Free Astronomy Magazine July-August 2026

25 JULY-AUGUST 2026 ASTRO PUBLISHING (over 3 million kilometers) per hour and appears to be the primary force driving a cool- er, well-studied, galaxy-scale wind. Researchers made the calcula- tions using data from the Re- solve instrument aboard the XRISM (X-ray Imaging and Spectroscopy Mission) space- craft. “The classic model of star- burst galaxies like M82 sug- gests that shock waves from star formation and super- novae near the center heat the gas, kick-starting a pow- erful wind,” said Erin Boett- cher, an astrophysicist at the University of Maryland, Col- lege Park and NASA’s God- dard Space Flight Center in Greenbelt, Maryland. “Prior to XRISM, though, we didn’t have the ability to measure the velocities needed to test that hypothesis. Now we see the gas moving even faster than some models predict, more than enough to drive the wind all the way to the edge of the galaxy.” The XRISM mission is led by JAXA (Japan Aerospace Ex- ploration Agency) in collaboration with NASA, along with contributions from ESA (European Space Agency). NASA and JAXA also codeveloped the Resolve instrument. Sometimes called the Cigar galaxy, M82 is located 12 million light-years away in the northern constellation Ursa Major. Astronomers classify it as a starburst galaxy because it’s form- ing stars at a much higher rate than typical for its size — about 10 times faster than the Milky Way. M82 is well known for its extended, cool wind, which stretches out to 40,000 light-years and propels huge quantities of gas and dust. Scientists have studied it with many missions, T his image of M82, captured by the Near-Infrared Camera aboard NASA’s James Webb Space Telescope, shows the center of the galaxy in such detail that astronomers can distinguish small bright sources that are either individual stars or star clusters. [NASA, ESA, CSA, STScI, Alberto Bolatto (UMD)] including NASA’s Chandra, Webb, Hubble, and retired Spitzer space tel- escopes, trying to connect the dots between the stellar activity and the large-scale outflow. Researchers particularly want to un- derstand the role of cosmic rays. These high-speed charged particles are found throughout the cosmos and are accelerated by some of the same events scientists think produce winds like in M82. There’s a possibil- ity they are a main source of out- ward pressure on the gas. The XRISM Resolve instrument’s high resolution and sensitivity allowed Boettcher and her colleagues to ac- curately measure the speed of the hot wind by looking at an X-ray sig- nal from superheated iron in the galactic center. The amount of X-ray light from iron and other elements told them the temperature — right within predic- tions at 45 million degrees Fahren- heit (25 million degrees Celsius). The heat exerts pressure on the gas and pushes it outward. This rushing from high pressure to low pressure forms the wind — the same reason winds blow through Earth’s atmosphere. The broadness of iron spectral lines conveyed the hot wind’s speed. This works through Doppler shifting, the same phenomenon that causes the pitch of a sound, like a siren, to rise