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Pulsars are extreme objects. They’re what’s left over when a massive star collapses on itself and explodes as a supernova. This creates a neutron star. Neutron stars spin, and some of them emit radiation. When they emit radiation from their poles that we can see, we call them pulsars.

In the last decade or so, astrophysicists have discovered many more millisecond pulsars, ones that rotate very rapidly. Not only is the number of known pulsars increasing, but researchers have also identified pulsar sub-types that have companions. These are called spider pulsars, and their companions face great peril. New research sheds light on how spider pulsars in Omega Centauri are tearing their companions to pieces with their powerful outflows.

The first spider pulsar ever discovered is PSR B1957+20, more widely known as the Black Widow Pulsar. It has a companion that’s either a brown dwarf or a super Jupiter. High-energy outflows from the Black Widow are destroying its companion. All pulsars that destroy their companions are known as spider pulsars, but there are two further sub-types of spider pulsars: redback pulsars and black widow pulsars.

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Artist’s impression of the pulsar PSR B1957+20 (seen in the background) through the cloud of gas enveloping its brown dwarf star companion. Credit: Dr. Mark A. Garlick; Dunlap Institute for Astronomy & Astrophysics, University of Toronto

Researchers working with the Chandra Space Telescope have examined Omega Centauri to learn more about how spider pulsars destroy their binary companions. Their work will be published in the Monthly Notices of the Royal Astronomical Society. The title is “A Chandra X-ray study of millisecond pulsars in the globular cluster Omega Centauri: a correlation between spider pulsar companion mass and X-ray luminosity.” The authors are Jiaqi Zhao and Craig O. Heinke, both from the Physics Department at the University of Alberta, Edmonton, Canada.

Omega Centauri is the largest globular cluster (GC) that we know of in the Milky Way. It’s almost 16,000 light-years away and contains about 10 million stars. Some of those stars are spider pulsars, a class of millisecond pulsars with companions.

Visualization of a fast-rotating pulsar. Credit: NASA's Goddard Space Flight Center Conceptual Image Lab
Visualization of a fast-rotating pulsar. Credit: NASA’s Goddard Space Flight Center Conceptual Image Lab

Spider pulsars are terribly destructive neighbours. Their energetic winds methodically strip away their companions’ outer layers. To understand more about this phenomenon, the pair of researchers examined Chandra data from Omega Centauri, home to 18 recently discovered spider pulsars.

“Millisecond pulsars (MSPs) are faint X-ray sources commonly observed in Galactic globular clusters (GCs),” the researchers write. “In this work, we investigate 18 MSPs newly found in the GC Omega Centauri and search for their X-ray counterparts using Chandra observations.”

Out of the 18 millisecond pulsars, 11 of them emit x-rays that Chandra can see. Five of them are spider pulsars near Omega Centauri’s center. They combined these with Chandra’s observations of 26 spider pulsars in 12 other globular clusters. Using this data, the pair of researchers examined empirical correlations between X-ray luminosities and the minimum masses of their companions.

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Hiking Half Dome: How to Do It Right and Get a Permit

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By Michael Lanza

No hike in the country really compares with Yosemite’s Half Dome. The long, very strenuous, challenging, and incredibly scenic day trip to one of the most iconic and sought-after summits in America begins with ascending the Mist Trail through the shower constantly raining down from 317-foot Vernal Fall and below thunderous, 594-foot Nevada Fall. Climbing the cable route up several hundred feet of steep granite slab delivers a thrill that partly explains the hike’s enormous popularity.

The 8,800-foot summit of Half Dome—where many hikers complete the experience by standing on The Visor, a granite brim jutting out over Half Dome’s sheer, 2,000-foot Northwest Face—delivers an incomparable view of Yosemite Valley and a 360-degree panorama of a big swath of the park’s mountains.

Half Dome validates every step of effort you put into it.

Having been up and down those cables a handful of times over more than 30 years of dayhiking and backpacking all over the country—including many years running this blog and previously as the Northwest Editor of Backpacker magazine for 10 years—I consider Half Dome one of the very best dayhikes in the entire National Park System and certainly one of America’s hardest dayhikes.

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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.

