понедельник, 17 сентября 2018 г.

Ptolemaic statue of sphinx discovered in Egypt

Egyptian archaeologists draining water from a temple in the southern city of Aswan have uncovered a sandstone sphinx likely dating to the Ptolemaic era, the antiquities ministry said on Sunday.











Ptolemaic statue of sphinx discovered in Egypt
The sandstone statue of Sphinx that was discovered in Kom Ombo Temple in Aswan in upper Egypt
[Credit: Egyptian Ministry of Antiquities via Reuters]

The sphinx, a mythical being with the head of a human and the body of a lion, was discovered at the Kom Ombo temple, where two engraved sandstone reliefs of King Ptolemy V had also recently been found, the ministry said in statement.











Ptolemaic statue of sphinx discovered in Egypt
The sandstone statue of the Sphinx at the time of discovery
[Credit: Egyptian Ministry of Antiquities]

Ptolemaic rule spanned about three centuries until the Roman conquest in 30 BC.


Source: Reuters [September 16, 2018]



TANN



Archive


Study provides roadmap for measuring animal, plant traits to meet biodiversity goals

An international team of researchers has outlined a plan for how to measure changes in key traits of animals and plants and provide these data to policymakers to improve natural resource management and keep nations on track to meet global biodiversity and sustainability goals.











Study provides roadmap for measuring animal, plant traits to meet biodiversity goals
Museum specimens can provide historical baseline data for many species traits. These birds represent three subspecies of
the northern Bobwhite, Colinus virginianus. From left to right, they are native to Cuba, Florida and southern Mexico
[Credit: Florida Museum/Rose Roberts]

Monitoring species traits – characteristics such as body size and behaviors such as migration patterns – can help researchers determine how animals and plants are responding to a rapidly transforming, human-dominated planet, highlighting species under threat from climate change, habitat loss, disease and other dangers.
Having this information in hand can empower policymakers to make strategic decisions that not only ensure species survive and flourish, but also meet staple human needs, such as food security, managing invasive species or mitigating the effects of climate change, said study senior author Rob Guralnick, associate curator of biodiversity informatics at the Florida Museum of Natural History.


“What we sometimes don’t realize is that the characteristics of organisms are fundamentally linked to human needs and survival,” he said. “Our ability to create biodiversity data products is valuable both because of the science it enables and because it can help us make better decisions about managing our planetary resources for the long-term.”











Study provides roadmap for measuring animal, plant traits to meet biodiversity goals
Understanding when plants produce leaves and flowers is crucial to determining how they are
responding to climate change. The Florida jujube plant, Ziziphus celata, was thought extinct 
until a few populations were rediscovered in 1987. It remains critically endangered
[Credit: Florida Museum]

Guralnick cited the overharvesting of large fish as one example of how species traits are directly linked to human well-being. Preferentially selecting bigger fish as food resources could lead to smaller fish populations -in terms of the number of fish available and their size as well.


“We could see a case where the biomass of the planet is effectively getting smaller over time,” he said. “That really has impacts on food security and how we’re going to manage that in the face of a growing population.”


Pinpointing which species traits to measure and standardizing how researchers collect and report these data marks a significant advancement in efforts by the Group on Earth Observations Biodiversity Observation Network, or GEO BON, an international collaboration between scientists seeking to sync observation programs to produce a clear picture of Earth’s biodiversity. “Species traits” is one of six classes in GEO BON’s framework for assessing progress toward national and international policy goals, including the United Nations’ Aichi Biodiversity Targets and Sustainable Development Goals for 2030. But while other classes have been well defined, species traits and how to monitor them have remained vague.











Study provides roadmap for measuring animal, plant traits to meet biodiversity goals
These three specimens represent subspecies of Schaus’ swallowtail, Heraclides aristodemus, one of Florida’s rarest
butterflies and a federally designated endangered species [Credit: Florida Museum/Rose Roberts]

Guralnick and the study’s first author Daniel Kissling, both of whom co-chair GEO BON’s data task force, led a team of data ecologists and scientists to refine trait categories and produce a step-by-step workflow for how they can be measured in ways that directly link to policy goals.
They defined species traits as any physical, physiological, reproductive, behavioral, or time- or season-sensitive characteristic of an animal or plant species.


