четверг, 18 октября 2018 г.

Longobard necropolis emerges on Doss Trento in Northern Italy

A Longobard necropolis with thirteen graves of both adults and children with objects of considerable interest was found on the Doss Trento, a small hill that stands on the right bank of the river Adige in the Italian municipality of Trento, during the works for the redevelopment and expansion of the Historical Museum of the Alps that began in May.











Longobard necropolis emerges on Doss Trento in Northern Italy
Credit: Il Dolomiti

The funerary structures are rather simple as they consist of simple pits surrounded by stones. The funerary goods, not present in all of the graves, include belt buckles, weapons (swords and daggers) and other items such as brooches, jewellery and bone combs.











Longobard necropolis emerges on Doss Trento in Northern Italy
Credit: Il Dolomiti

The graves are located in the uppermost section of an archaeological deposit of exceptional interest, still under excavation, characterized by the presence of structural remains of the Early and Final Bronze Age, the Chalcolithic and Neolithic Ages that together cover a chronological range from the fifth to the first millennia BC.











Longobard necropolis emerges on Doss Trento in Northern Italy
Credit: Il Dolomiti

The dominating position of the Doss Trento over the Adige Valley, in fact, has always attracted the interest of those who sought to control the surrounding territory. The strategic role of the Doss Trento is well documented since Late Antiquity. The famous letter from the beginning of the sixth century AD sent by Theodoric to all the Goths and Romans “who live around the castle of Verruca” urging them to fortify themselves against potential threats is a case in point.











Longobard necropolis emerges on Doss Trento in Northern Italy
Credit: Il Dolomiti

The presence of substantial archaeological finds spanning several periods has been known since the second half of the 19th century. At that time, on the occasion of the construction of military installations by the Austrian authorities, important archaeological discoveries were made.











Longobard necropolis emerges on Doss Trento in Northern Italy
Credit: Il Dolomiti

Francesco Ranzi, who is supervising the excavations, cites the discovery of tombs and architectural elements from the Roman era during the excavations for the construction of a powder magazine.











Longobard necropolis emerges on Doss Trento in Northern Italy
Credit: Il Dolomiti

However, the Doss Trento also saw a religious presence. Proof of this was the discovery of a Paleo-Christian church probably dating back to the fifth century AD and which remained in use until at least the seventh century AD. Ranzi believes that the Longobard graves are to be associated with this church.


The excavations are being carried out by the Archaeological Heritage Office of the Superintendence for Cultural Heritage of the Autonomous Province of Trento.


Source: Il Dolomiti [October 13, 2018]



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Archaeologists start research on culture of ancient Swat

To understand the lifestyle, fashion and technological use in vitreous materials, ornamental culture and ceramics used in the ancient Swat, international archaeologists launched different research studies in Swat.











Archaeologists start research on culture of ancient Swat
Ceramics from Aligrama in the storeroom of the mission house
[Credit: Università di Padova] 

The international archaeologists from the universities of Italy and United Kingdom have launched three different researches with the scientific agreement between the Italian Archaeological Mission in Pakistan (ISMEO) and the KP Directorate of Archaeology and Museums, with the aim to understand the use of technology, material, types and techniques in ceramics, ornamental stone beads, glass beads, bangles and other material used by the ancient people from Achaemenids to Kushanas living in the ancient Swat.
Professor Ivana Angelini from the Department of Cultural Heritage in the University of Padova, Italy, along with another scholar Cinzia Bettineschi said that they undertook the vitreous materials from Barikot in the framework of the Indo-Pakistani and Mediterranean glass technology and trade routes.


“The aim is to understand the evolution of this high-status craft, in terms of typology of the materials, compositional recipes and working/production techniques,” they told this correspondent.











Archaeologists start research on culture of ancient Swat
Aligrama ceramics under study [Credit: Università di Padova]

They said that the ornamental objects from Swat showed a wide variability of colours, shapes and technological solutions which testified early contacts with the Mediterranean basin, but also a noticeable local taste in the choice of the most widespread typologies of bangles, beads and pendants.
Another researcher Mubariz Ahmad Rabbani, who has undertaken his PhD research on the stone beads of Barikot from the University of Reading, UK, said that he was investigating, for example, how the beads were manufactured and how they developed across at that periods.


“I am also trying to find out how the inhabitants of Barikot used the beads to adorn themselves and how they used them to express their identity. Gandharan beads especially from Swat have never been scientifically and comprehensively studied before. Thus this study will shed light on a presently unexplored chapter of Gandharan archaeology,” he said.











Archaeologists start research on culture of ancient Swat
Irene Caldana draws one of the large Aligrama vases in the Archaeological Museum of Saidu Sharif
[Credit: Università di Padova]

He added that the study would eventually highlight that Gandhara was indeed an important centre of international connections, diversity, openness and learning.
At the same time two young researchers, Emanuele Lant and Irene Caldana of the Padova University under the supervision of Prof Massimo Vidale have undertaken a research study on the ceramics of Aligrama Swat.


