Hot Young Newborn Stars Get Cranky

And Cannibalize Their Starbirth CrĂȘches

The constellation Cygnus rides overhead for Northern Hemisphere viewers this time of year. Chart made using Stellarium software. (Stellarium.org)
The constellation Cygnus rides overhead for Northern Hemisphere viewers this time of year. Chart made using Stellarium software. (Stellarium.org)

If you go outside tonight and look in the direction of the constellation Cygnus, you’ll be gazing toward a region of sky that contains an association of hot young stars only recently emerged from their starbirth cocoons. The group is called the Cygnus OB2 association, and it contains 65 really hot, young O-type stars, plus another 500 or so B-type stars. O and B stars are young, hot, massive, and they are quite active. They blast ultraviolet radiation out to space and anything that gets in the way is affected. It turns out there’s a cloud of gas and dust near these stars, and their combined radiation is sculpting and carving the cloud. They’ve created a sort of cosmic caterpillar, with a somewhat twisty tail.

The action of radiation from nearby hot young stars has sculpted this cloud of gas and dust, and could be choking off the supply of gas the young star inside needs to continue forming.  Courtesy NASA, ESA, the Hubble Heritage Team (STScI/AURA), and IPHAS
The action of radiation from nearby hot young stars has sculpted this cloud of gas and dust, and could be choking off the supply of gas the young star inside needs to continue forming. Courtesy NASA, ESA, the Hubble Heritage Team (STScI/AURA), and IPHAS

This cosmic caterpillar is called IRAS 20324+4057, It’s actually a protostar in a very early stage of formation. The soon-to-be star is in the process of collecting material from the envelope of gas surrounding it.

In time, if it collects enough material, it could become a star like its older, more active siblings. However, the radiation from its fellow stars is eroding away the fuel this protostar needs to grow, and the final star may be much less massive than the ones nearby. It’s a common problem in starbirth regions: the first stars form and then get testy and fussy, and their blasts of radiation make it harder for other stars to grow.

According to the Hubble Space Telescope news site, this image of IRAS 20324+4057 is a composite of Hubble Advanced Camera for Surveys data taken in green and infrared light in 2006, and ground-based hydrogen data from the Isaac Newton Telescope in 2003, as part of the IPHAS H-alpha survey. Astronomers use infrared light to peer at objects inside clouds of gas and dust that would otherwise be hidden from our visible-light-sensitive telescopes and eyes.

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