Wide-field view of the Triangulum Galaxy showing the extent of the survey
Area around the Triangulum Galaxy (ground-based image)
Videos
Hubblecast 115 Light: Triangulum Galaxy in unrivalled detail
Zooming in on the Triangulum Galaxy
A close-up look at the Triangulum Galaxy
The NASA/ESA 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 three million light-years. This panoramic survey of the
third-largest galaxy in our Local Group of galaxies provides a
mesmerising view of the 40 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 33 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 54 separate images.
Under excellent 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 three million light-years from Earth, the Triangulum Galaxy is a notable member of the Local Group — it is the group’s third-largest galaxy, but also the smallest spiral galaxy in the group [1].
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 [2].
The Triangulum Galaxy is not only surpassed in size by the
other two 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 two orders of magnitude less than Andromeda. These
numbers are hard to grasp when already in this image 10 to 15 million
individual stars are visible.
In contrast to the two 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 gas and dust, giving rise to rapid star formation. New
stars form at a rate of approximately one solar mass every two years.
The abundance of gas clouds in the Triangulum Galaxy is precisely what drew astronomers to conduct this detailed survey. When stars are born,
they use up material in these clouds of gas and dust, leaving less fuel
for new stars to emerge. Hubble’s image shows two 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 is also among the largest known star
formation regions in the Local Group.
These detailed 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 astronomers to better understand star formation and stellar evolution.
Notes
[1] Our galaxy, the Milky Way, is part of the Local Group, an assembly of more than 50 galaxies bound together by gravity. Its largest member is the Andromeda Galaxy
— also known as Messier 31 — followed by the Milky Way and the
Triangulum Galaxy. The remaining members of the Local Group are dwarf
galaxies, each orbiting one of the three larger ones.
[2] The much bigger Andromeda Galaxy
was mapped by Hubble in 2015, creating the sharpest and largest image of
this galaxy and the largest Hubble image ever (heic1502).
Links
Contact
Mathias Jäger
ESA/Hubble, Public Information Officer
Garching, Germany
Tel: +49 176 62397500
Email: mjaeger@partner.eso.org
Source: ESA/Hubble/News
