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Astronaut craves salsa and surf after record 11 months aloft – larongeNOW

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Koch’s astronaut class of 2013 was split equally between women and men, but NASA’s astronaut corps as a whole is male dominated. Right now, four men and two women are living at the space station.

“Diversity is important, and I think it is something worth fighting for,” said Koch, an electrical engineer who also has a physics degree.

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Koch’s 328-day mission will be the second-longest by an American, trailing Scott Kelly’s flight by 12 days. She’s already set a record for the longest single spaceflight by a woman.

She took time out for a pair of news interviews Tuesday, the 34th anniversary of the space shuttle Challenger accident that claimed all seven lives on board.

She said she loves her work — she conducted six spacewalks and tended to science experiments — but she also misses her friends and family.

“If they could visit here, I would continue staying for a very long time,” said Koch, a first-time space flier. “For their sake, I think that it’s probably time to head home.”

Her biggest surprise is how easily and quickly she adapted both mentally and physically to weightlessness.

“I don’t even really realize that I’m floating any more,” she said.

Why do chips and salsa top her most-missed food list? Crunchy food like chips are banned on the space station because the crumbs could float away and clog equipment. “I haven’t had chips in about 10 1/2 months,” she explained, “but I have had a fresh apple” thanks to regular cargo deliveries.

Another thing she misses: the ability to put things down and not have them float away.

She’s gotten used to using Velcro and tape to make things stay put, “so I hope that when I go back to Earth, I don’t accidentally drop things, especially when I’m handing them to people.”

Kelly, whose mission spanned 2015 and 2016, has given her advance notice of what to expect.

“It’s a great reminder to keep mentoring,” Koch said. When her record is broken, “I hope to mentor that person just as I’ve been mentored.”

Koch said it was crucial staying connected to loved ones through phone calls and video conferences. She watched as her nieces and nephews opened their Christmas presents. But it’s also special celebrating holidays in space, she noted, which “kind of takes any sting off of missing your family.”

Koch grew up in Jacksonville, North Carolina, and now lives near the Gulf of Mexico in Galveston, Texas, with her husband, Bob. She said she can’t wait for their next wedding anniversary, Christmas at home and his birthday.

Her 41st birthday is Wednesday. How does she plan to celebrate?

Playing Scrabble with her U.S., Italian and Russian crew mates, as challenging as that might be in weightlessness. She packed a travel version of the game and has been too busy to enjoy it.

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The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.

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This story has been corrected to fix the number of spacewalks to six, not five.

Marcia Dunn, The Associated Press

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How Old Is The Sun? – Worldatlas.com

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The sun formed around 4.6-billion years ago, and all the planets formed within the next 100-million years. The age of the sun and the planets is one of the most widely accepted facts about our solar system, and the reason for this is that every line of evidence points to the same age. How is the age of the sun determined?

Finding The Oldest Thing In The Solar System

One way to determine the approximate age of the sun is to find the oldest object in the solar system. Fortunately, there are countless objects that formed along with the sun, such as asteroids, meteors, and planetesimals. These forms of planetary debris remain virtually unchanged for billions of years, and by using radiometric dating methods, scientists can determine their age, in turn directly telling us how old the sun is. Radiometric dating uses precise chemicals to determine the age of rocks, and it works by using something called a half-life. For example, carbon-14 dating is a reliable method for dating things like fossils, as carbon-14 is only present in organic matter. Carbon-14 has a half-life of 5,730 years, meaning that after 5,730 years, half of the carbon-14 will decay into another chemical, in this case, nitrogen-14. Every 5,730 years, another half will decay and so on. By determining the amount of carbon-14 present relative to the amount of nitrogen-14, scientists can determine the age of whatever it is that is being analyzed. While carbon-14 is a reliable method for determining the age of organic matter, it will not work for determining things that are billions of years old. 