They said that their research was focused on typological study of the ceramics from Aligrama site which was excavated from 1966 to 1983.











Archaeologists start research on culture of ancient Swat
Cinzia Bettineschi during the preliminary filing of glass materials by Barikot in the
Archaeological Museum of Saidu Sharif [Credit: Università di Padova] 

The researchers thanked KP Archaeology and Museum Department director Abdul Samad and curator of Swat Museum Faizur Rahman for assisting them in their researches.


For more information visit the Missione Archeologica Italiana in Pakistan – MAIP website


Author: Fazal Khaliq | Source: Dawn [October 13, 2018]



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Keezhadi excavation: How an ancient civilisation is being unearthed in Tamil Nadu

In 2013-2014, the Archaeological Survey of India had set out to explore the regions along the banks of river Vaigai in Tamil Nadu. Theni, Dindigul, Madurai, Sivaganga and Ramanathapuram districts all were part of the 293 sites set up to unearth artefacts and ruins to discover the culture that might have existed aeons ago.











Keezhadi excavation: How an ancient civilisation is being unearthed in Tamil Nadu
View of the excavations in a coconut plantation at Keezhadi [Credit: R. Ashok]

A Bengaluru-based excavation branch of the ASI took up the site at Keezhadi village, 12 km south-east of Madurai, in the Sivaganga district.


Three months into their excavation, the site began yielding interesting finds like beads made of glass, terracotta and even pearls. Other discoveries included figurines, roof tiles and also pottery.


One particular excavation area named – Pallichandai Thidal – was brimming with potential finds. The area – slightly elevated to 2.5 meters above ground level – is a mound with a circumference of 3.5 km, spanning 80 acres.


Due to this particular elevation of the Pallichandai Thidal, the site was relatively undisturbed and hence, housed intact bricks measuring 33 cm in length, 21 cm in breadth and 5 cm tall.











Keezhadi excavation: How an ancient civilisation is being unearthed in Tamil Nadu
Earthen pot with leaf decoration unearthed at the ASI’s excavation site at Keezhadi [Credit: R. Ashok]

An earthen pot with leaf decorations was also unearthed at the excavation site, adding to a repository of evidence that points to the existence of an urban habitation closer to the erstwhile capital of the Pandya kingdom.


The exquisitely crafted pot 72 cm wide and 42 cm long was found by an ASI team led by Superintending Archaeologist K Amarnath Ramakrishna.


Combine that with other findings like pottery with a Tamil-Brahmi script, the initial assumption of the town belonging to the Pandyas was materialising.


A fossilised piece of bone was also found which could have been used as an arrowhead, indicating the use of weapons. Not only that, square copper coins of Pandyan Peruvazhudhi with horse and turtle motifs were also found at the surface level, pointing towards the fact that the society used currency in its day-to-day life.











Keezhadi excavation: How an ancient civilisation is being unearthed in Tamil Nadu
Excavation of brick structure at Keezhadi [Credit: G. Moorthy]

Experts say that the town could have also played a role in the Roman trade of the day.


Two similar pots of different shapes have emerged in other pits of the excavation site. The huge red pot, which is among a variety of earthenware discovered in the area, was found embedded alongside a water storage facility.


The facility further pointed to another significant fact: the advancement of the society and the habitation during that time.


With such interesting finds, the excavation was extended to another year, and what they would go on to find would change pre-established notions.











Keezhadi excavation: How an ancient civilisation is being unearthed in Tamil Nadu
Black and red pottery found at the ASI’s excavation site at Keezhadi [Credit: ASI]

The excavation continued to its second phase from 2015-2016 with about 1,800 antiquities unearthed. It was high time to call for carbon dating of these antiquities, where selected pieces would be sent to Beta Analytic Inc., Florida, USA, for the procedure.


Meanwhile, the excavation was shedding light on the history of Tamil Nadu. The archaeological team had dug up 53 trenches, an extraordinary number, considering the assumption that there was no large urban settlement; but these findings proved the opposite.


Noted epigraphist V Vedachalam told The Hindu that the antiquities found at Pallichandai Thidal reaffirm the belief that nestled amidst three ancient places — Konthagai, Keezhadi and Manalur — was an urban settlement that had trade links with North India and the western world during the Sangam Age.


Brahmi-inscribed pots, pastime games like dice, graffiti of the sun and the moon, all hinted towards a sophisticated civilisation on the banks of river Vaigai. All these led to the conclusion that the Sangam period was way advanced than it was earlier thought to be.











Keezhadi excavation: How an ancient civilisation is being unearthed in Tamil Nadu
Brick structure found at the ASI’s excavation site at Keezhadi [Credit: ASI]

With this, the excavation was extended into the third phase, and the site was expanded to 110 acres of private lands.


In the meantime, the results of carbon dating from the Florida lab had emerged, and the artefacts were dated back to 200 BC. This meant that the findings related to a civilisation existing during the Sangam period.


