The NASA Hubble Space Telescope has captured the most detailed image yet of a close neighbour of the Milky Way — the Triangulum Galaxy, a spiral galaxy located at a distance of only 3 million light-years.
This panoramic survey of the third-largest galaxy in our local group of galaxies provides a mesmerising view of the forty billion stars that make up one of the most distant objects visible to the naked eye.
This new image of the Triangulum Galaxy — also known as Messier thirty three or NGC 598 — has a staggering 665 million pixels and showcases the central region of the galaxy and its inner spiral arms. To stitch together this gigantic mosaic, Hubble’s Advanced Camera for Surveys needed to create fifty four separate pictures.
Under Good Dark-Sky conditions, the Triangulum Galaxy can be seen with the naked eye as a faint, blurry object in the constellation of Triangulum (the Triangle), where its ethereal glow is an exciting target for amateur astronomers.
At only 3 million light-years from Earth, the Triangulum Galaxy is a notable member of the local group — it’s the group’s third-largest galaxy, but also the smallest spiral galaxy in the group. It measures only about 60,000 light-years across, compared to the 200,000 light-years of the Andromeda Galaxy; the Milky Way lies between these extremes at about 100 000 light-years in diameter.
The Triangulum Galaxy isn’t only surpassed in size by the other 2 spirals, but by the multitude of stars they contain. The Triangulum Galaxy has at least an order of magnitude less stars than the Milky Way and 2 orders of magnitude less than Andromeda. These numbers are hard to grasp when already in this image ten to fifteen million individual stars are visible.
In contrast to the 2 larger spirals, the Triangulum Galaxy doesn’t have a bright bulge at its centre and it also lacks a bar connecting its spiral arms to the centre. It does, however, contain a huge amount of dust and gas, giving rise to rapid star formation. New stars form at a rate of approximately one solar mass every 2 years.
Abundance of the gas Clouds in the Triangulum Galaxy is precisely what Drew Astronomers to conduct this detailed survey. when stars are born, they use material in these clouds of gas and dust, leaving less fuel for new stars to emerge.
Hubble’s image shows 2 of the four brightest of these regions in the galaxy: NGC 595 and NGC 604. The latter is the second most luminous region of ionised hydrogen within the local group and it’s also among the biggest known star formation regions in the local group.
These elaborate observations of the Triangulum Galaxy have tremendous legacy value — combined with those of the Milky Way, the Andromeda galaxy and the irregular Magellanic Cloud galaxies, they will help the Astronomers to better understand Stellar Evolution and Star formation.