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We often think of supernova explosions as inevitable for large stars. Big star runs out of fuel, gravity collapses its core and BOOM! But astronomers have long thought at least one type of large star didn’t end with a supernova. Known as Wolf-Rayet stars, they were thought to end with a quiet collapse of their core into a black hole. But a new discovery finds they might become supernovae after all.

Wolf-Rayet stars are among the most massive stars known. They are at the end of their short lives, but rather than simply running out of fuel and exploding, they push out their outer layers with an extremely powerful stellar wind. This produces a surrounding nebula rich in ionized helium, carbon, and nitrogen, but almost no hydrogen. The surface temperature of the remaining star can be over 200,000 K, making them the most luminous stars known. But because most of that light is in the ultraviolet range, they are not particularly bright to the naked eye.

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In a large star, different elements are in layers before the star explodes. Credit: Itai Raveh

Even with the outer layers of a Wolf-Rayet star cast off, the central star is still much more massive than the Sun. So you’d figure it’s only a matter of time before it becomes a supernova. No matter how far up the periodic table fusion occurs, it will eventually run out of fuel, leading to a core-collapse supernova. But we can see the spectra of elements within a supernova, and we’d never seen a spectrum that matched a Wolf-Rayet star. As our discovery of supernovae became commonplace, some astronomers began to wonder if Wolf-Rayet stars had a quiet death instead. The idea was that they would cast off enough outer layers that the remaining core would eventually just collapse directly into a black hole. No giant explosion needed. A silent death to a massive star.

This latest study shows that at least some Wolf-Rayet stars do become supernovae. The team looked at the spectrum of a supernova known as SN 2019hgp, which was discovered by the Zwicky Transient Facility (ZTF). The supernova’s spectrum had bright emission light indicating the presence of carbon, oxygen, and neon, but not hydrogen or helium. When the team looked at the data more closely, they found these particular emission lines weren’t caused by elements of the supernova directly. Instead, they were part of a nebula expanding away from the star at more than 1,500 km/s.

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A spectra from SN 2019hgp. Credit: Itai Raveh

In other words, before the supernova occurred, the progenitor star was surrounded by a nebula rich in carbon, nitrogen, and neon, while lacking the lighter elements of hydrogen and helium. The expansion of the nebula must have been driven by strong stellar winds. This matches the structure of a Wolf-Rayet star extremely well. So it looks like SN 2019hgp is the first example of a Wolf-Rayet supernova. Since then, similar supernovae have also been detected.

Because this supernova was identified by spectra of the surrounding nebula, it isn’t clear whether the explosion was a simple supernova, or whether it was a more complex hybrid process where the upper layer of the star exploded while the core collapsed directly to a black hole. It will take more observations to determine the details. What’s clear is that at least some Wolf-Rayet stars do not go silently into the night.

Reference: Gal-Yam, A., et al. “A WC/WO star exploding within an expanding carbon–oxygen–neon nebula.” Nature 601.7892 (2022): 201-204.

The post A new Kind of Supernova has Been Discovered appeared first on Universe Today.

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Powerful Jets From a Black Hole are Spawning Star Clusters

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Supermassive black holes are messy feeders, and when they’re gorging on too much material, they can hurl high-energy jets into the surrounding Universe. Astronomers have found one of the most powerful eruptions ever seen, emanating from a black hole 3.8 billion light-years away. The powerful jets are blowing out cavities in intergalactic space and triggering the formation of a huge chain of star clusters.

The black hole is part of a massive galaxy cluster, named SDSS J1531, which contains hundreds of individual galaxies, and all these galaxies have huge reservoirs of hot gas and dark matter. Using several telescopes for multiwavelength observations — including the Chandra X-ray Observatory, the Low Frequency Array (LOFAR) radio telescope, the Atacama Large Millimeter and submillimeter Array (ALMA), the Gemini North telescope’s Gemini Multi-Object Spectrograph (GMOS), and the Very Large Array (VLA) — astronomers were able to discern that two of the central galaxies were engaged in a major merger. The merger activated the supermassive black hole in the center of one of the large galaxies, which produced an extremely powerful jet. As the jet moved through space, it pushed the surrounding hot gas away from the black hole, creating a gigantic cavity.

