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\n This composite shows a section of the interstellar medium scientists X-rayed for sulfur using the Japan-led XRISM (X-ray Imaging and Spectroscopy Mission). X-ray binary GX 340+0 is the inside the red circle drawn in the center. The composite contains a blend of imagery in X-rays (represented in deep blue), infrared, and light. \u2014 NASA <\/p>\n
An international team of scientists have provided an unprecedented tally of elemental sulfur spread between the stars using data from the Japan-led XRISM (X-ray Imaging and Spectroscopy Mission) spacecraft.<\/p>\n
Astronomers used X-rays from two binary star systems to detect sulfur in the interstellar medium, the gas and dust found in the space between stars. It\u2019s the first direct measurement of both sulfur\u2019s gas and solid phases, a unique capability of X-ray spectroscopy, XRISM\u2019s (pronounced \u201ccrism\u201d) primary method of studying the cosmos.<\/p>\n
\u201cSulfur is important for how cells function in our bodies here on Earth, but we still have a lot of questions about where it\u2019s found out in the universe,\u201d said L\u00eda Corrales, an assistant professor of astronomy at the University of Michigan in Ann Arbor. \u201cSulfur can easily change from a gas to a solid and back again. The XRISM spacecraft provides the resolution and sensitivity we need to find it in both forms and learn more about where it might be hiding.\u201d<\/p>\n
A paper about these results, led by Corrales, published June 27 in the Publications of the Astronomical Society of Japan.<\/p>\n
Using ultraviolet light, researchers have found gaseous sulfur in the space between stars. In denser parts of the interstellar medium, such as the molecular clouds where stars and planets are born, this form of sulfur quickly disappears.<\/p>\n
Scientists assume the sulfur condenses into a solid, either by combining with ice or mixing with other elements.<\/p>\n
When a doctor performs an X-ray here on Earth, they place the patient between an X-ray source and a detector. Bone and tissue absorb different amounts of the light as it travels through the patient\u2019s body, creating contrast in the detector.<\/p>\n
To study sulfur, Corrales and her team did something similar.<\/p>\n
They picked a portion of the interstellar medium with the right density \u2014 not so thin that all the X-rays would pass through unchanged, but also not so dense that they would all be absorbed.<\/p>\n
Then the team selected a bright X-ray source behind that section of the medium, a binary star system called GX 340+0 located over 35,000 light-years away in the southern constellation Scorpius.<\/p>\n
Using the Resolve instrument on XRISM, the scientists were able to measure the energy of GX 340+0\u2019s X-rays and determined that sulfur was present not only as a gas, but also as a solid, possibly mixed with iron.<\/p>\n
\u201cChemistry in environments like the interstellar medium is very different from anything we can do on Earth, but we modeled sulfur combined with iron, and it seems to match what we\u2019re seeing with XRISM,\u201d said co-author Elisa Costantini, a senior astronomer at the Space Research Organization Netherlands and the University of Amsterdam. \u201cOur lab has created models for different elements to compare with astronomical data for years. The campaign is ongoing, and soon we\u2019ll have new sulfur measurements to compare with the XRISM data to learn even more.\u201d<\/p>\n<\/p>\n
Iron-sulfur compounds are often found in meteorites, so scientists have long thought they might be one way sulfur solidifies out of molecular clouds to travel through the universe.<\/p>\n
Astronomers used X-rays from two binary star systems to detect sulfur in the interstellar medium, the gas and dust found in the space between stars. It\u2019s the first direct measurement of both sulfur\u2019s gas and solid phases, a unique capability of X-ray spectroscopy, XRISM\u2019s (pronounced \u201ccrism\u201d) primary method of studying the cosmos. \u2014 NASA<\/p>\n
In their paper, Corrales and her team propose a few compounds that would match XRISM\u2019s observations \u2014 pyrrhotite, troilite, and pyrite, which is sometimes called fool\u2019s gold.<\/p>\n
The researchers were also able to use measurements from a second X-ray binary called 4U 1630-472 that helped confirm their findings.<\/p>\n
\u201cNASA\u2019s Chandra X-ray Observatory has previously studied sulfur, but XRISM\u2019s measurements are the most detailed yet,\u201d said Brian Williams, the XRISM project scientist at NASA\u2019s Goddard Space Flight Center in Greenbelt, Maryland. \u201cSince GX 340+0 is on the other side of the galaxy from us, XRISM\u2019s X-ray observations are a unique probe of sulfur in a large section of the Milky Way. There\u2019s still so much to learn about the galaxy we call home.\u201d<\/p>\n
XRISM is led by JAXA (Japan Aerospace Exploration Agency) in collaboration with NASA, along with contributions from ESA (European Space Agency). NASA and JAXA developed Resolve, the mission\u2019s microcalorimeter spectrometer.<\/p>\n