NASA, ESA, Space Telescope Science Institute/J. Lee;
Processing: NASA/Catholic University of America/Gladys Kober
It’s easy to get swept up in the swirling starry arms of this intermediate
spiral galaxy, NGC 4654, in the constellation Virgo. The galaxy has a bright
center and is labeled “intermediate” because it has characteristics of both
unbarred and barred spirals. NGC 4654 is just north of the celestial equator,
making it visible from the northern hemisphere and most of the southern hemisphere.
The galaxy is around 55 million light-years from Earth.
NGC 4654 is one of many Virgo
Cluster galaxies that have an asymmetric distribution of stars and of neutral
hydrogen gas. Astronomers reason that NGC 4654 may be experiencing a process
called “ram pressure stripping,” where the gravitational pull of the Virgo
galaxy cluster puts pressure on NGC 4654 as it moves through a superheated
plasma made largely of hydrogen called the “intracluster medium.” This pressure
feels like a gust of wind – think of a biker feeling wind even on a still day –
that strips NGC 4654 of its gas. This process produced a long, thin tail of
hydrogen gas on the galaxy’s southeastern side. Most galaxies that experienced
ram pressure stripping hold very little cold gas, halting the galaxy’s ability
to form new stars, since stars generate from dense gas. However, NGC 4654 has
star formation rates consistent with other galaxies of its size.
NGC 4654 also had an interaction
with the companion galaxy NGC 4639 about 500 million years ago. The gravity of
NGC 4639 stripped NGC 4654’s gas along its edge, limiting star formation in
that region and causing the asymmetrical distribution of the galaxy’s stars.
Scientists study galaxies like NGC
4654 to examine the connection between young stars and the cold gas from which
they form. NASA’s Hubble
Space Telescope took this image in visible, ultraviolet, and infrared light.
Hubble shared a brand-new galaxy image every day Oct. 2-7, 2023. See the new images and learn more about galaxies.
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