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Anyone familiar with astronomy will know that galaxies come in a fairly limited range of shapes, typically; spiral, elliptical, barred-spiral and irregular. The barred-spiral galaxy has been known to be a feature of the modern universe but a study from astronomers using the Hubble Space Telescope has recently challenged that view. Following on observations using the James Webb Space Telescope has found the bar feature in some spiral galaxies as early as 11 billion years ago suggesting galaxies evolved faster in the early Universe than previously expected. 

Our own Galaxy, the Milky Way is a spiral galaxy with a central nucleus and spiral arms emanating out from the centre. Our Solar System lies about 25,000 light years from the centre. Look at the galaxies in the sky though and you will see a real mix but generally they fall under the four main categories. Edwin Hubble tried to bring some structure to the different shapes by developing his galaxy classification scheme to articulate not only the shape but also the sub categories within them. 

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This research published in Nature is the first direct confirmation that supermassive black holes are capable of shutting down galaxies

It has been known for some time that galaxies aren’t static. They move and they evolve and change. Spiral galaxies for example, as they age, they often develop a bar feature. The bar joins up the spiral arms instead of a nucleus connecting them and it is believed they are temporary, forming when a build of gas creates a burst of star formation.

The existence of a bar in a spiral galaxy suggests that the galaxy is fairly stable. Understanding just how the bar feature forms is key to understanding the evolutionary process of the galaxy itself. All previous observations showed that the appearance of the bar significantly reduces from the nearby Universe to redshifts near a value of one. This tells us that the bar seemed to be a modern feature and not present in the early Universe. 

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The barred spiral galaxy NGC 1300. Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA)

In a new paper by lead author Zoe A Le Conte, observations from the more sensitive James Webb Space Telescope report that galaxies to greater redshift are studied for bar features. Data is used from the Cosmic Evolution Early Release Science Survey and the observations from the Public Release Imaging for Extragalactic Research studies. Only the galaxies that also appear in the Cosmic Assembly Near Infra Red Deep Extragalactic Legacy Survey are used giving a sample of 368 face on galaxies.

The team visually searched through the 368 galaxy selection to classify and identify those with bars between redshifts 1 and 2 and then repeated the exercise for those between redshift 2 and 3. As expected, the fraction of bars reduced from around 17.8% between a red shift of 1 and 2 down to 13.8% at the greater red shift of 2 to 3.

The study revealed that JWST’s infra-red sensitivity picked up twice as many barred-spiral galaxies than the HST’s more blue sensitive imaging platform. Le Conte and her team conclude that the evolution of bars in spiral galaxies began to appear at a much earlier epoch, around 11 billion years ago.

Source : A JWST investigation into the bar fraction at redshifts 1 ? z ? 3

The post Galaxies Evolved Surprisingly Quickly in the Early Universe appeared first on Universe Today.

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Astronomers See a Black Hole Wake Up from its Ancient Slumber

Four years ago, the supermassive black hole hidden in the heart of galaxy SDSS1335+0728 roared awake and announced its presence with a blast of radiation. It marks the first time astronomers witnessed a sudden activation of a supermassive black hole in real time.

“Imagine you’ve been observing a distant galaxy for years, and it always seemed calm and inactive,” said Paula Sánchez Sáez, an astronomer at ESO in Germany and lead author of the study of this object. “Suddenly, its [core] starts showing dramatic changes in brightness, unlike any typical events we’ve seen before.”

This is what happened to SDSS1335+0728, which is now officially classified as having an active galactic nucleus (AGN). It experienced what’s called a “nuclear transient.” Essentially, that means the galaxy now has a very bright compact region. However, it wasn’t always that bright and astronomers want to understand what caused it to wake up.

This artist’s impression shows two stages in the formation of a disc of gas and dust around the massive black hole at the center of the galaxy SDSS1335+0728. The core of this galaxy lit up in 2019 and keeps brightening today — the first time astronomers observed a massive black hole become active as it happened. Credit: ESO/M. Kornmesser

Looking for Transients in all the Right Places

The unusual brightness variations were detected by the Zwicky Transient Facility in California, which gives constant, real-time alerts about such things as transient flaring and brightening in the hearts of galaxies like SDSS1335+0728. In addition, several other facilities observed the variations, too, and brightness changes were found in archival data from several other observatories.

