воскресенье, 23 июня 2019 г.

Archaeological excavation at Carrowmore Megalithic Cemetery, Sligo

A team of archaeologists from IT Sligo have just completed a two-week archaeological excavation of a prehistoric monument in the heart of the Carrowmore megalithic complex in Sligo, Ireland. Carrowmore is the largest cemetery of megalithic tombs in Ireland, with 5,500 year old passage tombs dating from 3,600 BC.











Archaeological excavation at Carrowmore Megalithic Cemetery, Sligo
Excavation at Carrowmore megalithic cemetery
[Credit: IT Sligo]

IT Sligo archaeologists Dr Marion Dowd and Dr James Bonsall directed the excavation of a site that was formerly known as a barrow. Barrows are circular earthen monuments surrounded by a circular ditch.


These sites typically date to the Bronze Age and Iron Age, ranging from between 4,000 and 1,500 years old. In 2016, Dr Bonsall and IT Sligo archaeology students carried out a series of geophysical surveys at Carrowmore to see beneath the soil of this and several other monuments in the area.


“This particular site turned out to be very interesting. Our survey revealed several features that were not visible above ground. We discovered that the ‘barrow’ contained a central pit and a substantial circular ditch” said Dr Bonsall.


The results of the geophysical survey were one of the reasons why this particular site was chosen for investigation. “Antiquarians and archaeologists have been studying Carrowmore for over 200 years, but the focus has always been on the Neolithic megalithic tombs. We were keen to change focus and find out more about this particular ‘barrow’ monument, and how it related to the concentration of megalithic tombs at Carrowmore” said Dr Marion Dowd.











Archaeological excavation at Carrowmore Megalithic Cemetery, Sligo
Prehistoric chert scrapers and blades found at the excavation at Carrowmore
[Credit: IT Sligo]

“There are several barrows within the Carrowmore complex. These would generally be viewed as Bronze Age or Iron Age in date, coming several thousand years after the Neolithic tombs. We wanted to find out why a site that is normally considered to be much later in date was built amongst the passage tombs.”


The archaeological excavation produced quite exciting and unexpected results. Dr Dowd said “Our excavations have revealed that this monument does not appear to be a barrow at all. So far, we cannot find any parallel for it in Ireland.”


The team found that the circular ditch surrounded a central raised area that consisted of a thick circular layer of stone. Inside this was a sunken area with black, charcoal-rich soils. Several prehistoric tools made from a hard stone called chert were discovered within and around the monument.


“We have a lovely collection of chert scrapers and blades from the monument. These would have been used for activities such as working animal hides, cutting and preparing food, basket working and bone working” said Dr. Dowd, “essentially a prehistoric tool kit”.



The IT Sligo archaeologists carried out the first excavation at Carrowmore to modern scientific standards.


“The excavation trench covered just 10% of the archaeological site, so the majority of it has been left completely undisturbed. We have been given a unique insight into Carrowmore and prehistoric Sligo. We collected over 350 individual artefacts from the trench, some of which were found in the ploughsoil, as well as in the prehistoric monument itself. We also excavated and examined 15 tonnes of soil from the trench. Every single grain of soil was sieved through a fine wire mesh, ensuring that we recovered every possible artefact from the trench”, said Dr Bonsall.


Dr Dowd said “We are now focussed on post-excavation analyses of all the materials recovered during the excavation, and hope to have scientific dating in the next few months. At the moment what we can say is that we have quite an enigmatic prehistoric monument: something different and new.”


Source: Institute of Technology Sligo [June 18, 2019]



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2,200-year-old chamber tomb discovered in Taranto

After centuries, archaeological finds of historical and cultural importance re-emerge from the Taranto area. The latest discovery in the Apulian city is that of a chamber tomb found in Via Maturi, in the semi-periphery of Taranto. The tomb contains seven burials and dates back to the second century BC.











2,200-year-old chamber tomb discovered in Taranto
Credit: PugliaPress

The discovery was presented by the Superintendence of Archaeology, Fine Arts and Landscape during the Days of Archaeology. The discovery was made thanks to a stratigraphic survey carried out at Enel’s request for the positioning of a section of the underground grid.











