Astronomers using the NASA/ESA/CSA James Webb Space Telescope discovered a giant asteroid impact around Beta Gactris, the second brightest star in the constellation Scorpio.
Chen othersBeta Pictoris has a dynamic circumstellar environment, suggesting that periods of active collisions could produce large dust clouds that could blow through the planetary system and increase dust accretion to the giant planets Beta Pictoris b and c. Image credit: Roberto Molar Candanosa / Johns Hopkins University / Lynette Cook / NASA.
Beta Pictoris is an A5 type star located in the constellation Pictoris, approximately 63 light years from Earth.
The star has a mass about 1.8 times that of the Sun and is only 20 million years old.
It contains a circumstellar disk of gas and dust, numerous comet-like objects, and two giant planets, Beta Pictoris b and Beta Pictoris c.
Beta Pictoris b is a gas giant with a mass about 9-13 times that of Jupiter. It orbits its parent star at a distance of 9.8 astronomical units (AU) and completes one revolution around its parent star every 22 years.
Beta Pictoris c has a mass 8.2 times that of Jupiter and is located quite close to its star, orbiting it at a distance of 2.7 AU with an orbital period of about 1,200 days.
“Beta Pictoris is at an age where terrestrial planetary belt planet formation is still ongoing due to giant asteroid impacts, so what we're seeing here is essentially how rocky planets and other objects are forming in real time,” said Dr Christine Chen, an astronomer at Johns Hopkins University.
By comparing the new data with data from the Webb Space Telescope in 2004 and 2005, Dr Chen and his colleagues found a significant change in the energy characteristics emitted by the dust particles around Beta Pictoris.
Webb's detailed measurements allowed the researchers to track the composition and size of dust particles in the very region that Spitzer had previously analyzed.
The researchers focused on heat given off by crystalline silicates – minerals commonly found around young stars, on Earth and other celestial bodies – and found no trace of the particles observed in 2004 and 2005.
“This suggests that a catastrophic collision occurred between the asteroid and another object about 20 years ago, shattering the asteroid into microscopic dust particles smaller than pollen or powdered sugar,” Dr Chen said.
“We believe the dust is the same as that first observed in Spitzer data in 2004 and 2005.”
“The best explanation given by Webb's new data is that we have in fact witnessed the aftermath of a rare catastrophe between large, asteroid-sized objects, completely changing our understanding of this solar system.”
The new data suggests that dust dispersed outward by radiation from the system's central star can no longer be detected.
Initially, dust near the star heated up and emitted thermal radiation that Spitzer's instruments identified.
Now, as the dust cools away from the star, it no longer emits its thermal properties.
When Spitzer collected its previous data, scientists assumed that small objects abrading the ground would stir up the dust and steadily replenish it over time.
But Webb's new observations showed that the dust had disappeared and not been replaced.
“The amount of dust kicked up is about 100,000 times the size of the asteroid that wiped out the dinosaurs,” Dr Chen said.
The authors, Investigation result this week's 244th Meeting of the American Astronomical Society In Madison, Wisconsin.
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Christine Chen others2024. Spectroscopic evidence of a recent giant impact around Beta. 224 AustraliaAbstract number 313
Source: www.sci.news
