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Astronomers have observed an accreting white dwarf abruptly lose and gain its brightness for the first time. White dwarfs are stars that have run out of their basic fuel: hydrogen. Usually, researchers have observed white dwarfs losing their brightness over days or months. Astronomers were studying the white dwarf binary system, TW Pictoris, and the white dwarf in it lost its brightness in 30 minutes, which surprised astronomers. Astronomers said it was accreting, or feeding on the energy from an orbiting companion star. To observe the unique phenomenon, astronomers used NASA’s Transiting Exoplanet Survey Satellite (TESS) that helps in planet-hunting processes.

The brightness of a white dwarf is not dependent on its own hydrogen source, as it has already exhausted it. Its brightness depends on the amount of surrounding material that it feeds on. The abrupt switching on and off of the white dwarf may be due to some interference with food supply, said researchers.

The research was led by England’s Durham University. The findings were published on October 18, 2021, in the Nature Astronomy journal.

TW Pictoris comprises a white dwarf and a smaller companion star. The white dwarf feeds from the accretion disc that is fuelled by hydrogen and helium from the companion star. The more energy it feeds on, the brighter it becomes.

Researchers noticed the abrupt rise and fall in the brightness of this white dwarf, the likes of which they had never seen before. They believe this could be caused by reconfiguration of the white dwarf’s surface magnetic field.

At its brightest phase, the white dwarf feeds off the accretion disc. But suddenly the magnetic field starts spinning so rapidly that a centrifugal barrier is created. This stops the fuel from the accretion disc to reach the white dwarf.

The “magnetic gating” regulates the fuel passing from the disc to the white dwarf. Due to the small amount of fuel passing through the “gate” the white dwarf experiences semi-regular small increases in brightness.

Then, the system switches “on” again, allowing the white dwarf to feed normally from the disc. The brightness reaches its peak again.

Lead author Dr. Simone Scaringi said, “This really is a previously unrecognised phenomenon and because we can draw comparisons with similar behaviour in the much smaller neutron stars it could be an important step in helping us to better understand the process of how other accreting objects feed on the material that surrounds them and the important role of magnetic fields in this process.”

This extraordinary observation could lead to further studies of white dwarfs and neutron stars.


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How NASA Saved a Dying Camera Near Jupiter with Just Heat

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How NASA Saved a Dying Camera Near Jupiter with Just Heat

NASA’s Juno spacecraft, in orbit around Jupiter, had a huge problem when its JunoCam imager started to fail after sitting through the planet’s harsh radiation belts for so many orbits. Designed to only last through the initial few orbits, JunoCam astonishingly endured 34 orbits. Yet by the 47th orbit, the effects of radiation damage became visible, and by the 56th orbit, images were almost illegible. With few alternatives and time slipping away before a close flyby of Jupiter’s volcanic moon Io, engineers made a daring but creative gamble. Employing an annealing process, they sought to resuscitate the imager by warming it up—an experiment that proved successful.

Long-distance fix

According to NASA, JunoCam’s camera resides outside the spacecraft’s radiation-shielded interior and is extremely vulnerable. After several orbits, it started developing damage thought to be caused by a failing voltage regulator. From a distance of hundreds of millions of miles, the mission team implemented a last-ditch repair: annealing. The technique, which subjects materials to heat in order to heal microscopic defects, is poorly understood but has been succeeding in the lab. By heating the camera to 77°F, scientists wished to reorient its silicon-based parts.

At first, efforts were for naught, but only days before the December 2023 flyby of Io, the camera unexpectedly recovered—restoring close-to-original image quality just in time to photograph previously unseen volcanic landscapes.

Radiation Lessons for the Future

Though the camera showed renewed degradation during Juno’s 74th orbit, the successful restoration has led to broader applications. The team has since applied similar annealing strategies to other Juno instruments, helping them withstand harsh conditions longer. Juno’s findings are now informing spacecraft design across the board. “We’re learning how to build radiation-tolerant systems that benefit both defense and commercial satellites,” said Juno’s principal investigator Scott Bolton. These findings would inform future missions, such as those visiting outer planets or working in high-radiation environments near Earth, in the Van Allen belts. Juno’s mission continues to pay dividends with unexpected innovations—a lesson in how a small amount of heat can do wonders.