“Traits are not just things like body shape and size. They also include factors like when plants flower or when leaves appear,” Guralnick said. “Some of these are really sensitive to global climate changes. Building systems that allow us to understand how traits are responding to these shifts is critical because traits really drive how ecosystems work and what services they provide to us as humans.”











Study provides roadmap for measuring animal, plant traits to meet biodiversity goals
Physical characteristics, or morphology, can differ strikingly within species. These Diana fritillaries, Speyeria diana,
offer an example of sexual dimorphism, or differing appearances in males and females. The female butterflies
are blue, while males are orange [Credit: Florida Museum/Rose Roberts]

One major challenge of successfully building these data systems is standardizing the ways in which traits are monitored and how those data are reported.


“Instead of having everyone measuring a bunch of things in different ways and trying to draw different conclusions, we have to build a system for monitoring the planet’s biodiversity in a way that coordinates efforts and creates standards for how those data get to people who make decisions,” he said.


Creating a global network that takes the pulse of life on Earth might sound like an impossible feat, but Guralnick pointed to the climate science community as an example of a group that tackled similar, outsized obstacles and succeeded. He sees the global-scale collaborations that united climate scientists to collect, share and standardize data to yield highly precise models and forecasts as comparable to what GEO BON’s biodiversity monitoring efforts aim to achieve.











Study provides roadmap for measuring animal, plant traits to meet biodiversity goals
These fox squirrels represent two subspecies of Sciurus niger. The specimens on the left
and in the middle are Sciurus niger avicennia, a threatened subspecies that lives in
southwestern Florida, and the specimen on the right is Sciurus niger shermani,
a native of Florida and Georgia [Credit: Florida Museum/Rose Roberts]

The team outlines a workflow that combines trait data from natural history collections, observations on the ground and remote sensing from air and space – in which data resolution is nearly to the point where researchers can measure indicators of health in an individual tree.


“We know that forests are declining globally, and there are monitoring systems that can tell us the rate of forest loss per year or per month,” he said. “What if we were able to do the same kind of thing for how body size change is happening in fish populations across the globe in response to harvesting? Those are the kinds of models we want to be able to produce.”


Still, not every species can be monitored, and researchers will have to make choices about which measurements will be most relevant to scientific and societal needs, said Guralnick, who described Earth observation as a “triage enterprise.”











Study provides roadmap for measuring animal, plant traits to meet biodiversity goals
GEO BON has identified six classes of ‘essential biodiversity variables’ to track and monitor, represented by the teal dots
at the top of this figure. Guralnick and his colleagues refined the ‘species traits’ class by defining characteristics
 to measure and linking these to policy goals [Credit: Kissling et al. in Nature Ecology and Evolution, 2018]

Understanding the human aspects of conservation decision-making is a primary reason GEO BON has incorporated UN policy goals into its biodiversity monitoring efforts, he said.
“This is a social challenge as much as a technical or scientific one,” Guralnick said. “We can’t address environmental sustainability challenges unless we know what problems people are trying to solve at local, regional, national and global levels. Doing this to deliver something that no one is asking for would not be a great idea.”


Guralnick foresees a long road ahead – even on the data collection side – to building global biodiversity monitoring systems that coalesce and communicate data in a way that smoothly translates into policy. But he remains optimistic, in part because of the staggering advances in number, size and availability of biodiversity databases, such as iDigBio, in recent decades.











Study provides roadmap for measuring animal, plant traits to meet biodiversity goals
Scientists Larry Page, left, and Andre Lopez search for catfish. On-the-ground observations and remote sensing
can help  fill gaps in our understanding of biodiversity and how it is changing
[Credit: Florida Museum/Eric Zamora]

“The number of data resources that have proliferated in the last 30 years is just enormous. It’s a sea change,” he said.


