NGC 4622 Spiral Galaxy
Astronomers have found a spiral galaxy that may be spinning to the beat of a
different cosmic drummer. To the surprise of astronomers, the galaxy, called NGC
4622, appears to be rotating in the opposite direction to what they expected.
Pictures by NASA's Hubble Space Telescope helped astronomers determine that the
galaxy may be spinning clockwise by showing which side of the galaxy is closer
to Earth. A Hubble telescope photo of the oddball galaxy is this month's Hubble
Heritage offering. The image shows NGC 4622 and its outer pair of winding arms
full of new stars [shown in blue].
Astronomers are puzzled by the clockwise rotation because of the direction the
outer spiral arms are pointing. Most spiral galaxies have arms of gas and stars
that trail behind as they turn. But this galaxy has two "leading" outer arms
that point toward the direction of the galaxy's clockwise rotation. To add to
the conundrum, NGC 4622 also has a "trailing" inner arm that is wrapped around
the galaxy in the opposite direction it is rotating. Based on galaxy
simulations, a team of astronomers had expected that the galaxy was turning
NGC 4622 is a rare example of a spiral galaxy with arms pointing in opposite
directions. What caused this galaxy to behave differently from most galaxies?
Astronomers suspect that NGC 4622 interacted with another galaxy. Its two outer
arms are lopsided, meaning that something disturbed it. The new Hubble image
suggests that NGC 4622 consumed a small companion galaxy. The galaxy's core
provides new evidence for a merger between NGC 4622 and a smaller galaxy. This
information could be the key to understanding the unusual leading arms.
Galaxies, which consist of stars, gas, and dust, rotate very slowly. Our Sun,
one of many stars in our Milky Way Galaxy, completes a circuit around the Milky
Way every 250 million years. NGC 4622 resides 111 million light-years away in
the constellation Centaurus. The pictures were taken in May 2001 with Hubble's
Wide Field Planetary Camera 2.
The science team, consisting of Ron Buta and Gene Byrd from the University of
Alabama, Tuscaloosa, and Tarsh Freeman of Bevill State Community College in
Alabama, observed NGC 4622 in ultraviolet, infrared, and blue and green filters.
Their composite image and science findings were presented at the meeting of the
American Astronomical Society in January of 2002.
background of space.war:
Zarkos' armada of spaceships is on its way from the Spiral Galaxy NGC 4622
(Zarkos' home) to an interstellar conference on planet JP 1804, located in the
CRAB Nebula. Suddenly, sonar pings suggest that Zarkos' fleet is being monitored
by an enemy army of space cruisers. A ferocious deep space dog-fight ensues. But
Zarkos' army wins the battle, and the piece ends with Zarkos' warriors singing
their song of victory.