Speaking to The Hindu, Mr Ramakrishna, who heads the excavation project in Keezhadi, said, “So far, there has been an impression that urban civilisation did not exist in Tamil Nadu. The excavations and carbon dating have disproved the opinion.”


As of the now, the 100-acre site has yielded 13,000 artefacts, more than enough to establish the notion of a flourishing civilisation that existed on the banks of the Vaigai.











Keezhadi excavation: How an ancient civilisation is being unearthed in Tamil Nadu
Well found at the ASI’s excavation site at Keezhadi [Credit: R. Ashok]

The Keezhadi excavation continues well into the fourth season of excavation, with yields like small objects made of gold, terracotta figurines, a terracotta mould resembling a human face, two ring wells, ornamental objects made of ivory, and a large number of beads of different kinds.


Keezhadi is one of the most revered archaeological sites in India, owing to its habitation, which seems to co-exist with the period of the Harappan civilisation; a theory which had no basis even six years ago.


Author: Ahmed Sherrif | Source: The Better India [October 15, 2018]



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2018 October 18 Cherenkov Telescope at Sunset Image Credit…


2018 October 18


Cherenkov Telescope at Sunset
Image Credit & Copyright: Sarah Brands (University of Amsterdam)


Explanation: On October 10, a new telescope reflected the light of the setting Sun. With dark horizon above and sunset colors below, its segmented mirror inverts an image of the beautiful evening sky in this snapshot from the Roque del Los Muchachos Observatory on the Canary Island of La Palma. The mirror segments cover a 23 meter diameter and are mounted in the open structure of the Large Scale Telescope 1, inaugurated as the first component of the Cherenkov Telescope Array (CTA). Most ground-based telescopes are hindered by the atmosphere that blurs, scatters, and absorbs light. But cherenkov telescopes are designed to detect very high energy gamma rays and actually require the atmosphere to operate. As the gamma rays impact the upper atmosphere they produce air showers of high-energy particles. A large, fast camera at the common focus images the brief flashes of optical light, called Cherenkov light, created by the air shower particles. The flashes reveal the incoming gamma ray timing, direction, and energy. Ultimately more than 100 Cherenkov telescopes are planned for the CTA at locations in both northern and southern hemispheres on planet Earth.


∞ Source: apod.nasa.gov/apod/ap181018.html


We’re Landing a Rover on Mars in 2020…But How Do We Decide Where?

In 2020, we will launch our next Mars rover. It will journey more than 33 million miles to the Red Planet where it will land, explore and search for signs of ancient microbial life. But how do we pinpoint the perfect location to complete this science…when we’re a million miles away on Earth?


image

We utilize data sent to us by spacecraft on and orbiting Mars. That includes spacecraft that have recorded data in the past.


This week, hundreds of scientists and Mars enthusiasts are gathering to deliberate the four remaining options for where we’re going to land the Mars 2020 rover on the Red Planet.


image

The landing site for Mars 2020 is of great interest to the planetary community because, among the rover’s new science gear for surface exploration, it carries a sample system that will collect rock and soil samples and set them aside in a “cache” on the surface of Mars. A future mission could potentially return these samples to Earth. The next Mars landing, after Mars 2020, could very well be a vehicle which would retrieve these Mars 2020 samples.


Here’s an overview of the potential landing sites for our Mars 2020 rover…


Northeast Syrtis


image

This area was once warmed by volcanic activity. Underground heat sources made hot springs flow and surface ice melt. Microbes could have flourished here in liquid water that was in contact with minerals. The layered terrain there holds a rich record of interactions between water and minerals over successive periods of early Mars history.


Jezero Crater


image

This area tells a story of the on-again, off-again nature of the wet past of Mars. Water filled and drained away from the crater on at least two occasions. More than 3.5 billion years ago, river channels spilled over the crater wall and created a lake. Scientists see evidence that water carried clay minerals from the surrounding area into the crater after the lake dried up. Conceivably, microbial life could have lived in Jezero during one or more of these wet times. If so, signs of their remains might be found in lakebed sediments.


Columbia Hills


image

At this site, mineral springs once bubbled up from the rocks. The discovery that hot springs flowed here was a major achievement of the Mars Exploration Rover, Spirit. The rover’s discovery was an especially welcome surprise because Spirit had not found signs of water anywhere else in the 100-mile-wide Gusev Crater. After the rover stopped working in 2010, studies of its older data records showed evidence that past floods may have formed a shallow lake in Gusev.


Midway


image

Candidate landing sites Jezero and Northeast Syrtis are approximately 37 km apart…which is close enough for regional geologic similarities to be present, but probably too far for the Mars 2020 rover to travel. This midway point allows exploration of areas of both landing sites.


image

How Will We Select a Site?


The team is gathered this week for the fourth time to discuss these locations. It’ll be the final workshop in a series designed to ensure we receive the best and most diverse range of information and opinion from the scientific community before deciding where to send our newest rover.


