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The ESA’s Gaia Observatory continues its astrometry mission, which consists of measuring the positions, distances, and motions of stars (and the positions of orbiting exoplanets) with unprecedented precision. Launched in 2013 and with a five-year nominal mission (2014-2019), the mission is expected to remain in operation until 2025. Once complete, the mission data will be used to create the most detailed 3D space catalog ever, totaling more than 1 billion astronomical objects – including stars, planets, comets, asteroids, and quasars.

Another benefit of this data, according to a team of researchers led by the Chinese Academy of Sciences (CAS), is the ability to predict future microlensing events. Similar to gravitational lensing, this phenomenon occurs when light from background sources is deflected and amplified by foreground objects. Using information from Gaia‘s third data release (DR3), the team predicted 4500 microlensing events, 1664 of which are unlike any we have seen. These events will allow astronomers to conduct lucrative research into distant star systems, exoplanets, and other celestial objects.

The team consisted of researchers from the Yunnan Observatories, the Key Laboratory for the Structure and Evolution of Celestial Objects, the Center for Astronomical Mega-Science, the University of Chinese Academy of Sciences (UCAS), and the College of Information Engineering at Kunming University. The preprint of their paper, “Predicting Astrometric Microlensing Events from Gaia DR3,” recently appeared online, and an updated version appeared on November 7th in the Monthly Notices of the Royal Astronomical Society.

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Artist’s impression of the ESA’s Gaia Observatory. Credit: ESA

Gravitational lensing has proven to be of immense value to astronomers, allowing for observation campaigns like the Frontier Fields program. This consisted of the venerable Hubble Space Telescope using lenses created by massive galaxy clusters to take the deepest views of the Universe ever and observe galaxies that existed about 1 billion years after the Big Bang. The James Webb Space Telescope has carried on in this tradition and recently collaborated with Hubble to produce even more detailed images of lensing galaxies.

While similar in principle, microlensing has a different range of applications, including detecting and studying exoplanets and constraining the population of binary stars, neutron stars, brown dwarfs, and red dwarfs in our galaxy. But as lead author Su Jie told Universe Today via email, the applications go much farther:

“Astrometric microlensing can be used to make precise measurements of the masses of lens stars that are independent of their assumed internal physics. Such direct mass measurements, obtained purely by observing the gravitational effects of the stars on external objects, are crucial for validating theoretical stellar models. In addition, it can also detect faint and compact lenses such as isolated neutron stars and black holes because the luminosity of the lens is not necessarily measured.”

Like Gravitational Lensing, the Microlensing technique depends on chance alignments between massive objects and background sources. Given their importance to astronomers, the ability to predict when these microlensing events will occur is vitally important. This is where the ESA’s Gaia Observatory comes into play. For years, Gaia has gathered accurate information on the position, proper motion, and velocity of stars and other celestial objects in our Milky Way – which will be used to create the most detailed 3D space catalog ever made.

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Why is Jupiter’s Great Red Spot Shrinking? It’s Starving.

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The largest storm in the Solar System is shrinking and planetary scientists think they have an explanation. It could be related to a reduction in the number of smaller storms that feed it and may be starving Jupiter’s centuries-old Great Red Spot (GRS).

This storm has intrigued observers from its perch in the Jovian southern hemisphere since it was first seen in the mid-1600s. Continuous observations of it began in the late 1800s, which allowed scientists to chart a constant parade of changes. In the process, they’ve learned quite a bit about the spot. It’s a high-pressure region that generates a 16,000 km-wide anticyclonic storm with winds clocking in at more than 321 km per hour. The storm extends down through the atmosphere to a depth of about 250 km below the mainly ammonia cloud tops.

A zoomed-in view of the Great Red Spot based on Juno observations. Courtesy Kevin Gill.
A zoomed-in view of the Great Red Spot based on Juno observations. Courtesy Kevin Gill.