To find out when the sun first began to form, astronomers look for iron-60, a rare isotope of iron that is only produced during a supernova explosion. A supernova likely preceded the formation of our solar system, and the energy released from the explosion likely ignited the formation of the sun billions of years ago. Iron-60 has a half-life of 2.26-million years, wherein it decays into nickel-60. Like with carbon-14 and nitrogen-14, astronomers analyze rocks from asteroids and meteors to determine the ratio between iron-60 and nickel-60, which produces an age of around 4.6-billion years. Furthermore, other dating methods used on Earth and the moon have produced ages of around 4.5-billion years, offering further evidence that the sun is at least that old.

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Lifespan Of The Sun

The Sun

The sun is 4.6-billion years old, and astronomers believe that it is only about halfway through its life. We obviously cannot see into the future, and so how do scientists estimate the amount of time the sun will exist for? The process is actually rather simple, and it involves knowing how much fuel the sun has and rate at which it consumes that fuel. Like every other star in the universe, the sun is powered by the nuclear fusion of hydrogen nuclei in its core. When hydrogen is fused together, it produces helium and vast amounts of energy that power the star. So long as nuclear fusion is maintained within the core, the sun will remain a main sequence star. However, that fuel will eventually run out, and when it does, the sun will enter into the final stages of life. By knowing the amount of fuel the sun has and the rate at which it uses that fuel, astronomers estimate that the sun will continue fusing hydrogen in its core for at least another 4 to 5-billion years. When the sun does begin to run out of usable hydrogen, it will evolve into a red giant, eventually blowing off its outer layers. Those outer layers will form a shell of stellar material called a planetary nebula. Meanwhile, the core of the sun will collapse and become a white dwarf. 

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UBC Okanagan study to investigate where Eurasian watermilfoil occurs in lakes – Vernon Morning Star

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A UBC Okanagan pilot project is seeking to better pinpoint and map where the beginnings of Eurasian watermilfoil (EWM) infestation occurs in the large lakes within the Okanagan Valley watershed.

If this pilot project proves successful, it could become a blueprint for other jurisdictions to follow in their own battles with this aquatic plant or other invasive aquatic species, says UBCO assistant professor Mathieu Bourbonnais.

Bourbonnais, with the Irving K. Barber Faculty of Science, is overseeing the project with the assistance of masters graduate student Mackenzie Clarke.

The data modelling prototype is using the technology of topobathymetric lidar, the science of simultaneously measuring and recording three distinct surfaces – land, water and submerged land up to 20 metres below the water surface – using airborne laser-based infrared imagery sensors.

Bourbonnais says being able to better identify potential or small milfoil patches will give better control management tools for the Okanagan Basin Water Board’s Euroasian watermilfoil harvest program, which currently is about an $800,000 a year initiative to try and control the growth and limit the damage of the invasive water plant.

It could also potentially target specific watermilfoil growth sites before they grow out of control near valley lake areas deemed sensitive by Environment Canada for the preservation of the Rocky Mountain Ridge Mussels.

He said EWM has been a formidable invasive aquatic plant species to control since it was introduced into the Okanagan Valley lake system some 40 years ago.

It has also illustrated to the water board the need to be stringent when trying to avoid the Zebra and Quagga mussels from being introduced into the lake system.

Like watermilfoil, there is no solution for removing the mussels once they are introduced into a lake system. It is a rooted submerged plant inhabiting the shallows waters of lakes across North America.

EWM originated from Asia, Europe and Northern Africa and has spread rapidly, introduced in North America from the ballast water of ships or aquarium activities.

Bourbonnais said a lake choked with watermilfoil growth impacts the biodiversity and food webs reliant on the lake habitat, alter the water temperature and impacts its recreational use for swimmers and boaters.

“The impact of invasive species on our lake aquatic systems costs billions of dollars to deal with across the country. It definitely has an impact both ecologically and economically,” he said.

The pilot project fieldwork will be done by early spring, he said, with the hope it provides data upon which to target areas for harvesting leading up to the permit application process next year.

“The goal is the Okanagan Basin Water Board can take the data generated from this research model and liaise with the province and federal government on how to go forward,” he said.

