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Discovery of the least 'metallic' stellar structure in the Milky Way – Phys.org

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This illustration shows the location of the C-19 stellar stream (orange, vertical stream of stars in lower left), which was recently discovered at the edge of our Milky Way Galaxy. Observations using the Gemini North telescope—part of the international Gemini Observatory, a program of NSF’s NOIRLab—reveal that the stars in this stream were once part of an ancient globular star cluster that was torn apart by gravitational interactions with our galaxy. The Large Magellanic Cloud and Small Magellanic Cloud (satellite galaxies of the Milky Way) appear in the lower right. Credit: International Gemini Observatory /NOIRLab / NSF / AURA/ J. da Silva / Spaceengine / M. Zamani (NSF’s NOIRLab)

A primordial stellar stream discovered in the outer reaches of the Milky Way has a lower proportion of heavy elements than any known stellar system in our galaxy. Observations with the Gemini Observatory, a Program of NSF’s NOIRLab, showed that the stars in this stream were torn from an ancient star cluster and are relics from the early days of the Milky Way, which could provide insights into the formation of the first stars.

An international team of researchers including members from Europe, Canada, and Russia has discovered a unique stream of stars orbiting the Milky Way. Called C-19, the stellar stream is south of the spiral of the Milky Way, and its orbit extends about 20,000 light-years from the galactic center at its closest approach and roughly 90,000 light-years at its farthest. The stellar stream stretches across an impressive expanse of the night sky—roughly 30 times the width of the full moon—although it isn’t visible to the naked eye.

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Using the Gemini North telescope—located in Hawai’i as part of the international Gemini Observatory, a program of NSF’s NOIRLab—and the GRACES instrument, the team realized that C-19 is a remnant of a globular cluster. In addition, the stars in the stream possess a uniquely low proportion of heavy elements, or as astronomers phrase it, low “metallicity.” Globular clusters were previously thought to have metallicities no lower than 0.2%, but C-19 has an unprecedentedly low metallicity of less than 0.05%—lower than has ever been observed for a stellar system in the Milky Way or its surroundings.

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Astronomers have discovered the ruins of an ancient star cluster in the outer fringes of the Milky Way. This stellar stream, known as C-19, extends across a large area of the night sky, approximately 30 times the width of the full Moon. The stars in the stream have a uniquely low proportion of heavy elements—lower than any other stellar system in the Milky Way or its surroundings. This discovery was made using telescopes on the ground and in space, including the international Gemini Observatory, a Program of NSF’s NOIRLab. Credit: International Gemini Observatory / NOIRLab / NSF / AURA / J. da Silva / Spaceengine / M. Zamani (NSF’s NOIRLab)

The discovery that a low-metallicity stream originated from a globular cluster has implications for the formation of stars, star clusters, and galaxies in the early universe. The very existence of the stream proves that globular clusters and the first building blocks of the Milky Way must have been able to form in low-metal environments, before successive generations of stars supplied the universe with heavier elements.

“It was not known if globular clusters with so few heavy elements exist—some theories even hypothesized they couldn’t form at all,” commented Nicolas Martin of the Strasbourg Astronomical Observatory, who is the lead author of the Nature paper reporting this discovery. “Other theories suggest that they would all have long-since disappeared, which makes this a key discovery for our understanding of how stars form in the early universe.”

Discovery of the least 'metallic' stellar structure in the Milky Way
Distribution of very dense groups of stars in the Milky Way, called globular clusters, superimposed on a map of the Milky Way compiled from data obtained with the Gaia Space Observatory. Each dot represents a cluster of a few thousand to several million stars, as in the insert image of the Messier 10 cluster. The color of the dots shows their metallicity, in other words, their abundance of heavy elements relative to the Sun. The C-19 stars are indicated by the light blue symbols. Credit: N. Martin / Strasbourg Astronomical Observatory / CNRS; Canada-France-Hawaii Telescope / Coelum; ESA / Gaia / DPAC

Members of the team originally spotted C-19 in data from the Gaia mission using an algorithm they designed specifically to detect stellar streams. The stars in C-19 were also identified by the Pristine survey—a search for the lowest-metallicity stars in and around the Milky Way using the Canada-France-Hawaii Telescope in Hawai’i—as being interesting enough to merit follow-up observations. To identify the origin of C-19’s constituent stars, astronomers needed the detailed spectra from GRACES. The team also gathered data using a spectrograph mounted on the Gran Telescopio Canarias on La Palma in the Canary Islands.

“GRACES provided the critical clues that C-19 is a disrupted globular cluster and not the more common disrupted dwarf galaxy,” explained Kim Venn of the University of Victoria, the lead investigator for the GRACES observations. “We already knew that this was a very metal-poor stream, but identifying it as a globular cluster required the precision metallicities and detailed chemical abundances only available with high-resolution spectra.”

