Category: Nature

Auroras at Jupiter’s poles act independently

Researchers take advantage of rare opportunity to observe polar regions through Juno mission and space telescopes.

Auroras in Jupiter’s north and south polar regions act independently of one another, according to observations conducted by a study team using the European Space Agency’s (ESA) X-MM-Newton telescope and NASA’s Chandra X-ray Observatory.

Researchers at University College in London and at the Harvard-Smithsonian Center for Astrophysics led a study of high-energy X-ray auroras at both of Jupiter’s poles and were surprised to learn that unlike auroras on the poles of other planets, those at Jupiter’s poles do not mirror one another but pulse independently.

Activities of Earth’s north and south pole auroras mirror one another. Saturn does not appear to experience any X-ray auroras.

X-ray pulses at Jupiter’s south pole occur regularly every 11 minutes while those at its north pole are chaotic, with unpredictable increases and decreases in brightness.

“We didn’t expect to see Jupiter’s X-ray hot spots pulsing independently, as we thought their activity would be coordinated through the planet’s magnetic field,” explained study lead author William Dunn of both UCL Mullard Space Science Laboratory in the UK and the Harvard-Smithsonian Center for Astrophysics.

“We need to study this further to develop ideas for how Jupiter produces its X-ray aurora, and NASA’s Juno mission is really important for this.”

The researchers observed Jupiter using both space observatories in May and June of 2016 and in March 2007 to map the planet’s X-ray emissions and identify X-ray hot spots at its poles.

NASA’s Juno spacecraft, which arrived at Jupiter in 2016, does not have a science instrument capable of detecting X-rays; however, it is collecting other data at the polar regions that scientists hope to combine with the X-MM and Chandra data to better understand the planet’s auroras.

Scientists are fortunate that Juno is studying both of Jupiter’s poles at the same time, making it possible for them to compare activity at the poles with the giant planet’s complex magnetic interactions, emphasized study co-author Graziella Banduardi-Raymont of UCL Space and Climate Physics.

“If we can start to connect the X-ray signatures with the physical processes that produce them, then we can use those signatures to understand other bodies across the universe, such as brown dwarfs, exoplanets, or maybe even neutron stars,” Dunn stated.

One theory the researchers hope to test as they observe Jupiter’s polar activity over the next two years is that the northern and southern auroras form separately as a result of interactions between the planet’s magnetic field and the solar wind.

A paper discussing the findings has been published in the journal Nature Astronomy.

 

Astronomers find another potentially habitable planet 11 light-years away

Astronomers discovered a potentially Earth-like planet just 11 light-years from Earth. They said that it is at the right distance from its star to have liquid water and a climate mild enough to sustain life.

Astronomers in Chile have discovered a planet that may be capable of supporting life and is only 11 light-years away from Earth. In a report soon to be published in Astronomy and Astrophyics, they wrote that the planet could have liquid water and a temperature close to that of Earth.

The astronomers named the planet Ross 128B, after its star, a red dwarf called Ross 128. The planet and star are 20 times closer to each other than Earth is to the sun, according to the researchers, but they said that Ross 128’s radiation and heat are so much lower than our sun’s that the planet could still have an Earthlike temperature.

Xavier Bonfils, of the Institute of Planetology and Astrophysics in France, discovered the new planet in 2016 with Nicola Astudillo-Defru of the Geneva Observatory in Switzerland. Astudillo-Defru said that he and Bonfils made their discovery after a decade of “intensive monitoring” at the La Silla Observatory in Chile.

Ross 128B is the second-closest exoplanet to Earth that astronomers have found so far, according to Bonfils. He said that the closest is Proxima B, which orbits another red-dwarf star Proxima Centauri. Proxima Centauri emits much more radiation than Ross 128, however, and Proxima B receives too much of it to be conducive to life. Bonfils said that Ross 128 B looks much more promising, by comparison, but much would depend on the planet’s own ground conditions.

“We still need to know what the atmosphere of Ross 128 b is like. Depending on its composition and the reflectivity of its clouds, the exoplanet may be life friendly with liquid water as the Earth, or sterile like Venus,” Bonfils told the BBC.

Organics on Ceres are likely native

Distribution of organic materials is inconsistent with delivery by comets or asteroids.

Organic materials found on dwarf planet Ceres by NASA’s Dawn spacecraft are likely native to the small world, according to research by scientists at the Southwest Research Institute (SwRI) in San Antonio, Texas.

The researchers specifically focused on a localized region of organic-rich material near Ernutet Crater, a 32-mile- (52-km-) wide opening on Ceres’ northern hemisphere.

Two origins are theorized for these organic materials or carbon-based compounds. They could have been brought to Ceres by impacting asteroids or comets after the dwarf planet formed 4.5 billion years ago, or they could have been synthesized through an internal process on the dwarf planet.

Located at the boundary of the solar system’s rocky planets and gas giants, Ceres is composed of clays and both sodium- and ammonium-carbonates, all of which indicate the small planet underwent complex chemical evolution.

“Earlier research that focused on the geology of the organic-rich region on Ceres were inconclusive about their origin,” explained Simone Marchi, an SwRI principal investigator who presented the findings Wednesday at a press conference held at the American Astronomical Society’s 49th Division for Planetary Sciences Meeting in Provo, Utah.

“Recently, we more fully investigated the viability of organics arriving via an asteroid or comet impact.”

Through computer simulations, scientists considered a range of variables, including the sizes and velocities of impacting objects.

The simulations indicated comet-like objects that hit Ceres at very high velocities would have had their organic materials destroyed by a mechanism known as shock compression, in which total pressure is lost.

Impacting asteroids, which would have lower velocities, would hold onto between 20 and 30 percent of their organic materials, depending on the angle at which they hit.

However, the localized distribution of organic materials on Ceres is not consistent with what would be seen if those organics had been delivered by small asteroids from the belt between Mars and Jupiter.

While researchers admit they still do not have all the pieces of the puzzle when it comes to Ceres’ organics, “These findings indicate that the organics are likely to be native to Ceres,” Marchi said.

Ceres is geologically differentiated, with a rocky core and icy mantle, and may harbor a subsurface ocean that could possibly be home to microbial life.