The sudden brightenings could be due to many things, including the cannibalization of stars and clouds of gas that stray too near supermassive black holes. How often they brighten and how a quiescent galaxy nucleus changes to an active one are topics that astronomers are using such surveys and observations to understand. They’re looking not just at distant galaxies, but activity within the neighborhood of our own galaxy’s supermassive black hole, too.

Galaxy and Its Supermassive Black Hole

Most galaxies have stupendously massive black holes at their hearts. They typically sequester away at least a hundred thousand times the mass of the Sun (sometimes more). It’s all trapped by gravity and nothing ever escapes, not even light. “These giant monsters usually are sleeping and not directly visible,” said study co-author Claudio Ricci, from Chile’s Diego Portales University. “In the case of SDSS1335+0728, we were able to observe the awakening of the massive black hole, [which] suddenly started to feast on gas available in its surroundings, becoming very bright.”

A black hole itself doesn’t emit any light at all. Instead, it sucks everything in, including light. However, the region around the black hole—called the accretion disk—is a pretty active place. It’s where material trapped by the intense gravitational pull of the black hole swirls around like water going down a drain. All that stuff—mostly gas, some dust—is threaded through with magnetic fields. Friction between accretions of the material heats it up. And, that act of heating gives off radiation. If there’s enough of it, we see light being given off. Intense active regions emit x-rays, which indicate the level of activity.

Gravity’s Slice-and-dice Activity

There’s also something called tidal disruption, which happens when something like a star or a cloud of gas gets trapped in the gravitational field. These things take time—on the order of years to occur. When they happen, the gravitational pull of the black hole eventually rips the star or cloud apart. That also gives off radiation. In fact, a very slow-motion tidal disruption event may be occurring at the heart of SDSS1335+0728. If so, it could be one of the longest and dimmest ones ever seen.

Regardless of what’s causing the brightening, the ultimate fate of some of the material is to end up inside the black hole. The rest of it gets superheated in the accretion disk and signals its fate through increased radiation.

Black Hole Growth and a Wake-up Call

The supermassive black holes in the hearts of galaxies grow from smaller ones to larger ones through mergers. We don’t see those growth patterns in real time, since they occur over millions of years. The merger scenario says that when galaxies come together, their central black holes (if they have them) do, too.

Simulation of merging supermassive black holes. Credit: NASA's Goddard Space Flight Center/Scott NobleDid you miss our previous article…
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Photo Gallery: 40 Gorgeous Backcountry Lakes

Tet19 047 Me on Teton Crest Trail copy cropped 44

By Michael Lanza

Water makes up about 60 percent of our bodies—and, I suspect, 100 percent of our hearts. We crave it not only physically, for survival, but emotionally, for spiritual rejuvenation. We love playing in it for hours as children and we paddle and swim in it as adults. We’re drawn by the calming effects of sitting beside a stream or lake in a beautiful natural setting, an experience that possesses a certain je ne sais quoi—a quality difficult to describe, but that we can all feel.

And nothing beats taking a swim in a gorgeous backcountry lake.

I’ve come across quite a few wonderful backcountry lakes over more than three decades of exploring wilderness—including about 10 years as the Northwest Editor of Backpacker magazine and even longer running this blog. I’ve just updated and expanded this list of my favorites—adding five new lakes from trips I took last year in two places that are crazy with gorgeous lakes, Glacier National Park and the Wind River Range—to give you some eye candy as well as ideas for future adventures, and perhaps compare against your list of favorite backcountry lakes.

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Hi, I’m Michael Lanza, creator of The Big Outside. Click here to sign up for my FREE email newsletter. Join The Big Outside to get full access to all of my blog’s stories. Click here for my e-books to classic backpacking trips. Click here to learn how I can help you plan your next trip.

Click on the links to my stories in these brief writeups to learn more about each of these trips. Much of this story is free for anyone to read, but reading the entire story requires a paid subscription, which is also needed to read the individual stories about numerous trips at The Big Outside, and those include my tips on planning these trips. See my Custom Trip Planning page to learn how I can help you plan a trip to any of these lakes.

If you know some gorgeous lakes that are not on my list, please suggest them in the comments section below this story. I try to respond to all comments.

Here’s to your next peaceful moment beside a gorgeous lake deep in the mountains somewhere.