“We hope it can help the management strategy of where to send the lake rototillers to pull up the plants.”

READ MORE: Milfoil infestation continues to plague Okanagan watershed

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How Do Stars Get Kicked Out of Globular Clusters? – Universe Today

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Globular clusters are densely-packed collections of stars bound together gravitationally in roughly-shaped spheres. They contain hundreds of thousands of stars. Some might contain millions of stars.

Sometimes globular clusters (GCs) kick stars out of their gravitational group. How does that work?

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There are a few things that can cause GCs to eject stars. Gravitational scattering, supernovae, tidal disruption events, and physical collisions could all be responsible. Whatever’s behind it, the gradual ejection of stars from GCs is an established phenomenon.

The evidence for stellar ejection from GCs is in the tidal tails that stream out from them.

Palomar 5 is a globular cluster being torn apart by the Milky Way. Palomar 5 is the white blob at the center, and the orange is streams of stars. The yellow line with arrows represents the cluster's orbit around the Milky Way. Image Credit: Odenkirchen, Grebel, et al. 2002/Sloan Digital Sky Survey
Palomar 5 is a globular cluster being torn apart by the Milky Way. Palomar 5 is the white blob at the center, and the orange is streams of stars. The yellow line with arrows represents the cluster’s orbit around the Milky Way. Image Credit: Odenkirchen, Grebel, et al. 2002/Sloan Digital Sky Survey

A new study based on data from the ESA’s Gaia mission aims to understand how GCs eject stars. Its title is “Stellar Escape from Globular Clusters I: Escape Mechanisms and Properties at Ejection.” It’s been submitted to the Astrophysical Journal, and the lead author is Newlin Weatherford, an astronomy Ph.D. student at Northwestern University in Illinois.

“Recent exquisite kinematic data from the Gaia space telescope has revealed numerous stellar streams in the Milky Way (MW) and traced the origin of many to specific MWGCs, highlighting the need for further examination of stellar escape from these clusters,” the authors write. This study is the first of a series, and the authors examine all the escape mechanisms and how each one contributes to GC star loss.

GCs are some of the oldest stellar associations in the Milky Way. Individual GC stars are also older and have lower metallicity than the Milky Way’s general population. Nearly all galaxies host GCs, and in spiral galaxies like ours, the GCs are mostly found in the halo. The Milky way hosts more than 150 of them. Astronomers used to think that stars in a GC form from the same molecular cloud, but now they know that that’s not true. GCs contain stars of different ages and metallicities.

GCs are different from their cousins, the open clusters (OCs). OCs are most often found in the disks of spiral galaxies, have more heavy elements, and are less dense and also smaller than GCs. OCs have only a few thousand stars, and there are more than 1100 of them in the Milky Way.

NGC 6441 is one of the most luminous and massive globular clusters in the Milky Way. Image Credit: ESA/Hubble & NASA, G. Piotto
NGC 6441 is one of the most luminous and massive globular clusters in the Milky Way. Image Credit: ESA/Hubble & NASA, G. Piotto

GCs are unique, and astronomers consider them tracers of galactic evolution. Thanks largely to the ESA’s Gaia spacecraft, we know more about GCs. Gaia helped reveal the presence of numerous stellar streams coming from the Milky Way’s globular clusters. As the authors explain in their paper, “These drawn-out associations of stars on similar orbits are likely debris from disrupted dwarf galaxies and their GCs, shorn off by Galactic tides during accretion by the MW (Milky Way.)”

Gaia did more than spot these streams. It was able to connect some streams to specific GCs. “Gaia’s exquisite kinematic data has firmly tied the origins of ~10 especially thin streams to specific MWGCs,” the authors write. The Palomar 5 GC and its streams are well-known examples. The streams are excellent tracers of the Milky Way’s evolution. (Palomar 5 gained even more notoriety in astronomy recently when a 2021 paper found more than 100 black holes in its center.)

