Long filaments of ionized hydrogen gas (pink) extending 110,000 light years above the disk of the NGC 4388. Image courtesy Subaru Telescope, Mauna Kea, Hawaii. (NOTE: the long gray straight lines are actually detector artefacts.)
Stare into space long enough, with strong enough eyes at many wavelengths, and eventually you find things that look like the events happening in this image. This is an action shot, capturing a scene from the evolution of a galaxy. A supermassive black hole at the heart of the galaxy is devouring material. This accretion produces vast amounts of energy that outshine the light from all the stars in the galaxy. The surrounding gases are “excited” by the action, resulting in ionization. Light at a specific wavelength is emitted, allowing astronomers to see it.
When we say it’s an exciting universe, we aren’t just talking about cool stuff happening. The processes that heat gases and cause light to shine out across the parsecs so we can see it belie some of the most interesting and energetic events in the cosmos. Astronomy seeks to understand those processes and events. And that’s why snapshots like this one are so important. Build up enough of them and you start to get a feel for what’s happening in the cosmos–and why.
Neither did I, some 25 years ago when I first wrote about M82 in a planetarium show. At the time nobody was quite sure what was happening at the center of this galaxy. It looked like it could be blowing itself apart; a stellar city disrupted by tremendous forces. Well, times have changed. We have better telescopes, stronger “glasses” if you will, and now we can look into the heart of M82 and see that it’s really harboring a galactic construction site, a humongous starbirth nursery that’s blowing winds across space. To be sure there’s a little stardeath going on here, too. Supernovae—the deaths of massive stars—are also blowing strong winds across space, fueling the frenetic appearance of the scene. Here’s what the Astronomy Picture of the Day site says about this image:
“Star formation occurs at a faster pace in M82—a galaxy with about ten times the rate of massive star birth (and death) compared to our Milky Way. Winds from massive stars and blasts from supernova explosions have created a billowing cloud of expanding gas from this remarkable starburst galaxy. The above scientifically color-coded image highlights the complexity and origin of the plume by combining a wide field image from the WIYN Telescope in Arizona with a smaller high-resolution image from the orbiting Hubble Space Telescope. M82’s aspect in optical pictures has led to its popular moniker, the Cigar Galaxy. M82’s burst of star formation was likely triggered a mere 100 million years ago in the latest of a series of bouts with neighboring large galaxy M81.
This is what keeps me fascinated about astronomy. The better our tools become, the more we learn, and of course, the more questions we ask about the cosmos. I wonder what future telescopes will see at the heart of M82?
