ALMA: First Discovery of a Dust Disc around an Exoplanet

ALMA - DIsc around exoplanet

The presence of a dust disc around a Jupiter-like planet outside our Solar System has been caught unequivocally for the first time in astronomical history using the Atacama Large Millimeter/submillimeter Array (ALMA), in which the European Southern Observatory (ESO) is a partner. The ALMA telescope has paved the way for the research team led by Miriam Benisti of the University of Grenoble / University of Chile towards this revelation. This discovery elucidates the strategic formation of moons and planets in young stellar systems.

ALMA and PDS 70

This circumplanetary disc is located nearly 400 light-years away from Earth surrounding the PDS 70c gas giant, one of the two Jupiter-shaped planets that orbit the youthful star system PDS 70. Researchers say that it is 500 times larger than Saturn’s outer ring. High-resolution of the ALMA telescope has confirmed the presence of this previously suggested dust disc around PDS 70c. Moreover, it has also been revealed that the diameter of the disc is nearly the distance from our Sun to the Earth. Further studies reveal that it has enough mass to form up to three satellites the same size as the Earth’s Moon.

A protoplanetary disc around the young star PDS 70 was observed with the ALMA telescope. PDS 70 is in the centre of the double ring. Two extrasolar planets, PDS 70b and PDS 70c have been discovered in the dark area between the rings. The PDS 70b is not visible on ALMA observations and is believed to have no dust discs around it.

Credit: ALMA (ESO / NAOJ / NRAO) / Benisty et al.
A close-up image of the protoplanetary disk around the young star PDS 70 (left) and the orbiting planet PDS 70c (right). The PDS 70 is in the centre of the image on the left. What looks like a dot in the centre of the close-up image is the dust disk around the PDS 70c.
Credit: ALMA (ESO / NAOJ / NRAO) / Benisty et al.

The PDS 70b and PDS 70c were first detected using the Very Large Telescope (VLT) at the European Southern Observatory in 2018 and 2019. Their unique nature has intrigued astronomers to observe them many times with other telescopes and instruments before using the ALMA.

Significance of this Discovery

These new observations are also extremely important in proving a previously unverifiable theory of planet formation that could not be tested until now.

Jaehan Bae, Author of the study and a researcher from the Earth and Planets Laboratory of the Carnegie Institute for Science, USA.

Contrastingly, the ALMA telescope has not spotted a similar disc in PDS 70b, the other Jupiter-like planet that revolves around PDS 70. The reason may be that the PDS 70c has stolen the excess dust in the birth environment of the PSD 70b.

More than 4,000 exoplanets have been found, but all of them were detected in mature systems. PDS 70b and PDS 70c, which form a system reminiscent of the Jupiter-Saturn pair, are the only two exoplanets detected so far that are still in the process of being formed.

Miriam Keppler, a researcher at the Max PLanck Institute for Astronomy in Germany.

This colourful image shows the sky around the faint orange dwarf star PDS 70 (in the middle of the image). The bright blue star to the right is χ Centauri. Credit: ESO/Digitized Sky Survey 2.

Acknowledgement: Davide De Martin

Planets emerge in a disc of dust and gas around a young star. Meanwhile, they create cavities in the circumstellar disc, sucking in the surrounding matter to grow. The planets acquire the ability to create their own circumplanetary disc during this process of pulling in material. This regulates the material falling in. At the same time, the gas and dust in the disc accumulate into a larger celestial body, eventually creating a satellite. Although we don’t understand the process of satellite formation fully, newer and sharper instruments might unveil this mystery.

Image Courtesies


Leave a Reply

Your email address will not be published. Required fields are marked *

Back To Top
error: Content is protected !!