Galactic Fireworks

Credit: NASA, ESA, and K. McQuinn (Uni­ver­sity of Min­nesota, Minneapolis)

Watch­ing fire­works is always enjoy­able but see­ing bursts of star-making light up a galaxy caps a great year of astronomy.

Like a string of fast and furi­ous fire­crack­ers, intense, star-making activ­ity called star­bursts, lights up dwarf galaxy IC 4662. NASA’s Hub­ble Space Tele­scope catches this activ­ity in the inner part of the dwarf galaxy. Star­burst activ­ity orig­i­nally started on the fringes of the galaxy after a pos­si­ble col­li­sion with another galaxy. Dwarf galax­ies usu­ally make only eight stars every thou­sand years. Star­burst galax­ies make 40 stars per thou­sand years. As mas­sive stars on the fringes of the galax­ies explode in super­novae, they push mate­r­ial inward, cre­at­ing new stars. The wave of new stars moves inward toward the galac­tic core like fireworks.

Explore the image. With Hub­ble’s tele­scopes above the atmos­phere, we can see indi­vid­ual stars. Find stars of dif­fer­ent col­ors and bright­ness. This is the same process astronomers use when study­ing the galaxy. These two aspects of stars help us mea­sure a star’s age. With that infor­ma­tion, astronomers can recon­struct how the galaxy formed.

IC 4662 is one of the clos­est galax­ies to our Milky Way, located just 8 mil­lion light-years from Earth toward the south­ern con­stel­la­tion Pavo, the Pea­cock. A light-year is the dis­tance light trav­els in one year; about six tril­lion miles. The clos­est star sys­tem, Alpha Cen­tauri, is just over four light-years from Earth. The Canis Major Dwarf Galaxy is the clos­est galaxy to our Milky Way Galaxy at just 42,000 light years away. Light from the far­thest object we can see with our naked eye, the Androm­eda Galaxy, took two mil­lion years to reach Earth.