Planet formation


Have a snapshot from the Atacama Large Millimeter/submillimeter Array (ALMA), courtesy of a press release from the National Radio Astronomy Observatory.

Astronomers have captured the best image ever of planet formation around an infant star as part of the testing and verification process for the Atacama Large Millimeter/submillimeter Array’s (ALMA) new high-resolution capabilities.

This revolutionary new image reveals in astonishing detail the planet-forming disk surrounding HL Tau, a Sun-like star located approximately 450 light-years from Earth in the constellation Taurus.

ALMA uncovered never-before-seen features in this system, including multiple concentric rings separated by clearly defined gaps. These structures suggest that planet formation is already well underway around this remarkably young star.

A snapshot of planet formation! How cool is that?


ALMA image of the young star HL Tau and its protoplanetary disk. This best image ever of planet formation reveals multiple rings and gaps that herald the presence of emerging planets as they sweep their orbits clear of dust and gas. Credit: ALMA (NRAO/ESO/NAOJ); C. Brogan, B. Saxton (NRAO/AUI/NSF)

All stars are believed to form within clouds of gas and dust that collapse under gravity. Over time, the surrounding dust particles stick together, growing into sand, pebbles, and larger-size rocks, which eventually settle into a thin protoplanetary disk where asteroids, comets, and planets form.

Once these planetary bodies acquire enough mass, they dramatically reshape the structure of their natal disk, fashioning rings and gaps as the planets sweep their orbits clear of debris and shepherd dust and gas into tighter and more confined zones.

The new ALMA image reveals these striking features in exquisite detail, providing the clearest picture to date of planet formation. Images with this level of detail were previously only seen in computer models and artist concepts. ALMA, living up to its promise, has now provided direct proof that nature and theory are very much in agreement.

That’s exciting.

ALMA’s new high-resolution capabilities were achieved by spacing the antennas up to 15 kilometers apart. This baseline at millimeter wavelengths enabled a resolution of 35 milliarcseconds, which is equivalent to a penny as seen from more than 110 kilometers away.

“Such a resolution can only be achieved with the long baseline capabilities of ALMA and provides astronomers with new information that is impossible to collect with any other facility, including the best optical observatories,” noted ALMA Director Pierre Cox.

These long baselines fulfill one of ALMA’s major objectives and mark an impressive technological and engineering milestone. Future observations at ALMA’s longest possible baseline of 16 kilometers will produce even clearer images and continue to expand our understanding of the cosmos.

We live in interesting times.


  1. Hj Hornbeck says

    And that’s not the half of it! The telescopes they used can’t see in visible wavelengths, so what you’re looking at is a false colour image. The press release doesn’t say what exact wavelength they collected, unfortunately. Some Googling suggests this is like seeing your WiFi signal or the heat given off by Pluto.

    They’re also using their telescopes as an interferometer. To get an image that sharp with a conventional telescope, it’d need to be 16 kilometres in diameter (assuming they’re just using the primary ALMA dishes, which seems likely). But thanks to some fancy math they can get the same effect with a collection of much much much smaller telescopes. The cost: they need to stare at the sky for much much much longer, and they only get roughly 2,000 “pixels” across that 16 kilometres.

  2. soogeeoh says

    We live in interesting times.

    Are you referencing the “May you live in interesting times” curse?

  3. Crimson Clupeidae says

    We’ll have to take a snapshot of that every few years to watch what happens. :)

    It’s a long wavelength, so well into the infra-red range of the spectrum. I don’t know how long it will be emitting em in that wavelength, so we might have to use a different method to see it in a few (dozen) years.

  4. =8)-DX says

    Soogeeoh: May you live in interesting times!
    Also nice science, but not much reason to go there.

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