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This animation shows how a globular star cluster, orbiting a still-forming Milky Way Galaxy, can get torn apart by the gravity of the developing galaxy to become the C-19 stellar stream that now orbits the present-day Milky Way. Credit: Gabriel Pérez Díaz, SMM (IAC)

The Gemini observations suggest that the cluster must have formed from very early generations of stars, making C-19 a remarkable relic from the time when the very first groups of stars were being formed. Consequently, this discovery improves our understanding of the formation of stars and star clusters that arose shortly after the Big Bang, and provides a close-to-home natural laboratory in which to study the oldest structures in galaxies.

“This artifact from ancient times opens a direct and unique window onto the early epochs of star formation in the universe,” concluded co-investigator Julio Navarro of the University of Victoria. “While astronomers can look at the most distant galaxies to study the early universe, we now know that it is possible to study the oldest structures in our own galaxy as fossils from those ancient times.”

“This international collaboration reveals startling new insight into the structure, evolution, and formation of our galaxy,” added Martin Still, Gemini Program Director at the National Science Foundation. “The Gemini observatories continue to demonstrate key advances in the understanding of our night sky, concerning the cosmic ecosystem and our own place in the universe.”


Explore further

Cosmic galaxy assembly and the evolution of metals


More information:
Nicolas Martin, A stellar stream remnant of a globular cluster below the metallicity floor, Nature (2022). DOI: 10.1038/s41586-021-04162-2

Citation:
Discovery of the least ‘metallic’ stellar structure in the Milky Way (2022, January 5)
retrieved 5 January 2022
from https://phys.org/news/2022-01-discovery-metallic-stellar-milky.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.

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April 20: Why this Indigenous researcher thinks we can do science differently and more… – CBC.ca

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Quirks and Quarks54:00Why this Indigenous researcher thinks we can do science differently, and more…


On this episode of Quirks & Quarks with Bob McDonald:

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This researcher wants a new particle accelerator to use before she’s dead

Quirks and Quarks9:05This researcher wants a new particle accelerator to use before she’s dead

Physicists exploring the nature of reality need ever more capable particle colliders, so they’re exploring a successor to the Large Hadron Collider in Europe. But that new machine is at least decades away. Tova Holmes, an assistant professor at the University of Tennessee, Knoxville, is one of the physicists calling for a different kind of collider that can come online before the end of her career – or her life. This device would use a particle not typically used in particle accelerators: the muon.

A 2021 CERN file photo of the Large Hadron Collider inside the 27-kilometre tunnel near Geneva, Switzerland. The proposed new particle accelerator would require an even larger tunnel, one that’s over 100 kilometres. Physicists calling for the development of a muon accelerator say it will require much less space. (Samuel Joseph Hertzog/CERN)

Is venting the best way to deal with anger? The scientist says chill out.

Quirks and Quarks6:51Is venting the best way to deal with anger? The scientist says chill out

It turns out that acting out your anger might not be the best way to get rid of it. Sophie Kjaervik, a researcher at Virginia Commonwealth University in Richmond, Va., analyzed 154 studies of the different ways to deal with anger. Her results, published in the journal Clinical Psychology Review, suggest that techniques that reduce your heart rate and calm your mind are more effective than blowing off steam.


High intensity wildfires may release toxic forms of metals

Quirks and Quarks8:37High intensity wildfires may release toxic forms of metals

Wildfire smoke might be more dangerous than you think. A recent study in the journal Nature Communications found that when wildfires pass over soils or rocks rich in a normally harmless metal called chromium, it is transformed into a toxic form. The hotter and more intense the wildfire is, the more of this metal becomes toxic. Scott Fendorf, an Earth system science professor at Stanford University, said this study shows we should factor in the type of geology wildfires pass over to provide more targeted air quality warnings about smoke risks. 

A man sitting on a balcony with the backdrop of Montreal's skyline behind him is talking on the phone while wearing two masks: one surgical one still on his face and a black one that in this photo is pulled down below his chin.
A man wears a face mask as he cycles by the skyline of Montreal, Sunday, June 25, 2023. A smog warning is in effect for Montreal and multiple regions of the province due to forest fires. (Graham Hughes/The Canadian Press)

AI might help solve the problem of runaway conspiracy theories

Quirks and Quarks7:35AI might help solve the problem of runaway conspiracy theories

Conspiracy theories seem to have multiplied in the internet era and so far, we haven’t had much luck in debunking these beliefs. The preliminary findings of a new study on PsyArXiv, a site for psychology studies that have yet to be peer-reviewed, suggests that artificial intelligence may have more success. Thomas Costello, a postdoctoral psychology researcher at MIT was the lead author on this study, and said their findings can provide a window into how to better debunk conspiracy beliefs. 

