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Possible discovery of a new super-Earth orbiting Proxima Centauri – Phys.org

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Credit: Lorenzo Santinelli, CC BY-SA

Astronomers have discovered another candidate exoplanet orbiting our neighbor Proxima Centauri. A paper announcing these results was just published in the journal Science Advances. If confirmed, it will be the second exoplanet discovered to be orbiting the star.

It was big news in 2016 when astronomers discovered a planet orbiting Proxima Centauri (PC), the nearest star to our sun. That planet, named Proxima b, is potentially habitable, and at the time, there was speculation that we could send a robotic explorer there in only a few decades. The discovery of a second planet, even though it’s likely too far away from its star for liquid water, is intensifying interest in the PC system.

The discoverers of this new planet, Proxima c, say that follow-up observations are needed to confirm it as a planet. Changes in the stellar activity of Proxima Centauri indicated the presence of another planet. But they also say that the data they have can’t be explained in terms of any stellar activity itself. Due to its proximity, and also its angular separation from the star, it is a prime candidate for follow-up observations—and even imaging—with next generation telescopes.

Proxima c’s mass is about half that of Neptune and its orbit is about 1.5 times that of Earth. Its temperature is about -200 C, if it has no atmosphere. Proxima Centauri has undergone intense astronomical scrutiny in the last few years, and that has ruled out the presence of any Jupiter-sized between 0.8 and 5+ astronomical units from the star. But finding Proxima c is still surprising, because its presence challenges our models of how super-Earths form and evolve.

The lead author of this study is Mario Damasso from the INAF Astrophysical Observatory of Turin, Italy. The study is titled “A low-mass planet candidate orbiting Proxima Centauri at a distance of 1.5 AU.” It was published on January 15th, 2020.

Hugh Jones, a Professor of Astrophysics at Hertfordshire University, was also involved in the study. In an article in The Conversation, Jones pointed out how difficult it can be to separate data showing the presence of a planet, from data showing stellar activity at the host star. “Just like our sun, Proxima has spots caused by regions of intense magnetic activity which are moving in and out of view, changing in intensity on a variety of timescales. These features need to be considered when searching for any planetary signals.”

Even though stellar activity doesn’t match the data, the discoverers are being cautious until follow-up observations can either confirm or deny the presence of Proxima c, and definitively rule out stellar activity.

**Possible discovery of a new super-Earth orbiting Proxima Centauri
Red dwarfs host more small planets than other types of stars. This is an artist’s impression of the TRAPPIST-1 system, showcasing all seven planets in various phases. Credit: NASA/JPL-Caltech

The discovery of this new candidate exoplanet is contained in this new paper, but the history goes back a few years.

Multiple teams of scientists have scoured Proxima Centauri for exoplanets. Much of their work depended on radial velocity data, notably from the ESO’s HARPS (High Accuracy Radial velocity Planet Searcher.) Study by study, astronomers have excluded the presence of certain mass-range planets within certain AU ranges from PC.

A 1999 study excluded the presence of any planets beyond 1700 AUs of PC, because PC itself orbits Alpha Centauri AB. A 2019 study set an upper limit of 0.3 Jupiter masses for any planet within 10 AU of PC. That same study excluded the presence of planets between 10 and 50 AU in the mass range 0.3 to 8 masses of Jupiter. Other studies put on more constraints.

But astronomers also know that red dwarfs host more small planets than other types of stars. So they kept looking.

Can We Really Send a Spacecraft There?

The Breakthrough Starshot Initiative (BSI) thinks they can send a tiny spacecraft to Proxima Centauri.

When the Centauri b exoplanet was discovered in 2016, the BSI got to work. They think they can send a nano-spacecraft with cameras to within one AU of the planet and return images much more detailed than we can hope to achieve with any telescope. They say they should be able to return images showing continents and oceans. On their website, BSI says “To achieve comparable resolution with a space telescope in Earth’s orbit, the telescope would have to be 300km in diameter.”

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But even though PC is “close” in astronomical terms, it’s still an immense distance away. At 4.2 light years away, it would still take decades to get there, traveling at 20% the speed of light (about 216,000,000 kilometers per hour.) Currently, the fastest spacecraft is NASA’s Parker Solar Probe, which will reach a top speed of only 692,000 km/h.

But whether we can get a spacecraft there or not is only part of the story. Due to its proximity, the Proxima Centauri system is an observable laboratory for understanding other solar systems. And its presence and proximity might spur further technological development needed to study it and other systems in more detail.

As Hugh Jones said in his article at The Conversation, “Ultimately, the discovery of multiple signals from the very closest star shows that planets are more common than stars. Proxima represents an excellent location for understanding the closest exoplanets and developing new technologies to better understand the universe we live in.”

