New Observations Of A ‘dust Trap’ Around A Young Star Solve Long-standing Planet Formation Mystery

New Observations Of A ‘dust Trap’ Around A Young Star Solve Long-standing Planet Formation Mystery
New Observations Of A ‘dust Trap’ Around A Young Star Solve Long-standing Planet Formation Mystery
New Observations Of A ‘dust Trap’ Around A Young Star Solve Long-standing Planet Formation Mystery

New observations of a ‘dust trap’ around a young star solve long-standing planet formation mystery Astronomers using the new Atacama Large Millimeter/submillimeter Array have imaged a region around a young star where dust particles can grow by clumping together. This is the first time that such a dust trap has been clearly observed and modeled. It solves a long-standing mystery about how dust particles in discs grow to larger sizes so that they can eventually form comets, planets and other rocky bodies.

Astronomers now know that planets around other stars are plentiful. But they do not fully understand how they form and there are many aspects of the formation of comets, planets and other rocky bodies that remain a mystery. However, new observations exploiting the power of ALMA are now answering one of the biggest questions: how do tiny grains of dust in the disc around a young star grow bigger and bigger—to eventually become rubble, and even boulders well beyond a metre in size?

Computer models suggest that dust grains grow when they collide and stick together. However, when these bigger grains collide again at high speed they are often smashed to pieces and sent back to square one. Even when this does not happen, the models show that the larger grains would quickly move inwards because of friction between the dust and gas and fall onto their parent star, leaving no chance that they could grow even further.

Somehow the dust needs a safe haven where the particles can continue growing until they are big enough to survive on their own. Such “dust traps” have been proposed, but there was no observational proof of their existence up to now.

Bottom left image: Artist’s impression of the proposed disk structure of Oph IRS 48. The brown spots represent the large and small grains. The larger grains detected by ALMA are concentrated in the dust trap at the bottom of the image. The blue represents the distribution of carbon monoxide gas. The gap in the disk is shown with the proposed planetary body that is sweeping the area clear and providing the conditions necessary to form the dust trap. Credit: Nienke van der Marel

Nienke van der Marel, a PhD student at Leiden Observatory in the Netherlands, and lead author of the article, was using ALMA along with her co-workers, to study the disc in a system called Oph-IRS 48. They found that the star was circled by a ring of gas with a central hole that was probably created by an unseen planet or companion star. Earlier observations using ESO’s Very Large Telescope had already shown that the small dust particles also formed a similar ring structure. But the new ALMA view of where the larger millimetre-sized dust particles were found was very different!

“At first the shape of the dust in the image came as a complete surprise to us,” says van der Marel. “Instead of the ring we had expected to see, we found a very clear cashew-nut shape! We had to convince ourselves that this feature was real, but the strong signal and sharpness of the ALMA observations left no doubt about the structure. Then we realised what we had found.”

What had been discovered was a region where bigger dust grains were trapped and could grow much larger by colliding and sticking together. This was a dust trap—just what the theorists were looking for.

Bottom right image: ALMA image of the dust trap around Oph IRS 48. The distinctive crescent-shaped feature comes from the accumulation of larger dust grains in the outer regions of the disk. This provides the safe haven dust grains need to grow into larger and larger objects. Credit: ALMA (ESO/NAOJ/NRAO) / Nienke van der Marel

As van der Marel explains: “It’s likely that we are looking at a kind of comet factory as the conditions are right for the particles to grow from millimetre to comet size. The dust is not likely to form full-sized planets at this distance from the star. But in the near future ALMA will be able to observe dust traps closer to their parent stars, where the same mechanisms are at work. Such dust traps really would be the cradles for new-born planets.”

The dust trap forms as bigger dust particles move in the direction of regions of higher pressure. Computer modelling has shown that such a high pressure region can originate from the motions of the gas at the edge of a gas hole—just like the one found in this disc.

“The combination of modelling work and high quality observations of ALMA makes this a unique project”, says Cornelis Dullemond from the Institute for Theoretical Astrophysics in Heidelberg, Germany, who is an expert on dust evolution and disc modelling, and a member of the team. “Around the time that these observations were obtained, we were working on models predicting exactly these kinds of structures: a very lucky coincidence.”

The observations were made while the ALMA array was still being constructed. They made use of the ALMA Band 9 receivers—European-made devices that allow ALMA to create its so far sharpest images.

“These observations show that ALMA is capable of delivering transformational science, even with less than half of the full array in use,” says Ewine van Dishoeck of the Leiden Observatory, who has been a major contributor to the ALMA project for more than 20 years. “The incredible jump in both sensitivity and image sharpness in Band 9 gives us the opportunity to study basic aspects of planet formation in ways that were simply not possible before.”

More Posts from Outofambit and Others

1 year ago

Do you think the Powers that be would ever offer Carmela the Oath even though she’s past latency?

I have to say that I don't see it as something the Powers would do, or indeed, need to do.