The Mars 2020 mission is tasked with not only seeking signs of ancient habitable conditions on Mars, but also searching for signs of past microbial life itself. So how do we choose a landing site that will optimize these goals? Since InSight is stationary and needs a flat surface to deploy its instruments, we’re basically looking for a flat, parking lot area on Mars to land the spacecraft.


image

The first workshop started with about 30 candidate landing sites and was narrowed down to eight locations to evaluate further. At the end of the third workshop in February 2017, there were only three sites on the radar as potential landing locations…


…but in the ensuing months, a proposal came forward for a landing site that is in between Jezero and Northeast Syrtis – The Midway site. Since our goal is to get to the right site that provides the maximum science, this fourth site was viewed as worthy of being included in the discussions.


Now, with four sites remaining, champions for each option will take their turn at the podium, presenting and defending their favorite spot on the Red Planet.


image

On the final day, after all presentations have concluded, workshop participants will weigh the pros and cons of each site. The results of these deliberations will be provided to the Mars 2020 Team, which will incorporate them into a recommendation to NASA Headquarters. A final selection will be made and will likely be announced by the end of the year.


To get more information about the workshop, visit: https://marsnext.jpl.nasa.gov/workshops/wkshp_2018_10.cfm


Learn more about our Mars 2020 rover HERE.


Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.


What does a black hole look like?

At the center of our galaxy lies a swirling, energy-spewing supermassive black hole called Sagittarius A* or Sgr A*, for short. For billions of years, surrounding gas and dust have been falling into it. Every 10,000 years or so, it swallows a nearby star.











What does a black hole look like?
Credit: EHT

Sgr A* (pronounced Saj-A-star) is the largest black hole in our night sky, but we don’t know what it looks like up close because we’ve never been able to take a picture of it.


This is actually true of all black holes.


They’re ubiquitous in our universe, but they’re so small in the sky, we don’t have a detailed image of any of them.


Those pictures you see on the web or in TV documentaries are illustrations or simulations based on indirect evidence—observations of the region of space around the black hole. Scientists don’t doubt black holes exist, but without an image, they can’t prove it for certain.


This all may be about to change.


For the last four years, professor of astrophysics John Wardle has been working with a team of roughly 200 scientists and engineers to create an image of Sgr A* that would be our first ever picture of a black hole. The initiative, called the Event Horizon Telescope (EHT), finished collecting data in April 2017. Researchers are currently analyzing it.


Depending on the results, the image they produce of Sgr A* may look like one of these:











What does a black hole look like?
Computer simulations of the images EHT researchers hope to generate. The bright regions are hot gas surrounding
the black hole. The circular dark region is a shadow cast by the strong gravity of the black hole
[Credit: EHT]

This may not seem like much but generating this rough of a picture of Sgr A* is the equivalent of reading a newspaper headline on the moon while standing on Earth.


In fact, it is good enough to answer some of our biggest unanswered questions about one of the universe’s most mysterious phenomena: What do light and matter look like as they fall toward a black hole? What are the streams of energy shooting out of black holes made of? What role did black holes play in the formation of galaxies?


Though it’s unlikely, results from the EHT could even require adjustments to Einstein’s general theory of relativity.


But before we get to whether one of the greatest scientists who ever lived didn’t get it quite right, we have to start with the basics.


The facts


Black holes typically happen when a very massive star burns through its nuclear fuel and collapses cataclysmically into an incredibly dense point, or singularity.


When gas, stars and other matter come close enough to the black hole, they are drawn toward the black hole’s event horizon, an imaginary shell around the singularity. Nothing that passes across the threshold of the event horizon can escape the black hole’s gravitational pull. And as matter falls in, the black hole gets more massive and the event horizon expands.


It turns out that black holes are everywhere. Supermassive ones lie at the center of most galaxies. Less massive black holes are much more common. Our galaxy, the Milky Way, likely has around 100 million black holes, though we’ve only identified a few dozen of them.


As for Sgr A*, it’s about 26,000 light-years away from Earth with a mass four million times that of the sun. That makes it “wimpy” compared to other supermassive black holes, Wardle says. The other supermassive black hole the EHT studies, Messier 87 (M87) at the center of the Virgo cluster, has a mass of nearly seven billion times that of the sun.


The EHT chose Sgr A* and M87 because they are the largest supermassive black holes when viewed from Earth. They’re the easiest and most accessible candidates for study.


But how can we take a picture of a black hole when it’s black?


Good point. In fact, black holes are as black as the blackness of space. Any light that enters never escapes.


But around a black hole, there is light from a luminous swirl of superheated matter yet to fall into the black hole. When the light passes near the event horizon, it bends and gets distorted by the pull of the black hole’s strong gravity.


This lensing of the light outlines a dark region called the black hole’s shadow. The size of the shadow is expected to be two and a half times the size of the event horizon. The size of the event horizon is proportional to the mass of the black hole. For Sgr A* that works out to be about 15 million miles in diameter. And the diameter of M87, the other black hole the EHT is studying, is a thousand times larger than that.


