A wheel within a wheel
SPACE TELESCOPE SCIENCE INSTITUTE PHOTO RELEASE
Posted: September 5, 2002

A nearly perfect ring of hot, blue stars pinwheels about the yellow nucleus of an unusual galaxy known as Hoag's Object. This image from NASA's Hubble Space Telescope captures a face-on view of the galaxy's ring of stars, revealing more detail than any existing photo of this object. The image may help astronomers unravel clues on how such strange objects form.

HST
Image Credit: NASA and The Hubble Heritage Team (STScI/AURA); Acknowledgment: Ray A. Lucas (STScI/AURA)
 
The entire galaxy is about 120,000 light-years wide, which is slightly larger than our Milky Way Galaxy. The blue ring, which is dominated by clusters of young, massive stars, contrasts sharply with the yellow nucleus of mostly older stars. What appears to be a "gap" separating the two stellar populations may actually contain some star clusters that are almost too faint to see. Curiously, an object that bears an uncanny resemblance to Hoag's Object can be seen in the gap at the one o'clock position. The object is probably a background ring galaxy.

Ring-shaped galaxies can form in several different ways. One possible scenario is through a collision with another galaxy. Sometimes the second galaxy speeds through the first, leaving a "splash" of star formation. But in Hoag's Object there is no sign of the second galaxy, which leads to the suspicion that the blue ring of stars may be the shredded remains of a galaxy that passed nearby. Some astronomers estimate that the encounter occurred about 2 to 3 billion years ago.

This unusual galaxy was discovered in 1950 by astronomer Art Hoag. Hoag thought the smoke-ring-like object resembled a planetary nebula, the glowing remains of a Sun-like star. But he quickly discounted that possibility, suggesting that the mysterious object was most likely a galaxy. Observations in the 1970s confirmed this prediction, though many of the details of Hoag's galaxy remain a mystery.

The galaxy is 600 million light-years away in the constellation Serpens. The Wide Field and Planetary Camera 2 took this image on July 9, 2001.

The Space Telescope Science Institute (STScI) is operated by the Association of Universities for Research in Astronomy, Inc. (AURA), for NASA, under contract with the Goddard Space Flight Center, Greenbelt, MD. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency (ESA).

Hubble
Astronomy Now presents Hubble: the space telescope's view of the cosmos. A collection of the best images from the world’s premier space observatory.
 U.S. STORE
 U.K. & WORLDWIDE STORE
Apollo 15 DVDs
Bring a unique piece of space history to your living room. Two- and six-disc Apollo 15 DVDs will be shipping soon.
 U.S. STORE
 U.K. & WORLDWIDE STORE

ERROR: Random File Unopenable

ERROR: Random File Unopenable

The random file, as specified in the $random_file perl variable was unopenable.

The file was not found on your file system. This means that it has either not been created or the path you have specified in $trrandom_file is incorrect.
Columbia Report
The official accident investigation report into the loss of the space shuttle Columbia and its crew of seven. Includes CD-ROM.
 Choose your store:
U.S.

Apollo 11 special patch
Special collectors' patch marking the 35th anniversary of the historic Apollo 11 moon landing is now available.
 Choose your store:
U.S. - U.K. - E.U. - Worldwide

Inside Apollo mission control
An insider's view of how Apollo flight controllers operated and just what they faced when events were crucial.
 Choose your store:
U.S.

The ultimate Apollo 11 DVD
This exceptional chronicle of the historic Apollo 11 lunar landing mission features new digital transfers of film and television coverage unmatched by any other.
 Choose your store:
U.S. - U.K. - E.U. - Worldwide

Next ISS crew
Own a little piece of history with this official patch for the International Space Station's Expedition 11 crew. We'll ship yours today!
 Choose your store:
U.S.


INDEX | PLUS | NEWS ARCHIVE | LAUNCH SCHEDULE
ASTRONOMY NOW | STORE

ADVERTISE

© 2014 Spaceflight Now Inc.