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There’s a wobbly X-ray-bright binary object in our galaxy called Hercules X-1 that’s blowing a mighty wind off to surrounding space. The system consists of a neutron star paired with a sun-like star. The neutron star is drawing material away from its companion. Its resulting accretion spins rapidly, and that whips up powerful winds. They affect the region of nearby space. That’s eerily similar to how a quasar’s central black hole sends out winds to influence its entire host galaxy.

A team led by Peter Kosec, a postdoctoral researcher at Massachusetts Institute of Technology (MIT), wanted to measure the winds blowing off of Hercules X-1’s accretion disk. That’s because its wobble gives them a unique perspective.

“The disk is really wobbling over time every 35 days, and the winds are originating somewhere in the disk and crossing our line of sight at different heights above the disk with time,” said Kosec. “That’s a very unique property of this system which allows us to better understand its vertical wind properties.”

By taking advantage of the wobble (called “precession) it experiences, Kosec’s team got measurements of the wind from different perspectives. The result is a two-dimensional map of the wind’s vertical shape and structure. The measurements also tracked varying wind velocities at different lines of sight, ranging from 250-800 km/sec. The team’s analysis suggests the wind variations are connected to the disk wobble. It appears that the wind “structure” precesses along with the disk.

“Taking X-rays” of the Neutron Star’s Disk and Winds

The team used two X-ray telescopes—ESA’s XMM-Newton and NASA’s Chandra Observatory—to look at Hercules X-1. That provided a view of the edge of the neutron star’s spinning disk moving up and down as it wobbled. “What we measure is an X-ray spectrum, which means the amount of X-ray photons that arrive at our detectors, versus their energy. We measure the absorption lines or the lack of X-ray light at very specific energies,” Kosec said. “From the ratio of how strong the different lines are, we can determine the temperature, velocity, and the amount of plasma within the disk wind.”

The observations showed signs of disk winds at changing heights, rather than at a single, fixed height above a uniformly rotating disk. The X-ray emissions and absorption lines revealed the temperature and density of the winds at various heights above the disk. That data was then used to construct a two-dimensional map of the wind’s vertical structure. “What we see is that the wind rises from the disk, at an angle of about 12 degrees with respect to the disk as it expands in space,” Kosec says. “It’s also getting colder and more clumpy, and weaker at greater heights above the disk.”

Neutron Star Winds and Quasar Winds

An artist's concept of the quasar SDSS J135246.37+423923.5. It pushes thick winds out from the core. Could its windy disposition stem have similar origins as the winds flowing out from the neutron star in Hercules X-1? Gemini Observatory looked at this in infrared light, which allowed astronomers to measure the velocity of the windy outflow at almost 13% of the speed of light. Credit: International Gemini Observatory/NOIRLab/NSF/AURA/P. Marenfeld
An artist’s concept of the quasar SDSS J135246.37+423923.5. It pushes thick winds out from the core. Could its windy disposition stem have similar origins as the winds flowing out from the neutron star in Hercules X-1? Gemini Observatory looked at this in infrared light, which allowed astronomers to measure the velocity of the windy outflow at almost 13% of the speed of light. Credit: International Gemini Observatory/NOIRLab/NSF/AURA/P. Marenfeld

At first glance, the wind action around Hercules X-1 seems similar to what happens around supermassive black holes in the cores of galaxies. Quasars, for example, have these embedded black holes with winds blowing off their accretion disks. For most accretion disk systems, however, astronomers have very limited points of view. They don’t always get to see one
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The Best Backpacking Gear for the John Muir Trail

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June 5, 2023

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By Michael Lanza

So you’re planning to thru-hike the John Muir Trail and making all of the necessary preparations, and now you’re wondering: What’s the best gear for a JMT hike? Having thru-hiked the JMT as well as taken numerous other backpacking trips all over the High Sierra—mostly between late August and late September, which I consider that the best time to walk the Sierra, to avoid snow and the voracious mosquitoes and blazing hot afternoons of mid-summer—I offer the following picks for the best lightweight backpacking gear and apparel for a JMT thru-hike.

