Darkest-ever view of dense interstellar ices achieved
An international team used observations from the James Webb Space Telescope to achieve the darkest ever view of a dense interstellar cloud
These observations, by researchers from Southwest Research Institute (SwRI), Leiden University and NASA, have revealed the composition of a virtual treasure chest of ices from the early universe, providing new insights into the chemical processes of one of the coldest, darkest places in the universe as well as the origins of the molecules that make up planetary atmospheres.
SwRI research scientist Dr Danna Qasim, co-author of the study. “The JWST allowed us to study ices that exist on dust grains within the darkest regions of interstellar molecular clouds.
“The clouds are so dense that these ices have been mostly protected from the harsh radiation of nearby stars, so they are quite pristine. These are the first ices to be formed and also contain biogenic elements, which are important to Life.”
See also: JWST helps discovery of ‘oldest galaxies and star clusters’
NASA’s JWST has a 6.5m-wide mirror providing remarkable spatial resolution and sensitivity, optimised for infrared light. As a result, the telescope has been able to image the densest, darkest clouds in the universe for the first time.
Qasim said: “These observations provide new insights into the chemical processes in one of the coldest, darkest places in the universe to better understand the molecular origins of protoplanetary disks, planetary atmospheres, and other solar system objects.”
Most interstellar ices contain very small amounts of elements like oxygen and sulphur. Qasim and her co-authors seek to understand the lack of sulphur in interstellar ices.
She added: “The ices we observed only contain 1% of the sulphur we’re expecting. 99% of that sulphur is locked-up somewhere else, and we need to figure out where in order to understand how sulphur will eventually be incorporated into the planets that may host Life.”
In the study, Qasim and colleagues proposed that the sulphur may be locked in reactive minerals like iron sulphide, which may react with ices to form the sulphur-bearing ices observed.
She explained: “Iron sulphide is a highly reactive mineral that has been detected in the accretion disks of young stars and in samples returned from comets. It’s also the most common sulphide mineral in lunar rocks.
“If sulphur is locked-up in these minerals, that could explain the low amount of sulphur in interstellar ices, which has implications for where sulphur is stored in our solar system.
“For example, the atmosphere of Venus has sulphur-containing molecules, in which the sulphur could have partially come from interstellar-inherited minerals.”
The study is published in Nature Astronomy.
Image: An international team, including research scientist Dr Danna Qasim from Southwest Research Institute, used the James Webb Space Telescope to achieve the darkest and deepest view of ices in interstellar clouds. © NASA/ ESA/ CSA/ M Zamani (ESA/ Webb)/M K McClure (Leiden Observatory)/ F Sun (Steward Observatory)/ Z Smith (Open University)/ Ice Age ERS Team.