Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have identified a so-called dust trap — a region where dust particles can grow by clumping together — in a dynamic ring of gas and dust, known as a circumstellar disk, surrounding the young star V1247 Orionis.
This image from the Atacama Large Millimeter/submillimeter Array shows a central ring of matter and a crescent structure within the circumstellar disk around V1247 Orionis. Image credit: ALMA / ESO / NAOJ / NRAO / S. Kraus, University of Exeter.
V1247 Orionis, also known as HD 290764 and IRAS 05355-0117, is located approximately 1,000 light-years away from Earth in the constellation Orionis.
The new ALMA image revealed two structures in the dusty disk around the star: a sharply confined crescent structure and an asymmetric ring.
The region between the ring and crescent, visible as a dark strip, is thought to be caused by a young planet carving its way through the disk.
“As the planet orbits around its parent star, its motion creates areas of high pressure on either side of its path, similar to how a ship creates bow waves as it cuts through water,” said University of Exeter Professor Stefan Kraus and co-authors.
“These areas of high pressure could become protective barriers around sites of planet formation. Dust particles are trapped within them for millions of years, allowing them the time and space to clump together and grow.”
The exquisite resolution of ALMA allowed the team to study the intricate structure of such a dust-trapping vortex in V1247 Orionis’ circumstellar disk.
The image revealed not only the crescent-shaped dust trap at the outer edge of the dark strip, but also regions of excess dust within the ring, possibly indicating a second dust trap that formed inside of the potential planet’s orbit. This confirmed the predictions of earlier computer simulations.
“Dust trapping is one potential solution to a major stumbling block in current theories of how planets form, which predicts that particles should drift into the central star and be destroyed before they have time to grow to planetesimal sizes (radial drift problem),” the scientists said.
The findings are published in the Astrophysical Journal Letters.
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Stefan Kraus et al. 2017. Dust-trapping Vortices and a Potentially Planet-triggered Spiral Wake in the Pre-transitional Disk of V1247 Orionis. ApJL 848, L11; doi: 10.3847/2041-8213/aa8edc