Observations of these types of tails, both from stars ejected from GCs, and from interacting and merging galaxies, are an extremely active area of research. There are many astounding images of these interactions. But as the authors point out, “… the theoretical study of stellar escape from GCs has a longer history.” Astronomers have come up with different mechanisms for these escapes, and this paper starts with a review of each one.

Artist's impression of the thin stream of stars torn from the Phoenix globular cluster, wrapping around our Milky Way (left). Red giant stars make up a significant portion of the stream and helped astronomers map it. Credit: James Josephides (Swinburne Astronomy Productions) and the S5 Collaboration.
Artist’s impression of the thin stream of stars torn from the Phoenix globular cluster, wrapping around our Milky Way (left). Red giant stars make up a significant portion of the stream and helped astronomers map it. Credit: James Josephides (Swinburne Astronomy Productions) and the S5 Collaboration.

The authors divide escape mechanisms into two categories: Evaporation and Ejection. Evaporation is gradual, while ejection is more abrupt. The following are brief descriptions of each of the ejection methods, beginning with the Evaporation category.

Two-Body Relaxation: the motions of each body induce granular perturbations that create exchanges in energy and momentum in the bodies. Over time, stars can be ejected from GCs.

Cluster mass loss: stars lose mass over time, and that can affect the gravitational binding that holds stars in the cluster.

Sharply time-dependent tides: MWGCs orbit the Milky Way in eccentric and inclined orbits. The galactic tide will be stronger at some points in the orbit. The changing gravity can allow stars to exit the GCs.

The second broad category is Ejection. These are events typically involving single stars that are ejected rapidly and dramatically.

Strong Encounters: a close passage between two or more bodies that provides a strong enough kick to eject a star.

(Near)-Contact Recoil: encounters so close that tides, internal stellar processes, and/or relativistic effects are relevant. This includes collisions and gravitational waves.

Stellar Evolution Recoil: This includes the powerful forces unleashed when a star goes supernova, for example, or when a black hole or neutron star is formed.

Since there was no way to go and observe a statistically significant number of GC ejections, the team of researchers took what data was available and performed simulations. They used what’s called the CMC Cluster Catalog.

The study is concerned with the two types of GCs: non-core collapsed and core-collapsed. They’re different from each other and are a fundamental property of GCs, so the team simulated both types.

Core collapse in GCs occurs when the more massive stars in a GC encounter less massive stars. This creates a dynamic process that, over time, drives some stars out of the center of the GC towards the outside. This creates a net loss of kinetic energy in the core, so the remaining stars in the GCs core take up less space, creating a collapsed core.

This figure from the study shows the number of escaped single stars and stellar objects for the archetypal core-collapse GCs and non-core-collapse GCs. The x-axis is unlabelled but measures time in Gyrs. Each black marker is two Gyrs. Dashed lines are results from core-collapsed GCs, while solid lines are non-core-collapsed GCs. The plotted lines are colour coded according to the legend at the top. As the figure shows, most ejected stars are main-sequence stars, mirroring the population of the GCs themselves. Image Credit: Weatherford et al. 2022.
This figure from the study shows the number of escaped single stars and stellar objects for the archetypal core-collapse GCs and non-core-collapse GCs. The x-axis is unlabelled but measures time in Gyrs. Each black marker is two Gyrs. Dashed lines are results from core-collapsed GCs, while solid lines are non-core-collapsed GCs. The plotted lines are colour coded according to the legend at the top. As the figure shows, most ejected stars are main-sequence stars, mirroring the population of the GCs themselves. Image Credit: Weatherford et al. 2022.

An important astronomical principle plays a role in the team’s results. Two-body relaxation is a fundamental aspect of stellar associations that has far-reaching effects. It’s a complicated topic, but it basically describes the ways that stars in stellar associations, such as GCs, interact gravitationally and share kinetic energy with each other. It shows that star-to-star interactions drive GCs to evolve during the lifetime of the galaxy they’re attached to.

Not surprisingly, the researchers found that two-body relaxation plays a powerful role. That conclusion lines up with the established theory. “Consistent with longstanding theory and numerical modelling, we find that two-body relaxation in the cluster core dominates the overall escape rate,” they write.

