’s south pole region. The area is critical because it contains vast quantities of frozen water in its permanently shadowed crater. That water is a valuable resource for astronauts who’ll visit the Moon in the future and set up bases. It’s also the first time ISRO successfully landed a rover and lander on the Moon after its predecessor, Chandrayaan-2, crashed into the surface.
But it’s encouraging that Vikram and Pragyaan are still intact. ISRO hoped that the Sun would bring both back to life after the agency put them into sleep mode as night fell. There’s a chance that the sunlight would recharge the batteries.
“Once there is sufficient solar generation, they are expected to come back to life provided that they have survived the night.”
M Srikanth, Chandrayaan-3 Mission Operations Director.
ISRO released an update on Friday, the beginning of the new lunar day. Unfortunately, there was no response from either the lander or the rover.
Efforts have been made to establish communication with the Vikram lander and Pragyan rover to ascertain their wake-up condition.
As of now, no signals have been received from them.
Efforts to establish contact will continue.
— ISRO (@isro) September 22, 2023
When night falls on the Moon’s south pole, temperatures plummet as low as -200C to -250C (-328F to -418F.) The lander and rover were never designed to handle these temperatures. The rover has only a small battery—10 amp-hours—that provides the necessary power to deploy its solar array. It was also included to help the rover survive a periodic eclipse. The small battery was fully charged when night came, and the solar panels were positioned to receive incoming starlight when morning came. The Vikram lander was also ready for the morning, and its 62.5 amp hour was fully charged.
Both vehicles are pre-programmed to come back to life as the Sun reappears. “When sunlight comes back, there’s an autonomous logic pre-loaded on both the lander and rover,” said M Srikanth, Chandrayaan-3 Mission Operations Director, in an interview with the Times of India. “Once there is sufficient solar generation, they are expected to come back to life provided that they have survived the night.”
If ISRO’s Chandrayaan-3 mission is truly over, it was still a success. It was the first spacecraft to land at the Moon’s south pole region. Image Credit: ISRO
But according to Isro chief AS Kiran Kumar, the “chances of reawakening are dimming with each passing hour.” In an interview with the BBC, Kumar added, “The lander and rover have so many components which may not have survived the frigid temperatures on the Moon.” In fairness, they were never designed to.
It’s all up to the lander’s transmitter now. It’s ISRO’s link with the mission, and if it won’t function, it won’t matter if some of the spacecraft’s other systems are somehow still working. “It has to tell us that it’s alive. Even if all other sub-systems work, we have no way of knowing that,” Kumar added.
Some of ISRO’s hopefulness is based on China’s successful Chang’e 4 mission. It landed on the lunar far side and was plunged into darkness and freezing temperatures, too. It woke up with the sunrise more than once.
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Review: Patagonia R1 Air Full-Zip Hoody
Hooded Fleece Jacket
Patagonia R1 Air Full-Zip Hoody
$179, 12.5 oz./354g (men’s medium)
Sizes: men’s XS-XXL, women’s XXS-XL, kids XS-XXL
As I’ve repeatedly written at this blog, virtually no piece of outdoor apparel offers more versatility than a highly breathable, midweight insulation layer; arguably, the only “layer” you will wear more is your skin. Find a highly breathable midweight jacket that’s soft and fits like it was custom made for your torso and you have a winner. Patagonia’s R1 Air Full-Zip Hoody could play that role for almost any outdoor user, from hard-core backpackers, climbers, and backcountry skiers to the average dayhiker and fitness walker, as I found wearing it on backpacking trips in Glacier National Park and the Canadian Rockies, not to mention countless days around town and at home.
At 12.5 ounces/354 grams (men’s medium), this midweight fleece is designed for wearing as an outer or middle layer in a huge range of cool to cold temperatures, including activities and seasons as diverse as hiking or climbing in virtually any mountains in any month of the year, southern climes from fall through spring, or for any winter activity—skiing, hiking, running, walking, you pick.
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The Patagonia R1 Air Full-Zip Hoody.
” data-image-caption=”The Patagonia R1 Air Full-Zip Hoody.
” data-medium-file=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2023/09/Patagonia-R1-Air-Full-Zip-Hoody.jpg?fit=300%2C200&ssl=1″ data-large-file=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2023/09/Patagonia-R1-Air-Full-Zip-Hoody.jpg?fit=900%2C600&ssl=1″ src=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2023/09/Patagonia-R1-Air-Full-Zip-Hoody.jpg?resize=900%2C600&ssl=1″ alt=”The Patagonia R1 Air Full-Zip Hoody.” class=”wp-image-60252″ srcset=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2023/09/Patagonia-R1-Air-Full-Zip-Hoody.jpg?resize=1024%2C683&ssl=1 1024w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2023/09/Patagonia-R1-Air-Full-Zip-Hoody.jpg?resize=300%2C200&ssl=1 300w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2023/09/Patagonia-R1-Air-Full-Zip-Hoody.jpg?resize=768%2C512&ssl=1 768w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2023/09/Patagonia-R1-Air-Full-Zip-Hoody.jpg?resize=150%2C100&ssl=1 150w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2023/09/Patagonia-R1-Air-Full-Zip-Hoody.jpg?w=1200&ssl=1 1200w” sizes=”(max-width: 900px) 100vw, 900px” data-recalc-dims=”1″ />The Patagonia R1 Air Full-Zip Hoody.
It kept me warm without overheating—rarely even breaking a sweat—wearing it over one base layer while hiking with a full pack, uphill and downhill, on cool, generally calm mornings and some windy afternoons during a weeklong, nearly 70-mile September backpacking trip in Glacier National Park, and hiking in chilly, very strong wind on three-day hikes on both the Skyline Trail in Jasper National Park and the Nigel, Cataract, and Cline Passes Route in the White Goat Wilderness of the Canadian Rockies in the first week of August.
On those backpacking trips, I also wore it in camp both as an outer layer and, when temps dropped, under a down jacket—meaning the R1 Air Hoody doubled as an on-trail layer and a camp layer that allowed me to bring a lighter puffy and forego a midweight, long-sleeve shirt. To frame it another way: The R1 Air Hoody cut my layering system weight by replacing or reducing two other layers. Few pieces of apparel offer more versatility while reducing your pack weight.
I also wore it on breezy, cool evenings in the 50s between waves of thunderstorms
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