Astronomy would be much easier if there were no clouds of gas and dust in space. There would be no need for telescopes capable of seeing through these thick veils. Unfortunately, space is not only full of things we want to see, but also full of things that get in our way.
Astronomers want a clearer view of the star formation process. Unfortunately, the gas clouds from which stars form also obscure them from our view. In their earliest stages of formation, young would-be stars are enveloped in a thick cocoon of gas and dust.
The JWST was built in part to see through thick dust that obstructs other telescopes. This also applied to other telescopes such as ESA’s Euclid Space Telescope. As part of testing its viewing capabilities, Euclid took a look at part of the Orion molecular cloud complex called LDN 1641. This is a so-called dark cloud about 1,300 light-years away that is home to more than 1,000 young star objects (YSO).
Despite these many stars, LDN 1641 is still a low-density cloud. It also does not host massive O or B type stars, the hottest and most massive stars. One of the reasons LDN 1641 is called a dark cloud is that it lacks these types of massive and extremely luminous stars.
Euclid can see in the near infrared, and this helps him see through dust. Although visible light from stars is blocked by dust, the dust actually absorbs light and then emits it as infrared. This is why Euclid can see stars that would otherwise be obscured by dust. Its near-infrared spectrometer and photometer (NISP) can detect the infrared light from the dust.
Several individual stars are circled in the image. The magenta colors near them are outflows from young stellar objects. These outflows are a feature of YSOs and can carve out bubbles from the surrounding gas and dust. As the jets blow away more and more gas, the YSO enters later stages of stellar evolution from a Class 0 protostar known for being in a gas cocoon.
*This enlarged portion of the image shows how detailed Euclid’s images are. It shows a pair of YSOs and their drains. The star at bottom right has overcome two cone-shaped areas to the left and right of it and is spewing a jet of material through the center of these cones. The jet’s clumpy structure indicates that its magnetic field changes periodically. Image credits: ESA/Euclid/Euclid Consortium/NASA, image processing by M. Schirmer (MPIA, Heidelberg). LICENSE: CC BY-SA 3.0 IGO or ESA standard license*
At the top left of the main image you can see where the cloud ends or becomes much thinner and the universe beyond the cloud is visible.
This region of the sky was chosen for specific reasons that had little to do with astronomy. To test Euclid’s fine guidance system, the telescope had to be aimed at a region of the sky where only a few stars were visible in optical light. For this reason, this image was taken in September 2023. It took five hours of observation to capture it.
Euclid’s primary mission is not to observe dark clouds and YSOs. Its main concern is to create a comprehensive 3D map of the universe beyond the Milky Way. This is all part of an effort to understand dark energy and dark matter, two fundamental aspects of the universe that baffle cosmologists.
Along the way, the space telescope will provide images like this and of other interesting regions of the Milky Way and objects beyond, such as distant galaxies. Euclid’s gift to us is more expansive and detailed images of galaxies than we are used to. A single Euclid observation can capture an area of sky about 100 times larger than what the JWST can capture in a single image. It should be able to image millions of galaxies at once, and its images will be sharp enough to reveal morphological details in distant galaxies. Things like spiral arms and tidal tails will be visible. Even the globular clusters hosted by galaxies should be visible in detail.
*An outstanding tapestry in LDN 1641, courtesy of Euclid. Image credits: ESA/Euclid/Euclid Consortium/NASA, image processing by M. Schirmer (MPIA, Heidelberg). LICENSE: CC BY-SA 3.0 IGO or ESA standard license*
Euclid launched in July 2023 and its mission is designed to last six years. The space telescope is in a halo orbit at the Sun-Earth Lagrange point L2.
Interested readers can explore some of his images here.
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