2,200-year-old chamber tomb discovered in Taranto
Credit: PugliaPress

The funerary equipment found is very rich and valuable, and is currently being restored in the laboratory of the Superintendence. It contains pottery, votive objects and metal artefacts.











2,200-year-old chamber tomb discovered in Taranto
Credit: PugliaPress

The City of Taranto, through the Councillor for Town Planning, Augusto Ressa, expressed satisfaction with the new discovery and stressed the «close relationship» of the administration with the Superintendence «for the enhancement of the cultural heritage of the city and the particular attention paid to the ancient underground structures spread throughout the town.»











2,200-year-old chamber tomb discovered in Taranto
Credit: Soprintendenza archeologia belle arti e paesaggio Brindisi, Lecce e Taranto

Taranto was one of the most flourishing cities of Magna Graecia and is now home to a National Archaeological Museum.


Source: Meteo Web [June 18, 2019]



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The Acropolis Museum and the return of the Parthenon Sculptures: Back to the future

On 20 June 2019 Greece and the world museum community will celebrate the 10th anniversary of the opening of the Acropolis Museum in Athens. The state-of-the-art museum is regarded as one of the best in the world and its designers, builders and operators are justifiably entitled to celebrate this defining structure.











The Acropolis Museum and the return of the Parthenon Sculptures: Back to the future
The Acropolis Museum celebrates its 10th year, while the Reunification of the Parthenon Marbles
remains a dream [Credit: Neos Kosmos]

But amidst all the euphoria, let’s not forget that the museum was seen as the long-awaited catalyst for the return of the Elgin collection of Parthenon Sculptures currently on display in the British Museum. Ten years later, how closer is Greece to reunifying the Parthenon Sculptures?


It is important to recall that one of the main reasons for the new museum was to counter the British argument that the Greeks did not have a suitable museum for the Parthenon Sculptures even if they were ever returned to Athens. Indeed, as one historian has noted, the new museum was intended not only to create a modern museum space that related directly to the Scared Rock, but also served as a “political vehicle for the vociferous expression of the request for the return of the Parthenon marbles from the British Museum and a proof that they will take good care in the soil that gave birth to them”.


For years, the British Museum had dreaded the moment when an iconic new museum would rise from the ground in Athens. In fact, on 22 March 1991 the former Keeper of Greek and Roman Antiquities at the British Museum, B M Cook, had sent a memo to the British Museum director with this warning:


“The next phase of the campaign for repatriation is likely to begin any time after the actual start of construction of the new Acropolis Museum. The problem has not gone away, it is merely in hibernation; and when it wakes up, our successors will find that it is fiercer than before.”


The Greeks had also assumed that the new museum would make that case emphatically. As a 2002 report in the Washington Post noted, Greece was building the museum in hopes of reinforcing efforts to change the up-to-now negative stance of the British government and ”shaming the British government into giving back sculptures taken two centuries ago”.


Prior to the actual unveiling of the museum in 2009 the former Prime Minister Costas Karamanlis declared: “Once the museum is completed, Greece will have a very strong argument for the return of the Parthenon sculptures. We are taking a very important step to finally realise a dream that unites all Greeks.”


The Acropolis Museum has therefore always been the centrepiece of the campaign for the return of the Parthenon Sculptures but unfortunately it was assumed that, once built, the case for return would be made out.


At the actual opening, the then President of the Hellenic Republic, Karolos Papoulias, stated: “The whole world can see, all together, the most significant sculptures of the Parthenon. Some are missing. Now is the time to heal the monument’s wounds with the return of the marbles to where they belong … their natural setting.”


The Acropolis Museum has therefore always been the centrepiece of the campaign for the return of the Parthenon Sculptures but unfortunately it was assumed that, once built, the case for return would be made out.


For a start, the British Museum had other ideas. Over the last decade it has carefully rebranded itself as the universal museum, the “museum of the Enlightenment”, the “collective memory of mankind”, a museum at the “centre of a conversation with the world” and therefore the logical repository for the marbles. Today, it arrogantly describes itself as the “museum of and for the world”.


According to the British Museum, the life of the Elgin Marbles as part of the story of the Parthenon is over and they are now part of another narrative, that of the British Museum in London, in a not too subtle attempt to suppress the context of their origin.