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NASA’s X-59 Moves Closer to First Flight with Advanced Taxi Tests and Augmented Vision

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NASA’s X-59 Moves Closer to First Flight with Advanced Taxi Tests and Augmented Vision

X-59 of NASA has been designed from the ground to fly at a faster speed of sound without making thunderous sonic booms, which are usually associated with supersonic flight. This 99-foot aircraft, which features a logically elongated design, jettisons the front windscreen and is now heading towards the runway. Pilots can see what is at the front through an augmented reality (AR) enabled closed-circuit camera system, which is termed by NASA as the External Vision System (XVS). NASA took control of an experimental aircraft and performed taxi tests on it during this month.

X-59’s Futuristic Design: Eliminating Sonic Booms with External Vision System

According to As per NASA, the test pilot Nils Larson, during the test, drove the X-59 at the runway by keeping a low speed. This is done to ensure the working of the steering and braking systems of the jet. Lockheed Martina and NASA would perform the taxi tests at high speed, in which the X-59 will move faster to make it to the speed at which it will go for takeoff.

Taxi tests are held at the U.S. Air Force’s Plant 42 facility in Palmdale, California. The contractors and the Air Force utilise the plant for manufacturing and testing the aircraft. Lockheed Martin has developed this aircraft, whose Skunk Works is found in Plant 42.

Taxi Tests at Plant 42: NASA and Lockheed Martin Prepare X-59 for First Flight

Some advanced aircraft of the U.S. military were developed to a certain extent at Plant 42, together with the B-2 Spirit, the F-22 Raptor, and the uncrewed RQ-170 Sentinel spy drone.

SOFIA airborne observatory aircraft, which is a flying telescope called Plant 42, home recently retired. The space shuttle of the agency is the world’s first reusable spacecraft; these were assembled and tested at the facility.

Such taxi tests have started over the last months. NASA worked in collaboration with the Japan Aerospace Exploration Agency for testing a scale model of the X-59 in the supersonic wind tunnel to measure the noise created under the aircraft.

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Unusual Plasma Waves Above Jupiter’s North Pole Can Possibly Be Explained

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Unusual Plasma Waves Above Jupiter’s North Pole Can Possibly Be Explained

In recent observations, NASA’s Juno spacecraft has significantly detected the presence of a variety of plasma waves. The emergence of these waves on Jupiter’s powerful magnetic field is projected to be surprising, as their existence was never marked in the planetary magnetospheres. However, scientists might have come out with an explanation. Furthermore, the current studies have been questioned by scientists surfacing the activity at the North Pole. The article below will exemplify the findings and shed light on the plasmas. 

Uncovering Mystery at Jupiter’s North Pole 

According to a paper published in the Physical Review Letters, the scientists have uncovered the explanation behind the presence of these strange waves. They mainly suspect that the formation of these waves lies behind their evolution as a plasma, which later transforms into something different. 

Inside Jupiter’s Plasmas and Their Variants 

Plasmas are best referred to as the waves that pass through the amalgamation of the charged particles in the planet’s magnetosphere.These plasma waves come across in two forms: One, Langmuir waves, which are high-pitched lights crafted with electrons, while the other, Alfven waves, are slower, formed by ions (heavy particles). 

About Juno’s Findings

As unveiled by the Juno, the findings turned out to be questionable after the scientists noted that in Jupiter’s far northern region, the plasma waves were relatively slower. The magnetic field is about 40 times stronger than the Earth’s, but scientists were shocked to witness the results as the waves were slower. To analyse this further, a team from the University of Minnesota, led by Robert Lysak, identified the possibility of Alfven waves transforming into Langmuir waves. Post studying the data extracted from the Juno, the researchers then began to compare the relationship between the plasma wave frequency and number. 

According to Lysak’s research team, near Jupiter’s north pole, there might be a potential pathway of Alfven waves, which are massive in numbers, transforming into Langmuir waves. Scientists are also predicting that the reason behind evolution might be strong electrons that are shooting upwards at a very high energy. This discovery was made in the year 2016. Considering the current findings, the researchers indicate that Jupiter’s magnetosphere may comprise a new type of plasma wave mode that occurs during high magnetic field strength. 

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