Modeling a Shrinking and Growing Great Red Spot

Over the past century, scientists noticed the GRS shrinking, leaving them with a puzzle on their hands. Yale Ph.D. student Caleb Keaveney had the idea that perhaps smaller storms that feed the GRS could play a role in starving it. He and a team of researchers focused on their influence and conducted a series of 3D simulations of the Spot. They used a model called the Explicit Planetary Isentropic-Coordinate (EPIC) model, which is used in studying planetary atmospheres. The result was a suite of computer models that simulated interactions between the Great Red Spot and smaller storms of varying frequency and intensity.

A separate control group of simulations left out the small storms. Then, the team compared the simulations. They saw that the smaller storms seemed to strengthen the Great Red Spot and make it grow. “We found through numerical simulations that by feeding the Great Red Spot a diet of smaller storms, as has been known to occur on Jupiter, we could modulate its size,” Keaveney said.

If that’s true, then the presence (or lack thereof) of those smaller storms could be what’s changing the spot’s size. Essentially, a lot of smaller spots cause it to grow larger. Fewer little ones cause it to shrink. Furthermore, the team’s modeling supports an interesting idea. Without forced interactions with these smaller vortices, the Spot can shrink over a period of about 2.6 Earth years.

Using Earth Storms as a Comparison

The Great Red Spot isn’t the only place in the Solar System that sports such a long-lived high-pressure system. Earth experiences plenty of them, usually called “heat domes” or “blocks.” Most of us are familiar with heat domes because we experience them during the summer months. They happen frequently in the upper atmosphere jet stream that circulates across our planet’s mid-latitudes. We can blame them for some of the extreme weather people experience—such as heat waves and extended droughts. They tend to last a long time, and they are linked to interactions with smaller transient weather such as high-pressure eddies and anticyclones.

Given that the Great Red Spot is an anticyclonic feature, it has interesting implications for similar atmospheric structures on both planets, according to Keaveney. “Interactions with nearby weather systems have been shown to sustain and amplify heat domes, which motivated our hypothesis that similar interactions on Jupiter could sustain the Great Red Spot,” he said. “In validating that hypothesis, we provide additional support to this understanding of heat domes on Earth.”

The Ever-changing Great Red Spot

In addition to the changing size of the Great Red Spot, observers also notice shifts in its color. It’s mainly reddish-orange but has been known to fade to a pinkish-orange hue. The colors suggest some complex chemistry occurring in the region spurred by solar radiation. It has an effect on a chemical compound called ammonium hydrosulfide as well as the organic compound acetylene. That creates a substance called a tholin, which gives a reddish color wherever it exists.

At times the spot has nearly disappeared altogether due to some complex interaction with a feature called
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Review: Patagonia Black Hole Pack 32L Travel Pack

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Travel Pack
Patagonia Black Hole Pack 32L

$169, 32L/1,831 c.i., 1 lb. 12.6 oz./810g

One size

backcountry.com

If you’re like me, whenever you’re flying somewhere for a few days, maybe a week or more, you ask yourself the same question: Can I do this without checking luggage? Not only do I loathe paying a luggage fee, but I don’t want to give an airline the opportunity to lose my luggage. Plus, I like the convenience, low expense, and the ethically and morally correct choice (in this age of climate crisis) of using public transportation to and from airports—which is really only feasible when carrying one small, light, portable bag or pack. For me, the carry-on of choice is the Patagonia Black Hole Pack 32L.

For starters, I generally like having a small and light pack or bag with shoulder straps that I can throw onto my back to move quickly through airports; wheeled luggage of any size quickly loses its convenience when you’re in a serious rush in an airport, have no choice but to go up or down stairs (which I prefer, anyway, to standing on an escalator behind a line of stationary people), or are taking subways, buses, or trains.