In April 2018, the British Museum hauled some twelve pedimental sculptures, metopes and parts of the frieze into a separate hall in the museum under the pretext of displaying these works of art together with sculptures by the renown French sculptor, Auguste Rodin. In its press release the British Museum stressed that the exhibition “will provide a new opportunity to focus on the Parthenon Sculptures as individual works rather than as part of an ensemble” as an obvious counter to the claim that the sculptures are integral to a unique monument.”


This followed a similar exhibition – Defining Beauty – in 2015 and the notorious ‘loan’ of the River God Ilissos pedimetal sculpture to the Hermitage Museum in Russia in late 2014.


Whilst Greece may have a new museum in Athens, the British Museum has devised a new political and diplomatic playbook by which it promotes the Parthenon Sculptures as individual works of art which can be dispersed or dismembered as the Trustees see fit, with no intention of ever returning the collection to Athens.


Meanwhile, cultural diplomacy via mediation through UNESCO has been rejected. Resolutions made at the UNESCO Intergovernmental Committee on Cultural Property over the last 30 years for meaningful negotiations to be undertaken between Greece and Great Britain over the sculptures have also been routinely ignored by the British side.


So, while we can justifiably celebrate the tenth anniversary of the Acropolis Museum as a magnificent museum and the unifying element for the Parthenon and its sculptures, the unfortunate reality is that we are no closer to the return of the sculptures.


Whilst Greece may have a new museum in Athens, the British Museum has devised a new political and diplomatic playbook by which it promotes the Parthenon Sculptures as individual works of art which can be dispersed or dismembered as the Trustees see fit


The next Greek Government needs to carefully reassess its approach and to embrace all political, diplomatic and legal options that are available to bring about an effective resolution so that one day, when all the known surviving sculptures are finally reunited from the British Museum and elsewhere, the Parthenon Gallery of the Acropolis Museum can truly be called the most famous single room of Classical Greek art in the world.


Only then will the Greek Stones truly speak.


Author: George Vardas (Vice-Chair of Australians for the Return of the Parthenon Sculptures) | Source: Neos Kosmos [June 18, 2019]



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Roman lime kiln found under City Arcade in Exeter

Archaeologists have excavated incredible new evidence of the Roman fortress and barracks which occupied a chunk of riverside Exeter.











Roman lime kiln found under City Arcade in Exeter
The remains of a Roman lime kiln found under City Arcade in Exeter 
[Credit: Devon Live]

In the decades after the Roman Conquest (around AD55), City Arcade and Fore Street lay within a legionary fortress, and later formed part of the Roman town of Isca Dumnoniorum.


A drone photograph shows the incredible detail of the layout from above, after being unearthed during works to create luxury student flats.


It’s the second important Roman discovery made during works to build student flats in the West Quarter in recent years. In 2017 the home of a wealthy family was found under Quintana Gate.


A particularly unusual discovery at City Arcade is the visible, large oval sunken feature (5m in diameter and 1.7m deep) of Roman date which had a quantity of lime and charcoal in its base.


This is believed to be an early example of a lime kiln, where limestone would have been heated inside the kiln to make lime for use as mortar in buildings.


This is only the second example of a Roman lime kiln excavated in Devon to date and a rare find nationwide.


From circa 1200 St John’s church was located adjacent to the site and was connected to it by a long-demolished arch called St John’s Bow, which bridged John Street.


In more recent times, the Coachmaker’s Arms public house (now the Fat Pig pub) lay at the Smythen Street end of the plot, on the other side of John Street.


A very well-preserved group of finds dating from about 1700 has been recovered from a large rubbish pit, including numerous ceramic tankards, fragments of glass wine goblets, near complete clay pipes, and a whole two-handled drinking cup known as a tyg.











Roman lime kiln found under City Arcade in Exeter
Pottery from the 1700s including clay pipes
[Credit: Devon Live]

These finds are likely to have come from a nearby inn, almost certainly the former Coachmaker’s Arms, which is known to have been in existence in 1765 and probably before this.


Stuart Randall, who is leading the AC archaeology team, said: «It’s always great to work on a new site in central Exeter which is adding so much to our knowledge of the city.


«I must admit that finding the kiln was a bit of a surprise, as big industrial features within the Roman town boundaries are very unusual.»


Once the excavation has been completed, construction work will begin in earnest.