You get the picture: By studying the black hole’s shadow, the EHT researchers can figure out a heck of a lot about the black hole.


So technically speaking, the EHT’s scientists won’t be producing an image of a black hole. They will be using information about the shadow to deduce information about the black hole.


But since imaging a black hole isn’t an option (at least not at present), scientists consider an image of the shadow conclusive evidence of a black hole’s existence.


Enter John Wardle


When Wardle started out in astrophysics in the late 1960s analyzing radio waves emitted by galaxies, “black holes were just a curiosity that may or may not have existed,” he said. “They were a slightly disreputable field for an astronomer to be in.”


But a few years later, the field exploded, and since black holes power energetic jets that emit radio waves, he naturally gravitated in their direction (no pun intended).


As part of the Brandeis Radio Astronomy Group, Wardle studies “active galaxies,” a relatively rare type of super-luminous galaxy with supermassive black holes at their center.


The network


Sgr A* is so small in the sky that we don’t have one single telescope on Earth that can see it in enough detail to create a high-resolution photo.











What does a black hole look like?
The EHT consists of seven networked telescopes. The telescope in Greenland
 is so far north that it cannot see Sgr A*, which is in the southern sky
[Credit: APEX, IRAM, G. Narayanan, J. McMahon, JCMT/JAC,
S. Hostler, D. Harvey, ESO/C. Malin]

The EHT scientists overcame this by networking seven telescopes around the globe using a technique called very long baseline interferometry (VLBI). The result was a “virtual telescope” with the resolving power of a telescope the size of the diameter of Earth.


For a week in April of 2017, all seven of the EHT telescopes were recording signals from Sgr A*. Seven atomic clocks recorded the time of arrival of the signals at each telescope.


The nature of the signals and when they arrive at each telescope will enable scientists to work backward to construct a picture of Sgr A*. This is going to take a while to complete. The EHT telescopes collected enough data to fill 10,000 laptops.


Big jets


Wardle is especially interested in finding out more about the massive jets of energy that stream from black holes.


The jets form when matter outside a black hole gets heated to billions of degrees. It swirls around in what’s called the accretion disk. Some of it passes the point of no return, the event horizon, and enters the black hole.


But black holes are messy eaters. Some of the matter will be spit out in the form of tightly focused (collimated) jets. The jets travel at close to the speed of light for tens of thousands of light-years.


It’s possible that there are no jets coming from Sgr *A. It’s not been very active in the last few decades.


But if the jets do exist, the EHT’s telescopes will have picked up their radio signals. Then the EHT crew can use the information to try and answer what Wardle says are the big unanswered questions about the jets:


What are they made of, electrons and positrons, electrons and protons, or electromagnetic fields? How do they begin? How do they accelerate to nearly the speed of light? How do they stay tightly focused?


And now, finally, we get to Einstein


Up until very recently, evidence supporting the theory of general relativity (GR) has come from observations of our solar system. But conditions in our little speck of the universe are pretty mild. The extreme conditions found near a black hole will put GR to the ultimate test.


GR should accurately describe how light bends as the black hole’s massive gravitational pull curves spacetime and draws everything towards it. The data gathered by EHT will provide measurements of this phenomenon which can be compared with Einstein’s predictions.


GR’s formulas also suggest that the shadow cast by the accretion disk around Sgr A* will be almost circular. If it turns out to be shaped like an egg, it will tell us something is wrong about GR as well.


Wardle thinks GR will hold up under testing. Still, there’s always the chance GR “may have to be adjusted,” he said. “Then we’ll be in a severe straight jacket because you can’t make changes that mess up all the other bits that do work. That would be very exciting.”


Author: Lawrence Goodman | Source: Brandeis University [October 12, 2018]



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The Milky Way could be spreading life from star to star

For almost two centuries, scientists have theorized that life may be distributed throughout the universe by meteoroids, asteroids, planetoids, and other astronomical objects. This theory, known as Panspermia, is based on the idea that microorganisms and the chemical precursors of life are able to survive being transported from one star system to the next.











The Milky Way could be spreading life from star to star
Credit: NASA

Expanding on this theory, a team of researchers from the Harvard Smithsonian Center for Astrophysics (CfA) conducted a study that considered whether panspermia could be possible on a galactic scale. According to the model they created, they determined that the entire Milky Way (and even other galaxies) could be exchanging the components necessary for life.


The study, “Galactic Panspermia,” recently appeared online and is being reviewed for publication by the Monthly Notices of the Royal Astronomical Society. The study was led by Idan Ginsburg, a visiting scholar at the CfA’s Institute for Theory and Computation (ITC), and included Manasvi Lingam and Abraham Loeb – an ITC postdoctoral researcher and the director of the ITC and the Frank B. Baird Jr. Chair of Science at Harvard University, respectively.