Indisputably one of the best backpacking trips in America—and among the very best I’ve taken over three decades of backpacking, including 10 years I spent as Northwest Editor and lead gear reviewer for Backpacker magazine and even longer running this blog—the JMT meanders for 211 miles through the magnificent High Sierra, from Yosemite Valley to the summit of the highest peak in the Lower 48, 14,505-foot Mount Whitney (where backpackers must then descend another 11 miles to finish the trip at Whitney Portal trailhead). See my story about thru-hiking the JMT in seven days.

With few opportunities to resupply along the trail—and given the generally dry weather in the Sierra in summer—you can easily and should hike the JMT with the lightest gear that works for you (or that you can afford). Maximum pack weight will depend on how many days you spend on the trail and your food weight, but it’s quite feasible to keep your base pack weight (everything but food and water) within 15 pounds or less—and certainly no more than 20 pounds—without compromising safety or comfort in camp.

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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 backpacker hiking the John Muir Trail above Helen Lake in Kings Canyon N.P., High Sierra.
” data-image-caption=”Marco Garofalo backpacking the John Muir Trail above Helen Lake in Kings Canyon N.P. Click photo to learn how I can help you plan your JMT thru-hike.
” data-medium-file=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/10/JMT2-085-Marco-Garofalo-hiking-above-Helen-Lake-John-Muir-Trail-Kings-Canyon-N.P.-High-Sierra..jpg?fit=300%2C200&ssl=1″ data-large-file=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/10/JMT2-085-Marco-Garofalo-hiking-above-Helen-Lake-John-Muir-Trail-Kings-Canyon-N.P.-High-Sierra..jpg?fit=900%2C600&ssl=1″ decoding=”async” width=”900″ height=”600″ src=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/10/JMT2-085-Marco-Garofalo-hiking-above-Helen-Lake-John-Muir-Trail-Kings-Canyon-N.P.-High-Sierra..jpg?resize=900%2C600&ssl=1″ alt=”A backpacker hiking the John Muir Trail above Helen Lake in Kings Canyon N.P., High Sierra.” class=”wp-image-54840″ srcset=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/10/JMT2-085-Marco-Garofalo-hiking-above-Helen-Lake-John-Muir-Trail-Kings-Canyon-N.P.-High-Sierra..jpg?resize=1024%2C683&ssl=1 1024w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/10/JMT2-085-Marco-Garofalo-hiking-above-Helen-Lake-John-Muir-Trail-Kings-Canyon-N.P.-High-Sierra..jpg?resize=300%2C200&ssl=1 300w, https://i0.wp.com/thebigoutside
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CRS-28 Mission Control Audio

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June 5, 2023

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This is the vehicle trajectory and mission control audio without any additional commentary. There may be very long periods of silence. For our full hosted webcast, visit

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Photo Gallery: 36 Gorgeous Backcountry Lakes

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14 hours ago

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June 5, 2023

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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 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-guides 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. 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/thebigoutside.com/wp-content/uploads/2020/03/Gla6-018-Elizabeth-Lake-in-Glacier-National-Park.-2.jpg?fit=300%2C200&ssl=1″ data-large-file=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2020/03/Gla6-018-Elizabeth-Lake-in-Glacier-National-Park.-2.jpg?fit=900%2C600&ssl=1″ decoding=”async” width=”900″ height=”600″ src=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2020/03/Gla6-018-Elizabeth-Lake-in-Glacier-National-Park.-2.jpg?resize=900%2C600&ssl=1″ alt=”Elizabeth Lake in Glacier National Park.” class=”wp-image-38774″ srcset=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2020/03/Gla6-018-Elizabeth-Lake-in-Glacier-National-Park.-2.jpg?resize=1024%2C683&ssl=1 1024w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2020/03/Gla6-018-Elizabeth-Lake-in-Glacier-National-Park.-2.jpg?resize=300%2C200&ssl=1 300w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2020/03/Gla6-018-Elizabeth-Lake-in-Glacier-National-Park.-2.jpg?resize=768%2C512&ssl=1 768w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2020/03/Gla6-018-Elizabeth-Lake-in-Glacier-National-Park.-2.jpg?resize=1080%2C720&ssl=1 1080w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2020/03/Gla6-018-Elizabeth-Lake-in-Glacier-National-Park.-2.jpg?w=1200&ssl=1 1200w” sizes=”(max-width: 900px) 100vw, 900px” data-recalc-dims=”1″ />Elizabeth Lake in Glacier National Park.

Elizabeth Lake, Glacier National
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