Data collection and standardization are familiar challenges to natural history museums, which Guralnick sees as key players in the project. Museums are repositories for millions of physical specimens that provide historical baseline data for species traits and are also at the forefront of capturing some of these data in new ways through digitization and CT scanning.


“As a museum, we’re going to be a part of this discussion around collections and our connections to the broader world for decades,” he said. “That’s awesome. That’s just where we should be.”


The study is published in Nature Ecology & Evolution.


Author: Natalie van Hoose | Source: Florida Museum of Natural History [September 17, 2018]



TANN



Archive


Mummified penguins tell of past and future deadly weather

New research links the mummified remains of penguin chicks in Antarctica to two massive weather-related calamities that could become more commonplace with climate change.











Mummified penguins tell of past and future deadly weather
Active penguin, colony in East Antarctica near the study site 
[Credit: Yuesong Gao]

Chinese and Australian researchers found the mummified carcasses of hundreds of Adélie penguins on Long Peninsula, East Antarctica, in sediments that not only recorded heavy run-off events, but also helped to unlock the ages of the events.
Taken individually, penguin carcasses are not unusual, explained Yuesong Gao, a co-author of the paper in Journal of Geophysical Research – Biogeosciences, published by the American Geophysical Union. But when the researchers studied the sediments in which they found the mummies, most of the carcasses turned out to be from two specific calamities that occurred in breeding colonies about 750 and 200 years ago, according to radiocarbon dating of the mummies and the sediments.











Mummified penguins tell of past and future deadly weather
Penguin graveyard: 200-year-old abandoned penguin colony, littered with mummified carcasses
[Credit: Yuesong Gao]

“First of all, the extent of carcasses and abandoned colonies struck us,” said Gao, of the University of Science and Technology of China in Hefei. “Then we were surprised by the consistent dates of the mummies. We had expected a much larger range of dates.”
The researchers were also struck by the unusually thick layers of sediments in which the mummies were buried. These were evidence of a lot of water flowing over the surface over a short period of time. That would require anomalously wet weather in hyper-arid Antarctica, and it’s particularly deadly to penguin chicks which, unlike their parents, have not yet developed waterproof feathers. Snowy and rainy weather can soak chicks to the skin and sap away their body heat, causing them to weaken and die from hypothermia.


“We found that relatively short periods of climate anomaly in the past have caused terrible consequences to the penguin population,” said Gao.











Mummified penguins tell of past and future deadly weather
A mummified penguin chick, dated to 750 years ago 
[Credit: Yuesong Gao]

The meteorological recipe that best explains the penguin colony collapses is a climate anomaly known for bringing a lot of moisture south from the mid-latitudes and increasing near-shore ice – a pattern called zonal wave number 3, or ZW3, for short.
The frequency of ZW3 anomalies has increased in the late 20th century, as the Earth’s climate has changed in response to anthropogenic greenhouse gas emissions, according to previous research. As a result, some places in Antarctica have seen more snow accumulation between 1970 and 2009 than in the previous 1,000 years, the researchers report.











Mummified penguins tell of past and future deadly weather
Another abandoned penguin colony with mummified carcasses. This graveyard is dated to 750 years ago.
Living penguins can be seen in the upper left [Credit: Yuesong Gao]

If die-off events like those of 200 and 750 years ago become more common, it could be very bad news for the Adélie penguins, according to the study’s authors.


“We should pay attention to the threats of climate change to penguins,” Gao said.


Author: Larry O’Hanlon | Source: American Geophysical Union [September 17, 2018]


This article was originally published on AGU Blogs. Read the original article.



TANN



Archive


Fossils reveal diverse Mesozoic pollinating lacewings

Insect pollination played an important role in the evolution of angiosperms. Little is known, however, about ancient pollination insects and their niche diversity during the pre-angiosperm period due to the rarity of fossil evidence of plant-pollinator interactions.











