Astronomers using the NASA/ESA Hubble Space Telescope have produced an outstanding new image of the lenticular galaxy NGC 4694.
This Hubble image shows NGC 4694, a lenticular galaxy some 54 million light-years in the constellation of Virgo. The color image is made up of observations from Hubble’s Wide Field Camera 3 (WFC3) in the ultraviolet, near-infrared, and optical parts of the spectrum. It is based on data obtained through six filters. The color results from assigning different hues to each monochromatic image associated with an individual filter. Image credit: NASA / ESA / Hubble / D. Thilker.
NGC 4694 lies approximately 54 million light-years from Earth in the constellation of Virgo.
Also known as LEDA 43241, IRAS 12457+1115 and UGC 7969, the galaxy is a member of the Virgo galaxy cluster.
NGC 4694 was discovered by the German-born British astronomer William Herschel on March 15, 1784.
“Most galaxies we are familiar with fall into one of two easily-identified types,” the Hubble astronomers said in a statement.
“Spiral galaxies are young and energetic, filled with the gas needed to form new stars and sporting spiral arms hosting hot, bright stars.”
“Elliptical galaxies have a much more pedestrian look, their light coming from a uniform population of older and redder stars.”
“But other galaxies require in-depth study to understand: such is the case with NGC 4694.”
NGC 4694 has a smooth-looking, armless disk which — like an elliptical galaxy — is nearly devoid of star formation.
“However its stellar population is still relatively young and new stars are still actively forming in its core, powering the brightness we can see in this image and giving it a markedly different stellar profile from that of a classic elliptical galaxy,” the astronomers said.
“The galaxy is also suffused by the kinds of gas and dust normally seen in a young and sprightly spiral; elliptical galaxies often do host significant quantities of dust, but not the gas needed to form new stars.”
“NGC 4694 is surrounded by a huge cloud of invisible hydrogen gas, fuel for star formation.”
“As this Hubble image shows, the dust in this galaxy forms chaotic structures that indicate some kind of disturbance,” they said.
“It turns out that the cloud of hydrogen gas around NGC 4694 forms a long bridge to a nearby, faint dwarf galaxy named VCC 2062.”
“The two galaxies have undergone a violent collision, and the larger NGC 4694 is accreting gas from the smaller galaxy.”
“Based on its peculiar shape and its star-forming activity, NGC 4694 has been classified as a lenticular galaxy: lacking the unmistakable arms of a spiral, but not so bereft of gas as an elliptical galaxy, and still with a galactic bulge and disk.”
“Some galaxies just aren’t so easy to classify as one type or the other.”
