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Dark matter is a powerful cosmological model, but it isn’t without its problems. In addition to our inability to detect dark matter particles, one issue deals with the number of dwarf galaxies surrounding the Milky Way. According to the most popular models of dark matter, galaxies should be surrounded by clumps of dark matter within their dark matter halo. Since regular matter tends to gather around dark matter, that means the Milky Way should be surrounded by dwarf galaxies. While there are several known dwarf galaxies near the Milky Way, there are fewer than predicted by dark matter simulations. But perhaps there are many more dwarf galaxies we just haven’t noticed because they are made mostly of dark matter.

We have detected a few of them. They are known as Almost Dark Galaxies (ADGs), and they are particularly dim. We haven’t found enough of them to match the cold dark matter model, but we do keep finding them, as a recent study shows. It describes a newly found dwarf galaxy known as Nube. It was found just by chance in images gathered by the IAC Stripe82 Legacy Project. It is so dim that it doesn’t appear in the Sloan Deep Sky Survey (SDSS), which is a bit surprising. But the team noticed what looked like a dark galaxy in an image, and decided to use the Green Bank Telescope to study it further.

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The dark matter dwarf galaxy known as Nube. Credit: Montes, et al

Based on the Green Bank data, the galaxy is about 350 million light-years away and has a surface brightness of about 28 mag per square arc second. The galaxy is extremely diffuse, with half of its mass extended over more than 22,000 light years, nearly a quarter of the diameter of the Milky Way. It has a mass of about 26 billion solar masses, but the mass of the stars in the galaxy is only 390 million solar masses. The galaxy is mostly comprised of dark matter, and it is the largest ultra-diffuse galaxy known.

It was only through a bit of luck that we found this dark matter galaxy. Given its size, it’s quite likely that other dwarf galaxies are lurking in our celestial neighborhood, if we can only find them. But surprisingly, while galaxies such as these support the dark matter cosmological model, this particular galaxy doesn’t match the profile of the most popular variant known as cold dark matter. Instead, it best fits a version known as fuzzy dark matter. So while we’re getting closer to the predictions of dark matter simulations, it’s clear that there are a few surprises waiting to be accounted for.

So we must keep looking for more of these galaxies. The answers to our dark matter questions are surely there, gathered in the dark.

Reference: Montes, Mireia, et al. “An almost dark galaxy with the mass of the Small Magellanic Cloud.” arXiv preprint arXiv:2310.12231 (2023).

The post A Dwarf Galaxy That’s Almost All Dark Matter appeared first on Universe Today.

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The Early Universe Had No Problem Making Barred Spiral Galaxies

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Spiral galaxies like the Milky Way are like cosmic snowflakes—no two are exactly alike. For many years, astronomers thought spirals couldn’t exist until the universe was about half its present age. Now, a newly discovered galaxy in the early Universe is challenging that idea.

CEERS-2112 is an early “cosmic snowflake” with spiral arms and a bar across its middle. The amazing thing is that it’s showing this structure when the Universe was only 2 billion years old. That’s about five billion years earlier than astronomers expected something like that to exist. The fact that a perfectly formed spiral exists so early tells us that our ideas about galaxy formation in early cosmic history need some re-tuning.

Surveying the Early Universe

This galaxy showed up in a survey done by the JWST called “Cosmic Evolution Early Release Science” (CEERS). It uses JWST imaging and spectroscopy to do a survey of the early Universe to find the earliest galaxy. The analysis of the CEERS-2112 galaxy was done by an international team led by astronomer Luca Constantin of the Centro de Astrobiología in Spain.

CEERS results should show astronomers the early populations of galaxies at high redshifts (distances). They will also help them estimate related star-formation conditions and black hole growth. Finally, the work should give some insight into the formation of galaxy disks and bulges. Essentially, CEERS data should add to our store of knowledge about first light and reionization (which occurred after the Big Bang) and explain the formation and evolution of early galaxies.

