Connect with us

Science

This is an Actual Image of a Planet-Forming Disc in a Distant Star System – Universe Today

Published

on


In 2017, astronomers used ALMA (Atacama Large Millimeter/sub-millimeter Array) to look at the star AB Aurigae. It’s a type of young star called a Herbig Ae star, and it’s less then 10 million years old. At that time, they found a dusty protoplanetary disk there, with tell-tale gaps indicating spiral arms.

Now they’ve taken another look, and found a very young planet forming there.

Young Herbig Ae stars like AB Aurigae are of great interest to astronomers. They’re so young they’re not main sequence stars yet, and they’re still surrounded by their circumstellar disk of gas and dust. And out of that gas and dust, young planets are forming.

The disk around AB Aurigae, which is over 500 light years away, has spiral arms that meet in a knot. Scientists believe that the knot is the precise point where a young planet is forming. A new study used the SPHERE (Spectro-Polarimetric High-contrast Exoplanet REsearch) instrument on the Very Large Telescope (VLT) to take a closer look at AB Aurigae and the planets developing inside its disk.

The new study is titled “Possible evidence of ongoing planet formation in AB Aurigae.” Lead author of the study is Anthony Boccaletti from the Observatoire de Paris, PSL University, France. The paper is published in the journal Astronomy and Astrophysics.

“Thousands of exoplanets have been identified so far, but little is known about how they form,” said lead author Boccaletti in a press release. Observing young, still-forming planets is a big deal in astronomy right now, but it’s difficult. The circumstellar disk around the star is difficult to see into, and even our best technology is barely up to the task.

Artist’s impression of circumstellar disk of debris around a distant star. These disk are common around younger stars, and they’re difficult to see into. Credit: NASA/JPL

The SPHERE instrument was critical to this work. It’s an advanced adaptive optics system, combined with a coronoagraph. It was developed to advance the study of exoplanets, with low-resolution spectrographic and polarimetric images. It images in both optical and infrared light. SPHERE allowed the team behind this study to focus on the earliest stages of planetary formation.

“We need to observe very young systems to really capture the moment when planets form,” said Boccaletti. That twisted knot where the spiral arms of AB Aurigae’s circumstellar disk meet is as close as we’ve come to capturing that moment.

These spirals indicate the birth of a baby planet. That’s because the planet’s mass has an effect on the less dense gas and dust in the disk. Essentially, the planet kicks the material in the disk, creating a visible wave: the spirals.

“The twist of the spiral is perfectly reproduced with a planet-driven density wave model when projection effects are accounted for.”

From the Study “Possible evidence of ongoing planet formation in AB Aurigae.”

According to Emmanuel Di Folco of the Astrophysics Laboratory of Bordeaux (LAB), France, who took part in this study, the young planets create “disturbances in the disc in the form of a wave, somewhat like the wake of a boat on a lake.” And as the young planet rotates around the central star, those disturbances become spiral arms.

The images of the AB Aurigae system showing the disc around it. The image on the right is a zoomed-in version of the area indicated by a red square on the image on the left. It shows the inner region of the disc, including the very-bright-yellow ‘twist’ (circled in white) that scientists believe marks the spot where a planet is forming. This twist lies at about the same distance from the AB Aurigae star as Neptune from the Sun. The blue circle represents the size of the orbit of Neptune. The images were obtained with the SPHERE instrument on ESO’s Very Large Telescope in polarised light. Image Credit: ESO/Boccaletti et al, 2020
The images of the AB Aurigae system showing the disc around it. The image on the right is a zoomed-in version of the area indicated by a red square on the image on the left. It shows the inner region of the disc, including the very-bright-yellow ‘twist’ (circled in white) that scientists believe marks the spot where a planet is forming. This twist lies at about the same distance from the AB Aurigae star as Neptune from the Sun. The blue circle represents the size of the orbit of Neptune. The images were obtained with the SPHERE instrument on ESO’s Very Large Telescope in polarised light. Image Credit: ESO/Boccaletti et al, 2020

In their paper the authors caution us that we’re still learning what goes on inside these circumstellar veils that surround young stars. We’re still in the early days of seeing into those structures, and they aren’t certain that this twist is a planet.

“SPHERE has delivered the deepest images ever obtained for AB Aur in scattered light. Among the many structures that are yet to be understood, we identified not only the inner spiral arms, but we also resolved a feature in the form of a twist in the eastern spiral at a separation of about 30 au.”

Are they certain it’s a planet? Not exactly, but the twist feature matches modelling. “The twist of the spiral is perfectly reproduced with a planet-driven density wave model when projection effects are accounted for,” the authors write.

Initial observations of AB Aurigae made with ALMA, but without SPHERE, showed the pair of spiral arms. But ALMA alone didn’t reveal as much information. It revealed tantalizing hints, though, that planets were forming.