Fossils reveal diverse Mesozoic pollinating lacewings
(a) Jurassic kalligrammatids in the Daohugou forest; (b) Cretaceous kalligrammatids
in the Burmese amber forest [Credit: Yang Dinghua]

Recently, a research group led by Prof. WANG Bo from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS) has provided new insight into the niche diversity, chemical communication, and defense mechanisms of Mesozoic pollinating insects. Its findings were published in Nature Communications.
One of the most intensely investigated examples of pollination niches is the morphological match between insect proboscis and floral tube length, which Darwin described in a publication in 1877. Kalligrammatid lacewings are among the largest and most conspicuous Mesozoic insects with siphoning mouthparts.


The NIGPAS researchers reported 27 well-preserved kalligrammatids from late Cretaceous Burmese amber (99 Ma) and Chinese Early Cretaceous (125 Ma) and Middle Jurassic (165 Ma) compression rocks.











Fossils reveal diverse Mesozoic pollinating lacewings
Jurassic and Cretaceous kalligrammatids from China [Credit: NIGPAS]

Kalligrammatid proboscides vary greatly in length, from 0.6 to 3.2 mm in amber inclusions and about 5 to 18 mm in compression fossils. The high diversity of kalligrammatids and large variation in proboscis length strongly suggest diverse plant hosts with different floral tube lengths. Therefore, pollination niche partitioning may have been present among some Mesozoic insects.
If pollination niches were partitioned, as in extant ecosystems, this likely increased pollination effectiveness and reduced the cost of pollination mutualism, thus contributing to the high diversity of pollinating insects and the success of pollinator-dependent plants during the Cretaceous period.


Kalligrammatid species diversification was potentially promoted by coevolution between pollinating kalligrammatids and their host plants under highly partitioned pollination niches.











Fossils reveal diverse Mesozoic pollinating lacewings
Kalligrammatids in Burmese amber [Credit: NIGPAS]

Traits such as wing eyespots, which likely functioned as a defense in large-sized species, and sexually dimorphic antennae, which were likely used for pre-mating chemical communication, elucidate how kalligrammatids survived in the Mesozoic terrestrial ecosystem under intense competition.


However, such elaborate associations between kalligrammatids and their host plants (mostly confined to gymnosperms) could have been a key factor contributing to the extinction of kalligrammatids, which likely occurred during the late Cretaceous with the decline in gymnosperm diversity.


Source: Chinese Academy of Sciences [September 17, 2018]



TANN



Archive


Earth’s oldest animals formed complex ecological communities

A new analysis is shedding light on the earth’s first macroscopic animals: the 570-million-year-old, enigmatic Ediacara biota.











Earth's oldest animals formed complex ecological communities
Paleontologist Simon A.F. Darroch examines fossils in Namibia
[Credit: Simon A.F. Darroch]

Ediacaran fossils have a slightly bizarre appearance not shared by any modern animal groups. For decades, researchers believed these enigmatic fossils were ecologically simple. However, borrowing a method from modern ecology – fitting species to relative abundance distributions – Vanderbilt University paleontologist Simon A.F. Darroch and his team learned that these organisms were more like modern animals than once thought.
The analyses showed that a majority of fossil assemblages bear the hallmarks of being ecologically complex, and Ediacara biota were forming complex communities tens of millions of years before the Cambrian explosion. The creatures lived partially submerged in what was once the ocean floor, some of them suspension feeding, others filter feeding, still others passively absorbing nutrition. A few were even mobile.











Earth's oldest animals formed complex ecological communities
Ediacara biota fossil found during Darroch’s latest field work in Namibia 
[Credit: Simon A.F. Darroch]

Complex communities are ones that comprise species competing for numerous different resources or species that create niches for others (as in many modern-day ecosystems). The team found that the signature of complex communities extends all the way back to the oldest Ediacaran fossils. In other words, as soon as macroscopic life evolved, it began forming diverse ecological communities not unlike those in the present day.
“The main impact of our work was testing between the simple and complex models for Ediacaran ecosystems,” said Darroch, an assistant professor in Vanderbilt’s Earth and Environmental Sciences Department.











