James Webb telescope captures stunning new image of 'Whirlpool galaxy'

by Velvet Winter

The M51 galaxy is called the Whirlpool due to its distinct spiral arms.(Supplied: ESA/Webb, NASA & CSA, A. Adamo (Stockholm University)
and the FEAST JWST team)

The ultra-powerful James Webb Space Telescope has taken the clearest image of the M51 galaxy in almost two decades. 

A team of scientists at Stockholm university used the telescope to produce a clear image of the galaxy that exists millions of light years away from ours.

What is M51?

M51 — also known as NGC 5194 — lies about 27 million light-years away from Earth in the constellation Canes Venatici.

It stands out because, unlike other spiral galaxies that have jagged, incomplete arms, M51 boasts prominent, well-developed spiral arms like the ones showcased in this image.

The galaxy is nicknamed the Whirlpool because of its swirling structure.

Those swirling arms are actually long lanes of stars and gas laced with dust.

M51 has been of particular interest for astronomers due to its tumultuous relationship with its neighbour, the dwarf galaxy NGC 5195.

The gravitational pull of M51's smaller neighbour is thought to be partially responsible for M51's distinct spiral arms.

What can we learn from this image?

The new M51 image was observed as a part of the wider project Feedback in Emerging extrAgalactic Star clusTers — or FEAST.

FEAST observations are trying to shed light on star formation and stellar feedback — or the amount of energy stars pour into environments that form them — in galaxies outside the Milky Way.

Basically, FEAST is looking into how stars are formed.

In the new M51 image,  the dark red regions trace the filamentary warm dust permeating the medium of the galaxy.

The red regions show the reprocessed light from complex molecules forming on dust grains, while colours of orange and yellow reveal the regions of ionised gas by the recently formed star clusters.

So, is M51 really bright red and blue?

Not really.

That's because the image isn't a photograph.

In fact, the image above is actually a series of separate exposures that were originally in grey scale and were beamed back to Earth.

They were taken using JWST's Near infrared Camera (NIRCam), which covers infrared wavelength range from 0.6 to 5 microns, and Mid-InfraRed Instrument, which covers infrared wavelength range from 5 to 28 microns.

The equipment allows astronomers to take pictures of very faint objects around a central bright object, a NASA fact sheet says.

It works by blocking out the brighter object's light, which makes it possible to capture the dimmer object nearby.

"Just like shielding the Sun from your eyes with an upraised hand can allow you to focus on the view in front of you," NASA explains. 

Each image was taken using a different filter to capture different wavelengths, and each filter has been assigned a different colour.

The colour comes from layering all of these images on top of each other.

When's the last time we saw M51?

The last time we saw this sharp an image of M51 was all the way back in 2005.

It was taken with the Advanced Camera for Surveys aboard the NASA/ESA Hubble Space Telescope.

Back then, M51 was a little closer to us — a mere 25 million light years away.

The Hubble image of M51 shows that NGC 5195 is passing behind the Whirlpool.
(Supplied: NASA, ESA, S. Beckwith (STScI), and The Hubble Heritage Team)

First published at ABC News, September 3, 2023