Astronomy

The Hubble Space Telescope has captured two tangled galaxies, whose interactions have caused knots to form in the constellation Coma Berenice, or the "queen's hair."

Image: Getting Proba-3 fit for flight

Crew-8 commander Matthew Dominick says NASA is carefully making decisions for astronaut safety while the ISS deals with a leak, and spacesuit issues, related to aging hardware.

Expertise bulks up the brain’s ability to think deeply, a skill that may generalize across tasks

Antimicrobial resistance could claim 39 million lives by 2050, yet the pipeline for new antibiotics is drying up. U.S. policy makers can help fix it

Violins, the ink on the Declaration of Independence and other ways that insects shaped human history

ESA is taking a significant step towards creating a more digitally inclusive Europe through a new partnership that will bring internet access to the hardest-to-reach areas. Reliable connectivity has become essential in today's digital age, yet for many Europeans in rural villages, mountainous regions, and small islands, dependable internet access remains out of reach.

A new European Space Agency-backed study shows that the extreme heatwaves of 2023, which fuelled huge wildfires and severe droughts, also undermined the land’s capacity to soak up atmospheric carbon. This diminished carbon uptake drove atmospheric carbon dioxide levels to new highs, intensifying concerns about accelerating climate change.

President-elect Donald Trump has tapped Elon Musk and Vivek Ramaswamy to lead the new Department of Government Efficiency, which aims to 'dismantle government bureaucracy.'

The Jet Propulsion Laboratory, NASA's chief center for planetary exploration, is conducting its second round of layoffs in 2024, reducing its workforce by another 5%.

An annual accounting of CO2 emissions from burning fossil fuels and land use change finds no sign emissions will peak this year

An annual accounting of CO2 emissions from burning fossil fuels and land use change finds no sign emissions will peak this year

Eurasian reed warblers don’t just get a sense of direction from Earth’s magnetic field – they can also calculate their coordinates on a mental map

Eurasian reed warblers don’t just get a sense of direction from Earth’s magnetic field – they can also calculate their coordinates on a mental map

Filmmakers love New Zealand. Its landscapes evoke other worlds, which explains why so much of The Lord of the Rings was filmed there. The country has everything from long, subtropical sandy beaches to active volcanoes.

The country’s otherworldliness extends into its atmosphere, where a cloud nicknamed the “Taieri Pet” forms when conditions are right.

The Taieri Pet is a lenticular cloud, a stationary type of cloud that forms in certain circumstances. They form in the troposphere when the wind blows over an obstacle, typically a mountain range. There are three types: altocumulus standing lenticular (ACSL), stratocumulus standing lenticular (SCSL), and cirrocumulus standing lenticular (CCSL). Each type forms at a different altitude.

When the wind is forced to move up and over an obstacle, it creates a lower-pressure zone on the leeward side. As the wind moves, it creates standing waves. If conditions are right, these waves become visible when the moisture condenses.

The Taieri Pet forms over New Zealand’s Rock and Pillar Range in the Strath-Taieri region of Otago on New Zealand’s South Island.

The Otago region on New Zealand’s South Island is home to the Taieri Pet. Image Credit: Peetel, (Creative Commons Attribution-Share Alike 4.0 International.)

The cloud is a common feature near the town of Middlemarch. It’s mentioned in newspapers as far back as the 1890s. Locals sometimes took Taieri Pet’s appearance as a signal that a storm was coming.

This page is from the Otago Witness, Issue 2226, 29 October 1896. It describes the Taieri Pet as “our old prognosticator,” because it forms before a wind storm. Image Credit: No Known Copyright.

The Operational Land Image (OLI) on Landsat 8 captured this stunning image of the Taieri Pet in September. Landsat 8 follows a polar orbit that allows it to observe the entire surface of the Earth every 16 days.

This zoomed-in image shows the cloud and the surface in more detail. The image shows the Macraes Mine, New Zealand’s largest gold mine. Image Credit: NASA/Lauren Dauphin; USGS

The Landsat satellites have been monitoring Earth for over 50 years from their orbit 705 km above us. The images and data are widely used by scientists, but they’re also beautiful portraits of our extraordinary, once-in-a-solar-system planet.