Early deep-field images of very distant galaxies show shreds of galaxies and irregular clumps of stars in the early Universe. That was evident in some of the first Hubble Deep-Field images. The most distant ones in the images looked more blobby and indistinct. And, some of them appeared to be colliding, which fits into the collisional model of galaxy formation.

This view of nearly 10,000 galaxies is called the Hubble Ultra Deep Field. It shows some galaxies in the early Universe, (which appear as red blobs). Credit: NASA/ESA/HUDF
This view of nearly 10,000 galaxies is called the Hubble Ultra Deep Field. It shows some galaxies in the early Universe, (which appear as red blobs). Credit: NASA/ESA/HUDF

Forming Galaxies in the Early Universe

Prior to the Hubble and JWST eras, astronomers really felt that it would take a long time to form spiral galaxies. They often describe a hierarchical model of galaxy formation. That’s where smaller clumpy galaxies collide to form larger ones. Over time, those objects begin to develop structures like spiral arms and bars.

“In such galaxies, bars can form spontaneously due to instabilities in the spiral structure or gravitational effects from a neighboring galaxy,” according to astronomer and team member Alexander de la Vega. He is a post-doctoral researcher currently at the University of California Riverside. “In the past, when the Universe was very young, galaxies were unstable and chaotic. It was thought that bars could not form or last long in galaxies in the early universe.”

The spiral arms are likely the result of density waves moving through the galaxy. The bars also form from density waves radiating out from the center. That compresses material in the arms and bars, leading to bursts of star formation. That could explain why these regions in galaxies seem brighter, with their populations of hot young stars. All of this takes time to accomplish. That’s why astronomers suggested that it would take about half the age of the Universe to form spiral galaxies.

CEERS-2112 is Part of the Early Universe

CEERS-2112 upends the discussion about spiral formation, according to de la Vega. “Finding CEERS-2112 shows that galaxies in the early Universe could be as ordered as the Milky Way,” he said. “This is surprising because galaxies were much more chaotic in the early Universe and very few had similar structures to the Milky Way.”

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Apollo Samples Contain Hydrogen Hurled from the Sun

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According to the U.S. National Academies of Sciences, Engineering, and Medicine, men should drink 3.7litres of water a day and women 2.7litres. Now imagine a crew of three heading to the Moon for a 3 week trip, that’s something of the order of 189 litres of water, that’s about 189 kilograms! Assuming you have to carry all the water rather than recycle some of it longer trips into space with more people are going to be logistically challenging for water carriage alone. Researchers from the U.S. Naval Research Laboratory (NRL) have discovered lunar rocks with hydrogen in them which, when combined with lunar oxygen provide a possibly supply for future explorers.

A total of 382 kilograms of rock was brought back from the Moon by the Apollo program (I weigh about 80kg so that’s almost five of me in weight – and its all muscle I promise!) Some of the samples were immediately studied while others were sealed for future research hoping that future instrumentation would be more sensitive.

A research team from NRL, led by Katherine D. Burgess and team members Brittany A. Cymes and Rhonda M. Stroud, have recently announced their findings whilst studying some of the lunar rock. They wanted to understand the source of water on the Moon and to understand its formation. Future lunar exploration especially permanent lunar bases will rely heavily upon existing lunar resources. The paper articulates “Effective use of the resource depends on developing an understanding of where and how within the regolith the water is formed and retained”.

Image showing Buzz Aldrin's footprint in the dusty lunar regolith - Credit NASA
Buzz Aldrin’s footprint in the lunar regolith – the soft powdery material found over the surface of the Moon (Credit – NASA)

Transmission electron microscopy was used as part of the study to explore lunar sample 79221. The technique utilises a particle beam of electrons to visualise specimens and generate a highly magnified image. In particular, the team looked at grains of the minerals apatite and merrillite and discovered signs of ‘space’ weathering due to the solar wind. The solar wind is a stream of charged particles that rush outward from the Sun at speeds of up to 1.6 million km per hour!

They found hydrogen signatures in samples in vesicles – small holes left behind after lava cools. The discovery confirms that solar wind is being trapped in detectable quantities proving a potential reservoir that could be accessible to future explorers.