A hiker atop Half Dome in Yosemite National Park.
” data-image-caption=”Mark Fenton on The Visor of Half Dome, high above Yosemite Valley, in Yosemite National Park.
” data-medium-file=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2018/07/Yos11-041-Mark-summit-of-Half-Dome-Yosemite-N.P.-CA-2.jpg?fit=300%2C199&ssl=1″ data-large-file=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2018/07/Yos11-041-Mark-summit-of-Half-Dome-Yosemite-N.P.-CA-2.jpg?fit=900%2C598&ssl=1″ src=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2018/07/Yos11-041-Mark-summit-of-Half-Dome-Yosemite-N.P.-CA-2.jpg?resize=900%2C598&ssl=1″ alt=”A hiker atop Half Dome in Yosemite National Park.” class=”wp-image-35446″ srcset=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2018/07/Yos11-041-Mark-summit-of-Half-Dome-Yosemite-N.P.-CA-2.jpg?resize=1024%2C680&ssl=1 1024w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2018/07/Yos11-041-Mark-summit-of-Half-Dome-Yosemite-N.P.-CA-2.jpg?resize=300%2C199&ssl=1 300w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2018/07/Yos11-041-Mark-summit-of-Half-Dome-Yosemite-N.P.-CA-2.jpg?resize=768%2C510&ssl=1 768w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2018/07/Yos11-041-Mark-summit-of-Half-Dome-Yosemite-N.P.-CA-2.jpg?resize=1080%2C717&ssl=1 1080w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2018/07/Yos11-041-Mark-summit-of-Half-Dome-Yosemite-N.P.-CA-2.jpg?w=1200&ssl=1 1200w” sizes=”(max-width: 900px) 100vw, 900px” data-recalc-dims=”1″ />Mark Fenton on The Visor or Half Dome, high above Yosemite Valley, in Yosemite National Park. Click photo to read about this backpacking trip.

The cables are up for hiking Half Dome from late May through mid-October. A permit is required for this popular dayhike and a permit lottery takes place throughout March. Yosemite requires a reservation to drive into or through the park on some days from April 13 through Oct. 27; nps.gov/yose/planyourvisit/reservations.htm.

This story shares what I’ve learned about navigating the competitive permit system and embarking on such a demanding day of hiking that’s roughly 16 miles round-trip with almost 5,000 feet of elevation gain and loss. Please share your thoughts or questions about hiking Half Dome in the comments section at the bottom of this story. I try to respond to all comments
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New Study Addresses how Lunar Missions will Kick up Moondust.

Apollo salute gray regolith jpg

Before the end of this decade, NASA plans to return astronauts to the Moon for the first time since the Apollo Era. But this time, through the Artemis Program, it won’t be a “footprints and flags” affair. With other space agencies and commercial partners, the long-term aim is to create the infrastructure that will allow for a “sustained program of lunar exploration and development.” If all goes according to plan, multiple space agencies will have established bases around the South Pole-Aitken Basin, which will pave the way for lunar industries and tourism.

For humans to live, work, and conduct various activities on the Moon, strategies are needed to deal with all the hazards – not the least of which is lunar regolith (or “moondust”). As the Apollo astronauts learned, moondust is jagged, sticks to everything, and can cause significant wear on astronaut suits, equipment, vehicles, and health. In a new study by a team of Texas A&M engineers, regolith also poses a collision hazard when kicked up by rocket plumes. Given the many spacecraft and landers that will be delivering crews and cargo to the Moon in the near future, this is one hazard that merits close attention!

The study was conducted by Shah Akib Sarwar and Zohaib Hasnain, a Ph.D. Student and an Assistant Professor (respectively) with the J. Mike Walker ’66 Department of Mechanical Engineering at Texas A&M University. For their study, Sarwar and Hasnain investigated particle-particle collisions for lunar regolith using the “soft sphere” method, where Newton’s equations of motion and a contact force model are integrated to study how particles will collide and overlap. This sets it apart from the “hard sphere” method, which models particles in the context of fluids and solids.

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Apollo 15 astronaut salutes next to the American flag in 1971. The Moon’s regolith or soil appears in various shades of gray. Credit: NASA

While lunar regolith ranges from tiny particles to large rocks, the main component of “Moondust” is fine, silicate minerals with an average size of 70 microns. These were created over billions of years as the airless Moon’s airless surface was struck by meteors and asteroids that pounded much of the lunar crust into a fine powder. The absence of an atmosphere also meant that erosion by wind and water (common here on Earth) was absent. Lastly, constant exposure to solar wind has left lunar regolith electrostatically charged, which means it adheres to anything it touches.

When the Apollo astronauts ventured to the Moon, they reported having problems with regolith that would stick to their suits and get tracked back into their lunar modules. Once inside their vehicles, it would adhere to everything and became a health hazard, causing eye irritation and respiratory difficulties. But with the Artemis missions on the horizon and the planned infrastructure it will entail, there’s the issue of how spacecraft (during take-off- and landing) will cause regolith to get kicked up in large quantities and accelerated to high speeds.