Anybody can enjoy the Landsat galleries, found here.

The post An Otherworldly Cloud Over New Zealand appeared first on Universe Today.

The theory goes that black holes accrete material, often from nearby stars. However the theory also suggests there is a limit to how big a black hole can grow due to accretion and certainly shouldn’t be as large as they are seen to be in the early Universe. Black holes it seems, are fighting back and don’t care about those limits! A recent study shows that supermassive black holes are growing at rates that defy the limits of current theory. Astronomers just need to figure out how they’re doing it! 

Black holes usually form from the collapse of a massive star. The origin of their larger cousins, the supermassive black holes found at the centre of most galaxies, remains a mystery. Theories suggest they grew over billions of years by consuming stars, gas and maybe even other black holes. Others suggest they formed from the primordial conditions of the early Universe or maybe from dense clusters of hot young early stars. The immense gravity from them plays a significant part in shaping stellar formation and the evolution of their host galaxy. If a supermassive black hole is actively accreting material, they are often seen as quasars, extremely luminous objects that are visible across million, even billions of light years. 

Illustration of a powerful black hole and its magnetic field. Credit: L. Calçada/ESO

A recent discovery by a team of astronomers revealed a low-mass supermassive black hole that was devouring material at an extreme rate. The black hole is at a distance that means we are seeing light as it was 1.5 billion years after the Big Bang. This means we can learn about the processes that govern these objects when the Universe was a lot younger. 

The black hole known as LID-568 was detected by a team of astronomers led by the International Gemini Observatory/NSF NOIRLab astronomer Hyewon Suh. It was detected in images from the James Webb Space Telescope following on from assessment of galaxies from the Chandra X-ray Observatory’s COSMOS legacy survey. The galaxies observed are bright X-ray sources but not visible in optical or near-infrared surveys. The team used JWST’s NIRSpec instrument that is capable of getting a spectrum off each individual pixel in its field of view. 

The Gemini North telescope on the summit of Mauna Kea (Gemini Observatory/AURA)

The study allowed the team to make the rather unexpected discovery of immense flows of gas out from the region around the centre of the black hole.  Suh and team could infer from this that a significant fraction of the growth of LID-568  may well have occurred in one single rapid accretion event. They calculated that it must be feeding on matter at a rate which is 40 times the Eddington limit. The limit relates to the maximum luminosity it can achieve acknowledging there is a balance between the outward force of radiation and the inward force of gravity. When the two forces balance, it is known as hydrostatic equilibrium. If an object exceeds the limit then an immense outward force will result in it losing mass. When the luminosity of LID-568 was calculated it was much higher then should be theoretically possible. 

The discovery provides an excellent opportunity for astronomers to study black holes in the early Universe and in particular those that challenge the Eddington limit theory. It would however suggest that the outflows of energy are acting to release energy that has built up during extreme accretion periods. Follow up observations are required. 

Source : NSF NOIRLab Astronomers Discover the Fastest-Feeding Black Hole in the Early Universe

The post Early Black Holes Fed 40x Faster than Should Be Possible appeared first on Universe Today.

NASA astronaut Suni Williams says her weight is stable aboard the International Space Station, rebutting tabloid claims that her orbital stay has made her emaciated.

Eventually, every stellar civilization will have to migrate to a different star. The habitable zone around all stars changes as they age. If long-lived technological civilizations are even plausible in our Universe, migration will be necessary, eventually.

Could Extraterrestrial Intelligences (ETIs) use stars themselves as stellar engines in their migrations?

In broad terms, a stellar engine uses a star to generate work. A simple example is solar panels, which use the Sun’s radiation to generate electricity that we use to perform work. But the scaled-up idea is to use the star to produce thrust. That thrust could be used to move the star itself. An ETI capable of doing that would be a Type II civilization on the Kardashev Scale.

