Credit: ESA/Hubble & NASAAcknowledgement: Judy Schmidt
Despite the advances made in past decades, the process of galaxy formation remains an open question in astronomy. Various theories have been suggested, but since galaxies come in all shapes and sizes — including elliptical, spiral, and irregular — no single theory has so far been able to satisfactorily explain the origins of all the galaxies we see throughout the Universe.
To determine which formation model is correct (if
any), astronomers hunt for the telltale signs of various physical
processes. One example of this is galactic coronas,
which are huge, invisible regions of hot gas that surround a galaxy’s
visible bulk, forming a spheroidal shape. They are so hot that they can
be detected by their X-ray emission, far beyond the optical radius of
the galaxy. Because they are so wispy, these coronas are extremely
difficult to detect. In 2013, astronomers highlighted NGC 6753, imaged
here by the NASA/ESA Hubble Space Telescope,
as one of only two known spiral galaxies that were both massive enough
and close enough to permit detailed observations of their coronas. Of
course, NGC 6753 is only close in astronomical terms — the galaxy is
nearly 150 million light-years from Earth.
NGC 6753 is a whirl of colour in this image — the bursts of
blue throughout the spiral arms are regions filled with young stars
glowing brightly in ultraviolet light, while redder areas are filled with older stars emitting in the cooler near-infrared.
Source: ESA/Hubble/Potw
