Astronomers have captured a stunning image of one of the Milky Way’s neighboring spiral galaxies. The portrait was taken using an instrument that was first created to hunt down dark energy – the enigmatic, invisible force that may be responsible for accelerating the expansion of the universe.
The instruments used by astronomers to probe the secrets of the heavens are phenomenally difficult, time-consuming and expensive to build. Because of this, the scientific community often finds additional uses for them once their primary mission has been completed.
The newly released vista of the Southern Pinwheel galaxy is one such example of scientific community making the most of its resources to collect extra usable data and, in this case, to capture a breathtaking image of a galactic neighbor to boot.
This was achieved with the help of the 520-megapixel Dark Energy Camera (DECam) instrument which is mounted on the Victor M. Blanco Telescope at the Cerro Tololo Inter-American Observatory in Chile. DECam’s primary mission had been to help map the structures of hundreds of millions of galaxies between 2013 – 2019, in an attempt to shed light on a phenomenon known to astronomers as dark energy.
Unlike dark matter – an invisible substance that is believed to exert a strong attracting gravitational influence – dark energy is believed to repel ordinary baryonic matter, and in doing so is thought by some to have accelerated the rate of expansion of the cosmos.
Rather than retiring DECam once its primary mission had run its course, it was decided that astronomers would be able to apply for time with the instrument, and so continue to benefit from its powerful imaging capabilities. It took a grand total of 163 exposures collected over the course of 11.3 hours to create the new image of the Southern Pinwheel galaxy.
This vast cosmic structure stretches roughly 50,000 light-years from end to end, and is located 15 million light-years from Earth in the direction of the constellation of Hydra. Even at this distance, the DECam and its 4–meter telescope mount were able to capture fine details in the sweeping arms of the well formed spiral galaxy.
Astronomers used a range of six filters to image the galaxy. This allowed the team to capture sources of light that shone in different parts of the electromagnetic spectrum, and so get a more complete view of the vast cosmic structure.
Dark lanes of dust can be seen threaded throughout the disk of the galaxy, which is seen orientated almost face on to Earth. Meanwhile the reddish clumps of light studding the edges of the dust lanes represent nurseries in which new stars are being born. The intense ultraviolet light blasted out from the surfaces of these young, energetic stellar bodies is absorbed by the surrounding hydrogen clouds, which in turn causes them to glow.
However, the light from these nurseries is eclipsed by the glare of the galactic center, in which a hive of stars radiate their light outward in all directions, masking the presence of the two black holes lurking at its heart.
The video below zooms in on the Southern Pinwheel galaxy from the perspective of Earth.
Source: NSF NOIRLab