“We don’t know a lot about it,” said Brendan Bowler of the University of Texas AustinGiant planetHow is it formed. “This planetary system provides us with the first testimony to how matter accumulates on planets. Our results open up a new area for this research.”
Although astronomers have classified more than 4,000 exoplanets so far, the telescope has only directly imaged about 15 exoplanets. The planets are very far and very small, and are usually just a dot in the clearest way.
The research team used the latest Hubble technology to directly photograph the planet, and opened a new way to further search for exoplanets, especially during the period of planet formation.
This massive exoplanet is designated PDS 70b, orbiting the orange dwarf PDS 70. The orange dwarf is known to have two planets formed in a massive stellar disk surrounded by dust and gas. The system is located in the constellation Centaurus, 370 light-years from Earth.
This is the smallest real planet that Hubble has ever photographed directly, ”said Chu Yifan of the University of Texas at Austin. He said it around the age of five. A million years ago, the planet is still absorbing matter and accumulating mass.
Hubble’s sensitivity to ultraviolet radiation has the unique ability to monitor radiation from extremely hot gases falling onto the planet.
“Hubble’s observations allow us to estimate the speed at which planets are gaining mass,” added Chu Chofan.
By adding UV observations, the research team directly measured the growth rate of the planet’s mass for the first time. In about five million years, this planet reached five times the mass of Jupiter. The current measured rate of accretion has decreased sharply: if this rate of accretion remained the same for about a million years, the planet would only increase by about 1/100 of the mass of Jupiter.
Van and Boller stressed on Monday that these observations are only data in a short period of time, and more data is needed to determine whether the planetary mass rate of planetary accumulation is increasing or decreasing. “Our measurements indicate that the planet is at the end of its formation.”
The new PDS 70 system is filled with primitive dust tablets, which can provide fuel for planetary growth throughout the system. Planet PDS 70b is surrounded by its own dust and gas disk, which absorbs material from the massive interstellar dust disk. The research team speculated that magnetic field lines extend from the outer planetary disk down into the atmosphere of the exoplanets, and direct matter to the planet’s surface.
“If this material enters the planet from the dust disk, the hot spots will be seen locally. These hot spots may be at least ten times higher than the Earth’s temperature,” Zhu Yifan said.
These areas will glow violently under UV rays.
These observations also provide clues to the massive gas planets that formed around our sun 4.6 billion years ago. Jupiter may have been caused by the accumulation of fluff disks around it. Its main satellite will also be formed from the remains in the dish.
The results of this new study will be published in the Astronomical Review on April 29, 2021.
Responsible Editor: Lin Yan #