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Astronomers used X-rays to calculate a black hole spinning at nearly half the speed of light.

Astronomers have discovered a new way to study black holes, the mysterious cosmic entities that destroy anything in their path. By observing X-ray bursts from a star being torn apart by a black hole, researchers calculated the black hole’s spin rate for the first time using X-rays. The black hole was found spinning at nearly 50 percent of the speed of light. This research, published in Science, opens new possibilities for understanding black holes’ behavior and evolution.

Stellar Destruction and X-ray Emissions

The discovery dates back to November 2014, when astronomers observed a supermassive black hole in a galaxy 300 million light years away. This black hole ripped apart a star that had ventured too close, an event known as a tidal disruption flare. The flare generated intense bursts of X-rays that were visible from Earth. Since black holes themselves don’t produce many X-rays, researchers saw an opportunity to study this flare closely.

Led by scientists from MIT, the team analyzed data from various space telescopes and found something unusual. They noticed that X-ray emissions were appearing every 131 seconds near the black hole’s event horizon, the boundary where objects start to be pulled in. These periodic X-ray bursts, which lasted over 450 days, increased the total X-ray emissions by 40 percent. This consistent pattern provided crucial clues about the black hole’s spin.

A Two-Star System at Play

The team believes that two stars, not just one, were involved in this event. In 2014, the black hole destroyed a passing star, and the remnants were pulled into its gravitational field. Some of the stellar debris was devoured by the black hole, while other fragments settled into the innermost stable circular orbit (ISCO) around the black hole, where they continued to emit X-rays.

Interestingly, the researchers think that a second star, likely a white dwarf, was already orbiting the black hole in the same region. The gravitational pull of this dense white dwarf may have attracted the X-ray-emitting debris, forming a ring of radiation that brightened each time the star orbited the black hole. This orbit occurred every 131 seconds, creating the periodic X-ray flares that researchers detected.

By combining the orbital speed of the star with the estimated mass of the black hole—about one million times the mass of the Sun—the team calculated the black hole’s rotation speed. They determined that it was spinning at roughly half the speed of light.

Unlocking Black Hole Secrets

Although the black hole’s speed is slower than other known black holes, which can spin at 99 percent of the speed of light, this marks the first time researchers have used tidal disruption flares to measure a black hole’s spin. Lead author Dheeraj Pasham of MIT explained, “This is the first time we’re able to use tidal disruption flares to constrain the spins of supermassive black holes.”

Because tidal disruption flares only emit X-rays for a limited time, witnessing one is extremely rare. Still, the researchers plan to study more flare events in both younger and older black holes to understand whether black holes speed up as they age. This information could provide new insights into how black holes evolve and how they interact with the stars in their galaxies.

The kilonova from a neutron star collision formed a surprisingly perfect spherical explosion, baffling scientists.

In 2017, astronomers witnessed the first-ever recorded collision of two neutron stars, named GW170817. This event provided groundbreaking insights into neutron star collisions and their aftermaths. However, recent analysis of the explosion, known as a kilonova, has revealed an unexpected and puzzling discovery: the explosion was a near-perfect sphere. This finding has surprised scientists, challenging long-standing theories about such collisions.

A Spherical Mystery

Astrophysicists expected the kilonova explosion to be asymmetrical, based on models developed over the past 25 years. These models predicted a flattened, irregular shape due to the nature of the collision, where two super-dense stars orbit each other hundreds of times per second before merging. Instead, what the researchers found was a completely spherical explosion. This revelation has left experts questioning their previous understanding of neutron star collisions.

Darach Watson, an astrophysicist at the Niels Bohr Institute, expressed his astonishment at the findings. “It makes no sense that it is spherical, like a ball,” he remarked. According to the researchers, this means there are gaps in the current theories and simulations of kilonovae, suggesting that unknown physics might be at play.

