Hubble Space Telescope captures countless stars at the centre of the star-forming Triangulum Galaxy

A familiar favourite as you’ve never seen it before.

By Iain Todd

Published: Friday, 23 August 2024 at 06:01 AM

The Triangulum Galaxy is one of the most famous spiral galaxies in astronomy, it’s one of our own Galaxy’s closest neighbours, and its core has been captured in exquisite detail by the Hubble Space Telescope.

Also known as Messier 33, being the 33rd entry in the famous Messier Catalogue of deep-sky objects, the Triangulum Galaxy is the third largest member of the Local Group of galaxies, after the Andromeda Galaxy and our Milky Way.

Hubble Space Telescope image showing the centre of the Triangulum Galaxy. Click image to expand. Credit: NASA, ESA, M. Boyer (STScI), and J. Dalcanton (University of Washington); Processing: Gladys Kober (NASA/Catholic University of America)

Triangulum Galaxy and star formation

The Triangulum Galaxy is bursting with star formation, 10 times greater even than the Andromeda Galaxy.

It’s also an incredibly neat and pristine example of a spiral galaxy with well-defined arms that, say astronomers, indicate it’s not currently being gravitationally perturbed by interactions with neighbouring galaxies.

M33’s propensity for star formation is due to the fact it contains so much cosmic gas and dust: the key ingredients for forming new stars.

It contains so-called H-II regions, which are clouds of ionised hydrogen that fuel star formation.

Astronomers say there’s evidence that high-mass stars are forming in collisions between massive molecular clouds in the Triangulum Galaxy.

Inset image shows Hubble's view of the centre of the Triangulum Galaxy. Credit: NASA, ESA, M. Boyer (STScI), J. Dalcanton (University of Washington), and ESO; Processing: Gladys Kober (NASA/Catholic University of America)
Inset image shows Hubble’s view of the centre of the Triangulum Galaxy. Click image to expand. Credit: NASA, ESA, M. Boyer (STScI), J. Dalcanton (University of Washington), and ESO; Processing: Gladys Kober (NASA/Catholic University of America)

This Hubble Space Telescope image showing the centre of the Triangulum Galaxy reveals those ionised hydrogen clouds in red.

Cutting through the clouds are dark lanes of cosmic dust.

And if you think this looks rather grainy for a Hubble image, that ‘graininess’ is actually countless stars.

The Hubble Space Telescope is so powerful it can resolve individual stars in the Triangulum Galaxy, even though the galaxy is 2.73 million lightyears from Earth.

Hubble Space Telescope image of the Triangulum Galaxy, released in 2019. Credit: NASA, ESA, and M. Durbin, J. Dalcanton, and B. F. Williams (University of Washington)
Hubble Space Telescope image of the Triangulum Galaxy, released in 2019. Click image to expand. Credit: NASA, ESA, and M. Durbin, J. Dalcanton, and B. F. Williams (University of Washington)

Triangulum’s ultimate fate

The Triangulum is something of a rarity, in that it’s a ‘pure disk galaxy’, which means it has no supermassive black hole at its centre and has no central, concentrated bulge of stars.

However, the Triangulum Galaxy’s ultimate fate might be the same as our own.

The Milky Way is destined to collide with the Andromeda Galaxy in the future, and this event is known as the Andromeda-Milky Way collision.

Astronomers think that the Triangulum Galaxy may be on a collision course with Andromeda and the Milky Way, meaning its pristine shape won’t last forever.

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