One eye takes up the entire frame and directly in the centre of their pupil, you see the reflection of the ChatGPT logo.
This illustration photograph taken with a macro lens shows The OpenAI company logo reflected in a human eye at a studio in Paris on June 6, 2023. ChatGPT is a conversational artificial intelligence software application developed by OpenAI. (Joel Saget/AFP/Getty Images)

An Indigenous scientist explores the medicine the Earth needs

Quirks and Quarks19:12An Indigenous ecologist on why we need to stop and listen to save the planet

Earth day is April 22. And Earth is not in great shape to celebrate the day. Overheated, overpopulated, overexploited – we’re not being particularly careful with our planet. We talk to Indigenous ecologist Jennifer Grenz of the University of British Columbia about her new book, which is part memoir, part prescription for the medicine our planet needs – a compound of science and traditional wisdom.  Her book is Medicine Wheel for the Planet: A journey toward personal and ecological healing.

READ MORE: An Indigenous ecologist on why we need to stop and listen to save the planet

A shot of a woman wearing big green glasses outside, looking at a tree branch.
Jennifer Grenz is an Indigenous Ecologist and author of Medicine Wheel for the Planet: A journey toward personal and ecological healing. (Paulo Ramos/UBC)

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Dragonfly: NASA greenlights most important mission of the century – Earth.com

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In a remarkable development, NASA has given the green light to the Dragonfly mission, a revolutionary rotorcraft designed to investigate the complex chemistry of Saturn‘s moon Titan.

This confirmation allows the mission to proceed with the final design, construction, and testing of the spacecraft and its scientific instruments.

Deciphering the prebiotic chemistry on Titan

The Dragonfly mission, led by Dr. Melissa Trainer of NASA’s Goddard Space Flight Center, will carry a cutting-edge instrument called the Dragonfly Mass Spectrometer (DraMS).

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This powerful tool will help scientists delve into the intricate chemistry at work on Titan, potentially shedding light on the chemical processes that led to the emergence of life on Earth, known as prebiotic chemistry.

“We want to know if the type of chemistry that could be important for early pre-biochemical systems on Earth is taking place on Titan,” explains Dr. Trainer, a planetary scientist and astrobiologist specializing in Titan.

Titan: Dragonfly’s target

Titan, the largest moon of Saturn, is shrouded in a dense nitrogen-rich atmosphere, bears a striking resemblance to Earth in many ways. With a diameter of 5,150 kilometers, Titan is the second-largest moon in our solar system, surpassed only by Jupiter’s Ganymede.

Dense atmosphere and unique climate

One of Titan’s most distinctive features is its thick atmosphere, which is composed primarily of nitrogen and methane. This dense atmosphere creates a surface pressure 1.5 times higher than Earth’s, making it the only moon in our solar system with a substantial atmosphere.

The presence of methane in Titan’s atmosphere leads to a fascinating hydrological cycle, similar to Earth’s water cycle, but with methane as the primary liquid.

Titan’s surface is dotted with numerous lakes and seas of liquid hydrocarbons, predominantly methane and ethane. These liquid bodies, some of which are larger than the Great Lakes on Earth, are the result of Titan’s unique climate and atmospheric conditions.

The Cassini mission, which explored the Saturn system from 2004 to 2017, provided stunning images and data of these extraterrestrial lakes and seas.

Dragonfly mission to search Titan for prebiotic chemistry and life

The complex chemistry occurring on Titan’s surface and in its atmosphere has drawn significant attention from astrobiologists.

With its abundant organic compounds and the presence of liquid methane, Titan is considered a prime candidate for studying prebiotic chemistry and the potential for life to emerge in environments different from Earth.

Beneath Titan’s icy crust lies another intriguing feature: a global subsurface ocean of liquid water and ammonia. This ocean, which is believed to be salty and have a high pH, may potentially host microbial life.

The presence of this subsurface ocean, along with the unique chemistry on Titan’s surface, makes this moon a fascinating target for future exploration and scientific research.

Pushing the boundaries of rotorcraft exploration

Nicky Fox, associate administrator of the Science Mission Directorate at NASA Headquarters, emphasized the significance of the Dragonfly mission, stating, “Exploring Titan will push the boundaries of what we can do with rotorcraft outside of Earth.”

Titan’s unique characteristics, including its abundant complex carbon-rich chemistry, interior ocean, and past presence of liquid water on the surface, make it an ideal destination for studying prebiotic chemical processes and the potential habitability of an extraterrestrial environment.