Earth's oldest animals formed complex ecological communities
Ediacara biota fossils found during Darroch’s latest research in Namibia 
[Credit: Simon A.F. Darroch]

“Supporting a simple model would suggest that these mysterious organisms were universally primitive, sharing the same basic ecology and all competing for the same resources,” he said. “Support for the complex model would instead suggest that they likely competed for a variety of different resources, just like modern animals. Our analyses support the complex model, illustrating that – even though they may look bizarre – these mysterious fossils may have far more in common with modern animals than we thought.”
The team first compiled all Ediacaran fossil data from the published literature then added a dataset collected during fieldwork in southern Namibia. These Namibian fossils are the some of the youngest from anywhere in the world and record communities that were living immediately prior to the onset of the Cambrian explosion.



The fossils formed one of the few simple communities in the analysis, suggesting that these organisms were ecologically stressed. That lends support to the idea that the Ediacara biota were gradually going extinct in the run-up to the Cambrian explosion. Although it’s an exciting idea, Darroch said, it’s only one data point and will need much more research to prove.


The team is also using 3D modeling based on the fossil record to better characterize Ediacara biota, which completely disappeared 540 million years ago – as early arthropods, mollusks and sponges began to appear.


The study is published in Nature Ecology & Evolution.


Source: Vanderbilt University [September 17, 2018]



TANN



Archive


Tiny fossils reveal how shrinking was essential for successful evolution

A new study published in Nature shows that getting smaller was a key factor contributing to the exceptional evolution of mammals over the last 200 million years.











Tiny fossils reveal how shrinking was essential for successful evolution
Life reconstruction of the mammaliaform Morganucodon found in Jurassic sediments of Wales and China.
Morganucodon was one of the smallest fossil mammal ancestors with a size of 4-6cm
[Credit: Bob Nicholls, Paleocreations.com]

The origin of modern mammals can be traced back more than 200 million years to the age of dinosaurs. But while dinosaurs evolved to become some of the largest land animals, for the following 150 million years, the ancestors of all modern mammals pursued an entirely different strategy: getting very small.


An international team of scientists from the United Kingdom and the US have used modern computer analysis to take a look at what happened to the skeleton of our tiny mammal ancestors.


Modern mammals are unique in having a lower jaw consisting of just a single bone that bears teeth. In contrast, all other vertebrates possess complex lower jaws formed by at least five or more bones joined together. In the course of evolution, fossils show that the lower jaw of mammalian ancestors became simplified and a new jaw joint was formed, while some of the other bones moved into the middle ear to aid in hearing.


The team’s research focussed on the long-standing question of how it was possible to simplify and restructure the lower jaw, while still being able feed and hear. Using X-ray computed tomography (CT) scanning of several fossil skulls and lower jaws, the researchers generated digital models which were subjected to different computer simulations.


Their results showed that the small size of the fossil mammals significantly reduced the stresses in the jaw bones when feeding, while still being powerful enough to capture and bite through prey, such as insects.


Dr Stephan Lautenschlager, lead author and lecturer at the University of Birmingham, said: “Our results provide a new explanation of how the mammalian jaw evolved over 200 million years ago. Getting very small appears to have been crucial for our mammalian ancestors. This allowed them to reduce the stresses in the jaw during feeding and made the restructuring of the jaw bones possible.”


Professor Emily Rayfield from the University of Bristol who lead the study added: “The evolution of the mammalian jaw joint has perplexed palaeontologists for over 50 years. Using computational methods we can offer explanations to how our mammalian ancestors were able to maintain a working jaw while co-opting bones into a complex sound detection system. Our research is about testing ideas of what makes mammals unique among the animal kingdom, and how this may have come about.”


