And Cannibalize Their Starbirth Crêches

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.

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.

What’s In It For You

Happy September, all!  In three weeks, northern hemisphere seasons will change from summer to autumn, while southern hemisphere seasons move from winter to spring. Where I live, the weather is starting to feel distinctly fall-ish at night, and that means when I go check out the planets and stars, I need to start wearing more clothes to keep warm. It always seems a little strange to be viewing my favorite summer constellations while wearing a heavy jacket and hat, but that’s the nature of seasonal change and sky observing.

Before you head out to stargaze, check out the September edition of Our Night Sky, the short observing show I do for Astrocast.tv each month. This month we look at the planets Venus and Saturn low in the west after sunset. For early morning observers, we check out Mars and Jupiter. Then, we move on to some familiar constellations for each hemisphere, giving you a quick and panoramic view of “what’s up”.  Finally, we chat a little bit about Nova Delphini 2013. It’s a nova, a term reserved for a star that flares suddenly in brightness. Astronomers think this one flared up after the buildup of gas from a smaller companion star got to be too much. The gas ignited, brightening the star tremendously in just a short time. It’s slowly fading out now, but you can still see it if you know where to look. So, check out the September edition of Our Night Sky and get out there under the starry skies!  By the way, Our Night Sky is now available in Hindi! Many thanks to my colleague in astronomy popularization, Rimjhin Singh, for making this new edition possible!