Some people, I think, are potentially far more effective without wizardry than with it. We are after all dealing here with a young woman who once shot the Lone Power point-blank (and snickered and said "Oops!" afterwards), and who stopped a violent alien insurrection with a block of Valrhona chocolate.

What we have to remember is that, in its way, wizardry's a bit of a kludge. If everything was working as originally intended, it wouldn't have been needed. But then the Lone One came up with that new and interesting concept It added to the worlds, and since the aftermath, all the greater Pleroma's code has needed constant tweaking. (eyeroll) After all, the addition of wizardry to the equation inevitably costs more energy... and the whole concept of things since the Lone Power's annoying addition of entropy has required saving energy. It's a pain to maintain the balance.

Doubtless there are some of the Powers—most likely the ur-demiurge we'd identify with Thoth, this seems like it'd be in Their bailiwick: code is after all language—who sit around tsk-ing at the mess the code's gotten into, and meanwhile side-eyeing with a certain dry satisfaction those creatures creative enough to intervene unusually effectively in the world without needing to have wizardry added on.

My image of the larger meta of this whole situation, therefore, is of the Powers standing around some kind of viewing instrumentality (why do I keep coming back to that pool in Jason and the Argonauts? Who knows) waiting to see what she's going to do next.

...And laying bets. :)


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12 years ago
White Dwarfs Polluted With Planetary Debris

White dwarfs polluted with planetary debris

The Hubble Space Telescope has found chemical evidence for the building blocks for rocky planets in an extremely unusual place: the atmospheres of two burned-out stars. Called white dwarfs, these stars are small, dim shadows of stars that would have once been like our sun, and they reside 150 light-years from Earth in the young star cluster of Hyades. Hubble’s spectroscopic observations identified silicon and low levels of carbon, both of which are strong indicators of a rocky material similar to that which makes up Earth. “When these stars were born, they built planets,” said Jay Farihi, lead author of the study, “and there’s a good chance they currently retain some of them… Based on the silicon-to-carbon ratio in our study, we can actually say that this material is basically Earth-like.” The material is thought to have ended up in the atmosphere of these stars after they collapsed into white dwarfs, and the larger planets in their solar system nudged asteroids into star-grazing orbits. The stars’ gravitational pull tore the asteroids apart, and the pulverised debris fell into a ring around the white dwarfs and were eventually funnelled inwards to pollute the stars themselves. The discovery suggests that rocky planets may commonly assemble around stars, and may help us to understand what will happen to our solar system in five billion years, when our own sun burns out.

10 years ago
“But Then She Was A Dancer. Dancers Are Tough.” -“The Wizard’s Dilemma,” Diane Duane, (x) (x)
“But Then She Was A Dancer. Dancers Are Tough.” -“The Wizard’s Dilemma,” Diane Duane, (x) (x)

“But then she was a dancer. Dancers are tough.” -“The Wizard’s Dilemma,” Diane Duane, (x) (x) Dedicated to Betty Callahan.


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9 years ago

I just realized that the first antagonist Kit and Nita faced together was a helicopter parent.


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yw
10 years ago
Orbital Mechanics By Tatiana Plakhova 
Orbital Mechanics By Tatiana Plakhova 
Orbital Mechanics By Tatiana Plakhova 
Orbital Mechanics By Tatiana Plakhova 
Orbital Mechanics By Tatiana Plakhova 
Orbital Mechanics By Tatiana Plakhova 
Orbital Mechanics By Tatiana Plakhova 
Orbital Mechanics By Tatiana Plakhova 
Orbital Mechanics By Tatiana Plakhova 
Orbital Mechanics By Tatiana Plakhova 

Orbital Mechanics by Tatiana Plakhova 

11 years ago

"All Our Myriad Worlds Lie Whole"

I realize my blog is a bit scattered, and mostly fandom based, and probably no small amount of ridiculous, but I’m going to share a fandom-related story with you lovely followers. ^___^ What follows is a ramble-y account of my love affair with the Young Wizards Series.

I went to NYC for a choir trip during my senior year of high school (which was a lot longer ago than I feel like it should be…), and while we were there we visited a few museums…as one does on field trips, you know? Well, the highlight of our trip, for me, was definitely getting to weigh myself on all the planets, because of the scene in High Wizardry by Diane Duane. And, yes, I checked to make sure the ladies’ didn’t lead to Mars…I was disappointed to find just toilets, I’ll admit. (Just kidding! …well, mostly.)

It’s weird to realize the impact a book series can have on you, the ways in which the written word can influence you. But I’ve been reading the Young Wizards Series for so long now (and that’s a story in and of itself, which I’ll probably share at some point), that in many, many ways I feel as if the characters know me as well as I know them. I sometimes imagine that maybe, somewhere out there, there’s a universe where literary characters are all real, and are reading about our universe’s fantastical adventures. If the universe is infinite, and if there are an infinite number of universes, then who’s to say there isn’t a world like that, after all? Maybe in some place, Nita and Kit are reading about my Ordeal, or my little sister running off all over the universe (she does run off to Europe on occasion…the rest of the galaxy isn’t such a far stretch, at that…).