The archaeologists will then have the task of carrying out research on the archaeological records generated as part of the excavation, specialists will carry out analysis on the various artefacts found and ultimately a detailed report will be prepared on the overall findings.


It is not known whether URBN will incorporate any of the findings into the building.


Christian Hookway of URBN Construction commented: «It has been an interesting exercise undertaking the archaeological investigation at the former City Arcade site; the finding of the Roman industrial -scale lime kiln was fascinating to see excavated to such precision and that the structure has been fully intact below ground for a couple of thousand years.


«The quantity of the smaller items being found is astounding, in that complete and fragmented tankards, glass vessels, clay pipes and Roman pottery are uncovered daily by the archaeological team, giving historical significance to the current project and contributing to furthering the catalogue of the history of Exeter’’.


Andrew Pye of Exeter City Council commented: «It is an important site, located just within the Roman legionary fortress and the Roman and medieval walled city, and demonstrates just how much of Exeter’s history can survive beneath modern buildings, despite damage caused by bombing and modern concrete foundations.


«It is a good example of how the planning system and developers work together to make sure that remains affected by new development are properly excavated and recorded, thereby adding to our knowledge of the development of the fortress and of the city that followed, for the public benefit.


«I look forward to in due course to seeing the published report and hopefully some of the finds on display.”


Author: Alex Richards | Source: Devon Live [June 18, 2019]



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Roman lead sarcophagus accidentally found in Granada

When archaeologists began exploring underneath a building in Granada, in the southern Spanish region of Andalusia, they weren’t expecting to find anything of importance. After all, they were just completing a standard prospection of the Villamena building, as required for any planned underground work in the city to rule out the existence of historic remains. The survey was going  ahead as planned. They found a few remains from the Christian era and from the days of Muslim rule, but nothing truly relevant.











Roman lead sarcophagus accidentally found in Granada
Raising the Roman lead sarcophagus, 2-3rd century AD
[Credit: Gespad Al-Andalus Archeology]

But before finishing the work, they decided to explore a little deeper. And that’s when they found it: a Roman grave covered with sandstone and mud, 2.5 meters below the surface.
For Ángel Rodríguez, the archaeologist in charge of the survey, the discovery was not a big surprise at first – not until they removed the slab and found a lead sarcophagus underneath. Now this was certainly unexpected.


Rodríguez believes the sarcophagus dates back to the 2nd or 3rd century AD, a time when lead sarcophagi were not at all common. In Andalusia, they were expensive as well as difficult to obtain, because the industry only existed in Córdoba, over 200 kilometers away. “Córdoba is the only place where they made lead sarcophagi,” Rodríguez explains.











Roman lead sarcophagus accidentally found in Granada
Lead sarcophagus after removal from grave
[Credit: Gespad Al-Andalus Archeology]

According to this expert, the sarcophagus “probably belonged to a wealthy family, but that doesn’t mean that we are going to find great jewels inside.” The items buried inside may not be that valuable, given that precious goods were left “for the living,” says the archaeologist.
The main interest in this type of sarcophagus comes from the fact that lead conserves remains very well. This means that, if all goes as the archaeologists hope, inside there will be a body, personal valuables and textiles in good condition, which will allow the team to “learn a lot about the burial ritual,” says Rodríguez.


The sarcophagus was moved last week to the Archaeological and Ethnological Museum of Granada. It will remain there until researchers decide on how to proceed with the opening. A multidisciplinary team of physical anthropologists, restorers and archaeologists will be present for the exciting reveal. Once opened, the body will go to the forensic anthropology laboratory at Granada University, while the sarcophagus and goods inside will remain in the museum to be studied, explains Rodríguez.











Roman lead sarcophagus accidentally found in Granada
Sarcophagus loaded on back of truck for transport to museum
[Credit: Gespad Al-Andalus Archeology]

In Roman times, the historic center of Granada was actually a rural area on the outskirts of the city, and the real epicenter was the Albaicín district. But there was something interesting about the area: the Darro river ran through it. The river stopped flowing overground more than a century ago in this part of the city, when it was buried underground.
This was where the sarcophagus was found. Rodríguez explains that this area, on the banks of the Darro, was used to grow crops, “it was not a cemetery, but perhaps because of the Darro river, it had a special meaning as a funeral area.”