As they indicate their study, most of the past research into panspermia has focused on whether life could had been distributed through the solar system or neighboring stars. More specifically, these studies addressed the possibility that life could have been transferred between Mars and Earth (or other Solar bodies) via asteroids or meteorites. For the sake of their study, Ginsburg and his colleagues cast a wider net, looking at the Milky Way Galaxy and beyond.


As Dr. Loeb told universe Today via email, the inspiration for this study came from the first-known interstellar visitor to our solar system – the asteroid “Oumuamua:











The Milky Way could be spreading life from star to star
A new study expands on the classical theory of panspermia, addressing whether
or not life could be distributed on a galactic scale [Credit: NASA]

“Following that discovery, Manasvi Lingam and I wrote a paper where we showed that interstellar objects like `Oumuamua could be captured through their gravitational interaction with Jupiter and the Sun. The solar system acts as a gravitational “fishing net” that contains thousands of bound interstellar objects of this size at any given time. These bound interstellar objects could potentially plant life from another planetary system and in the solar system. The effectiveness of the fishing net is larger for a binary star system, like the nearby Alpha Centauri A and B, which could capture objects as large as the Earth during their lifetime.”


“We expect most objects to likely be rocky, but in principle they could also be icy (cometary) in nature,” Ginsburg added. “Regardless of whether they are rocky or icy, they can be ejected from their host system and travel potentially thousands of light-years away. In particular the center of the galaxy can act as a powerful engine to seed the Milky Way.”


This study builds on previous research conducted by Ginsburg, Loeb and Gary A. Wegner of the Wilder Lab at Dartmouth College. In a 2016 study published in the Monthly Notices of the Royal Astronomical Society, they suggested that the center of the Milky Way could be the instrument through which hypervelocity stars are ejected from a binary system and then captured by another system.


For the sake of this study, the team created an analytic model to determine just how likely it is that objects are being traded between star systems on a galactic scale. As Loeb explained:











The Milky Way could be spreading life from star to star
Artist’s impression of the first interstellar asteroid/comet, “Oumuamua”. This unique object was discovered
on 19 October 2017 by the Pan-STARRS 1 telescope in Hawaii [Credit: ESO/M. Kornmesser]

“In the new paper we calculated how many rocky objects that are ejected from one planetary system can be trapped by another one across the entire Milky Way galaxy. If life can survive for a million years, there could be over a million `Oumuamua-size objects that are captured by another system and can transfer life between stars. Therefore panspermia is not exclusively limited to solar-system sized scales, and the entire Milky Way could potentially be exchanging biotic components across vast distances.”


“[O]ur physical model calculated the capture rate of objects in the Milky Way which strongly depend upon velocity and the lifetime of any organisms that may travel on the object,” added Ginsburg. “No one had done such a calculation before, and we feel this is quite novel and exciting.”


From this, they found that the possibility of galactic panspermia came down to a few variables. For one, the capture rate of objects ejected from planetary systems is dependent on the velocity dispersion as well as the size of the captured object. Second, the probability that life could be distributed from one system to another is strongly dependent upon the survival lifetime of the organisms.


However, in the end they found that even in the worst case scenarios, the entire Milky Way could be exchanging biotic components across vast distances. In short, they determined panspermia is viable on galactic scales, and even between galaxies. As Ginsburg said:











The Milky Way could be spreading life from star to star
An artist’s conception of a hypervelocity star that has escaped the Milky Way [Credit: NASA]

“Smaller objects are more likely to be captured. If you consider Saturn’s moon Enceladus (which is very interesting in itself) as an example, we estimate that as many as 100 million such life-bearing objects may have traveled from one system to another! Again, I think it’s important to note that our calculation is for life-bearing objects.”


The study also bolsters a possible conclusion raised in two previous studies conducted by Loeb and James Guillochon (an Einstein Fellow with the ITC) back in 2014. In the first study, Loeb and Guillochon traced the presence of hypervelocity stars (HVSs) to galactic mergers, which caused them to leave their respective galaxies at semi-relativistic speeds – one-tenth to one-third the speed of light.


In the second study, Guillochon and Loeb determined that there are roughly a trillion HVSs in intergalactic space and that hypervelocity stars could bring their planetary systems along with them. These systems would therefore be capable of spreading life (which could even take the form of advanced civilizations) from one galaxy to another.


“In principle, life could even be transferred between galaxies, since some stars escape from the Milky Way,” said Loeb. “Several years ago, we showed with Guillochon that the universe is full of a sea of stars that were ejected from galaxies at speeds up to a fraction of the speed of light through pairs of massive black holes (formed during galaxy mergers) which act as slingshots. These stars could potentially transfer life throughout the universe.”











The Milky Way could be spreading life from star to star
In addition to small objects (like meteoriods), life could be distributed throughout our galaxy by interstellar asteroids,
and between galaxies by stars systems [Credit: NASA/Jenny Mottor]

As it stands, this study is sure to have immense implications for our understanding of life as we know it. Rather than coming to Earth on a meteorite, possibly from Mars or somewhere else in the solar system, the necessary building blocks for life could have arrived on Earth from another star system (or another galaxy) entirely.


