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Astronomical advancement

Webb telescope means we are 'entering a new era' of space science

Teaching and Learning

By Dr. Hilding Neilson

The famous Hubble deep field was first observed in 1995 when the telescope was pointed at a dark patch of the universe and stared for 10 straight days at a tiny patch of sky near the Big Dipper.

On July 11, 2022, the now-largest optical telescope in space, the JWST, released its own deep field image that is much bigger, more detailed, and more exciting than the one from Hubble and shows us a view of the universe as it was 4.6 billion years ago, at the same time the sun was being formed and the Earth was being born.

These first images included new images of the Carina nebula, a star-forming region of our galaxy; the Southern Ring, the site of the death of a star and its transition to a white dwarf stellar remnant; and amazing views of the interacting galaxies, Stephan’s Quintet.

The first release also included a detailed measurement of water in the atmosphere of the Jupiter-like planet WASP-96b, which orbits a completely different star. These observations were not novel, but just so much better than any measurements of the same fields and objects than ever before. And this is just the beginning of the era of JWST.

The JWST is the successor of the Hubble space telescope and was built in a collaboration between NASA and the Canadian and European space agencies. The telescope has a 6.5-meter mirror, as opposed to Hubble’s one-meter mirror. If you imagine that a telescope is a giant bucket for collecting photons, then a bigger mirror means we can collect more photons over the same amount of time. The mirror is so big that when the JWST was launched into space in December 2021, the mirror had to be folded like a flower. When it reached its destination at a distance of 1.5-million kilometres from us, the mirrors unfolded and operations began. The JWST is also special because it observes at infrared wavelengths. On Earth, we would think of it as night vision and, as such, the JWST will observe objects in space that are cooler in temperature and dimmer.

The image is divided horizontally by an undulating line between a cloudscape forming a nebula along the bottom portion and a comparatively clear upper portion. Speckled across both portions is a starfield, showing innumerable stars of many sizes. The smallest of these are small, distant, and faint points of light. The largest of these appear larger, closer, brighter, and more fully resolved with 8-point diffraction spikes. The upper portion of the image is blueish, and has wispy translucent cloud-like streaks rising from the nebula below. The orangish cloudy formation in the bottom half varies in density and ranges from translucent to opaque. The stars vary in color, the majority of which have a blue or orange hue. The cloud-like structure of the nebula contains ridges, peaks, and valleys – an appearance very similar to a mountain range. Three long diffraction spikes from the top right edge of the image suggest the presence of a large star just out of view.
In the near-infrared image, we see hundreds of stars and background galaxies. Meanwhile, the mid-infrared shows dusty planet-forming disks (in red and pink) around young stars.

The mission of the telescope is to search for the first stars born in the universe and to look for signatures of life on planets orbiting other stars; exploring the birth, life and death of stars; and how galaxies form and evolve.

These topics are also central to astrophysics courses offered at Memorial: Physics 3150: Astrophysics I and Physics 3151: Astrophysics II. The first course will be taught in the fall 2022 semester; students will learn about the lives of stars and how they die, how telescopes like the JWST work and how scientists measure water on planets orbiting other stars from the change of light observed from a star when a planet passes in front of it.

Students will learn about how scientists interpret and learn from these amazing images. We are entering a new era of astronomy and space science. For those interested in a more general discussion, much of the science from those images will be discussed in Physics 2151: Stellar Astronomy and Astrophysics.

A group of five galaxies that appear close to each other in the sky: two in the middle, one toward the top, one to the upper left, and one toward the bottom. Four of the five appear to be touching. One is somewhat separated. In the image, the galaxies are large relative to the hundreds of much smaller (more distant) galaxies in the background. All five galaxies have bright white cores. Each has a slightly different size, shape, structure, and coloring. Scattered across the image, in front of the galaxies are number of foreground stars with diffraction spikes: bright white points, each with eight bright lines radiating out from the center.
In the JWST’s image of Stephan’s Quintet, we see five galaxies, four of which interact. These colliding galaxies are pulling and stretching each other in a gravitational dance.


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