Pic of the Week: Hickson Compact Group 40

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Image (Credit): The NASA/ESA Hubble Space Telescope view of five galaxies, called the Hickson Compact Group 40. (NASA/ESA Hubble)

This week’s image is from the NASA/ESA Hubble Space Telescope. It shows an amazing collection of five galaxies in close proximity to one another in what is known as the Hickson Compact Group 40. In about one billion years they are expected to coalesce into one large galaxy.

Here is the summary from the Hubble site:

This menagerie includes three spiral-shaped galaxies, an elliptical galaxy and a lenticular (lens-like) galaxy. Somehow, these different galaxies have crossed paths to create an exceptionally crowded and eclectic galaxy sampler.

Caught in a leisurely gravitational dance, the whole group is so crowded that it could fit within a region of space that is less than twice the diameter of our Milky Way’s stellar disc.

Though such galaxy groupings can be found in the heart of huge galaxy clusters, these galaxies are notably isolated in their own small patch of the Universe, in the direction of the constellation Hydra.

One possibility is that there’s a lot of dark matter (a poorly understood and invisible form of matter) associated with these galaxies. If they come close together the dark matter can form a big cloud within which the galaxies orbit. As the galaxies plough through the dark matter they feel a frictional force that results from its gravitational effects. This slows their motion and makes the galaxies lose energy, so they fall together. Therefore, this snapshot catches the galaxies at a very special moment in their lifetimes. In about 1 billion years they will eventually collide and merge to form a single giant elliptical galaxy.

Astronomers have studied this compact galaxy group not only in visible light, but in radio, infrared, and at X-ray wavelengths. Almost every one of the galaxies has a compact radio source at its core, which could be evidence for the presence of a supermassive black hole. X-ray observations show that the galaxies have been gravitationally interacting as witnessed by the presence of a lot of hot gas amongst them. Infrared observations reveal clues to the rate of formation of new stars.

Though over 100 such compact galaxy groups have been catalogued in sky surveys going back several decades, Hickson Compact Group 40 is one of the most densely packed. Observations suggest that such tight groups may have been more abundant in the early Universe and provided fuel for powering black holes, known as quasars, whose light from superheated inflating material blazed across space. Studying the details of galaxies in nearby groups like this helps astronomers sort out when and where galaxies assembled themselves, and what they are assembled from.

Pic of the Week: A View of Peru

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Image (Source): View of the Pacific from the ISS. More information provided below. (NASA)

This week’s image is from the International Space Station (ISS). It shows an October 1, 2022 photo of European Space Agency (ESA) astronaut Samantha Cristoforetti enjoying a view of the Pacific Ocean off the coast of Peru. She is sitting in the ISS’s so called “window to the world.” You can learn more about photo’s taken from this window via this short NASA video.

Pic of the Week: Marian Dust Devils

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Image (Credit): Dust devils swirling across Jezero Crater, as viewed by NASA’s Perseverance Mars rover. (NASA/JPL-Caltech/SSI)

This week’s image is from earlier this year when NASA’s Perseverance Mars rover captured whirling dust on the Red Planet’s surface. Here is more on the dust devils from NASA:

During its first couple hundred days in Jezero Crater, NASA’s Perseverance Mars rover saw some of the most intense dust activity ever witnessed by a mission sent to the Red Planet’s surface. Not only did the rover detect hundreds of dust-bearing whirlwinds called dust devils, Perseverance captured the first video ever recorded of wind gusts lifting a massive Martian dust cloud.

A paper recently published in Science Advances chronicles the trove of weather phenomena observed in the first 216 Martian days, or sols. The new findings enable scientists to better understand dust processes on Mars and contribute to a body of knowledge that could one day help them predict the dust storms that Mars is famous for – and that pose a threat to future robotic and human explorers.

“Every time we land in a new place on Mars, it’s an opportunity to better understand the planet’s weather,” said the paper’s lead author, Claire Newman of Aeolis Research, a research company focused on planetary atmospheres. She added there may be more exciting weather on the way: “We had a regional dust storm right on top of us in January, but we’re still in the middle of dust season, so we’re very likely to see more dust storms.”

Pic of the Week: Webb’s First Deep Field

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Image (Credit): JWST deep field view of the cosmos. (NASA, ESA, CSA, STScI)

This week we have another recent image from the James Webb Space Telescope (JWST) showing a thousands of galaxies, some of which have images distorted by the gravity of other galaxies. It is quite a collection of distant worlds.

Here is the story from NASA:

Thousands of galaxies flood this near-infrared image of galaxy cluster SMACS 0723. High-resolution imaging from NASA’s James Webb Space Telescope combined with a natural effect known as gravitational lensing made this finely detailed image possible.

First, focus on the galaxies responsible for the lensing: the bright white elliptical galaxy at the center of the image and smaller white galaxies throughout the image. Bound together by gravity in a galaxy cluster, they are bending the light from galaxies that appear in the vast distances behind them. The combined mass of the galaxies and dark matter act as a cosmic telescope, creating magnified, contorted, and sometimes mirrored images of individual galaxies.

Clear examples of mirroring are found in the prominent orange arcs to the left and right of the brightest cluster galaxy. These are lensed galaxies – each individual galaxy is shown twice in one arc. Webb’s image has fully revealed their bright cores, which are filled with stars, along with orange star clusters along their edges.

Not all galaxies in this field are mirrored – some are stretched. Others appear scattered by interactions with other galaxies, leaving trails of stars behind them.

Pic of the Week: The Pillars of Creation

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Image (Credit): JWSP’s view of The Pillars of Creation. (NASA, ESA, CSA, STScI; Joseph DePasquale (STScI), Anton M. Koekemoer (STScI), Alyssa Pagan (STScI))

This week’s image is a redo of an earlier Hubble Space Telescope image (shown below), but this time we see the Pillars of Creation through the eyes of the James Webb Space Telescope (JWST). The pillars is part of the Eagle Nebula, which lies 6,500 light-years away.

Here is more from NASA on the JWST image:

Newly formed stars are the scene-stealers in this image from Webb’s Near-Infrared Camera (NIRCam). These are the bright red orbs that typically have diffraction spikes and lie outside one of the dusty pillars. When knots with sufficient mass form within the pillars of gas and dust, they begin to collapse under their own gravity, slowly heat up, and eventually form new stars.

What about those wavy lines that look like lava at the edges of some pillars? These are ejections from stars that are still forming within the gas and dust. Young stars periodically shoot out supersonic jets that collide with clouds of material, like these thick pillars. This sometimes also results in bow shocks, which can form wavy patterns like a boat does as it moves through water. The crimson glow comes from the energetic hydrogen molecules that result from jets and shocks. This is evident in the second and third pillars from the top – the NIRCam image is practically pulsing with their activity. These young stars are estimated to be only a few hundred thousand years old.

Although it may appear that near-infrared light has allowed Webb to “pierce through” the clouds to reveal great cosmic distances beyond the pillars, there are no galaxies in this view. Instead, a mix of translucent gas and dust known as the interstellar medium in the densest part of our Milky Way galaxy’s disk blocks our view of the deeper universe.

Image (Credit): Hubble Space Telescope’s view of The Pillars of Creation in 2014. (NASA, ESA, and the Hubble Heritage Team)