Perhaps someday we will encounter life beyond our solar system that bears some resemblance to our own, at least at the genetic level. Perhaps we may even come across some advanced species that are distant (very distant) relatives, and collectively ponder where the basic ingredients that made us all possible came from.


Author: Matt Williams | Source: Universe Today [October 12, 2018]



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The state of the early universe: The beginning was fluid

Scientists from the Niels Bohr Institute, University of Copenhagen, and their colleagues from the international ALICE collaboration recently collided Xenon nuclei, in order to gain new insights into the properties of the Quark-Gluon Plasma (the QGP) – the matter that the universe consisted of up to a microsecond after the Big Bang.


The state of the early universe: The beginning was fluid










The state of the early universe: The beginning was fluid
Above: An event from the first Xenon-Xenon collision at the Large Hadron Collider at the top energy of the Large Hadron
 Collider (5.44 TeV ) registered by ALICE. Every colored track (The blue lines) corresponds to the trajectory of a charged
particle produced in a single collision; Below: formation of anisotropic flow in relativistic heavy-ion collisions due
to the geometry of the hot and dense overlap zone (shown in red color) [Credit: University of Copenhagen]

The QGP, as the name suggests, is a special state consisting of the fundamental particles, the quarks, and the particles that bind the quarks together, the gluons. The result was obtained using the ALICE experiment at the 27 km long superconducting Large Hadron Collider (LHC) at CERN. The result is now published in Physics Letters B.


The beginning was a liquid state of affairs


The particle physicists at the Niels Bohr Institute have obtained new results, working with the LHC, replacing the lead-ions, usually used for collisions, with Xenon-ions. Xenon is a “smaller” atom with fewer nucleons in its nucleus. When colliding ions, the scientists create a fireball that recreates the initial conditions of the universe at temperatures in excess of several thousand billion degrees.


In contrast to the Universe, the lifetime of the droplets of QGP produced in the laboratory is ultra short, a fraction of a second (In technical terms, only about 10-22 seconds). Under these conditions the density of quarks and gluons is very large and a special state of matter is formed in which quarks and gluons are quasi-free (dubbed the strongly interacting QGP). The experiments reveal that the primordial matter, the instant before atoms formed, behaves like a liquid that can be described in terms of hydrodynamics.


How to approach “the moment of creation”


“One of the challenges we are facing is that, in heavy ion collisions, only the information of the final state of the many particles which are detected by the experiments are directly available – but we want to know what happened in the beginning of the collision and first few moments afterwards”, You Zhou, Postdoc in the research group Experimental Subatomic Physics at the Niels Bohr Institute, explains. “We have developed new and powerful tools to investigate the properties of the small droplet of QGP (early universe) that we create in the experiments”.


They rely on studying the spatial distribution of the many thousands of particles that emerge from the collisions when the quarks and gluons have been trapped into the particles that the Universe consists of today. This reflects not only the initial geometry of the collision, but is sensitive to the properties of the QGP. It can be viewed as a hydrodynamical flow.” The transport properties of the Quark-Gluon Plasma will determine the final shape of the cloud of produced particles, after the collision, so this is our way of approaching the moment of QGP creation itself”, You Zhou says.


Two main ingredients in the soup: Geometry and viscosity


The degree of anisotropic particle distribution – the fact that there are more particles in certain directions – reflects three main pieces of information: The first is, as mentioned, the initial geometry of the collision. The second is the conditions prevailing inside the colliding nucleons. The third is the shear viscosity of the Quark-Gluon Plasma itself. Shear viscosity expresses the liquid’s resistance to flow, a key physical property of the matter created. “It is one of the most important parameters to define the properties of the Quark-Gluon Plasma”, You Zhou explains, ” because it tells us how strongly the gluons bind the quarks together “.


The Xenon experiments yield vital information to challenge theories and models


“With the new Xenon collisions, we have put very tight constraints on the theoretical models that describe the outcome. No matter the initial conditions, Lead or Xenon, the theory must be able to describe them simultaneously. If certain properties of the viscosity of the quark gluon plasma are claimed, the model has to describe both sets of data at the same time, says You Zhou. The possibilities of gaining more insight into the actual properties of the “primordial soup” are thus enhanced significantly with the new experiments. The team plans to collide other nuclear systems to further constrain the physics, but this will require significant development of new LHC beams.


Science is not a lonesome affair, far from it


“This is a collaborative effort within the large international ALICE Collaboration, consisting of more than 1800 researchers from 41 countries and 178 institutes”. You Zhou emphasised.


Source: Faculty of Science – University of Copenhagen [October 15, 2018]



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Giant planets around young star raise questions about how planets form

Researchers have identified a young star with four Jupiter and Saturn-sized planets in orbit around it, the first time that so many massive planets have been detected in such a young system. The system has also set a new record for the most extreme range of orbits yet observed: the outermost planet is more than a thousand times further from the star than the innermost one, which raises interesting questions about how such a system might have formed.