Uncovering Possible Explanations

The spherical shape hints at a new layer of energy involved in these collisions. One possible explanation revolves around the idea of a hypermassive neutron star that forms briefly before collapsing into a black hole. This extremely powerful neutron star, supported by an immense magnetic field, may cause a “magnetic bomb” effect when it collapses. This massive energy release could explain why the kilonova appears spherical, smoothing out any asymmetry that would typically occur in such explosions.

There’s also the question of how heavy elements, such as gold and uranium, form in these collisions. Sneppen’s team detected strontium, a relatively lighter element, distributed symmetrically across the explosion. However, heavier elements were expected to form in different regions of the kilonova. This has led to speculation that neutrinos, elementary particles emitted during the event, might play a critical role in influencing how these elements are forged. These neutrinos could be converting neutrons into protons and electrons, creating more light elements than previously predicted.

The Road Ahead

While these findings have posed new questions, they have also opened the door to further research. The perfect spherical shape and the role of neutrinos hint at complex mechanisms occurring during neutron star collisions that scientists have yet to fully understand. More observations of similar collisions could help unravel these mysteries.

For now, the spherical kilonova from GW170817 has sparked renewed interest in neutron star mergers and the physics behind them, with scientists hoping that future detections will provide more clues about the unseen forces shaping these cosmic events.

The research has been published in Nature.

Less than 1 in 1,000 stars could host a Dyson Sphere, study of 260,000 stars shows.

A team of researchers has recently analyzed 260,000 stars in the Milky Way to explore the possibility of finding Dyson Spheres—hypothetical structures built by advanced civilizations to harness energy from their stars. Their findings, published on the arXiv preprint server, are based on observations from the Gaia Observatory and the AllWISE infrared survey, providing valuable insights into how rare these alien megastructures might be.

What is a Dyson Sphere?

First proposed by physicist Freeman Dyson in 1960, a Dyson Sphere is a theoretical megastructure designed to surround a star and capture its energy output. Dyson suggested that an advanced extraterrestrial civilization would require enormous amounts of energy to fuel its development and might build such a structure to meet its needs. While Earth receives only a tiny fraction of the Sun’s energy, a Dyson Sphere could capture much more, significantly increasing the energy available for a civilization’s use.

Dyson also recommended that the search for extraterrestrial intelligence (SETI) should include infrared radiation, which could indicate the presence of a Dyson Sphere. This is because a megastructure absorbing a star’s energy would emit infrared radiation as a byproduct.

Estimating the Rarity of Dyson Spheres

In the recent study, lead researcher Macy Huston and her team used data from the Gaia Observatory and AllWISE to search for signs of Dyson Spheres. They analyzed the brightness, temperature, and luminosity of the stars to identify any that could be compatible with the characteristics of a Dyson Sphere.

The team modeled Dyson Spheres with a temperature of around 300 Kelvin, estimating how much of a star’s surface they would cover (from 10% to 90%). By comparing these models to real-world star data, they determined how many stars could theoretically support such a structure.

Their results showed that less than one out of every 1,000 stars could support a Dyson Sphere with 10% coverage, less than one in 10,000 for 50% coverage, and fewer than one in 100,000 for 90% coverage. However, Huston cautioned that these are only upper limits, meaning some of the observed stars might have natural causes for their infrared excess that mimic the effects of a Dyson Sphere.

Next Steps in the Search

With the initial analysis complete, the team plans to further investigate the stars that may host Dyson Spheres. By analyzing the full spectral data of these stars, they hope to rule out natural phenomena, such as dusty objects, that could be mistaken for megastructures. They are eagerly awaiting new data from the Gaia mission, expected this summer, which will provide additional information to help refine their search.

The study represents an important step in the ongoing search for extraterrestrial intelligence, offering a glimpse into how rare Dyson Spheres—and potentially alien civilizations—might be in the Milky Way.

The Sun completes one orbit around the Milky Way every 230 million years at 448,000 mph.

It may be surprising, but just like Earth orbits the Sun, our entire solar system, including the Sun, is on a journey through the Milky Way. Our solar system is orbiting the galaxy’s supermassive black hole at the center, and the trip it takes is far more complex than the path planets follow around a star.