According to the archaeologist, a similar lead sarcophagus was discovered in 1902, but it was plundered by the workers who found it before it reached researchers, who only found “some bones.”


The lead sarcophagus found under the Villamena building, next to Granada Cathedral, weighs between 300 and 350 kilograms, and has the same dimensions of a classic coffin: 1.97 meters long and 40 centimeters high. It is slightly wider at the head (56 centimeters) than at the foot (36 centimeters).


On first inspection, Rodríguez says there is no sign of an inscription, but adds that “it still has a lot of clay and sand,” and “we’ll see when we clean it.” The outside of the sarcophagus has already given researchers many insights, and the inside is expected to give many more when it is opened in a few weeks.


Author: Javier Arroyo (transl. Melissa Kitson) | Source: El Pais [June 19, 2019]



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Building Muscle Our bodies are remarkably good at repairing…


Building Muscle


Our bodies are remarkably good at repairing themselves, even if it doesn’t always feel that way when your ankle still hurts weeks after a sprain. Skeletal muscle, those connected to our bones, are particularly good at self-repair, with constant damage and rebuilding at the heart of their strengthening process. However, even this has its limits, and severe injuries can cause irreparable damage. To help recover from these setbacks, researchers have engineered artificial scaffolds to support rebuilding. Crucially, a new technique uses nano-patterned scaffolds to help lend structure to the process, with muscle tissue regrowing in aligned patterns (top right) on an orderly scaffold (bottom right), just like real muscle, compared to haphazard growth on a disordered base (left) in experiments with injured mice. The researchers hope that these tests might provide a springboard for new approaches to regenerative tissue engineering, to help give the body’s repair systems a boost.


Written by Anthony Lewis



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2019 June 23 Carina Nebula Panorama from Hubble Image Credit:…


2019 June 23


Carina Nebula Panorama from Hubble
Image Credit: NASA, ESA, N. Smith (U. California, Berkeley) et al., and The Hubble Heritage Team (STScI/AURA)


Explanation: How do violent stars affect their surroundings? To help find out, astronomers created a 48-frame high-resolution, controlled-color panorama of the center of the Carina Nebula, one of the largest star forming regions on the night sky. The featured image, taken in 2007, was the most detailed image of the Carina Nebula yet taken. Cataloged as NGC 3372, the Carina Nebula is home to streams of hot gas, pools of cool gas, knots of dark globules, and pillars of dense dusty interstellar matter. The Keyhole Nebula, visible left of center, houses several of the most massive stars known. These large and violent stars likely formed in dark globules and continually reshape the nebula with their energetic light, outflowing stellar winds, and ultimately by ending their lives in supernova explosions. Visible to the unaided eye, the entire Carina Nebula spans over 450 light years and lies about 8,500 light-years away toward the constellation of Ship’s Keel (Carina).


∞ Source: apod.nasa.gov/apod/ap190623.html


Image of the Week — June 24, 2019CIL:38957 -…


Image of the Week — June 24, 2019


CIL:38957http://cellimagelibrary.org/images/38957


Description: A colorized scanning electron micrograph of a human egg, which is the huge cell colored yellow at the bottom of this image. The follicle cells that surround it (top) send out long projections that penetrate through the tough outer coating (the zona pellucida) into the egg cell itself giving it the nourishment it needs to develop to maturity. Even when the egg is released from the ovary at ovulation it remains surrounded by a cloud of follicle cells that only gradually fall away as the egg progresses along the Fallopian tube.


Author: Yorgos Nikas


Licensing: Attribution-NonCommercial-NoDerivs 2.0 UK: England & Wales (CC BY-NC-ND 2.0 UK)


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Amazing Opalised belemnite rostrum, Australia | #Geology…


Amazing Opalised belemnite rostrum, Australia | #Geology #GeologyPage #Fossils


The secret of platinum deposits revealed by novel field…


The secret of platinum deposits revealed by novel field observations in the Bushveld Complex http://www.geologypage.com/2019/06/the-secret-of-platinum-deposits-revealed-by-novel-field-observations-in-the-bushveld-complex.html


Deep-Sea Fish Do Not Signal Upcoming Earthquake in Japan…


Deep-Sea Fish Do Not Signal Upcoming Earthquake in Japan http://www.geologypage.com/2019/06/deep-sea-fish-do-not-signal-upcoming-earthquake-in-japan.html