This figure from the study shows binary objects ejected in the simulation. The number of objects is on the y-axis, and time in two-Gyr increments is on the x-axis. Dashed lines are results from core-collapsed GCs, while solid lines are non-core-collapsed GCs. Image Credit: Weatherford et al. 2022.
This figure from the study shows binary compact objects ejected in the simulation. The number of objects is on the y-axis, and time in two-Gyr increments is on the x-axis. Dashed lines are results from core-collapsed GCs, while solid lines are non-core-collapsed GCs. Image Credit: Weatherford et al. 2022.

They also found that “… central strong encounters involving binaries contribute especially high-speed
ejections, as do supernovae and gravitational wave-driven mergers.” This also lines up with other research.

This figure from the study shows binary objects containing a compact object and a main-sequence or giant star ejected from GCs. The number of objects is on the y-axis, and time in two-Gyr increments is on the x-axis. Dashed lines are results from core-collapsed GCs, while solid lines are non-core-collapsed GCs. Image Credit: Weatherford et al. 2022.
This figure from the study shows binary objects containing a compact object and a main-sequence or giant star ejected from GCs. The number of objects is on the y-axis, and time in two-Gyr increments is on the x-axis. Dashed lines are results from core-collapsed GCs, while solid lines are non-core-collapsed GCs. Image Credit: Weatherford et al. 2022.

But one of their results is new. It concerns three-body binary formation (3BBF.) 3BBF is when three bodies collide to form a new binary object. “We have also shown for the first time that three-body binary formation plays a significant role in the escape dynamics of non-core-collapsed GCs typical of those in the MW. BHs are an essential catalyst for this process,” they write. “3BBF dominates the rate of present-day high-speed ejections over any other mechanism,” they explain, as long as significant numbers of BHs remain in the GCs core. 3BBFs also produce a significant number of hypervelocity stars.

In their conclusion, the authors explain that “… this study provides a broad sense of the escape mechanisms and demographics of escapers from GCs,” while also noting that the results are “not immediately comparable to Gaia observations.” That’s why this work is the first in a series of papers. In their follow-up paper, they intend to integrate the trajectories of escaped stars and construct their velocity distributions to reproduce tidal tails. After that work, they hope that they’ll have a clearer understanding of how stars escaping from GC contribute to galactic evolution.

In a third paper, they intend to “… identify likely past members (‘extratidal candidates’) of specific MWGCs and directly compare the mock ejecta from our cluster models to the Gaia data.” This will get closer to some of the core questions surrounding GCs and the Milky Way’s evolution: how do stellar streams form? How many BHs are there in GCs? What role do supernovae play?

“Ultimately, we hope to better understand stellar stream formation and, in an ideal case, leverage the new
observables from Gaia to better constrain uncertain properties about MWGCs, such as BH content, SNe kicks, and the initial mass function, which affect ejection velocities and the cluster evaporation rate.”

The ESA's Gaia spacecraft doesn't make a lot of headlines in regular media because it doesn't take gorgeous images. But as this study shows, its contribution to important topics like galactic evolution can't be overstated. Artist's impression of the ESA's Gaia Observatory. Credit: ESA
The ESA’s Gaia spacecraft doesn’t make a lot of headlines in regular media because it doesn’t take gorgeous images. But as this study shows, its contribution to important topics like galactic evolution can’t be overstated. (Those who know, know.) Artist’s impression of the ESA’s Gaia Observatory. Credit: ESA

This study is an interesting look at how a number of natural phenomena all contribute to galactic evolution. The evolution of individual stars, how individual stars interact gravitationally and how they form binary objects, the tidal interactions between globular clusters and their host galaxies, two-body relaxation, and even three-body binary formation. Throw in supernovae and hypervelocity stars.

Each one of these topics can form the basis of an entire career in astrophysics. It’s easy to see why follow-up studies are needed. Once they’re completed, we’ll have a much better picture of how galaxies, specifically our own Milky Way, evolve.

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