понедельник, 18 февраля 2019 г.

2019 February 18 Dragon Aurora over Iceland Image Credit &…


2019 February 18


Dragon Aurora over Iceland
Image Credit & Copyright: Jingyi Zhang & Wang Zheng


Explanation: Have you ever seen a dragon in the sky? Although real flying dragons don’t exist, a huge dragon-shaped aurora developed in the sky over Iceland earlier this month. The aurora was caused by a hole in the Sun’s corona that expelled charged particles into a solar wind that followed a changing interplanetary magnetic field to Earth’s magnetosphere. As some of those particles then struck Earth’s atmosphere, they excited atoms which subsequently emitted light: aurora. This iconic display was so enthralling that the photographer’s mother ran out to see it and was captured in the foreground. No sunspots have appeared on the Sun so far in February, making the multiple days of picturesque auroral activity this month somewhat surprising.


∞ Source: apod.nasa.gov/apod/ap190218.html


Llyn Cerrig Bach, an Iron Age Votive Lake, Anglesey, North Wales, 17.2.19.

Llyn Cerrig Bach, an Iron Age Votive Lake, Anglesey, North Wales, 17.2.19.





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Soar Prehistoric Standing Stone, Anglesey, North Wales, 17.2.19.

Soar Prehistoric Standing Stone, Anglesey, North Wales, 17.2.19.





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Liberal Sprinkling of Salt Discovered around a Young Star


Artist impression of Orion Source I, a young, massive star about 1,500 light-years away. New ALMA observations detected a ring of salt — sodium chloride, ordinary table salt — surrounding the star. This is the first detection of salts of any kind associated with a young star. The blue region (about 1/3 the way out from the center of the disk) represents the region where ALMA detected the millimeter-wavelength “glow” from the salts. Credit: NRAO/AUI/NSF; S. Dagnello. Hi-res image



ALMA image of the salty disk surrounding the young, massive star Orion Source I (blue ring). It is shown in relation to the Orion Molecular Cloud 1, a region of explosive starbirth. The background near infrared image was taken with the Gemini Observatory. Credit: ALMA (NRAO/ESO/NAOJ); NRAO/AUI/NSF; Gemini Observatory/AURA. Hi-res image




New ALMA observations show there is ordinary table salt in a not-so-ordinary location: 1,500 light-years from Earth in the disk surrounding a massive young star. Credit: ALMA (NRAO/ESO/NAOJ); NRAO/AUI/NSF; Gemini Observatory/AURA



New ALMA observations show there is ordinary table salt in a not-so-ordinary location: 1,500 light-years from Earth in the disk surrounding a massive young star. Though salts have been found in the atmospheres of old, dying stars, this is the first time they have been seen around young stars in stellar nurseries. The detection of this salt-encrusted disk may help astronomers study the chemistry of star formation as well as identify other similar protostars hidden inside dense cocoons of dust and gas.


A team of astronomers and chemists using the Atacama Large Millimeter/submillimeter Array (ALMA)has detected the chemical fingerprints of sodium chloride (NaCl) and other similar salty compounds emanating from the dusty disk surrounding Orion Source I, a massive, young star in a dusty cloud behind the Orion Nebula.


“It’s amazing we’re seeing these molecules at all,” said Adam Ginsburg, a Jansky Fellow of the National Radio Astronomy Observatory (NRAO) in Socorro, New Mexico, and lead author of a paper accepted for publication in the Astrophysical Journal. “Since we’ve only ever seen these compounds in the sloughed-off outer layers of dying stars, we don’t fully know what our new discovery means. The nature of the detection, however, shows that the environment around this star is very unusual.”


To detect molecules in space, astronomers use radio telescopes to search for their chemical signatures – telltale spikes in the spread-out spectra of radio and millimeter-wavelength light. Atoms and molecules emit these signals in several ways, depending on the temperature of their environments.


The new ALMA observations contain a bristling array of spectral signatures – or transitions, as astronomers refer to them – of the same molecules. To create such strong and varied molecular fingerprints, the temperature differences where the molecules reside must be extreme, ranging anywhere from 100 kelvin to 4,000 kelvin (about -175 Celsius to 3700 Celsius). An in-depth study of these spectral spikes could provide insights about how the star is heating the disk, which would also be a useful measure of the luminosity of the star.


“When we look at the information ALMA has provided, we see about 60 different transitions – or unique fingerprints – of molecules like sodium chloride and potassium chloride coming from the disk. That is both shocking and exciting,” said Brett McGuire, a chemist at the NRAO in Charlottesville, Virginia, and co-author on the paper.