But back to my point. I stood there, my hand on the same asteroid that Kit and Nita discuss as having come such a long way, and for me the moment was beautifully surreal. I don’t think any of my classmates had such a profound experience as I did on that trip, because I finally had arrived at a place that I had been reading about since I first got into fantasy, and it was a real place, not something unattainable like The Leaky Cauldron, or a magical wardrobe to Narnia.

It was real, and I could touch it.

I think that’s the real power of words, right there; the real magic in our universe. That one person’s words can leave such a lasting impression on another human being isremarkableandpowerful, and has the same chance of being misused as the magic I so dearly love to read about. Because as surely as words can heal and inform and touch, they can just as surely be used to hurt and twist and maim.

And I think, maybe, much of my fascination with words and languages comes from Diane Duane’s books, too, as surely as my fascination with that asteroid came from her books.

I’ve been called childish and ridiculous—been told that no one can take me seriously. I’ve been bullied, and was pushed off swing sets when I was little, and I’ve been called all sorts of unpleasant names like “nerd” and “loser”, among others, and been told I read too much (as if there is such a thing!). Maybe these things are why I empathized so totally with Nita, that very first time I read So You Want to be a Wizard, but she kind of became something of a guiding light to me. At first it was just that Nita had a profound impact on me, as a character with whom I shared so much, but later, as I grew older and continued to reread the series, it became less Nita, and more the entire feel of the series. There is so much good in this series, so many “words to live by” and the characters are so unconsciously good that to the reader it becomes second nature, too. Kit and Nita are like two bright standard bearers in a world that seems progressively darker, that more and more places emphasis on characters who do bad things for the right reasons, instead of character who do good things because that is the right reason.

I don’t even know if I can still call the impact these books had on me “subtle” because I feel like I’ve embraced the philosophies of the characters with every fiber of my being.

I’m going into anthropology, probably with an emphasis on archaeology, which is all about understanding other peoples, and in some cases preserving those cultures which are rapidly losing themselves to “modernization”. Maybe this makes me silly, but whenever I think about what I’ll be doing later in my life, working to understand and write about cultures unlike my own, I can’t help but also hear the words of the Oath in the back of my mind. I live by those words. I think they are perfect, and important, and I still read them out loud every time I get to that page, because whether or not they can make me a wizard, they are still a promise that I made to myself when I was eleven, and I intend to keep that promise—magic or not.


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10 years ago
Sunset On Mars
Sunset On Mars

Sunset on Mars


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5 years ago

Okay, so I’ve just started Games Wizards Play book 10 in the Young Wizards series, which means it’s time for some thoughts on my FAAAAAAAV YA SERIES OF ALL TIME. (No offense HP, no offense)

ROSHAUN MY CHILD MY SON COME BACK TO ME!!! COME BACK TO ME BABY! IT HAS BEEN ONE WHOLE BOOK  AND HE’S NOT BACK YET I AM NOT OKAY! I AM NOT ALRIGHT! THE MADNESS MUST END! PLEASE GOD MAKE IT STOP JUST BRING BACK MY BABY PLEASE OH PLEASE OH PLEASE! WE LOST PONCH I CAN’T HAVE THIS TOO I CAN’T TAKE THIS OH GODDDDDDD *INCOHERENT SOBBING*

And I am done. This is basically my internal stream of consciousness all through A Wizard of Mars tbh. I have basically been a blithering, sobbing, screaming wreck since Wizards at War. Life’s been hard. And since my house burned down, I don’t even have my ENTIRE COMPLETE collection to reference : |

Some further reviews on the Young Wizards series:

So You Want To Be a Wizard…

You will cry because of a car

Deep Wizardry

You will cry because of a shark

High Wizardry

You will cry because of a space turtle

A Wizard Abroad

You will cry because of Ireland

A Wizard’s Dilemma

You will cry because of a parrot. Also cancer.

A Wizard Alone

You will cry because of autism

Wizard’s Holiday

You will cry because of a barren hellscape

Wizards at War

You will cry because of OH GOD NOT THE DOG PLEASE NOT THE DOG OH GOD NO

A Wizard of Mars

You will cry because you are no longer capable of feeling anything because the last book emotionally broke you.

Great series. 10/10. Would recommend to all your friends and loved ones and then you can all cry together.

1 year ago
Sometimes I Read Stuff And I Just Wanna Shake Someone Like "WHY IS NOBODY TALKING ABOUT THIS"

Sometimes I read stuff and I just wanna shake someone like "WHY IS NOBODY TALKING ABOUT THIS"

12 years ago

Thank you for the welcome! This is one of my oldest fandoms (started reading around the time Wizard's Dilemma came out) and I can't believe it took me this long to make a blog for it... :) I love this fandom's tumblr presence. You're all such lovely people!

Started this blog because everyone needs a place to dump their space porn and YW fandom stuff….right?


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outofambit - Out of Ambit
Out of Ambit

A personal temporospatial claudication for Young Wizards fandom-related posts and general space nonsense.

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