Look at this beautiful galaxy. It should really have a flashier name than UGC 6093. How about Megamaser Galaxy? Yeah, that’s better. UGC 6093 is a barred spiral galaxy 500 million light years away in the constellation Leo. The “barred” part refers to the gorgeous arms that swirl outwards from a thick bar of stars slicing through the galaxy’s center.
Astronomers classify it as an active galaxy because inside there’s a compact region at the galaxy’s center where material is being dragged towards a supermassive black hole. As this black hole devours the surrounding matter it emits intense radiation, causing it to shine brightly. But there’s much more going here on not visible in ordinary photographs. The black hole’s interaction with the dust, gas and stars it’s devouring has also created a giant astronomical laser but one that beams microwaves. We call it a maser. Laser is an acronym for Light Amplification by Stimulated Emission of Radiation. If you replace the “L” with “M” for microwave, you get a maser.
A maser works exactly the same way a laser does but shoots out a narrow beam of microwaves instead of red or green light. We can’t see microwaves, but they’re a form of light just like the color green but have much longer waves, beyond the red end of the color spectrum. The energy they contain does a great job vibrating water molecules which cooks up many a dish in the microwave oven.
In the highly energized environment of a black hole, where matter’s being torn apart and radiation abounds, water vapor and other molecules can be excited to higher energy levels and then dump that energy in concert in a single, coherent beam of microwave light like a bullet. As long as radiation’s available, molecules continually get pumped and dumped.
There must be a lot of excitement in the nucleus of UGC 6093 because the galaxy is classified as a megamaser some 100 million times brighter than the masers found in galaxies like the Milky Way. Think how brilliant the galaxy would appear if we could see it with microwave vision — probably a lot brighter than its visual brightness of magnitude 14.8.
Like I said, masers and lasers work the same except for the wavelength or color of light they beam. In nature, light waves of all different wavelengths pour down from the sun and come together to produce white light. The light in a laser beam is all the same color or wavelength, most familiar to us as a particular shade of red or green. All the waves in a laser beam are also lined up or “in phase” to create a very narrow, focused beam that concentrates light’s energy. Carbon dioxide (CO2) lasers can cut metal!
Here are a couple great sites to learn more about how masers and lasers work:
On the lower energy but just as exciting side, Mars and Jupiter are causing a stir in the morning sky again. If you missed last week’s close conjunction, this Thursday at dawn (Jan. 11), the crescent moon will join the pair in the southern sky. Give a look if it’s clear. The planets will both be about 3½° from the moon, so the whole scene will fit in one binocular field of view. Sweet!