Proxima c’s existence is problematic, or at least significant, for our planet formation models. Among super-Earth planets around low-mass detected by radial velocity, Proxima c would have both the longest period and the lowest mass. It would also be the furthest distance from its parent star than the frost line in the original protoplanetary disk. The frost line was probably at 0.15 AU.

The authors say that it’s unlikely that Proxima c was kicked out from its initial position closer to the star due to some instability, “because its orbit is consistent with a circular one, and because of the absence of more massive planets on shorter orbital distance.”

In their paper, they say, “The formation of a super-Earth well beyond the snowline challenges formation models according to which the snowline is a sweet spot for the accretion of super-Earths, due to the accumulation of icy solids at that location.”

Proxima Centauri is a red dwarf star, or M dwarf. It’s about 4.2 away from the sun, making it our closest neighbor. It’s the third star in a trinary system, with the Alpha Centauri AB binary star. Proxima Centauri is about 13,000 AU from Alpha Centauri AB, and was discovered in 1915.


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Evidence of another possible planet orbiting Proxima Centauri


More information:
Mario Damasso et al. A low-mass planet candidate orbiting Proxima Centauri at a distance of 1.5 AU, Science Advances (2020). DOI: 10.1126/sciadv.aax7467

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Powerful gases ripping a hole in the ozone

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Half of Arctic climate change between 1955 and 2005 may be attributed to ozone-depleting substances banned in 1987 by the Montreal Protocol.
Image: Mario Tama / Getty Images
They were once abundant, in our hairsprays, bug sprays, and refrigerators. And then scientists figured out these substances ripped a hole in the ozone layer, leading to a 1987 plan to phase them out that over time would be agreed to by every country in the world.

More than three decades later, researchers have made a new discovery.

Ozone-depleting substances do more than just gnaw at Earth’s protective layer. They’re also greenhouse gases, so they contribute to the planet’s overall warming by trapping heat, too. And now we may know just how much these substances have contributed to Arctic warming, thanks to a study published in the science journal Nature on Monday.

Between 1955 and 2005, ozone-depleting gases caused half of Arctic climate change (and a third of overall global warming), the study finds. This is primarily due to their heat-trapping qualities, not their ozone munching. The Arctic has seen rapidly melting sea ice for years and is warming faster than the rest of the world. When the sea ice melts in the Earth’s northernmost region, sea levels rise across the globe leading to potential flooding.

Between 1955 and 2005, ozone-depleting gases caused half of Arctic climate change.

These ozone-depleting gases include chlorofluorocarbons (CFCs), which we’ve been cracking down on since the global agreement known as the Montreal Protocol was finalized 33 years ago. CFCs, which include propellants and refrigerants, have been around since the 1920s and 1930s. Their popularity peaked in the late 20th century and have been on the decline since the Montreal Protocol.

To quantify the climate impact of ozone-depleting gasses, scientists from Columbia University, the Institute for Atmospheric and Climate Sciences in Switzerland, and University of Toronto used climate models to run a variety of simulations. In one, they tested what would happen if stratospheric ozone and the pesky gases that hurt it stayed at 1955 levels. Research on CFCs’ climate impacts beyond ozone depletion is scant, even though they can trap more heat than climate change poster child carbon dioxide, the study notes.

The study’s findings not only give an extra gold star to the much-acclaimed Montreal Protocol, but also provide a bit of hope when so much climate change research focuses on doom and gloom.

“Our findings also have implications for the future because the phase-out of [ozone-depleting substances], which is well under way, will substantially mitigate Arctic warming and sea-ice melting in the coming decades,” the study explains.

Indeed, Cecilia Bitz, a climate scientist at the University of Washington in Seattle who was not involved in the study, told Nature, “It’s a very important paper because it has a little shred of optimism.”

Don’t get too excited just yet, though. More studies that replicate these findings need to be done to corroborate the evidence, Bitz, the study authors, and other scientists say.

Then there’s also the problem of CFCs still being used despite global crackdowns. For example, China is struggling to tamp down on illegal CFC production. In addition, we’ve just begun to tackle hydrofluorocarbons (HFCs), which air conditioner and refrigerator manufacturers turned to when they were blocked from CFCs, on a global scale. HFCs are less harmful for the ozone than CFCs, but like their loathed counterpart, they’re more powerful than carbon dioxide when it comes to trapping heat.

And to be clear, weakening the ozone is still a very bad trait to have. Scientists expect it’ll take another 50 years before the ozone hole over Antarctica is back to its 1980 level.

Sorry to be a downer.