Zipingpu Reservoir reveals climate-tectonics interplay around…


Zipingpu Reservoir reveals climate-tectonics interplay around 2008 Wenchuan earthquake http://www.geologypage.com/2019/06/zipingpu-reservoir-reveals-climate-tectonics-interplay-around-2008-wenchuan-earthquake.html


Earthquake swarms reveal missing piece of tectonic plate-volcano…


Earthquake swarms reveal missing piece of tectonic plate-volcano puzzle http://www.geologypage.com/2019/06/earthquake-swarms-reveal-missing-piece-of-tectonic-plate-volcano-puzzle.html


Stresses from past earthquakes explain location of seismic…


Stresses from past earthquakes explain location of seismic events http://www.geologypage.com/2019/06/stresses-from-past-earthquakes-explain-location-of-seismic-events.html


New ‘king’ of fossils discovered on Kangaroo Island…


New ‘king’ of fossils discovered on Kangaroo Island http://www.geologypage.com/2019/06/new-king-of-fossils-discovered-on-kangaroo-island.html


Cool halo gas caught spinning like galatic disks



J165930+373527 is among the galaxies detected with corotating halo gas. this high-resolution nirc2 image (red) combined with hubble space telescope wfc3 imaging (blue and green) resolves the galactic disk. the galactic rotation was measured from w. m. keck observatory and apache point observatory emission-line spectra.




Corotation Found to be Typical, Suggesting Cool Halo Gas Prolongs Galaxy Growth


Maunakea, Hawaii – A group of astronomers led by Crystal Martin and Stephanie Ho of the University of California, Santa Barbara, has discovered a dizzying cosmic choreography among typical star-forming galaxies; their cool halo gas appears to be in step with the galactic disks, spinning in the same direction.


The researchers used W. M. Keck Observatory to obtain the first-ever direct observational evidence showing that corotating halo gas is not only possible, but common. Their findings suggest that the whirling gas halo will eventually spiral in towards the disk.


“This is a major breakthrough in understanding how galactic disks grow,” said Martin, Professor of Physics at UC Santa Barbara and lead author of the study. “Galaxies are surrounded by massive reservoirs of gas that extend far beyond the visible portions of galaxies. Until now, it has remained a mystery how exactly this material is transported to galactic disks where it can fuel the next generation of star formation.”


The study is published in today’s issue of The Astrophysical Journal and shows the combined results of 50 standard star-forming galaxies taken over a period of several years.


Nearly a decade ago, theoretical models predicted that the angular momentum of the spinning cool halo gas partially offsets the gravitational force pulling it towards the galaxy, thereby slowing down the gas accretion rate and lengthening the period of disk growth.


The team’s results confirm this theory, which show that the angular momentum of the halo gas is high enough to slow down the infall rate but not so high as to shut down feeding the galactic disk entirely.



Figure 1: Artist conception of gas streams (blue) feeding a galactic disk. The inflow fuels new star formation, and because the infalling gas is spinning, the size of the disk grows. Image credit: James Josephides, Swinburne Astronomy Productions.



Methodology


The astronomers first obtained spectra of bright quasars behind star-forming galaxies to detect the invisible halo gas by its absorption-line signature in the quasar spectra. Next, the researchers used Keck Observatory’s laser guide star adaptive optics (LGSAO) system and near-infrared camera (NIRC2) on the Keck II telescope, along with Hubble Space Telescope’s Wide Field Camera 3 (WFC3), to obtain high-resolution images of the galaxies.



“What sets this work apart from previous studies is that our team also used the quasar as a reference ‘star’ for Keck’s laser guide star AO system,” said co-author Stephanie Ho, a physics graduate student at UC Santa Barbara. “This method removed the blurring caused by the atmosphere and produced the detailed images we needed to resolve the galactic disks and geometrically determine the orientation of the galactic disks in three-dimensional space.”



The team then measured the Doppler shifts of the gas clouds using the Low Resolution Imaging Spectrometer (LRIS) at Keck Observatory, as well as obtaining spectra from Apache Point Observatory. This enabled the researchers to determine what direction the gas is spinning and how fast. The data proved that the gas is rotating in the same direction as the galaxy, and the angular momentum of the gas is not stronger than the force of gravity, meaning the gas will spiral into the galactic disk.