To most of us, it seems like a wildly improbable idea. But who knows what’s out there? If an ETI can survive long enough, it may become a Type II civ.

The stellar engine idea dates back to science fiction author Olaf Stapledon. A couple of decades after Stapledon, astronomer Fritz Zwicky also discussed manipulating stars with advanced technology, even turning them into spacecraft. In the decades since, the idea has persisted, and other researchers have delved into it. In 1988, Leonid Shakdov developed the first detailed stellar engine model called the Shakdov Thruster.

In new research, Clement Vidal, from Vrije Universiteit in Brussels, Belgium, examines how an advanced civilization could use a binary star as a stellar engine. The paper is titled “The Spider Stellar Engine: a Fully Steerable Extraterrestrial Design?”

“Since about half the stars in our galaxy are in binary systems where life might develop too, we introduce a model of a binary stellar engine,” Vidal writes. “We apply the model to candidate systems, spider pulsars, which are binary stars composed of one millisecond pulsar and a very low-mass companion star that is heavily irradiated by the pulsar wind.”

Vidal is concerned with stellar engine technosignatures. Research has focused on hypervelocity stars as potential stellar engine technosignatures because they’re easily observable. Other researchers have also proposed other stellar engine concepts, but according to Vidal, they’re “poorly linked to observable technosignatures. ”

Vidal’s main goal in this work is to determine what types of technosignatures a binary stellar engine would emit. He discusses what potential signatures might be emitted by acceleration, deceleration, steering, and maneuvers such as gravitational assists or captures. However, unlike some other researchers, he focuses on a specific type of binary system: spider pulsars, which are a subclass of binary millisecond pulsars.

Pulsars are what remains of some massive stars. At the end of their lives, some massive stars collapse to form neutron stars. When these neutron stars spin rapidly, they produce beams of radiation from their poles. If the radiation is aimed at Earth, then we can observe the pulses of energy. These pulses have exquisitely precise timing, and astronomers use them to determine cosmic distances.

A spider pulsar is a pulsar with a companion, usually a red dwarf, a brown dwarf, or even a planetary-mass object. They’re called spider pulsars because it’s as if the pulsar spins a web of powerful beams of radiation that strips away the companion’s mass, eventually destroying it.

Artist’s impression of a so-called “Black Widow” pulsar PSR B1957+20 (seen in the background) through the cloud of gas enveloping its brown dwarf star companion. Credit: Dr. Mark A. Garlick; Dunlap Institute for Astronomy & Astrophysics, University of Toronto

Vidal’s paper describes the payload as a pulsar with about 1.8 solar masses and the propellant as its low-mass companion star with between 0.01 and 0.7 solar masses.

In essence, the gravitationally bound binary system is the vehicle, and the smaller companion star is the propellant. The spider pulsar generates thrust by expelling propellant out of the gravitational system, and the propellant is the matter stripped from the companion.

The binary pair orbits a common center of gravity. The idea behind this binary stellar engine (BSE) is that as they orbit, the pulsar’s radiation strikes the companion or propellant star. A close binary is more effective because the closer the pulsar is to the propellant, the more thrust is generated. The assumption is that a Type II civilization would have the technology to moderate this thrust to serve their purposes by timing the radiation and heating the outer layers of the propellant star with X-ray or gamma radiation.

To decelerate, the BSE would produce active thrust in the opposite direction of travel. It could also use a passive magnetic sail deployed from the pulsar to transfer momentum to the interstellar medium.

The BSE steers by selectively evaporating the star during different orbital phases. “To choose a direction, it suffices to evaporate the companion star once per orbit, at a specific orbital phase, in order to create consistent thrust in one direction,” Vidal explains.

The top panels show the BSE in different configurations, with the top being the direction of travel. (a) The BSE is in acceleration mode. (b) the BSE is steering to the left. (c) the BSE is decelerating. (d) is a side view that shows changes in the orbital plane by asymmetric heating of the companion, which creates a lifting
force in relation to the orbital plane. The binary separation is not to scale. Image Credit: Vidal et al. 2024.