The merger and the resulting jets from the black hole created a remarkable and stunning chain of 19 young stellar superclusters wound the two galaxies like a string of beads.

In their paper, the astronomers said the dynamic environment of SDSS J1531 offers an excellent laboratory to study the interplay between mergers, and their multiwavelength studies allowed them to uncover the origin and evolution of the “beads on a string” star formation complex.

“We’ve reconstructed a likely sequence of events in this cluster that occurred over a vast range of distances and times,” said co-author Grant Tremblay, from the Harvard & Smithsonian Center for Astrophysics CfA). “It began with the black hole a tiny fraction of a light-year across forming a cavity almost 500,000 light-years wide. This single event set in motion the formation of the young star clusters nearly 200 million years later, each a few thousand light-years across.”

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A labeled view of the multiwavelength Image of SDSS J1531. Credit: X-ray: NASA/CXC/SAO/O. Omoruyi et al.; Optical: NASA/ESA/STScI/G. Tremblay et al.; Radio: ASTRON/LOFAR; Image Processing: NASA/CXC/SAO/N. Wolk.

Chandra’s X-ray vision allowed the scientists to see wing-shaped emissions in bright X-rays, which traced dense gas near the center of SDSS J1531. The said these wings make up the edge of the cavity, and then LOFAR revealed radio waves from the remains of the jet’s energetic particles filling in the giant cavity. Together, these data provide compelling evidence of an ancient, massive explosion.

Osase Omoruyi, also from CfA who led the study, compared finding this cavity to unearthing a buried fossil.

“We are already looking at this system as it existed four billion years ago, not long after the Earth formed,” she said. “This ancient cavity, a fossil of the black hole’s effect on the host galaxy and its surroundings, tells us about a key event that happened nearly 200 million years earlier in the cluster’s history.”

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This Hubble Space Telescope image from 2014 shows two galaxies (yellow, center) from the cluster SDSS J1531 found to be merging into one and a “chain” of young stellar super-clusters are seen winding around the galaxies’ nuclei. The galaxies are surrounded by an egg-shaped blue ring caused by the immense gravity of the cluster bending light from other galaxies beyond it. Credit: NASA/ESA/Grant Tremblay

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Finally! Blue Origin’s New Glenn Goes Vertical on the Launch Pad

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If you think about space travel and the means of escaping the confines of the Earth then most people, currently, are likely to think about the new Artemis project and the Space Launch System. That’s not the only new development though, Blue Origin have been working on their New Glenn rocket and finally we have got a glimpse of their new offering. The rocket was finally rolled onto the launch pad at Cape Canaveral for testing to commence and we may even see a launch later this year.

Blue Origin was founded in 2000 by the founder of Amazon, Jeff Bezos. It is American aerospace manufacturer based in Washington, USA and specialises in producing rocket engines for the Vulcan rocket and manufactures satellites, spacecraft and a variety of space based tech. Securing the deal to become the second provider of the Lunar lander for Artemis project, Blue Origin has most certainly become a major player in the space industry.

Their latest announcement came with the incredible sight of the New Glenn vehicle rolling out onto Launch Complex 36 at Cape Canaveral. This was the first glimpse the world got of their new advanced heavy-lift vehicle which promises to support a number of different commercial customer missions and NASA’s Artemis program to get humans back to the Moon.

Space lovers will perhaps recognise the name Glenn from the first American to orbit the Earth, John Glenn. It stands an impressive 98m tall (only about 12m shorter than Saturn V used by the Apollo astronauts). It has an impressive 7m payload bay which is double the volume of most commercial launch capabilities available today. I don’t know about you but I struggle to visualise what that means but to give it context, Blue Origin state that it could accommodate three school busses! 

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Apollo 11 launch using the Saturn V rocket

The first stage, like the Falcon rockets, are reusable and designed to be used for at least 25 launches. They will land on a sea-based platform almost 1,000km downrange from the launch site. As with the Falcon systems, the reusability of the first stage helps to keep costs per launch down.

