Hubble discovers a planet that forms in an unconventional way | Urania

The Hubble Space Telescope has photographed direct evidence of the formation of a Jupiter-like protoplanet. Scientists describe the event as an “intense and violent process.” This finding supports the long-discussed theory of the formation of planets like Jupiter, known as “disk instability.”

Interpreting this system is extremely difficult. That’s one of the reasons Hubble was needed for this project: a bright image to better separate the light from the disk and each planet.

The new world under construction is embedded in a protoplanetary disk of dust and gas, with a distinct spiral structure swirling around a young star estimated to be 2 million years old. This is around the age of our solar system when the planets were forming (the solar system is now 4.6 billion years old).

– Nature is smart; it can create planets in many different ways Adds Thayne Currie of the Subaru Telescope and Eureka Scientific, the lead scientist on the study.

All planets are made of material from the circumstellar disk. The dominant theory of Jupiter’s formation has been termed “nuclear accretion,” a bottom-up approach in which planets embedded in a disk grow from tiny objects — ranging in size from dust grains to boulders — that collide and stick together as they revolve around the star. This core then slowly collects gas from the disk. The disk instability approach, on the other hand, is a top-down model in which, as the massive disk around the star cools, gravity causes the disk to rapidly decay into one or more fragments of planetary mass.

The newly formed planet, called AB Aurigae b, is probably about nine times more massive than Jupiter and orbits its parent star at a great distance, more than twice as far as Pluto from our sun. At this distance, it would take a long time for a planet the size of Jupiter to form as a result of nuclear accretion. This leads scientists to conclude that the instability of the disk allowed this planet to form over such great distances. And this is in stark contrast to the expectations of planet formation by the widely accepted nuclear accretion model.

The new analysis combines data from two Hubble instruments: the Space Telescope Imaging Spectrograph and Near Infrared Camera, and the Multi-Object Spectrograph. These data were compared with data obtained from a state-of-the-art planet-imaging instrument called SCExAO on the Japanese 8.2-meter Subaru Telescope, atop Mauna Kea in Hawaii. The wealth of data from space and ground-based telescopes proved crucial because it is very difficult to distinguish between young planets and complex non-planetary features of the disk.

Scientists have been able to directly photograph the newly formed exoplanet AB Aurigae b over a period of 13 years using the Hubble Space Telescope Imaging Spectrograph (STIS) and its near-infrared camera and multi-object spectrograph (NICMOS). In the upper right corner, the 2007 Hubble NICMOS image shows AB Aurigae b just south of its parent star, obscured by the instrument’s coronograph. A photo taken by STIS in 2021 shows the protoplanet moving counterclockwise in time.


Pictured: Scientists have directly imaged the newly formed exoplanet AB Aurigae b over 13 years using the Hubble Space Telescope Imaging Spectrograph (STIS) and its near-infrared camera and multi-object spectrograph (NICMOS). At the top right is the NICMOS image taken in 2007 showing AB Aurigae b south of its parent star, obscured by the instrument’s coronograph. An image taken by STIS in 2021 shows the protoplanet moving counterclockwise over time. Image Credit: Science: NASA, ESA, Thayne Currie (Subaru Telescope, Eureka Scientific Inc.); Image Processing: Thayne Currie (Subaru Telescope, Eureka Scientific Inc.), Alyssa Pagan (STScI)

Currie emphasized that Hubble’s longevity played a special role in helping scientists measure the orbit of a protoplanet. Initially, he was very skeptical that AB Aurigae b was a planet. The Hubble archive data combined with images from Subaru proved a turning point in his change of mind.

– We couldn’t detect this movement for about a year or two Currie explains. Hubble provided a timeline, combined with Subaru data, over 13 years, which was enough to detect orbital motion

– This result uses ground and space observations, we can go back in time with Hubble Archival Observations.”Added Olivier Guyon of the University of Arizona at Tucson and Subaru Telescope in Hawaii. – AB Aurigae b was now analyzed at multiple wavelengths and a consistent image emerged – very solid.

– This new discovery is strong evidence that some gas giants can arise thanks to the disk instability mechanism – emphasizes Alan Boss of the Carnegie Institution of Science in Washington. – After all, only gravity matters as the remnants of the star formation process are pulled together by gravity to somehow form planets

Understanding the early stages of Jupiter-like planet formation provides astronomers with more context into the history of our solar system. This discovery paves the way for future research into the chemistry of protoplanetary disks such as AB Aurigae, including with the James Webb Space Telescope. The Hubble Space Telescope is an international collaborative project between NASA and ESA (European Space Agency). NASA’s Goddard Spaceflight Center in Greenbelt, Maryland, operates the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, leads Hubble’s science operations. STScI is administered for NASA by the Association of Universities for Research in Astronomy in Washington.

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Source: CEO SSE Project / SSE Space Academy

Prepared by: Elżbieta Kuligowska

In the image: Nature herself lent a hand: The huge disk of dust and gas swirling around the star AB Aurigae is almost tilted with a plane facing our view from Earth. Source: SSE Space Academy

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