This spectacular image was taken in infrared (IR) light by the Hubble Space Telescope (HST). It shows a region of active star formation within the emission nebula Sh2-284, located 15,000 light-years from Earth in the constellation Monoceros. It’s near the end of a spiral arm of the Milky Way, close to the edge of the galaxy. And there’s a lot of hydrogen in the galactic suburbs left over from the Milky Way’s formation.
Emission nebulae are vast clouds of dust and gas illuminated by stars in their interiors. Follow that link for some gorgeous images. The HST is able to see the stars inside because IR light passes easily through dust and gas. Stars show as pink points with diffraction spikes around them. This is a false color image that replaces light we cannot see with arbitrary colors. These are “baby” stars, only a few hundred million years old.
Spectroscopic analysis shows these stars are burning hydrogen, supporting the idea that this is a starburst region where “first generation” stars are forming. It’s a situation much like prevailed in the early universe, before second generation (high metallicity) stars formed from the ejecta of first generation supernovae.
Of course, this is not what your eyes would see if using a visible light telescope on Sh2-284. You’d see the glowing clouds of dust, but few of the stars behind the dust that are causing it to glow. It would look like this in visible light (region imaged by HST circled):
That sparkling stellar nursery in Sh2-284 is reminiscent of the early universe. The actual first generation of stars formed about 400 million years after the Big Bang. At that time there was only hydrogen, helium, and a spritz of lithium available as fuel. It was what is called a low metallicity environment. After what is called the Dark Ages of the Universe, gravity relentlessly collapsed vast clouds of hydrogen into stars, and the lights came on.
The second image shows some interesting structures astronomers call “elephant trunks” — extended narrow regions of dust and gas caused by stellar winds and radiation pressure from the hot new stars within. You can see one here at about the 3 o’clock position. It looks like a closed hand pointing toward the center of the nebula, and is about 7 light-years long! Elephant trunks can be found in most emission nebulae in a variety of shapes and sizes. Perhaps the most famous is Pillars of Creation in the Eagle Nebula, also an HST image.
If you enjoy seeing beautiful natural phenomena, I highly recommend Astronomy Picture of the Day. I have it bookmarked in my browser and check it daily. In fact, I go there before the news just to start my day on a positive note.
Next Week in Sky Lights ⇒ Meteor Crater