The Sun’s Orbit and Speed

The Sun, along with our solar system, is currently traveling through space at a speed of 448,000 mph (720,000 km/h), according to Space.com. Even at this incredible velocity, it takes around 230 million years to complete one full orbit around the Milky Way’s center. For perspective, the last time the Sun was in its current position, dinosaurs still roamed the Earth.

Since the Sun is about 4.6 billion years old, it is estimated that the Sun has made roughly 20 orbits around the galaxy. Earth, which formed about 100 million years after the Sun, has completed approximately 98% of those trips. However, these numbers are estimates and are influenced by the Sun’s changing position over time.

Radial Migration and Galactic Evolution

The Sun’s path through the Milky Way hasn’t remained constant. According to astrophysicist Victor Debattista from the University of Central Lancashire, the Sun likely formed much closer to the Milky Way’s center—about 16,300 light-years away. Today, it resides about 26,100 light-years from the galactic core. This outward movement, known as “radial migration,” is common in galaxies like the Milky Way. Stars can be pushed along the spiral arms of the galaxy, much like how a surfer rides a wave.

This migration means that when the Sun was younger, its orbital period was much shorter, likely around 125 million years. Over billions of years, as it moved outward, its orbital period increased to the current 230 million years. Although the exact number of times the Sun has traveled around the Milky Way is hard to pin down, the phenomenon of radial migration suggests it could have made more orbits than initially calculated.

The Future of the Sun’s Orbit

The Sun’s current orbit is considered relatively stable, but that doesn’t mean its migration is over. Debattista notes that the Sun could continue to move outward, though it’s impossible to predict by how much. Radial migration isn’t unique to our star—Debattista estimates that around half of the stars near the Sun were born elsewhere and have been similarly pushed outward over time.

In summary, while the Sun’s journey around the Milky Way is an incredibly long and complex process, it provides an important glimpse into the dynamic nature of our galaxy and the ever-changing position of stars within it.

X-37B spaceplane’s aerobraking maneuvers could lower orbit without using much fuel.

After spending over nine months in an unusual elliptical orbit, the US military’s secretive X-37B spaceplane is preparing to gradually lower its altitude using a process called aerobraking. This maneuver will enable the spaceplane to reduce its speed by passing through the thin layers of Earth’s upper atmosphere without expending much fuel. The Space Force announced this as part of a plan to ensure the X-37B’s safe return to Earth and prevent space debris accumulation from its jettisoned service module.

A Novel Aerobraking Technique

Aerobraking is a technique in which a spacecraft uses atmospheric drag to slow down, allowing it to change its orbit without using excessive amounts of fuel. For the X-37B, the purpose is twofold: it reduces the spacecraft’s speed and altitude, and it ensures the safe disposal of the service module, a part of the craft designed to carry additional payloads. The Space Force doesn’t want the service module to remain in orbit as space debris, so it will be jettisoned before reentry.

The Space Force called this aerobraking maneuver “novel” and stated that it will allow the X-37B to safely complete its mission, which has been ongoing since its launch aboard a SpaceX Falcon Heavy rocket on December 28. Once the aerobraking is finished, the X-37B will resume its experiments before finally deorbiting and landing, just as it has done on six prior missions.

Space Force’s Focus on Mobility in Orbit

This mission marks a key milestone for the Space Force, which is focused on achieving greater mobility in orbit for future space missions. Current satellites are limited in their movement due to the fuel they carry, but military leaders envision a future where spacecraft can move freely between orbits without worrying about fuel consumption. Aerobraking is one way to achieve this goal, as it allows spacecraft to adjust their orbits without depleting valuable fuel reserves.

Gen. Chance Saltzman, the chief of space operations for the Space Force, emphasized the importance of the X-37B’s aerobraking maneuver, calling it an “important milestone” in the development of space mobility.

