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Category: space – Page 632

Record-Breaking Laser Pulses Allow Astrophysical Phenomena to Be Studied in the Lab

Researchers have demonstrated a record-high laser pulse intensity of over 1023 W/cm2 using the petawatt laser at the Center for Relativistic Laser Science (CoReLS), Institute for Basic Science in the Republic of Korea. It took more than a decade to reach this laser intensity, which is ten times that reported by a team at the University of Michigan in 2004. These ultrahigh intensity light pulses will enable exploration of complex interactions between light and matter in ways not possible before.

The powerful laser can be used to examine phenomena believed to be responsible for high-power cosmic rays, which have energies of more than a quadrillion (1015) electronvolts (eV). Although scientists know that these rays originate from somewhere outside our solar system, how they are made and what is forming them has been a longstanding mystery.

“This high intensity laser will allow us to examine astrophysical phenomena such as electron-photon and photon-photon scattering in the lab,” said Chang Hee Nam, director of CoReLS and professor at Gwangju Institute of Science & Technology. “We can use it to experimentally test and access theoretical ideas, some of which were first proposed almost a century ago.”

A NASA Spacecraft Just “Touched” the Outer Layer of the Sun

NASA’s Parker Solar Probe just took its closest pass to the Sun yet, veering so close that it “touched” the star’s blisteringly hot outer atmosphere — and gave NASA an unprecedented firsthand look at it.

The car-sized spacecraft has zoomed past the Sun a few times now, veering closer and closer each time, according to CNET. Each time, it uses nearby Venus’ gravitational pull as a sort of slingshot that helps it travel closer to the Sun and propels it at higher and higher speeds each time.

The slingshot is working so well that the space probe broke two records during its most recent solar approach last week.

Study places new constraints on the time variation of gravitational constant G

Past physics theories introduced several fundamental constants, including Newton’s constant G, which quantifies the strength of the gravitational interaction between two massive objects. Combined, these fundamental constants allow physicists to describe the universe in ways that are straightforward and easier to understand.

In the past, some researchers wondered whether the value of changed over cosmic time. Moreover, some alternative theories of gravity (i.e., adaptations or substitutes of Einstein’s theory of general relativity), predict that the constant G varies in time.

Researchers at the International Centre for Theoretical Sciences of the Tata Institute for Fundamental Research in India recently proposed a method that can be used to place constraints on the variation of G over cosmic time. This method, outlined in a paper published in Physical Review Letters, is based on observations of merging binary neutron stars.

Gravitational-wave scientists propose new method to refine the Hubble Constant—the expansion and age of the universe

A team of international scientists, led by the Galician Institute of High Energy Physics (IGFAE) and the ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav), has proposed a simple and novel method to bring the accuracy of the Hubble constant measurements down to 2% using a single observation of a pair of merging neutron stars.

The universe is in continuous expansion. Because of this, distant objects such as galaxies are moving away from us. In fact, the further away they are, the faster they move. Scientists describe this expansion through a famous number known as the Hubble constant, which tells us how fast objects in the universe recede from us depending on their distance to us. By measuring the Hubble constant in a precise way, we can also determine some of the most fundamental properties of the universe, including its age.

For decades, scientists have measured Hubble’s constant with increasing accuracy, collecting electromagnetic signals emitted throughout the universe but arriving at a challenging result: the two current best measurements give inconsistent results. Since 2015, scientists have tried to tackle this challenge with the science of gravitational waves, ripples in the fabric of space-time that travel at the speed of light. Gravitational waves are generated in the most violent cosmic events and provide a new channel of information about the universe. They’re emitted during the collision of two —the dense cores of collapsed —and can help scientists dig deeper into the Hubble constant mystery.

NASA’s Parker Solar Probe Discovers Radio Signal in Venus’ Atmosphere

During a brief swing by Venus, NASA ’s Parker Solar Probe detected a natural radio signal that revealed the spacecraft had flown through the planet’s upper atmosphere. This was the first direct measurement of the Venusian atmosphere in nearly 30 years — and it looks quite different from Venus past. A study published today confirms that Venus’ upper atmosphere undergoes puzzling changes over a solar cycle, the Sun’s 11-year activity cycle. This marks the latest clue to untangling how and why Venus and Earth are so different.

Born of similar processes, Earth and Venus are twins: both rocky, and of similar size and structure. But their paths diverged from birth. Venus lacks a magnetic field, and its surface broils at temperatures hot enough to melt lead. At most, spacecraft have only ever survived a couple hours there. Studying Venus, inhospitable as it is, helps scientists understand how these twins have evolved, and what makes Earth-like planets habitable or not.

On July 11, 2020, Parker Solar Probe swung by Venus in its third flyby. Each flyby is designed to leverage the planet’s gravity to fly the spacecraft closer and closer to the Sun. The mission — managed by Johns Hopkins Applied Physics Laboratory in Laurel, Maryland — made its closest flyby of Venus yet, passing just 517 miles (833 km) above the surface.

Researchers discover the mechanism that likely generates huge white dwarf magnetic fields

A dynamo mechanism could explain the incredibly strong magnetic fields in white dwarf stars according to an international team of scientists, including a University of Warwick astronomer.

One of the most striking phenomena in astrophysics is the presence of magnetic fields. Like the Earth, and stellar remnants such as have one. It is known that the magnetic fields of white dwarfs can be a million times stronger than that of the Earth. However, their origin has been a mystery since the discovery of the first magnetic white dwarf in the 1970s. Several theories have been proposed, but none of them has been able to explain the different occurrence rates of magnetic white dwarfs, both as individual stars and in different binary star environments.

This uncertainty may be resolved thanks to research by an international team of astrophysicists, including Professor Boris Gänsicke from the University of Warwick and led by Professor Dr. Matthias Schreiber from Núcleo Milenio de Formación Planetaria at Universidad Santa María in Chile. The team showed that a dynamo mechanism similar to the one that generates magnetic fields on Earth and other planets can work in white dwarfs, and produce much stronger fields. This research, part-funded by the Science and Technology Facilities Council (STFC) and the Leverhulme Trust, has been published in the prestigious scientific journal Nature Astronomy.

New Laser to Help Clear the Sky of Space Debris

Researchers at The Australian National University (ANU) have harnessed a technique that helps telescopes see objects in the night sky more clearly to fight against dangerous and costly space debris.

“Adaptive optics is like removing the twinkle from the stars.”

The researchers’ work on adaptive optics — which removes the haziness caused by turbulence in the atmosphere — has been applied to a new ‘guide star’ laser for better identifying, tracking and safely moving space debris.