The James Webb Space Telescope (JWST) is a large, infrared-optimized space telescope that is set to be launched in 2021. It is being developed by NASA, with significant contributions from the European Space Agency (ESA) and the Canadian Space Agency (CSA). The JWST is expected to have a number of scientific capabilities, including the ability to observe the Universe in the infrared range, which will allow it to see objects that are too cool or too distant to be seen by other telescopes. It will be able to study the early Universe, the formation of stars and planets, and the potential for life on other worlds.
The inner workings of a dusty disk surrounding a nearby red dwarf star have been imaged by NASA’s James Webb Space Telescope. This is the first time that the previously unknown disk has been imaged at these infrared wavelengths of light. They also provide information about the disk’s composition.
AU Microscopii, also known as AU Mic, is a star system 32 light-years away in the southern constellation Microscopium. It’s about 23 million years old, which means that planet formation has ended, as that process usually takes less than 10 million years. Other telescopes have discovered two known planets around the star. The dusty debris disk that remains is the result of collisions between leftover planetesimals – a more massive equivalent of the dust in our solar system that creates a phenomenon known as zodiacal light.
Our first look at the data far exceeded expectations. It was more detailed than we expected. It was brighter than we expected. We detected the disk closer in than we expected. We’re hoping that as we dig deeper, there’s going to be some more surprises that we hadn’t predicted.
Josh Schlieder
“A debris disk is continuously replenished by collisions of planetesimals. By studying it, we get a unique window into the recent dynamical history of this system,” said Kellen Lawson of NASA’s Goddard Space Flight Center, lead author on the study and a member of the research team that studied AU Mic.
“This system is one of the very few examples of a young star with known exoplanets and a debris disk that is close enough and bright enough to study holistically using Webb’s uniquely powerful instruments,” said Josh Schlieder of NASA’s Goddard Space Flight Center, principal investigator for the observing program and study co-author.
The team studied AU Mic with Webb’s Near-Infrared Camera (NIRCam). They were able to study the region very close to the star by using NIRCam’s coronagraph, which blocks the intense light of the central star. The NIRCam images allowed the researchers to trace the disk as close to the star as 5 astronomical units (460 million miles) – the equivalent of Jupiter’s orbit in our solar system.
“Our first look at the data far exceeded expectations. It was more detailed than we expected. It was brighter than we expected. We detected the disk closer in than we expected. We’re hoping that as we dig deeper, there’s going to be some more surprises that we hadn’t predicted,” stated Schlieder.
The observing program obtained images at wavelengths of 3.56 and 4.44 microns. The team found that the disk was brighter at the shorter wavelength, or “bluer,” likely meaning that it contains a lot of fine dust that is more efficient at scattering shorter wavelengths of light. This finding is consistent with the results of prior studies, which found that the radiation pressure from AU Mic — unlike that of more massive stars — would not be strong enough to eject fine dust from the disk.
While detecting the disk is significant, the team’s ultimate goal is to search for giant planets in wide orbits, such as Jupiter, Saturn, or our solar system’s ice giants. These worlds are extremely difficult to detect in the vicinity of distant stars using either the transit or radial velocity methods.
“This is the first time we have the sensitivity to directly observe planets with broad orbits that are significantly less massive than Jupiter and Saturn. In terms of direct imaging around low-mass stars, this is truly uncharted territory” Lawson elaborated.
These findings were presented today at the American Astronomical Society’s 241st meeting in a press conference. Webb’s Guaranteed Time program 1184 was used to collect the observations.
