Some 4,100 light years away in the Sagittarius constellation, a stellar nursery births new stars. Known as Messier 8, or the Lagoon Nebula, this region is one of the most visible nebulas from Earth. It is filled with turbulent gases and dark strands of dust. Near the centerline of the image is the bright, hourglass shape of the NGC 6530 star cluster. Its intense ultraviolet light ionizes surrounding gases, creating the distinctive red glow surrounding the nebula. (Image credit: J. Drudis and C. Sasse; via APOD)
Tag: star formation
Turbulence and Star Formation
Space, as I’ve discussed previously, is surprisingly full of matter, especially clouds of dust. And yet the rate of star formation we observe is bizarrely low; the Milky Way, for example, produces only about one solar mass worth of new stars every year. If gravity were the sole force driving star formation, we’d see far more stars forming. Recent research suggests that turbulence plays a major role in regulating the star formation process, both by countering gravity’s attempts to collapse gases into a proto-star and by creating supersonic shocks that drive material together to jump-start star formation. There seem to be other important ingredients as well: young stars tend to form jets that blow material back into the interstellar clouds they’re forming in, feeding the turbulent background. For more, check out Physics Today. (Image credit: ESA/NASA/Hubble/ESO, via APOD; research credit: C. Federrath)
Protostellar Jets
As young stars form, they often produce narrow high-speed jets from their poles. By astronomical standards, these fountains are dense, narrowly collimated, and quickly changing. The jets have been measured at velocities greater than 200 km/s and Mach numbers as high as 20. The animation above (which you should watch in its full and glorious resolution here) is a numerical simulation of a protostellar jet. Every few decades the source star releases a new pulse, which expands, cools, and becomes unstable as it travels away from the star. Models like these, combined with observations from telescopes like Hubble, help astronomers unravel how and why these jets form. (Image credit: J. Stone and M. Norman)
ETA: As it happens, the APOD today is also about protostellar jets, so check that out for an image of the real thing. Thanks, jshoer!
Astronomical Jets
Researchers have pieced together Hubble images of jets from newborn stars into timelapse movies that reveal the interstellar fluid mechanics responsible for the formation of stars like our sun. These jets stream out clumps of matter that has fallen on the new star. When faster moving eddies impact slower ones, bow shocks can form, much like shockwaves running before an airplane. See more HD video of these jets and bow shocks here. #
