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James Webb Telescope Provides New Clues About Nature of Our Milky Way Galaxy | Radio-Canada

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THE James Webb Space Telescope continues to amaze astronomers with new images of the universe impossible to obtain with other instruments. A recently released Gallery shows stunning details of 19 nearby spiral galaxies, similar to our own Milky Way.

In a ongoing project called PHANGS (High Angular Resolution Physics in Nearby Galaxies), recent images of galaxies taken by Webb will be combined with images taken by the The Hubble Space TelescopeTHE European Southern ObservatoryThe very large telescope of MUSE (Multi-unit spectroscopic explorer) and ALMA (Atacama Millimeter/submillimeter Array) in Chile.

The goal is to examine nearby spiral galaxies, which have the same swirl shape as the Milky Way in as many different wavelengths of light as possible – from visible to ultraviolet, radio and infrared waves – to better understand the interaction between the small-scale physics of gas and star formation and the structures of galaxies on a larger scale and their evolution.

A dazzling spiral galaxy with only two main arms sparkles with a bright white core and amber, magenta, and diffuse white arms spiraling above and below like an upside-down spiral. "s."
This image of the spiral galaxy NGC 1300 combines several telescope observations from ALMA, MUSE and Hubble before Webb’s observations were included. (Alyssa Pagan/STScl/NASA/ESA/ESO-Chile/ALMA/NAOJ/NRAO)

Spiral galaxies are a favorite subject for astronomers, not only because they are the most beautiful to observe, but also because they provide the best information about the nature of the Milky Way. We can’t actually see our own galaxy because we’re in it.

Astronomers have a rough idea of ​​its spiral shape from the movement of stars, but the image of our galaxy lacks precise detail. It’s like trying to see the layout of your city or town while standing right outside the front door of your house; you would have to fly over the city to get an overview.

It will be a long time before we get a flyby image of the entire Milky Way, because at over 100,000 light years across, we would need to fly thousands of light years directly above the plane before the entire structure is visible. Currently, we have no way to fly that far.

The view from inside the Milky Way appears filled with stars on a black background in a colorful spectrum, from cyan to magenta.
The 50 light-years of the James Webb Space Telescope allow us to observe the dense interior of the Milky Way. (Samuel Crowe/UVA/STScI/NASA/ESA/CSA/NASA/ESA/CSA)

Webb’s contribution to the study of galaxies is invaluable for two reasons. First: its primary mirror, 6.5 meters in diameteris the largest telescope ever launched into space, giving it more six times the light-collecting area of ​​the Hubble Space Telescope.

The gigantic golden eye in the sky can see fainter, more distant objects, or nearby objects, in finer detail than ever before.

Second: Unlike Hubble, which sees in visible light like our eyes, Webb sees in infrared light, which is invisible to us, although we can feel infrared radiation as heat.

The longer wavelength of infrared light allows it to penetrate the vast dust clouds that are scattered among the stars of galaxies and that obscure Hubble’s view. Webb can see through these clouds and reveal details that have been hidden until now.

A stunning view of a spiral galaxy is a collage of two images, split from top right to bottom left.  The Hubble image at the bottom shows thin amber threads, magenta star clusters among a diffuse white star cloud.  The Webb image at top shows much more detail with obvious holes among the reddish to amber dust and stars.
Observations of the spiral galaxy NGC 629 by the James Webb Space Telescope, left, show bright dust in much finer detail than observations by the Hubble Space Telescope, right. (Janice Lee/Thomas Williams/STScI/Oxford/PHANGS Team/NASA/ESA/CSA)

Galaxies are where stars are born, live their lives and die. The Webb images show that this process occurs from the inside out, with the oldest stars near the center and the youngest in the spiral arms. This matches the position of our 4.6 billion-year-old Sun, a relative newcomer to the Milky Way, located in one of the spiral arms about two-thirds of the way from the center.

The new images reveal huge gas bubbles blown by exploding stars. These remains of dead stars are the seeds for the formation of younger stars like our Sun.

A gallery of different spiral galaxies shows them with bright white interiors and amber to reddish hues to represent the incredible details of dust and stars.
The Webb Telescope’s new galaxy gallery includes images of 19 nearby spiral galaxies. (Elizabeth Wheatley/Thomas Williams/Janice Lee/Oxford/STScl/PHANGS Team/CSA/ESA/NASA)

Last September, in another survey, scientists used Webb to look back to the beginning of time and were surprised to see only fully formed spiral galaxies. 3.7 billion years after the Big Bang, approximately 13.7 billion years ago. This was a surprise because spirals were thought to be a later stage in the evolution of galaxies. Astronomers are now rethinking the evolution of galaxies over the past 10 billion years.

Astronomy looks outward to study the universe beyond our home. But in the same way as the first astronauts to visit the Moon looked back Seeing their home, for the first time as a small blue orb floating in the darkness of space, the study of galaxies gives us perspective on our greater home: the city of stars that we inhabit called the Milky Way.

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