Free Astronomy Magazine November-December 2025

18 NOVEMBER-DECEMBER 2025 ASTRO PUBLISHING cretion models that were fit to the data, to basically tell us what kind of star is in the center. These models imply that the star is about 10 times the mass of the Sun and is still growing and has been powering this outflow.” For more than 30 years, as- tronomers have dis- agreed about how massive stars form. Some think a mas- sive star requires a very chaotic process, called competitive accretion. In the competitive accretion model, ma- terial falls in from many different di- rections so that the orientation of the disk changes over time. The outflow is launched perpendicularly, above and below the disk, and so would also appear to twist and turn in dif- ferent directions. “However, what we’ve seen here, because we’ve got the whole history – a tapestry of the story – is that the opposite sides of the jets are nearly 180 degrees apart from each other. That tells us that this central disk is held steady and validates a predic- tion of the core accretion theory,” said Tan. Where there’s one massive star, there could be others in this outer frontier of the Milky Way. Other massive stars may not yet have reached the point of firing off Roman-candle-style outflows. Data from the Atacama Large Millimeter Array in Chile, also presented in this study, has found another dense stel- lar core that could be in an earlier stage of construction. C olor composite image of the Sh2-284 region, obtained by combining Herschel images at 250 µ m (blue), 350 µ m (green), and 500 µ m (red). The colored rectangles or circles indicate the field of view (FOV) of observations from several facilities, including ALMA, JWST, HST, Gemini, and Chandra. For Chandra the FOV of an archival observation program targeting the Dolidze 25 cluster is also shown (dashed rectangle; M. G. Guarcello et al. 2021). [ApJ, Y. Cheng et al.] T his video shows the relative size of two different protostellar jets im- aged by NASA’s James Webb Space Telescope. The first image shown is an extremely large protostellar jet lo- cated in Sh2-284, 15,000 light-years away from Earth. The outflows from the massive central protostar, which weighs 10 times our Sun, span about 8 light-years across. In comparison, a jet imaged by Webb in the nearby low-mass star-forming region of Rho Ophiuchi is just one light-year long. [NASA, ESA, CSA, STScI, Yu Cheng (NAOJ); Animation: Joseph DePasquale (STScI)] in such environments could proceed via a relatively stable disk around the star that is expected in theoret- ical models of star formation known as core accretion,” said Tan. “Once we found a massive star launching these jets, we realized we could use the Webb observations to test the- ories of massive star formation. We developed new theoretical core ac- !