Giant planets around young star raise questions about how planets form
Artist’s impression of four gas giant in orbit around CI Tau [Credit: Amanda Smith, Institute of Astronomy,
 University of Cambridge]

The star is just two million years old — a ‘toddler’ in astronomical terms — and is surrounded by a huge disc of dust and ice. This disc, known as a protoplanetary disc, is where the planets, moons, asteroids and other astronomical objects in stellar systems form.


The star was already known to be remarkable because it contains the first so-called hot Jupiter — a massive planet orbiting very close to its parent star — to have been discovered around such a young star. Although hot Jupiters were the first type of exoplanet to be discovered, their existence has long puzzled astronomers because they are often thought to be too close to their parent stars to have formed in situ.


Now, a team of researchers led by the University of Cambridge have used the Atacama Large Millimeter/submillimeter Array (ALMA) to search for planetary ‘siblings’ to this infant hot Jupiter. Their image revealed three distinct gaps in the disc, which, according to their theoretical modelling, were most likely caused by three additional gas giant planets also orbiting the young star. Their results are reported in The Astrophysical Journal Letters.


The star, CI Tau, is located about 500 light years away in a highly-productive stellar ‘nursery’ region of the galaxy. Its four planets differ greatly in their orbits: the closest (the hot Jupiter) is within the equivalent of the orbit of Mercury, while the farthest orbits at a distance more than three times greater than that of Neptune. The two outer planets are about the mass of Saturn, while the two inner planets are respectively around one and 10 times the mass of Jupiter.


The discovery raises many questions for astronomers. Around 1% of stars host hot Jupiters, but most of the known hot Jupiters are hundreds of times older than CI Tau. “It is currently impossible to say whether the extreme planetary architecture seen in CI Tau is common in hot Jupiter systems because the way that these sibling planets were detected — through their effect on the protoplanetary disc — would not work in older systems which no longer have a protoplanetary disc,” said Professor Cathie Clarke from Cambridge’s Institute of Astronomy, the study’s first author.


According to the researchers, it is also unclear whether the sibling planets played a role in driving the innermost planet into its ultra-close orbit, and whether this is a mechanism that works in making hot Jupiters in general. And a further mystery is how the outer two planets formed at all.


“Planet formation models tend to focus on being able to make the types of planets that have been observed already, so new discoveries don’t necessarily fit the models,” said Clarke. “Saturn mass planets are supposed to form by first accumulating a solid core and then pulling in a layer of gas on top, but these processes are supposed to be very slow at large distances from the star. Most models will struggle to make planets of this mass at this distance.”


The task ahead will be to study this puzzling system at multiple wavelengths to get more clues about the properties of the disc and its planets. In the meantime, ALMA — the first telescope with the capability of imaging planets in the making — will likely throw out further surprises in other systems, re-shaping our picture of how planetary systems form.


Source: University of Cambridge [October 15, 2018]




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Charcoal inscription points to date change for Pompeii eruption

The volcanic eruption that destroyed the ancient Roman city of Pompeii probably took place two months later than previously thought, Italian officials said on Tuesday.











Charcoal inscription points to date change for Pompeii eruption
Charcoal inscription dating the eruption of Vesuvius to October
[Credit: Ciro Fusco/ANSA]

Historians have traditionally dated the disaster to Aug. 24 79 AD, but excavations on the vast site in southern Italy have unearthed a charcoal inscription written on a wall that includes a date which corresponds to Oct. 17.


The writing came from an area in a house that was apparently being renovated just before the nearby Mount Vesuvius erupted, burying Pompeii under a thick blanket of ash and rock.


“Being charcoal, fragile and evanescent, which could not last a long time, it is more than likely that it was written in October 79 AD,” said Massimo Osanna, head of the Pompeii site.


The Aug. 24 date derives from an account of the blast given by Pliny the Younger, who witnessed the eruption and wrote about it almost 30 years after the event in two letters to his friend, the Roman historian Tacitus.











Charcoal inscription points to date change for Pompeii eruption
Charcoal inscription dating the eruption of Vesuvius to October
[Credit: Ciro Fusco/ANSA]

However, previous excavations have uncovered a calcified branch bearing berries that normally only come out in autumn. The discovery of some braziers over the years also suggested the disaster did not strike at the height of summer.


Osanna suggested the correct date might have been Oct. 24.


Showing off the faint writing on an uncovered white wall, Culture Minister Alberto Bonisoli hailed it as an “extraordinary discovery”.


“Today, with a lot of humility, maybe we’re rewriting the history books because we’re dating the eruption to the second half of October,” Bonisoli said.


Source: Reuters [October 16, 2018]



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HiPOD (17 October 2018): A Possible Carbonate-Rich Butte   – The…




HiPOD (17 October 2018): A Possible Carbonate-Rich Butte


   – The hydration signature in this observation is definite. (259 km above the surface. Black and white is less than 5 km across; enhanced color is less than 1 km).


NASA/JPL/University of Arizona


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