These various maneuvers and manipulations with the BSE would emit technosignatures. Have astronomers observed any candidate BSEs in the Milky Way? Possibly.

“Could our galaxy host a kind of fully steerable binary stellar engine that we proposed? This is a plausible hypothesis in the context of the stellivore hypothesis, which reinterprets some observed accreting binary stars as advanced civilizations feeding on stars,” Vidal writes.

A stellivore is a hypothesized type of civilization first proposed by Vidal that has the technology to consume its home star via accretion. They use the star’s energy to sustain their existence. Vidal writes that rather than consume the energy, they could use it to migrate to a more favourable location in the galaxy.

“For most of its time, a stellivore civilization would eat its home star via accretion. However, energy is never eternal, and instead of eating its star until the end and dying, a stellivore civilization would use its low-mass companion star as fuel not to be accreted but to be evaporated in order to create thrust and travel towards a nearby star,” Vidal explains.

This brings us to spider pulsars. Rather than accreting material, a spider pulsar appears to be evaporating its propellant companion.

There are two types of spider pulsars: Black Widows and Redblacks. The distinction is in the mass of the companion. In a black widow (BW), the companion is less than 0.1 stellar masses. In a redblack, the companion is between 0.1 and 0.7 stellar masses. Spider pulsars are different from other pulsar binaries because they evaporate their companions rather than accrete them. When pulsars accrete too much material, they can form black holes. Spider pulsars don’t tempt the same fate. Vidal calls these spider stellar engines (SSEs) rather than binary stellar engines (BSEs).

The panels in this figure show PSR J1959+2048, the original Black Widow pulsar. Left: the BW pulsar (in blue) is plotted in the RA-DEC plane, and its proper motion vector is displayed until it reaches a close encounter with a target star, in orange. Middle: a Chandra X-ray view of the BW pulsar, displaying a comet-like tail; the candidate target star is also visible in the bottom right (visualization with ESASky). Right: The composite image on the right shows the X-ray tail (in red/white) and a bow shock visible in the optical (green). Credit: X-ray: NASA/CXC/ASTRON/B. Stappers et al.; Optical: AAO/J.Bland-Hawthorn & H. Jones.

Previous researchers have studied the original BW, and Vidal writes, “… the 3D motion of the system appears to be nearly aligned with the spin axis of the MSP.” This fits in with the SSE interpretation because this perfect alignment is necessary to produce maximum thrust. A stellivore civilization would have a destination in mind, and Vidal says that he’s found a potential destination for the original Black Widow pulsar. He says that the pulsar will reach this target star in about 420 years while also acknowledging the uncertainty in this determination.

PSR J1959+2048, the original BW, also modulates itself, which could be interpreted as steering. However, it also displays other characteristics and moderation that call into question the ‘steering’ interpretation.

Ultimately, Vidal’s SSE may have a shorter duty cycle than other proposed stellar engines, limiting its usefulness. However, it has advantages in steering over others. “Transposing it on a smaller scale, it might also be an inspirational design for advanced propulsion solutions, or for planetary defence purposes such
as deflecting asteroids,” Vidal writes.

The idea may seem preposterous to some, but that’s incidental. Many ideas in history seemed preposterous until they weren’t.

Vidal isn’t claiming that we’re seeing the technosignatures of stellar engines. He’s arguing that it’s worth pursuing the idea of observing them. He sees these candidates and predictions of what their signals might look like as clues and as starting points for further investigation.

“Spider pulsars thus offer observable stellar engine technosignature candidates, with decades of data, active studies that discover, model and monitor these dazzling systems,” he concludes.

The post A Spider Stellar Engine Could Move Binary Stars Halfway Across a Galaxy appeared first on Universe Today.

Data from China's Zhurong rover has revealed what appears to be an ancient shoreline streaking through Mars' northern hemisphere.

Samantha Harvey has won the UK's top fiction prize for a novel that takes place over 24 hours on the International Space Station