Using the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers have imaged the debris disk of nearby star HD 53143 at millimeter wavelengths for the first time, and it appears nothing as they expected. Based on early coronagraphic data, scientists expected ALMA to confirm that the debris disk was a face-on ring strewn with clumps of dust. Instead, the observations took a surprising turn, revealing the most complicated and eccentric debris disk observed to date. The observations were presented today at a press conference at the 240th meeting of the American Astronomical Society (AAS) in Pasadena, Calif., and will be published in an upcoming issue of The Astrophysical Journal Letters (ApJL).
HD 53143 – an approximately billion-year-old Sun-like star located 59.8 light-years from Earth in the constellation Carina – was first observed with the Advanced Coronagraphic Camera for Surveys on the Hubble Space Telescope (HST) in 2006. It is also surrounded by a disk of debris – a belt of comets orbiting a star that constantly collides and crumbles into dust and smaller debris – that scientists previously believed to be a face ring similar to the debris disk surrounding our Sun, better known as the Kuiper Belt.
The new observations were made on HD 53143 using the highly sensitive Band 6 receivers on ALMA, an observatory cooperated by the US National Science Foundation’s National Radio Astronomy Observatory (NRAO), and revealed that the disk of star system debris is actually very eccentric. In ring-shaped debris disks, the star is usually located at or near the center of the disk. But in elliptical-shaped eccentric disks, the star resides at one focus of the ellipse, away from the center of the disk. This is the case with HD 53143, which had not been observed in previous coronagraphic studies because coronagraphs deliberately block light from a star in order to see nearby objects more clearly. The star system may also host a second disk and at least one planet.
“Until now, scientists have never seen a debris disk with such a complicated structure. In addition to being an ellipse with a star at one focus, it also likely has a second inner disk that is misaligned or tilted relative to the outer drive,” he added. said Meredith MacGregor, an assistant professor at the Center for Astrophysics and Space Astronomy (CASA) and the Department of Astrophysical and Planetary Sciences (APS) at CU Boulder, and lead author of the study. “In order to produce this structure, there must be a planet or planets in the system that gravitationally perturb the disk material.”
This level of eccentricity, said MacGregor, makes HD 53143 the most eccentric debris disk observed to date, being twice as eccentric as the Fomalhaut debris disk, which MacGregor imaged entirely at wavelengths millimeters using ALMA in 2017. “So far, we haven’t found many disks with significant eccentricity. In general, we don’t expect disks to be very eccentric unless something, like a planet, sculpts them and forces them to be eccentric. Without this force, the orbits tend to circularize, like what we see in our own solar system.”
Importantly, MacGregor notes that debris disks aren’t just collections of dust and rocks in space. They are a historical record of planetary formation and the evolution of planetary systems over time. and provide insight into their future. “We can’t study the formation of the Earth and the solar system directly, but we can study other systems that look similar but younger than ours. It’s a bit like looking back in time,” said she declared. “Debris disks are the fossil record of planet formation, and this new result is confirmation that there is much more to learn from these systems and that knowledge can provide insight into the complex dynamics of young star systems. similar to our own solar system.”
Dr. Joe Pesce, NSF Program Manager for ALMA, added: “We find planets everywhere we look, and these fabulous results from ALMA show us how planets form, both around other stars and in our own solar system. This research shows how astronomy works and how advancements are being made, informing not only what we know about the field but also about ourselves.”
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