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'Dancing dragon' feathered dinosaur fossil discovered in China – CNN

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Researchers named the dinosaur Wulong bohaiensis, which translates to “a dancing dragon.”
The dinosaur was about the size of a raven but double its length with a long, bony tail. Its entire body was covered with feathers, complete with two plumes at the tail’s end.
Despite its small size, it had a fierce, narrow face and a mouth full of sharp teeth. Like a bird, it had small, light bones and wing-like forelimbs. And there were also a number of feathers on its legs.
The fossil was initially discovered in the fossil-filled Jehol Province a decade ago by a farmer and was placed in China’s Dalian Natural History Museum.
Researchers, including Ashley Poust, a postdoctoral researcher at the San Diego Natural History Museum, later analyzed the fossil (at the time, Poust was still a student at Montana State University).
Insects trapped in amber show that lice munched on feathered dinosaurs
The findings were published last week in the journal The Anatomical Record.
“The new dinosaur fits in with an incredible [range] of feathered, winged animals that are closely related to the origin of birds,” Poust, the study’s author, said. “Studying specimens like this not only shows us the sometimes surprising paths that ancient life has taken, but also allows us to test ideas about how important bird characteristics, including flight, arose in the distant past.”
An artist rendering of what Wulong bohaiensis might have looked like. An artist rendering of what Wulong bohaiensis might have looked like.
This dinosaur was a juvenile when it died, according to its bones, but its feathers resembled that of a mature adult. This suggests that the feathers grew quickly, unlike modern birds, which take time to grow their mature feathers.
“Either the young dinosaurs needed these tail feathers for some function we don’t know about, or they were growing their feathers really differently from most living birds,” Poust said.
Trapped in place: A weird ancient bird foot in amber and the lizard in a Microraptor's stomachTrapped in place: A weird ancient bird foot in amber and the lizard in a Microraptor's stomach
The dinosaur was an early relative of Velociraptors, which lived 75 million years ago. Its contemporaries would have been Microraptors, small feathered dinosaurs that resembled birds.
The researchers actually sliced into several bones from the fossil and studied them with microscopes to understand the different regions of the skeleton. They also compared it to a close relative that also appeared more mature, known as the Sinornithosaurus.
'Frozen dragon of the north wind' was one of the largest animals to ever fly'Frozen dragon of the north wind' was one of the largest animals to ever fly
Surprisingly, that dinosaur was also still growing when it died. The researchers said that histology, or cutting up the bones, was the only way for them to truly know the life stage of the dinosaurs when they died.
Fluffy dinosaurs used to live at the South Pole, scientists sayFluffy dinosaurs used to live at the South Pole, scientists say
“We’re talking about animals that lived twice as long ago as T. rex, so it’s pretty amazing how well-preserved they are,” Poust said. “It’s really very exciting to see inside these animals for the first time.”
Fossils from the Jehol Province have painted a portrait of the diverse life that once flourished there. It’s an area in northeastern China full of exceptionally preserved fossil discoveries that has been studied for the past 90 years.
A closer look at the skull, along with a detailed drawing.A closer look at the skull, along with a detailed drawing.
Researchers learned that birds, pterosaurs and bird-like dinosaurs all lived in the environment at the same time. This is also when flowering plants initially began to flourish.
“There was a lot of flying, gliding and flapping around these ancient lakes,” Poust said. “As we continue to discover more about the diversity of these small animals, it becomes interesting how they all might have fit into the ecosystem. It was an alien world, but with some of the earliest feathers and earliest flowers, it would have been a pretty one.”

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Space rock twice the size of Big Ben to skim past Earth – MENAFN.COM

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(MENAFN – IANS)

Washington, Jan 20 (IANS) NASA is closely monitoring an asteroid with an estimated diameter of about 755 feet — larger than the Golden Gate Bridge tower or more than twice the height of London’s Big Ben — that is currently heading towards Earth and is expected to skim past the planet on Monday.

Flying towards the planet at a speed of over 61,500 miles per hour, the Near-Earth Object (NEO) is big enough to destroy an entire city if collides with the Earth.

The approaching asteroid has been identified as “2020 AQ1”.

According to Express.co.uk, the asteroid will make its closest Earth approach on January 20 at around 2.54 am EST (1.24 pm India time).

The European Space Agency (ESA) has identified 21,655 NEO asteroids and 109 NEO comets.

The asteroid will hurtle past the planet on what astronomers have described as a “close approach” trajectory.

NASA’s trackers estimate the rock measures somewhere in the range of 328 feet -754 feet across – more than twice the height of London’s Big Ben.

Last September, a pair of asteroids flew past the Earth.

“These asteroids have been well observed and their orbits are very well known,” said NASA’s Planetary Defence Officer Lindley Johnson.

“Both of these asteroids are passing at about 14 lunar distances from the Earth, or about 3.5 million miles away, but small asteroids pass by Earth this close all the time,” he added.

–IANS

na/ksk/

MENAFN2001202002310000ID1099574382

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