As Sarwar related to Universe Today via email, this is one of the key ways lunar regolith will be a major challenge for regular human activities on the Moon:

“During a retro-propulsive soft landing on the Moon, supersonic/hypersonic rocket exhaust plumes can eject a large quantity (108 – 1015 particles/m3 seen in Apollo missions) of loose regolith from the upper soil layer. Due to plume-generated forces – drag, lift, etc. – the ejecta can travel at very high speeds (up to 2 km/s). The spray can harm the spacecraft and nearby equipment. It can also block the view of the landing area, disrupt sensors, clog mechanical elements, and degrade optical surfaces or solar panels through contamination.”

Data acquired from the Apollo missions served as a touchstone for Sarwar and Hasnain, which included how ejecta from the exhaust plume from the Apollo 12 Lunar Module (LM) damaged the Surveyor 3 spacecraft, located 160 meters (525 ft) away. This uncrewed vehicle had been sent to explore the Mare Cognitum region in 1967 and characterize lunar soil in advance of crewed missions. Surveyor 3 was also used as a landing target site for Apollo 12 and was visited by astronauts Pete Conrad and Alan Bean in November 1969.

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The 10 Best Backpacking Packs of 2024

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By Michael Lanza

Backpacks come in many sizes and designs for a reason: so do backpackers. Some of us need a pack for moderate loads, some for heavy loads, and others, increasingly, for lightweight or ultralight backpacking. Some prefer a minimalist pack, others a range of features and access. Everyone wants the best possible fit and comfort, and almost everyone has a budget. But no matter which type of backpacker you are, this review covers the best packs in each of those categories.

Each of my picks for the 10 best backpacking packs stands out for different reasons. I also point out two excellent packs for kids and small adults (at the bottom of the Gregory Paragon/Maven review). My judgments draw from many thousands of miles and more than three decades of backpacking and a quarter-century of testing and reviewing gear—including the 10 years I spent as the lead gear reviewer for Backpacker magazine and even longer running this blog. Few reviewers have lugged as many packs around the backcountry as me.

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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.

The Granite Gear Blaze 60 in the Grand Canyon.
” data-image-caption=”Testing the Granite Gear Blaze 60 in the Grand Canyon. Click photo to read about “the best backpacking trip in the Grand Canyon.”
” data-medium-file=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2019/05/Granite-Gear-Blaze-60-lead-2.jpg?fit=300%2C200&ssl=1″ data-large-file=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2019/05/Granite-Gear-Blaze-60-lead-2.jpg?fit=900%2C600&ssl=1″ src=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2019/05/Granite-Gear-Blaze-60-lead-2.jpg?resize=900%2C600&ssl=1″ alt=”The Granite Gear Blaze 60 in the Grand Canyon.” class=”wp-image-33676″ srcset=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2019/05/Granite-Gear-Blaze-60-lead-2.jpg?resize=1024%2C683&ssl=1 1024w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2019/05/Granite-Gear-Blaze-60-lead-2.jpg?resize=300%2C200&ssl=1 300w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2019/05/Granite-Gear-Blaze-60-lead-2.jpg?resize=768%2C512&ssl=1 768w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2019/05/Granite-Gear-Blaze-60-lead-2.jpg?resize=1080%2C720&ssl=1 1080w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2019/05/Granite-Gear-Blaze-60-lead-2.jpg?w=1200&ssl=1 1200w” sizes=”(max-width: 900px) 100vw, 900px” data-recalc-dims=”1″ />Testing the Granite Gear Blaze 60 in the Grand Canyon. Click photo to read about “the best backpacking trip in the Grand Canyon.”

I’m confident at least one of these packs will be perfect for you—plus you’ll find the best prices for them through the affiliate links to online retailers below. Purchasing gear through my affiliate links supports my work on this blog. Thanks for doing that.

I’ve listed the pack reviews below in order by weight because that’s the metric that most defines and influences a pack’s design and functionality. The ratings admittedly tend to favor more-featured packs, which are heavier, and that may not meet your needs; use the ratings as a comparison with packs of similar weight. The pack you ultimately choose may depend partly on weight, but also on design and on your budget. Each pack review in this article links to that pack’s complete review at The Big Outside.

A backpacker above Toxaway Lake, Sawtooth Mountains, Idaho.
” data-image-caption=”Testing the Osprey Aura AG 65 in Idaho’s Sawtooth Mountains. Click photo to read about the best backpacking trip in the Sawtooths.
” data-medium-file=”https://i0.wp.com/thebigoutside
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