Source: University of Birmingham [September 17, 2018]



TANN



Archive


Twisted Sense Our sense of hearing begins with minute…


Twisted Sense


Our sense of hearing begins with minute deflections of sensory hairs on the inner hair cells of the cochlea, a coiled structure in the inner ear, ultimately causing electrical signals to reach the brain. Cells known as type I spiral ganglion neurons (SGNs) are responsible for signal transmission: pictured in a section of mouse cochlea, SGN cell bodies (in green, bottom right-hand corner) extend long projections, or peripheral processes (in red and yellow) to contact hair cells (top left, also in green), then send signals downstream to the brain through the auditory nerve. Recent research shows that type I SGNs fall into three distinct subtypes, which express different sets of proteins, supporting earlier evidence of variation in SGN sensitivity to sound. As work in mice suggests one specific SGN subtype may be linked to age-related hearing loss, appreciating SGN diversity could be critical to tackling different types of hearing defects.


Written by Emmanuelle Briolat



You can also follow BPoD on Instagram, Twitter and Facebook


Archive link


ISRO – PSLV-C42 Mission Success


ISRO – Indian Space Research Organisation logo.


Sept. 17, 2018



PSLV-C42 Liftoff

PSLV-C42 Successfully Launches two foreign satellites from Satish Dhawan Space Centre (SDSC), SHAR, Sriharikota on September 16, 2018 at 16:38 GMT.


This mission was designed to launch two earth observation satellites, NovaSAR and S1-4 (together weighing nearly 889 kg) of M/s Surrey Satellite Technologies Limited (SSTL), United Kingdom under commercial arrangement with Antrix Corporation Limited, Department of Space. Both satellites were injected into 583 km Sun Synchronous Orbit.



PSLV-C42 Liftoff and Onboard Camera View

NovaSAR is a S-Band Synthetic Aperture Radar satellite intended for forest mapping, land use & ice cover monitoring, flood & disaster monitoring.



S1-4 is a high resolution Optical Earth Observation Satellite, used for surveying resources, environment monitoring, urban management and for the disaster monitoring.


The NovaSAR 1 spacecraft carries a radar imaging instrument, and the mission was developed in partnership between the British government and the British satellite manufacturer SSTL. The SSTL S1-4 satellite, also built by SSTL, is a high-resolution optical Earth observation satellite identical to three DMC3/TripleSat reconnaissance craft launched in 2015. Beijing-based 21AT will lease imaging capacity on the SSTL S1-4 satellite.


Related article:


SSTL confirms the successful launch of NovaSAR-1 and SSTL S1-4 satellites
https://www.sstl.co.uk/media-hub/latest-news/2018/sstl-confirms-the-successful-launch-of-novasar-1-a


For more information about Indian Space Research Organisation (ISRO), visit: https://www.isro.gov.in/


For more information about Surrey Satellite Technologies Limited (SSTL). visit: https://www.sstl.co.uk/


Images, Videos, Text, Credits: ISRO/SSTL/Orbiter.ch Aerospace/Roland Berga.


Best regards, Orbiter.chArchive link


2018 September 17 Cosmic Collision Forges Galactic Ring Image…


2018 September 17


Cosmic Collision Forges Galactic Ring
Image Credit: X-ray: Chandra (NASA, CXC, INAF, A. Wolter et al.); Optical: Hubble (NASA, STScI)


Explanation: How could a galaxy become shaped like a ring? The rim of the blue galaxy pictured on the right is an immense ring-like structure 150,000 light years in diameter composed of newly formed, extremely bright, massive stars. That galaxy, AM 0644-741, is known as a ring galaxy and was caused by an immense galaxy collision. When galaxies collide, they pass through each other – their individual stars rarely come into contact. The ring-like shape is the result of the gravitational disruption caused by an entire small intruder galaxy passing through a large one. When this happens, interstellar gas and dust become condensed, causing a wave of star formation to move out from the impact point like a ripple across the surface of a pond. The likely intruder galaxy is on the left of this combined image from Hubble (visible) and Chandra (X-ray) space telescopes. X-ray light is shown in pink and depicts places where energetic black holes or neutron stars, likely formed shortly after the galaxy collision, reside.


