Hubble photographs grand spiral galaxy Messier 81

May 29, 2007
Hubble photographs grand spiral galaxy Messier 81
The sharpest image ever taken of the large "grand design" spiral galaxy M81 is being released today at the American Astronomical Society Meeting in Honolulu, Hawaii. A spiral-shaped system of stars, dust, and gas clouds, the galaxy's arms wind all the way down into the nucleus. Though the galaxy is located 11.6 million light-years away, the Hubble Space Telescope's view is so sharp that it can resolve individual stars, along with open star clusters, globular star clusters, and even glowing regions of fluorescent gas. The Hubble data was taken with the Advanced Camera for Surveys in 2004 through 2006. This colour composite was assembled from images taken in blue, visible, and infrared light.

The beautiful galaxy Messier 81 is tilted at an oblique angle on to our line of sight, giving a "birds-eye view" of the spiral structure. The galaxy is similar to our Milky Way, but our favourable view provides a better picture of the typical architecture of spiral galaxies. Though the galaxy is 11.6 million light-years away, the vision of the NASA/ESA Hubble Space Telescope is so sharp that it can resolve individual stars, along with open star clusters, globular star clusters, and even glowing regions of fluorescent gas.

The spiral arms, which wind all the way down into the nucleus, are made up of young, bluish, hot stars formed in the past few million years. They also host a population of stars formed in an episode of star formation that started about 600 million years ago. The greenish regions are dense areas of bright star formation. The ultraviolet light from hot young stars are fluorescing the surrounding clouds of hydrogen gas. A number of sinuous dust lanes also wind all the way into the nucleus of Messier 81.

The galaxy’s central bulge contains much older, redder stars. It is significantly larger than the Milky Way's bulge. The central black hole is 70 million solar masses, or 15 times the mass of the Milky Way's black hole. Previous Hubble research shows that the size of the central black hole in a galaxy is proportional to the mass of a galaxy’s bulge.

Messier 81 may be undergoing a surge of star formation along the spiral arms due to a close encounter it may have had with its nearby spiral galaxy NGC 3077 and a nearby starburst galaxy (Messier 82) about 300 million years ago. Astronomers plan to use the Hubble image to study the star formation history of the galaxy and how this history relates to the neutron stars and black holes seen in X-ray observations of Messier 81 with NASA’s Chandra X-ray Observatory.

Messier 81 is one of the brightest galaxies that can be seen from the Earth. It is high in the northern sky in the constellation Ursa Major, the Great Bear. At an apparent magnitude of 6.8 it is just at the limit of naked-eye visibility. The galaxy's angular size is about the same as that of the Full Moon.

The Hubble data was taken with the Advanced Camera for Surveys in 2004 through 2006. The colour composite measures 22,620 x 15,200 pixels and was assembled from images taken in blue, visible, and infrared light. It was released today at the American Astronomical Society Meeting in Honolulu, Hawaii, USA.

Souce: ESA

Explore further: Short, sharp shocks let slip the stories of supernovae

Related Stories

Galaxy's snacking habits revealed

May 20, 2015

A team of Australian and Spanish astronomers have caught a greedy galaxy gobbling on its neighbours and leaving crumbs of evidence about its dietary past.

More evidence that the Milky Way has four spiral arms

May 12, 2015

Astronomers have been arguing over just how many spiral arms our galaxy exhibits. Is the Milky Way a four or two-armed spiral galaxy? Astronomers had often assumed the Milky Way was potentially a four-armed ...

Image: Hubble eyes galactic refurbishment

May 04, 2015

The smudge of stars at the center of this NASA/ESA Hubble Space Telescope image is a galaxy known as UGC 5797. UGC 5797 is an emission line galaxy, meaning that it is currently undergoing active star formation. ...

Recommended for you

Hubble observes one-of-a-kind star nicknamed 'Nasty'

May 21, 2015

Astronomers using NASA's Hubble Space Telescope have uncovered surprising new clues about a hefty, rapidly aging star whose behavior has never been seen before in our Milky Way galaxy. In fact, the star is ...

Galaxy's snacking habits revealed

May 20, 2015

A team of Australian and Spanish astronomers have caught a greedy galaxy gobbling on its neighbours and leaving crumbs of evidence about its dietary past.

Supernova ignition surprises scientists

May 20, 2015

Scientists have captured the early death throes of supernovae for the first time and found that the universe's benchmark explosions are much more varied than expected.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.