Ornaments

Credit: NASA, ESA, and J. Maíz Apellániz (Insti­tuto de Astrofísica de Andalucía, Spain)

Like a hol­lowed out orna­ment, NGC 6357 glows red in the con­stel­la­tion Scor­pius. Or, maybe, what I see in this NASA Hub­ble Space Tele­scope image is a Christ­mas tree reach­ing for the stars of the open star clus­ter Pis­mis 24.

The stars of Pis­mis 24 are mas­sive; some more than 100 times heav­ier than our Sun. The new stars also unleash a pow­er­ful stel­lar wind that shapes the neb­ula below. Explore the image and wan­der from the stars down to the neb­ula. You’ll encounter tall pil­lars of dense dust and wispy ten­drils of gas. My favorite shape in this cloud is the hand and fin­ger point­ing up at Pis­mis 24. Can you find it? All pil­lars, or ele­phant trunks, point back toward the flow of the stel­lar wind. You can also find a new star near the bot­tom of the image hol­low­ing out a bub­ble in the neb­ula. Can you find other shapes in the neb­ula, such as tad­poles and worms? These denser pock­ets of gas may shrink down and ignite on their own as stars.

NGC 6357 glows because of the light of the newly formed stars. Intense ultra­vi­o­let radi­a­tion com­ing from the star clus­ter, excites the gas mol­e­cules in the neb­ula and causes them to glow. Astronomers call this kind of neb­ula and emis­sion neb­ula. NGC 6357 and Pis­mis 24 are found in the con­stel­la­tion Scor­pius, the scor­pion, about 8,000 light-years from Earth. In our star­ship, trav­el­ing at the speed of light, ten years would pass while mov­ing from the star at the bot­tom of the neb­ula to the star clus­ter at the top.