“Just as ice skaters build up momentum and spin when they bring their arms inward, the halo gas is likely spinning today because it was once at much larger distances where it was deposited by galactic winds, stripped from satellite galaxies, or directed toward the galaxy by a cosmic filament,” said Martin.


Next Steps


The next step for Martin and her team is to measure the rate at which the halo gas is being pulled into the galactic disk. Comparing the inflow rate to the star formation rate will provide a better timeline of the evolution of normal star-forming galaxies, and explain how galactic disks continue to grow over very long timescales that span billions of years.




About adaptive optics


The astronomers first obtained spectra of bright quasars behind star-forming galaxies to detect the invisible halo gas by its absorption-line signature in the quasar spectra. Next, the researchers used Keck Observatory’s laser guide star adaptive optics (LGSAO) system and near-infrared camera (NIRC2) on the Keck II telescope, along with Hubble Space Telescope’s Wide Field Camera 3 (WFC3), to obtain high-resolution images of the galaxies.



“What sets this work apart from previous studies is that our team also used the quasar as a reference ‘star’ for Keck’s laser guide star AO system,” said co-author Stephanie Ho, a physics graduate student at UC Santa Barbara. “This method removed the blurring caused by the atmosphere and produced the detailed images we needed to resolve the galactic disks and geometrically determine the orientation of the galactic disks in three-dimensional space.”



The team then measured the Doppler shifts of the gas clouds using the Low Resolution Imaging Spectrometer (LRIS) at Keck Observatory, as well as obtaining spectra from Apache Point Observatory. This enabled the researchers to determine what direction the gas is spinning and how fast. The data proved that the gas is rotating in the same direction as the galaxy, and the angular momentum of the gas is not stronger than the force of gravity, meaning the gas will spiral into the galactic disk.



“Just as ice skaters build up momentum and spin when they bring their arms inward, the halo gas is likely spinning today because it was once at much larger distances where it was deposited by galactic winds, stripped from satellite galaxies, or directed toward the galaxy by a cosmic filament,” said Martin.

About NIRC2


The Near-Infrared Camera, second generation (NIRC2) works in combination with the Keck II adaptive optics system to obtain very sharp images at near-infrared wavelengths, achieving spatial resolutions comparable to or better than those achieved by the Hubble Space Telescope at optical wavelengths. NIRC2 is probably best known for helping to provide definitive proof of a central massive black hole at the center of our galaxy. Astronomers also use NIRC2 to map surface features of solar system bodies, detect planets orbiting other stars, and study detailed morphology of distant galaxies.


About LRIS


The Low Resolution Imaging Spectrometer (LRIS) is a very versatile visible-wavelength imaging and spectroscopy instrument commissioned in 1993 and operating at the Cassegrain focus of Keck I. Since it has been commissioned it has seen two major upgrades to further enhance its capabilities: addition of a second, blue arm optimized for shorter wavelengths of light; and the installation of detectors that are much more sensitive at the longest (red)wavelengths. Each arm is optimized for the wavelengths it covers. This large range of wavelength coverage, combined with the instrument’s high sensitivity, allows the study of everything from comets (which have interesting features in the ultraviolet part of the spectrum), to the blue light from star formation, to the red light of very distant objects. LRIS also records the spectra of up to 50 objects simultaneously, especially useful for studies of clusters of galaxies in the most distant reaches, and earliest times, of the universe. LRIS was used in observing distant supernovae by astronomers who received the Nobel Prize in Physics in2011 for research determining that the universe was speeding up in its expansion.


About W.M. Keck Observatory


The W. M. Keck Observatory telescopes are the most scientifically productive on Earth. The two, 10-meter optical/infrared telescopes atop Maunakea on the Island of Hawaii feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrometers, and world-leading laser guide star adaptive optics systems. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors recognize and acknowledge the very significant cultural role that the summit of Maunakea has always had within the Native Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.






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Swinside or Sunkenkirk Neolithic Stone Circle, nr. Millom, Lake District, 22.6.19.

Swinside or Sunkenkirk Neolithic Stone Circle, nr. Millom, Lake District, 22.6.19.












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