ALMA image of the dust ring (red) and gaseous spirals (blue) of the circumstellar disk AB Aurigae reveal gaseous spiral arms inside a wide dust gap, providing a hint of planet formation. By ALMA (ESO/NAOJ/NRAO)/Tang et al. – https://www.almaobservatory.org/en/press-release/astronomers-found-spirals-inside-a-dust-gap-of-a-young-star-forming-disk/, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=87359440

Though ALMA is a powerful tool, SPHERE is even more powerful. It can see the very faint light from dust grains, and emissions that come from the inner disk. Astronomers were able to see the details in the spirals, and the “twist” at their center.

“The twist is expected from some theoretical models of planet formation,” says co-author Anne Dutrey, also at LAB. “It corresponds to the connection of two spirals  — one winding inwards of the planet’s orbit, the other expanding outwards — which join at the planet location. They allow gas and dust from the disc to accrete onto the forming planet and make it grow.”

The disk is an elaborate structure, and astronomers observed many other structures within it. Two of them were of particular interest, marked f1 and f2 in this image. Both of these are SPHERE images, each one with a different intensity threshold. Image Credit: Boccaletti et al, 2020.
The disk is an elaborate structure, and astronomers observed many other structures within it. Two of them were of particular interest, marked f1 and f2 in this image. Both of these are SPHERE images, each one with a different intensity threshold. Image Credit: Boccaletti et al, 2020.

There’s ample theory to support the birth of planets at the twist point. “In the early stage of planet formation, hydrodynamical simulations indicate that the accretion process generates at the planet location an inner and outer spiral pattern due to Lindblad resonances induced by disk-planet interactions,” the team writes.

But the observational evidence to back it all up has been difficult to come by. This study presents some of the best observations yet that back the theory up.

In their conclusion, the authors write “…the SPHERE observations of AB Aur in scattered light combined to the ALMA data in the thermal regime provide strong evidence that we are actually witnessing ongoing planet formation revealed by its associated spiral arms.”

[embedded content]

But it’s not proven yet. “Further observations would be required to confirm this result and to derive better mass estimates for potential planets in this location.”

Those further observations might not be too far in the future. The ESO’s Extremely Large Telescope (ELT) should see first light in 2025. With a 39 meter mirror, the ELT will be an enormous boost to our astronomical observing power.

“We should be able to see directly and more precisely how the dynamics of the gas contributes to the formation of planets,” lead author Boccaletti concluded.

More:

Let’s block ads! (Why?)



Source link

Continue Reading

Science

Rare comet passing over Manitoba sky | CTV News – CTV News Winnipeg

Published

on


WINNIPEG —
Stargazers in Manitoba can get a glimpse of the brightest comet in years as it hurtles past Earth over the next several days.

Comet NEOWISE C/2020 F3, named after the satellite that first discovered it, has been travelling towards Earth in recent days, before it returns to the outer edges of the solar system.

Photos submitted from Manitobans show the comet as it appeared in the morning sky on Thursday.

(Comet NEOWISE C/2020 F3 is pictured over Winnipeg in a pair of photos take July 9, 2020. Source: Roy Jemison)

comet neowise

(Comet NEOWISE C/2020 F3 is visible over Steinbach on July 9, 2020. SOURCE: Christopher Bleasdale)

Scott Young, who is the manager of the Planetarium and Science Gallery at the Manitoba Museum, said this comet wasn’t expected to be as bright as it is.

“This wasn’t predicted to be all that impressive but as it swung around the soon it suddenly burst into brightness,” said Young.

It’s one of the few “naked-eye comets” of the 21st century, meaning it can be seen without a telescope. The comet was first discovered on March 27, 2020, and NASA was unsure if it would make it to Earth as the comet travelled towards the sun.

Young said over the next several days this will be the only time to see the comet.

“We won’t see it again for at least 6,000 years. So it’s kind of your only chance.”

comet

(SOURCE: Scott Young/Manitoba Museum)

Young added the reason why this comet is so unique is because of how bright it is.

“I can count on the fingers of one hand how many comets we’ve had that have been this impressive. I mean, I have seen a lot of comets, but there’s only a couple that have outshone this in my entire lifetime.”

NASA said the comet will likely be visible in the early morning sky until July 11. It will be visible in the early evening sky after July 11.

Young says if people want to see it, it’s best to be away from the city and all the lights.

comet

(SOURCE: Scott Young/Manitoba Museum)

– With files from CTV’s Jackie Dunham.

Correction:

This is a corrected story. The original story said the comet was discovered in 2009, when it was discovered this year.

Let’s block ads! (Why?)



Source link

Continue Reading

Science

Scientists Discover Unexplained Glowing Circles of Energy in Space – VICE

Published

on


​The Tycho supernova. Image: NASA/CXC/RIKEN & GSFC/T. Sato et al; Optical: DSS

The Tycho supernova. Image: NASA/CXC/RIKEN & GSFC/T. Sato et al; Optical: DSS 

Astronomers have discovered a bunch of weird unidentified circles in space, visible only in radio light, thanks to images captured by one of the most sensitive observatories on the planet.