The researchers speculate that these salts come from dust grains that collided and spilled their contents into the surrounding disk. Their observations confirm that the salty regions trace the location of the circumstellar disk.


“Usually when we study protostars in this manner, the signals from the disk and the outflow from the star get muddled, making it difficult to distinguish one from the other,” said Ginsburg. “Since we can now isolate just the disk, we can learn how it is moving and how much mass it contains. It also may tell us new things about the star.”


The detection of salts around a young star is also of interest to astronomers and astrochemists because some of constituent atoms of salts are metals – sodium and potassium. This suggests there may be other metal-containing molecules in this environment. If so, it may be possible to use similar observations to measure the amount of metals in star-forming regions. “This type of study is not available to us at all presently. Free-floating metallic compounds are generally invisible to radio astronomy,” noted McGuire.


The salty signatures were found about 30 to 60 astronomical units (AU, or the average distance between the Earth and the Sun) from the host stars. Based on their observations, the astronomers infer that there may be as much as one sextillion (a one with 21 zeros after it) kilograms of salt in this region, which is roughly equivalent to the entire mass of Earth’s oceans.


“Our next step in this research is to look for salts and metallic molecules in other regions. This will help us understand if these chemical fingerprints are a powerful tool to study a wide range of protoplanetary disks, or if this detection is unique to this source,” said Ginsburg. “In looking to the future, the planned Next Generation VLA would have the right mix of sensitivity and wavelength coverage to study these molecules and perhaps use them as tracers for planet-forming disks.”


Orion Source I formed in the Orion Molecular Cloud I, a region of explosive starbirth previously observed with ALMA. [And here.] “This star was ejected from its parent cloud with a speed of about 10 kilometers per second around 550 years ago ,”** said John Bally, an astronomer at the University of Colorado and co-author on the paper. “It is possible that solid grains of salt were vaporized by shock waves as the star and its disk were abruptly accelerated by a close encounter or collision with another star. It remains to be seen if salt vapor is present in all disks surrounding massive protostars, or if such vapor traces violent events like the one we observed with ALMA.”


The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.






Contact:


Charles Blue, 
Public Information Officer
(434) 296-0314; 
cblue@nrao.edu



Reference:


“Orion SrcI’s disk is salty,” A. Ginsburg, et al., scheduled for publication on 2019 Feb. 11, Astrophysical Journal [https://doi.org/10.3847/1538-4357/aafb71] Preprint [https://arxiv.org/abs/1901.04489]



** Light from this object took about 1,500 years to reach Earth. Astronomers are seeing it as if looking through that window of time, which reveals how it looked 550 years after it was ejected from its stellar nursery.



A journey to the Orion Molecular Cloud 1 can be seen via the World Wide Telescope here.


The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Southern Observatory (ESO), the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the Ministry of Science and Technology (MOST) in Taiwan and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).



ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.







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Safety in Stripes Body painting is a culturally significant…


Safety in Stripes

Body painting is a culturally significant practice in many indigenous tribes, and recent research suggests it could have hidden health benefits. While specific patterns vary widely between tribes, pale stripes are a common feature, as pictured here in examples from Africa. Inspired by studies suggesting that zebra stripes may help deter biting flies from landing, researchers investigated whether striped body paintings could have similar advantages for humans. To test this, they used plastic mannequins, with and without striped patterns, and coated them with a sticky substance to trap horseflies (Tabanidae) landing on each model type. As predicted, horseflies appeared to avoid stripes: over several weeks in the field, a plain brown model attracted 10 times more flies than one with white stripes. Although the patterns of body paintings are clearly culturally-driven, a reduced risk of painful horsefly bites, and potential disease transmission from other insects, could be a welcome by-product of these traditions.


Written by Emmanuelle Briolat


Image by Gábor Horváth and colleagues

Environmental Optics Laboratory, Department of Biological Physics, ELTE Eötvös Loránd University, Budapest, Hungary

Image originally published under a Creative Commons Licence (BY 4.0)

Published in the Royal Society Open Science Journal, January 2019

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Ty-Gwyn Prehistoric Standing Stone, Anglesey, North Wales, 17.2.19.

Ty-Gwyn Prehistoric Standing Stone, Anglesey, North Wales, 17.2.19.



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On Maykop ancestry in Yamnaya

What Maykop ancestry in Yamnaya? There is none, or at least not enough worth discussing, except in one highly unusual female outlier from a burial in what is now eastern Ukraine. But apparently this is still up for debate?
More details tomorrow…
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