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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 Patagonia Black Hole Pack 32L back panel and shoulder straps.
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” data-medium-file=”https://i0.wp.com/tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2023/07/06224812/Patagonia-Black-Hole-Pack-32L-harness-2.jpg?fit=225%2C300&ssl=1″ data-large-file=”https://i0.wp.com/tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2023/07/06224812/Patagonia-Black-Hole-Pack-32L-harness-2.jpg?fit=768%2C1024&ssl=1″ tabindex=”0″ role=”button” src=”https://i0.wp.com/tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2023/07/06224812/Patagonia-Black-Hole-Pack-32L-harness-2-768×1024.jpg?resize=768%2C1024&ssl=1″ alt=”The Patagonia Black Hole Pack 32L back panel and shoulder straps.” class=”wp-image-59669″ style=”width:602px;height:auto” srcset=”https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2023/07/06224812/Patagonia-Black-Hole-Pack-32L-harness-2.jpg 768w, https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2023/07/06224812/Patagonia-Black-Hole-Pack-32L-harness-2.jpg 225w, https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2023/07/06224812/Patagonia-Black-Hole-Pack-32L-harness-2.jpg 640w, https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2023/07/06224812/Patagonia-Black-Hole-Pack-32L-harness-2.jpg 150w, https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2023/07/06224812/Patagonia-Black-Hole-Pack-32L-harness-2.jpg 900w” sizes=”(max-width: 768px) 100vw, 768px” data-recalc-dims=”1″ />The Patagonia Black Hole Pack 32L back panel and shoulder straps.

On my most recent trip, flying cross-country to visit family and friends—two flights and a layover of 90 minutes or more in each direction—I wanted to avoid checking luggage (for all the reasons given above). Packing frugally, I fit everything I needed into my Black Hole Pack 32L for
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Pulsars are the Ideal Probes for Dark Matter

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Pulsars are the remnants of the explosion of massive stars at the end of their lives. The event is known as a supernova and as they rapidly spin they sweep a high energy beam across the cosmos much like a lighthouse. The alignment of some pulsar beams mean they sweep across Earth predictably and with precise regularity. They can be, and often are used as timing gauges but a team of astronomers have found subtle timing changes in some pulsars hinting at unseen mass between pulsars and telescopes—possibly dark matter entities.

The discovery in 1967 of pulsars has revolutionised our understanding of stellar evolution. The are formed during the collapse of supermassive stars at the end of their life. As the fusion in the core ceases, the inrushing stellar material crashing down onto the core compresses it to incredible density. The material that once made up the star is, through this process compressed into a sphere just a few tens of kilometres across. Pulsars are closely related to neutron stars which are formed though the same process and it is believed, the only difference is that one has a highly energetic beam that flashes across the Earth and one doesn’t. 

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

A team studying pulsars has recently detected hints of potential dark matter objects through changes in pulsar timing events as they rotate. Professor John LoSecco from the University of Notre Dame, presented at the National Astronomy Meeting at the University of Hull and emphasised the precision of pulsar-based timekeeping. “Science has advanced with precise time measurement methods,” he noted, comparing Earth’s atomic clocks with pulsars in space. While gravitational effects on light have been understood for over a century, their applications in uncovering hidden masses remain largely unexplored until now.

Professor LoSecco and the team noted tiny deviations in the pulsar timing, suggesting that radio waves may be getting redirected around an unseen mass located somewhere between the pulsar and the telescope. LoSecco theorised that the masses could potentially be dark matter!

By examining the delays and analysing the radio pulse arrivals (which were typically accurate to within a nanosecond) they explored the pathway of radio signals within the latest Parkes Pulsar Timing Array survey. Other telescopes involved in this initiative were the Effelsberg, Nançay, Westerbork, Green Bank, Arecibo, Parkes, and the Lovell telescope in Cheshire. Using this and Parkes data, the pulse arrival times were analysed.

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The Arecibo Radio Telescope Credit: UCF

The results showed that the pulses occur regularly every three weeks across three observational bands. However, when dark matter causes delays in arrival times, these delays display distinct shapes proportional to the mass of the dark matter. Regions with dark matter slow down the passage of light and effect the pulsar timings. The Sun for example, could produce a delay of about 10 microseconds however the timing differences 10,000 times smaller.  A detailed examination of precise data from 65 ‘millisecond pulsars’ has identified approximately twelve instances suggestive of interactions with dark matter.

Source : How astronomers are using pulsars to observe evidence of dark matter

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