New Radio View Uncovers More Activity

Back when I was a much younger astronomer-in-training, I saw a picture of the galaxy M82 and it looked like a galaxy exploding from the inside out. I remember writing a short piece about it, suggesting that this was an irregular galaxy tearing itself apart through huge explosions. That was decades ago, and now with the advent of high-resolution methods of observation in multiple wavelengths, we know so much more about this galaxy. It’s more complex than I first thought.

It turns out that M82 has two spiral symmetrically shaped spiral arms, but they were hard to spot due to a lot of galactic dust and material from stellar explosions obscuring the view. 

M82 is about twelve million light-years  away from us in the direction of the constellation Ursa Major (in the northern hemisphere sky). Today, we also know that this is a starburst galaxy and is many times brighter than the Milky Way. Hubble Space Telescope has observed starburst regions in the central portion of the galaxy, and it’s thought that interactions with the neighboring galaxy M81 are triggering massive waves of star formation.

Recently the Very Large Array radio telescope in New Mexico took a look at the central region of M82. It focused in on an  area covering about 5,200 light-years across and detected radio emissions from ionized gas and fast-moving electrons that are interacting with magnetic fields extending between the stars.  The bright dots indicate regions where stars are being born and other areas where supernova remnants are extending out to interstellar space.

The faint wispy features are quite intriguing. They’re a relatively  new discovery, and could have some connection to superwinds driven by giant knots of star formation. Stars are often very “windy” after they are born, and when you have collections of newborn stars in close proximity to each other, they could drive tremendously strong “winds” away, carrying superheated material with them.

This image is a great example of how modern astronomy is giving us looks at distant objects in more than one wavelength of light. Not all the action in a galaxy is going to be visible to our unaided visible-light-sensitive eyes. Sometimes you have to look beyond what the eye can see, and move beyond what we knew in the past to learn more about an object in the universe.