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Scientists use Hubble and Webb to confirm there are as yet no planets forming in Vega’s accretion disk

Hubble and Webb images of Vega's accretion disk
Click for original image.

Using both the Hubble and Webb space telescopes, scientists have now confirmed, to their surprise, that the accretioni disk that surrounds the nearby star Vega is very smooth with almost no gaps, and thus apparently has not new exoplanets forming within it.

The two pictures to the right, cropped and reduced to post here, come from two different papers. The Hubble paper is here [pdf] while the Webb paper is here [pdf]. From the press release:

Webb sees the infrared glow from a disk of particles the size of sand swirling around the sizzling blue-white star that is 40 times brighter than our Sun. Hubble captures an outer halo of this disk, with particles no bigger than the consistency of smoke that are reflecting starlight.

The distribution of dust in the Vega debris disk is layered because the pressure of starlight pushes out the smaller grains faster than larger grains. “Different types of physics will locate different-sized particles at different locations,” said Schuyler Wolff of the University of Arizona team, lead author of the paper presenting the Hubble findings. “The fact that we’re seeing dust particle sizes sorted out can help us understand the underlying dynamics in circumstellar disks.”

The Vega disk does have a subtle gap, around 60 AU (astronomical units) from the star (twice the distance of Neptune from the Sun), but otherwise is very smooth all the way in until it is lost in the glare of the star. This shows that there are no planets down at least to Neptune-mass circulating in large orbits, as in our solar system, say the researchers.

At the moment astronomers consider the very smooth accretion disk surrounding Vega to be rare and exception to the rule, with most debris disks having gaps that suggest the presence of newly formed exoplanets within them. That Vega breaks the rule however suggests the rule might not be right in the first place.

Genesis cover

On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.

 

The print edition can be purchased at Amazon. from any other book seller, or direct from my ebook publisher, ebookit. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.


The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
 

"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News

One comment

  • Ryan Lawson

    Did Vega come out of a normal stellar nursery or is it like an isolated system? I’d have to do some reading, but maybe things form differently if more isolated.

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