Astronomers using NASA’s Hubble Space Telescope have captured a new image of an actively star-forming galaxy known as NGC 7090.
Discovered in 1834 by astronomer John Herschel, NGC 7090 lies about 30 million light-years away in the southern constellation of Indus.
The galaxy is viewed edge-on from the Earth, meaning we cannot easily see the spiral arms, which are full of young, hot stars. However, a side-on view shows the galaxy’s disc and the bulging central core, where typically a large group of cool old stars are packed in a compact, spheroidal region. In addition, there are two interesting features present in the image that are worth mentioning.
First, we are able to distinguish an intricate pattern of pinkish red regions over the whole galaxy. This indicates the presence of clouds of hydrogen gas. These structures trace the location of ongoing star formation, visual confirmation of recent studies that classify NGC 7090 as an actively star-forming galaxy.
Second, we observe dust lanes, depicted as dark regions inside the disc of the galaxy. In NGC 7090, these regions are mostly located in lower half of the galaxy, showing an intricate filamentary structure. Looking from the outside in through the whole disc, the light emitted from the bright center of the galaxy is absorbed by the dust, silhouetting the dusty regions against the bright light in the background.
Dust in our Milky Way Galaxy has been one of the worst enemies of observational astronomers for decades. But this does not mean that these regions are only blind spots in the sky. At near-infrared wavelengths – slightly longer wavelengths than visible light – this dust is largely transparent and astronomers are able to study what is really behind it. At still longer wavelengths, the realm of radio astronomy, the dust itself can actually be observed, letting astronomers study the structure and properties of dust clouds and their relationship with star formation.