∞ Source: apod.nasa.gov/apod/ap180917.html


Image of the Week – September 17, 2018CIL:38810…


Image

of the Week – September 17, 2018


CIL:38810 – http://www.cellimagelibrary.org/images/38810


Description: Scanning

electron micrograph of a cluster of breast cancer cells showing visual evidence

of programmed cell death (apoptosis) in yellow. Each cell is 15 micrometers

across.


Author: Annie

Cavanagh


Licensing: Attribution-NonCommercial-NoDerivs 2.0 UK:

England & Wales (CC BY-NC-ND 2.0 UK)


Archive link


Magnetic Waves Create Chaos in Star-Forming Clouds




Offner’s research will shed light on the processes inside star-forming regions such as 30 Doradus, seen in this view from Hubble Space Telescope. Credit: NASA/ESA/F. Paresce/R. O’Connell/WFC3 (Click image to access download options from hubblesite.org). Hi-res images




Cloud Models 

Models of two turbulent clouds without stars (left) and with stars launching winds (right). The colors show gas speed: grey (6-10 km/s), blue (12-25 km/s), and red (180-250 km/s). Credit: Stella Offner/UT Austin



Magnetic Waves from a Young Star

Gas density and velocity (top) and magnetic field strength and magnetic field lines (bottom) showing magnetic waves propagating ahead of the wind shell. The left and right panels show different models. The waves stand out when the surrounding gas is not turbulent. Credit: Stella Offner/UT Austin



New research by Stella Offner, assistant professor of astronomy at The University of Texas at Austin, finds that magnetic waves are an important factor driving the process of star formation within the enormous clouds that birth stars. Her research sheds light on the processes that are responsible for setting the properties of stars, which in turn affects the formation of planets orbiting them, and, ultimately, life on those planets. The research is published in the current issue of the journal Nature Astronomy.


Offner used a supercomputer to make models of the multitude of processes happening inside a cloud where stars are forming, in an effort to sort out which processes lead to which effects.


“These clouds are violent places,” Offner said. “It’s an extreme environment with all kinds of different physics happening at once,” including gravity and turbulence as well as radiation and winds from forming stars (called stellar feedback). The fundamental question, Offner said, is: “Why are the motions in these clouds so violent?”


Some astronomers attribute the observed motions to gravitational collapse, while others attribute it to turbulence and stellar feedback. Offner wanted to test these theories and study how stars shape their birth environment, but it’s virtually impossible to use telescope observations of these clouds to separate the influence of the various processes, she said.


“That’s why we need computer models,” Offner explained.


After comparing models of clouds with gravity, magnetic fields, and stars, Offner noticed extra motions.


 Her models showed that stellar winds interacting with the cloud magnetic field generated energy and influenced gas at far greater distances across the cloud than previously thought: These local magnetic fields caused action at a distance.


“Think of the magnetic fields like rubber bands that stretch across the cloud,” Offner said. “The winds push the field — it’s like rubber bands being plucked. The waves outrun the wind and cause distant motions.”


This research has implications for the tug-of-war between feedback — that is, the effect that the newly formed star has on its environment — and gravity on the scale of solar systems up to entire galaxies, Offner said.


As for the next step, Offner says she plans to study this process on larger scales, both in time and space. Her current study focused on one area within star-forming clouds; she said future studies will study the effects of magnetic fields and feedback on scales larger than a single cloud.



Media Contact:


Rebecca Johnson, Communications Mgr.
McDonald Observatory
The University of Texas at Austin
512-475-6763

Science Contact:

Dr. Stella Offner, Asst. Professor
Department of Astronomy
The University of Texas at Austin
512-471-3853





Archive link


Featured

Полет на параплане с обрыва на мысу Куяльницкого лимана, соленого озера. Экстремальный развлекательный полет проводится для любителей. ...

Popular