Elizabeth Lake in Glacier National Park.
” data-image-caption=”Early morning at Elizabeth Lake in Glacier National Park. Click photo to learn how I can help you plan your Glacier trip.
” data-medium-file=”https://i0.wp.com/tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2020/03/06231037/Gla6-018-Elizabeth-Lake-in-Glacier-National-Park.-2.jpg?fit=300%2C200&ssl=1″ data-large-file=”https://i0.wp.com/tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2020/03/06231037/Gla6-018-Elizabeth-Lake-in-Glacier-National-Park.-2.jpg?fit=900%2C600&ssl=1″ src=”https://i0.wp.com/tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2020/03/06231037/Gla6-018-Elizabeth-Lake-in-Glacier-National-Park.-2-1024×683.jpg?resize=900%2C600&ssl=1″ alt=”Elizabeth Lake in Glacier National Park.” class=”wp-image-38774″ srcset=”https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2020/03/06231037/Gla6-018-Elizabeth-Lake-in-Glacier-National-Park.-2.jpg 1024w, https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2020/03/06231037/Gla6-018-Elizabeth-Lake-in-Glacier-National-Park.-2.jpg 300w, https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2020/03/06231037/Gla6-018-Elizabeth-Lake-in-Glacier-National-Park.-2.jpg 768w, https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2020/03/06231037/Gla6-018-Elizabeth-Lake-in-Glacier-National-Park.-2.jpg 1080w, https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2020/03/06231037/Gla6-018-Elizabeth-Lake-in-Glacier-National-Park.-2.jpg 1200w” sizes=”(max-width: 900px) 100vw, 900px” data-recalc-dims=”1″ />Elizabeth Lake in Glacier National Park.

Elizabeth Lake, Glacier
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It’s Not Just Rocks, Scientists Want Samples Mars’s Atmosphere

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Mars holds a very special place in our hearts. Chiefly because of all the other planets in the Solar System Mars is probably the place we are going to find some tantalising clues or maybe even evidence of prehistoric life. NASA Perseverance Rover has been trundling around the Jezero Crater looking for evidence that it was once hospitable to life. To that end it has not only been collecting rock samples but air samples too and scientists can’t wait to get their hands on them. 

The Mars Perseverance Rover is part of NASA’s Mars 2020 mission. It launched on 30 July 2020 and landed in the Jezero Crater successfully on 18 February 2021. The site was picked because it’s a dried up river bed and if there is any evidence of ancient primitive life on Mars, it is a likely location. Perseverance is equipped with a host of instruments including a drone named Ingenuity to survey the planet. 

Mars Perseverence rover sent back this image of its parking spot during Mars Solar Conjunction. Courtesy NASA/JPL-Caltech
Mars Perseverence rover sent back this image of its parking spot during Mars Solar Conjunction. Courtesy NASA/JPL-Caltech

One exciting element of the mission is the collection of rock samples as part of the Mars Sample Return Campaign. Twenty four core samples have been collected to date and deposited on the surface ready for collection by a future mission. It’s not just rock samples that have been collected though. Known as ‘headspace’ there is air in the space around the rock samples and it is this that has got scientists excited.

Not only do the rocks hold secrets about Mars but the atmosphere does too. It’s an atmosphere rich in Carbon Dioxide but is expected to have trace amounts of other gasses  too. Information about the current climate can be gained from the trapped gasses but it’s also possible to learn about the evolution of the atmosphere through analysis of the rocks. There is one particularly important tube that has been filled entirely with gas from the atmosphere. 

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Image of the Martian atmosphere and surface obtained by the Viking 1 orbiter in June 1976. (Credit: NASA/Viking 1)

With the sample sat on the surface of Mars potentially for many years, the gas trapped will interact with the rock in the sample tube. It will only be when the tubes are opened up when they arrive back here on the Earth that the interaction will cease. It’s hoped to understand more about the levels of water vapour near the Martian surface.

It isn’t just the water vapour that is of interest but the levels of trace gas too are of interest. Through analysing the gas samples we can tell if there are gasses like neon, argon and xenon which are non reactive gasses. Because these gasses do not react then there presence in the tube samples may suggest that Mars stated with an atmosphere. We know that it had a much thicker atmosphere in the past but we don’t know whether it has always been there or whether it developed later.

There are many benefits that will come from analysing the samples even, the prevalence of dust that will help future human exploration. As Justin Simon from NASA’s Johnson Space Center in Houston said “The gas samples have a lot to offer Mars scientists, even those who don’t study Mars would be interested because it will shed light on how the planet forms and evolves.”

Source : Why Scientists Are Intrigued by Air in NASA’s Mars Sample Tubes

The post It’s Not Just Rocks, Scientists Want Samples Mars’s Atmosphere appeared first on Universe Today.

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