The mysterious rings “do not seem to correspond to any known type of object” and so have been simply dubbed Odd Radio Circles, or ORCs, according to a new study, led by Western Sydney University astrophysicist Ray Norris.

“We have discovered, to the best of our knowledge, a new class of radio-astronomical object, consisting of a circular disc, which in some cases is limb-brightened, and sometimes contains a galaxy at its centre,” Norris and his colleagues said in the study, which was recently posted on the preprint server arXiv and has not yet been peer-reviewed.

“None of the known types of radio object seems able to explain it,” the team said.

The team describes four of these inscrutable ORCs, three of which were detected by the Australian Square Kilometre Array Pathfinder (ASKAP) telescope, a network of radio antennae that covers four square kilometers of the Australian Mid West. ASKAP has been scanning the sky in the radio spectrum to create an Evolutionary Map of the Universe that could help scientists better understand the development of stars and galaxies.

Norris and his colleagues noticed three odd blobs in ASKAP’s 2019 observations. Each of the circles measures about one arcminute across, which is roughly equivalent to 3 percent the diameter of the Moon. However, it’s difficult to tell how far away the ORCs are based on these images, and that in turn makes it challenging to estimate the actual size of the objects, at least until more detailed observations are made.

The glowing circles are so bizarre that Norris and his colleagues wondered if they might be an instrumental glitch, especially since radio imagery often contains errors that look like rounded apparitions, according to the study.

But when the team went hunting through archival datasets, they were surprised to discover that a fourth ORC was imaged all the way back in 2013 by India’s Giant Metrewave Radio Telescope, though nobody had made note of it at the time.

By combing through past radio surveys, as well as obtaining new images with the Australia Telescope Compact Array, the researchers were able to collect at least two independent observations of each ORC. The fact that the circles show up across multiple telescope datasets makes instrumental error “a very improbable explanation,” the team said in the study.

So if the ORCs are real celestial objects, what could they be? Norris and his colleagues outline several possible identities for the objects, though none of them are an obvious fit.

The circles might be the fallout of exploded stars, or bubbles blown out by winds in galactic star factories, or “Einstein rings,” which are signatures of warped spacetime created by the gravity of massive objects. They could be the ghosts of highly energetic events that occurred millions of years ago, such as gamma ray bursts, fast radio bursts, or plasma jets emitted by active galactic cores.

“We also acknowledge the possibility that the ORCs may represent more than one phenomenon,” the team noted, adding that they may have been “discovered simultaneously because they match the spatial frequency characteristics of the ASKAP observations, which occupy a part of the observational parameter space which has hitherto been poorly studied.”

Norris and his colleagues plan to continue examining the ORCS to see if they can tease out some of these tantalizing mysteries. One thing’s clear, however: discoveries like this are likely to become more common as radio astronomy matures in the coming years.

Within the next decade or so, ASKAP will join the Square Kilometre Array, a massive intercontinental observatory currently in construction, which will be by far the most sensitive radio instrument on Earth once it’s operational. The discovery of the ORCs is fascinating by itself, but it also foreshadows a new era of astronomy that is already sharpening our view of space.

This article originally appeared on VICE US.

Let’s block ads! (Why?)



Source link

Continue Reading

Science

CINDY DAY: Don’t miss this once in a lifetime event to see Comet NEOWISE – SaltWire Network

Published

on


If you’ve been paying attention to the news lately, you are most likely familiar with the word “NEOWISE.” If not, let me introduce you:

NEOWISE is the name of a comet that was discovered in March 2020. This comet is visiting from the most distant parts of our solar system and for the next couple of weeks, could put on quite a show. The comet made its once-in-a-lifetime close approach to the Sun on July 3 and will cross outside Earth’s orbit on its way back to the outer parts of the solar system by mid-August.

On July 22, the comet will reach its closest point to Earth — a distance of 103 million kilometres — but because comets can be unpredictable, a little like the weather, experts are not sure that it will still be visible to the naked eye.

For the last few days, NEOWISE has been visible an hour before sunrise, very low in the northeastern sky. As of Sunday, the comet will be visible in the evening as well. About an hour after sunset, it will appear near the northwestern horizon. As the month goes on, it will rise higher in the sky, moving toward the Big Dipper. Right now, the comet is visible to the naked eye, but a good pair of binoculars would offer a better view. In very dark skies, you should be able to spot a nucleus and get a pretty good look at the fuzzy comet and its long, streaky tail.

Its name, in fact, is an acronym. The comet was discovered by NASA’s Near-Earth Object Wide-field Infrared Survey Explorer or NEOWISE.

From its infrared signature, experts have discovered that the icy visitor is about five kilometres in diameter. It has a nucleus that is covered with sooty, dark particles left over from its formation near the birth of our solar system about 4.6 billion years ago.

After this encounter, astronomers expect Comet NEOWISE to bid farewell for quite some time. Its long, looping orbit around our star will bring it back to Earth’s vicinity more than 6,000 years from now.



Cindy Day is the chief meteorologist for SaltWire Network

Let’s block ads! (Why?)



Source link

Continue Reading

Trending