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Astronomers detect for the first time an accretion disk around an exoplanet

The exoplanet and its accretion disk
Click for full image.

Using the Atacama Large Millimetre/submillimeter Array (ALMA) in Chile, astronomers have made the first confirmed images of a moon-forming accretion disk around another a very young exoplanet.

The photo to the right shows this, with the top image the wide view showing the exoplanet in its orbit around the star, in an area inside the star’s own accretion disk (the larger ring) that the planet has apparently cleared of debris as it gathered itself. The bottom image zooms into the planet to show its own disk of material.

From the press release:

The disc in question, called a circumplanetary disc, surrounds the exoplanet PDS 70c, one of two giant, Jupiter-like planets orbiting a star nearly 400 light-years away. Astronomers had found hints of a “moon-forming” disc around this exoplanet before but, since they could not clearly tell the disc apart from its surrounding environment, they could not confirm its detection — until now.

In addition, with the help of ALMA, Benisty and her team found that the disc has about the same diameter as the distance from our Sun to the Earth and enough mass to form up to three satellites the size of the Moon.

The exoplanet’s disk is thus very large compared to our solar system, but that isn’t surprising considering the difficulty of observing it at such distances. Disks comparable in size to our solar system and the Earth-Moon system are simply too small for any telescope to yet image in this way.

The new data also found this interesting fact: The other known Jupiter-like exoplanet in this system does not have its own accretion disk or any visible debris orbiting it. Why one planet still has such debris and the other does not is a mystery related to the formation of solar systems that is at present not understood.

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.

 
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"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

3 comments

  • George

    Perhaps the second planet is a captured wanderer and not part of the forming system originally? Very cool that we go from “we think it works this way” to “see, this is what we show how it works.”

  • pzatchok

    Images like this are beauty to my eyes.

    It almost looks like the proto planet is pulling material off of the inside edge on the larger disk.

  • It does look that way.

    The time scales involved in this sort of thing break my brain. It’s “only” 400 light years away, so it probably still looks much the same, now. Yes, I realize that’s a somewhat (completely?) meaningless statement. I can’t help it, my brain is Newtonian, not Einsteinian.

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