20 April 2017 News

ALMA research team captures first clear image of accretion disk around a star

An illustration of an accretion disk feeding a central young star, or protostar, and the gaseous jet ejected from the protostar. Credit: Yin-Chih Tsai/ASIAA
An illustration of an accretion disk feeding a central young star, or protostar, and the gaseous jet ejected from the protostar. Credit: Yin-Chih Tsai/ASIAA

Scientists from the U.S. and Taiwan have captured the first clear image of an accretion disk around a young star. According to most commonly accepted theories, young stars feed on accretion disks as they grow. The disk may also make up the material that would eventually turn into planets. The image captured by the ALMA radio telescope in Chile is the first clear image of an accretion disk – earlier technology was not able to obtain clear images. ALMA was able to zoom in on a star named IRAS 05413-0104, part of a system believed to be just 40,000 years old, and take an image of its rotating accretion disk.

ALMA, the most expensive radio telescope ever built, was completed only four years ago, and has since steadily provided clear-resolution images of unprecedented quality. This new image of the accretion disk disproves the theory that the magnetic core of a young star would prevent the accretion disk from spinning and therefore prevent its ability to gather matter. The image clearly shows that the disk is, indeed, spinning.



accretiondisk2.jpg
Jet and disk in the HH 212 protostellar system: (a) A composite image of the jet, produced by combining images from different telescopes. The orange image around the center shows the accretion disk at 200 AU resolution. (b) Close-up of the center of the dusty disk at 8 AU resolution. Asterisks mark the possible position of the central protostar. A dark lane is seen in the equator. Our solar system is shown in the lower right corner for size comparison. (c) An accretion disk model that can reproduce the observed dust emission in the disk. Credit: ALMA (ESO/NAOJ/NRAO)/Lee et al.

Accretion disks are most likely made of silicate, iron, and other interstellar matter. Due to their triple-layer appearance, the research team has described the accretion disk as very similar to a hamburger.

The complete study of the accretion disk image, “First detection of equatorial dark dust lane in a protostellar disk at submillimeter wavelength”, was published in Science Advances on April 19, 2017.

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