The Secretive X-37B Mission

While the X-37B’s aerobraking plans have been announced, much about the mission remains classified. The Pentagon rarely provides updates during an X-37B flight, and specifics about its activities in space are kept secret. However, the Space Force did reveal that the X-37B has been conducting radiation experiments and testing space domain awareness technologies. These activities have taken place in a highly elliptical orbit that brings the spacecraft through the Van Allen radiation belts and near various US and foreign satellites.

In previous missions, the X-37B has tested new space technologies, including a Hall-effect ion thruster, and has deployed small military satellites. The spaceplane is not designed to carry people, and its cargo bay, which is about the size of a pickup truck bed, is used to carry experimental payloads.

In summary, the X-37B’s mission highlights the Space Force’s growing capabilities in space, with aerobraking providing an efficient way to return the spaceplane to Earth while maintaining fuel reserves and avoiding space debris.

As it’s so close to Earth, Mars is the planet that humans will most likely step foot on and explore first.

Ultra Safe Nuclear Corporation (USNC) has introduced a groundbreaking thermal nuclear engine design that could drastically shorten the time it takes for astronauts to travel to Mars. This innovative engine could carry a crew to the Red Planet in just three months and return them to Earth in the same amount of time, cutting current travel estimates by half. This is made possible by USNC’s use of high assay low enriched uranium (HALEU) fuel in ceramic microcapsules, which allows for a lighter and safer nuclear reactor, specifically designed for space travel.

Thermal Nuclear Propulsion: An Old Idea, New Potential

The concept of nuclear propulsion has been around for decades. While the use of nuclear reactions to generate immense heat is well-established in weapons, it has yet to be fully realized for spacecraft propulsion. Past designs lingered in the experimental phase before being abandoned, though they have been revisited occasionally for further research. Unlike chemical rockets, which use liquid oxygen or similar propellants to create combustion, nuclear thermal engines use the heat from nuclear reactions to push rockets at far higher speeds. This advancement brings nuclear-powered rockets closer to the speed required for efficient space travel, making Mars missions more feasible.

USNC’s thermal nuclear engine design arrives at a pivotal moment, shortly after Elon Musk suggested that nuclear propulsion could be critical for ensuring astronaut safety during Mars missions. Musk’s primary concern is the health risk posed by prolonged exposure to cosmic radiation during space travel. A faster trip would significantly reduce the time astronauts are exposed to this dangerous radiation.

The Department of Energy has also weighed in on the safety of HALEU fuel. Although handling nuclear materials always carries risks, HALEU is considered to be less dangerous than many other nuclear options. Moreover, cosmic radiation exposure during a long journey to Mars is likely a far greater threat to astronauts’ safety than handling HALEU fuel.

Leveraging Nuclear Technology for Space Travel

USNC’s nuclear thermal engine builds on existing nuclear technology, particularly its microreactor systems. While USNC is divided into two divisions—USNC-Tech, focused on space reactors, and USNC-Power, focused on terrestrial reactors—both divisions share common technological goals. The same ceramic-encapsulated HALEU fuel used in USNC’s nuclear thermal propulsion system will also be used in its terrestrial microreactor energy facilities. This overlap allows USNC to apply advancements in nuclear technology to both space and Earth-based systems.

According to USNC-Tech CEO Paolo Venneri, the ability to transfer nuclear technology between terrestrial and space applications is key to the company’s success. Their nuclear engine is designed to provide twice the thrust of traditional chemical engines while offering improved stability, thanks to the encapsulated fuel. This increased thrust is crucial, as chemical rockets have nearly reached their maximum efficiency and capacity. To move beyond the limits of chemical propulsion, nuclear technology is seen as the most viable path forward.

In conclusion, USNC’s new nuclear engine marks a major step toward more rapid and efficient space travel. If successful, this technology could revolutionize how we explore distant planets, potentially bringing human missions to Mars within reach. With its combination of safety, speed, and stability, nuclear propulsion could be the key to unlocking the next era of space exploration.