Before the New Glenn could be lifted up onto the pad the journey started toward the end of 2023 when the first stage module was transported to the Integration Facility 15km away. The facility allowed the modules to be assembled in preparation for installing on the launch pad. Now the rocket is vertical, the coming weeks will see a series of tests from loading the cryogenic fuel into the seven BE-4 engines. These are the most powerful liquid oxygen and liquefied natural gas engines developed since Saturn V’s F1 engines. They will test pressure control and launch and ground systems in preparation for its first launch later this year.

Blue Origin are rather confident these tests will be a success though as they are already manufacturing several New Glenn vehicles with a full set of customers queueing up to use them. They include NASA, Project Kuiper (another global internet project to launch over 3,000 satellites into low Earth orbit), Telesat, Eutelsat and the US Space Force for National Security Space Launch programs.

Source : Blue Origin Debuts New Glenn on Our Launch Pad

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Can We Survive in Space? It Might Depend on How Our Gut Microbiome Adapts

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For over a century, people have dreamed of the day when humanity (as a species) would venture into space. In recent decades, that dream has moved much closer to realization, thanks to the rise of the commercial space industry (NewSpace), renewed interest in space exploration, and long-term plans to establish habitats in Low Earth Orbit (LEO), on the lunar surface, and Mars. Based on the progression, it is clear that going to space exploration will not be reserved for astronauts and government space agencies for much longer.

But before the “Great Migration” can begin, there are a lot of questions that need to be addressed. Namely, how will prolonged exposure to microgravity and space radiation affect human health? These include the well-studied aspects of muscle and bone density loss and how time in space can impact our organ function and cardiovascular and psychological health. In a recent study, an international team of scientists considered an often-overlooked aspect of human health: our microbiome. In short, how will time in space affect our gut bacteria, which is crucial to our well-being?

The team consisted of biomedical researchers from the Ionizing and Non-ionizing Radiation Protection Research Center (INIRPRC) at the Shiraz University of Medical Sciences (SUMS), the Lebanese International University, the International University of Beirut, the MVLS College at The University of Glasgow, the Center for Applied Mathematics and Bioinformatics (CAMB) at Gulf University in Kuwait, the Nuclear Physics Institute (NPI) of the Czech Academy of Sciences (CAS), and the Technische Universität Wien Atominstitut in Vienna. The paper that describes their findings recently appeared in Frontiers of Microbiology.

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Artist’s impression of the Space Launch System (SLS) taking off. Credit: NASA

A microbiome is the collection of all microbes that live on and within our bodies, including bacteria, fungi, viruses, and their respective genes. These microbes are key to how our body interacts with the surrounding environment since they can affect how we respond to the presence of foreign bodies and substances. In particular, some microbes alter foreign bodies in ways that make them more harmful, while others act as a buffer that mitigates the effects of toxins. As they note in their study, the microbiota of astronauts will encounter elevated stress from microgravity and space radiation, including Galactic Cosmic Rays (GCR).

Cosmic rays are a high-energy form of radiation that consists primarily of protons and atomic nuclei stripped of their electrons that have been accelerated to close to the speed of light. When these rays are generated from elements heavier than hydrogen or helium, their high-energy nuclei components are known as HZE ions, which are particularly hazardous. When these impact our atmosphere or protective shielding aboard spacecraft or the International Space Station (ISS), they result in showers of secondary particles.

While Earth’s protective magnetosphere and atmosphere prevent most of these particles from reaching the surface, astronauts in space are exposed to them regularly. As the authors noted, previous research has shown how this exposure could potentially enhance astronaut resilience to radiation, a process known as radio-adaptation. However, they also noted that the extent to which astronauts adapted varied from one astronaut to the next, with some experiencing adverse biological effects before embarking on a deep space mission.

For this reason, they recommend conducting further research to determine the risks associated with the space environment, as it mostly consists of protons, which astronauts will be exposed to before encountering HZE particles. Third, NASA’s Multi-Mission Model suggests that an astronaut’s first mission can be an adapting dose. However, the team notes that current research suggests that a second spaceflight does not necessarily increase the chances of genetic abnormalities as much as expected. This could mean that the
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