Hydrogen itself is a tremendously useful resource and if that can be mined from the lunar surface material it can aide many aspects of exploration. The real buzz around the discovery is that it may finally resolve the mystery about the origins of lunar water and that it might well be the result of chemical interactions between the solar wind and lunar rocks. If we can understand the origins of the lunar water – and we may finally be close to that now – then we can be sure we use it effectively to reach out further into the Solar System.

Source : Hydrogen detected in lunar samples, points to resource availability for space exploration

The post Apollo Samples Contain Hydrogen Hurled from the Sun appeared first on Universe Today.

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The Best Clothing Layers for Winter in the Backcountry

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By Michael Lanza

There’s one certainty about the clothing layers we use in winter: We get our money’s worth out of them. While a rain shell or puffy jacket may rarely come out of our pack on a summer hike or climb, we almost invariably wear every article of clothing we carry when backcountry, Nordic, or downhill skiing, snowshoeing, snowboarding, climbing, or trail running in winter. That’s money spent wisely to make us more comfortable and safer.

Every winter, I test out new clothing layers doing many of those activities frequently—something I’ve been doing for more than 25 years, previously as the lead gear reviewer for Backpacker magazine for 10 years and even longer running this blog. This review spotlights the best shell and insulated jackets, base layers, and pants I’ve found for high-exertion and moderate-exertion activities in winter.

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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-guides to classic backpacking trips. Click here to learn how I can help you plan your next trip.

A backcountry skier in Idaho’s Boise Mountains.
” data-image-caption=”My son, Nate, backcountry skiing in Idaho’s Boise Mountains.
” data-medium-file=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/01/DSC_3743.jpg?fit=300%2C200&ssl=1″ data-large-file=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/01/DSC_3743.jpg?fit=900%2C600&ssl=1″ src=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/01/DSC_3743.jpg?resize=900%2C600&ssl=1″ alt=”A backcountry skier in Idaho’s Boise Mountains.” class=”wp-image-50099″ srcset=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/01/DSC_3743.jpg?resize=1024%2C683&ssl=1 1024w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/01/DSC_3743.jpg?resize=300%2C200&ssl=1 300w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/01/DSC_3743.jpg?resize=768%2C512&ssl=1 768w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/01/DSC_3743.jpg?resize=150%2C100&ssl=1 150w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/01/DSC_3743.jpg?w=1200&ssl=1 1200w” sizes=”(max-width: 900px) 100vw, 900px” data-recalc-dims=”1″ />My son, Nate, backcountry skiing in Idaho’s Boise Mountains.

In my story “How to Dress in Layers for Winter in the Backcountry,” I offer advice—based on four decades of backcountry experience—on how to choose a specific, personalized layering system for different exertion levels and body types in temperatures near or below freezing. Use the tips in that story, along with this review, to make the best choices in winter outdoor apparel for your activities, your climate, and your body.

Please share your experiences with any of these products in the comments section at the bottom of this review. I try to respond to all comments. And if you make a purchase through any of the affiliate links to online retailers in this story or other reviews at The Big Outside, you support my work on this blog at no cost to you. Thanks for doing that.

Don’t go out in the cold without my “12 Pro Tips For Staying Warm Outdoors in Winter.”

Backcountry avalanche instructor Chago Rodriguez skiing in the shadow of Mount Heyburn in Idaho’s Sawtooth Mountains.
” data-image-caption=”Expert backcountry avalanche instructor Chago Rodriguez skiing in the shadow of Mount Heyburn in Idaho’s Sawtooth Mountains. Click photo to learn about his courses.
” data-medium-file=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2015/01/Saw13-028-Pass-north-of-Mt.-Heyburn-Sawtooths-ID.jpg?fit=300%2C199&ssl=1″ data-large-file=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2015/01/Saw13-028-Pass-north-of-Mt.-Heyburn-Sawtooths-ID.jpg?fit=900%2C598&ssl=1″ src=”https://i0.wp.com/thebigoutside
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