Innovative design and cutting-edge technology

The Dragonfly robotic rotorcraft will leverage Titan’s low gravity and dense atmosphere to fly between different points of interest on the moon’s surface, spanning several miles apart.

This innovative approach allows the entire suite of instruments to be relocated to new sites once the previous one has been thoroughly explored, providing access to samples from diverse geological environments.

DraMS, developed by the same team responsible for the Sample Analysis at Mars (SAM) instrument suite aboard the Curiosity rover, will analyze surface samples using techniques tested on Mars.

Dr. Trainer emphasized the benefits of this heritage, stating, “This design has given us an instrument that’s very flexible, that can adapt to the different types of surface samples.”

Dragonfly mission challenges and funding

The Dragonfly mission successfully passed its Preliminary Design Review in early 2023. However, due to funding constraints, the mission was asked to develop an updated budget and schedule.

The revised plan, presented and conditionally approved in November 2023, hinged on the outcome of the fiscal year 2025 budget process.

With the release of the president’s fiscal year 2025 budget request, Dragonfly is now confirmed with a total lifecycle cost of $3.35 billion and a launch date set for July 2028.

This reflects a cost increase of approximately two times the initially proposed cost and a delay of more than two years from the original selection in 2019.

Despite the challenges posed by funding constraints, the COVID-19 pandemic, supply chain issues, and an in-depth design iteration, NASA remains committed to the Dragonfly mission.

Additional funding has been provided for a heavy-lift launch vehicle to shorten the mission’s cruise phase and compensate for the delayed arrival at Titan.

Rigorous testing and validation

To ensure the success of the Dragonfly mission, researchers on Earth have conducted extensive testing and validation of the designs and models for the nuclear-powered, car-sized drone.

The mission team has carried out test campaigns at NASA’s Langley Research Center, utilizing the Subsonic Tunnel and the Transonic Dynamics Tunnel (TDT) to validate computational fluid dynamics models and gather data under simulated Titan atmospheric conditions.

Ken Hibbard, Dragonfly mission systems engineer at APL, emphasized the importance of these tests, stating, “All of these tests feed into our Dragonfly Titan simulations and performance predictions.”

As the Dragonfly mission progresses, it marks a new era of exploration and scientific discovery. Dr. Trainer expressed her excitement, saying, “Dragonfly is a spectacular science mission with broad community interest, and we are excited to take the next steps on this mission.”

Turning science fiction into fact with the Dragonfly mission

In summary, the Dragonfly mission embodies the essence of human curiosity and the relentless pursuit of knowledge. As NASA prepares to send this revolutionary rotorcraft to the alien world of Titan, we stand on the brink of a new era of exploration and discovery.

With its innovative design, cutting-edge technology, and the unwavering dedication of the mission team, Dragonfly will unlock the secrets of prebiotic chemistry and shed light on the potential for life beyond Earth.

As we eagerly await the launch of this titanic mission, we can only imagine the wonders that await us on Saturn’s enigmatic moon. The Dragonfly mission is a testament to the indomitable human spirit and our boundless capacity to push the frontiers of knowledge.

In the words of Ken Hibbard, “With Dragonfly, we’re turning science fiction into exploration fact,” and that fact will undoubtedly inspire generations to come.

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Marine plankton could act as alert in mass extinction event: UVic researcher – Langley Advance Times

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A University of Victoria micropaleontologist found that marine plankton may act as an early alert system before a mass extinction occurs.

With help from collaborators at the University of Bristol and Harvard, Andy Fraass’ newest paper in the Nature journal shows that after an analysis of fossil records showed that plankton community structures change before a mass extinction event.

“One of the major findings of the paper was how communities respond to climate events in the past depends on the previous climate,” Fraass said in a news release. “That means that we need to spend a lot more effort understanding recent communities, prior to industrialization. We need to work out what community structure looked like before human-caused climate change, and what has happened since, to do a better job at predicting what will happen in the future.”

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According to the release, the fossil record is the most complete and extensive archive of biological changes available to science and by applying advanced computational analyses to the archive, researchers were able to detail the global community structure of the oceans dating back millions of years.

A key finding of the study was that during the “early eocene climatic optimum,” a geological era with sustained high global temperatures equivalent to today’s worst case global warming scenarios, marine plankton communities moved to higher latitudes and only the most specialized plankton remained near the equator, suggesting that the tropical temperatures prevented higher amounts of biodiversity.

“Considering that three billion people live in the tropics, the lack of biodiversity at higher temperatures is not great news,” paper co-leader Adam Woodhouse said in the release.

Next, the team plans to apply similar research methods to other marine plankton groups.

Read More: Global study, UVic researcher analyze how mammals responded during pandemic

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