Posts Tagged ‘dwarf galaxy’


Credit: NASA, ESA, A. Aloisi (STScI/ESA), and The Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration

To me, this image from NASA‘s Hubble Space Telescope looks like a lumbering, long-necked Brontosaurus. Maybe a turtle with a long tail. What do you see in this image?

Dwarf galaxy NGC 4449 is home to a massive star-formation explosion. Scientists call this intense period of star-making a starburst. Astronomers believe the increase was likely triggered by a close interaction or merger with a smaller companion.

Explore the image from the tip of the head at the left to the tail on the right. Hundreds of thousands of red and blue stars blaze this galaxy. Huge bluish-white clusters of massive stars are seen scattered throughout. Reddish clouds of interstellar gas and dust show regions of current star formation. The stars are redder here because the dust clouds between us are thick. Thicker dust clouds are silhouetted against the galactic starlight.

NGC 4449 is part of a group of galaxies in the small, northern constellation Canes Venatici that is only 12.5 million light years from Earth; right in the neighborhood of the Milky Way. Canes Venatici was created by Johnannes Hevelius in the 17th century. The name is Latin for hunting dogs, representing the mythological dogs Chara and Asterion being held by the neighboring constellation Boötes, the Herdsman.

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.


The ancient peoples saw pictures in the sky. From those patterns in the heavens, ancient storytellers created legends about heroes, maidens, dragons, bears, centaurs, dogs and mythical creatures...
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