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  • richardmitnick 2:14 pm on March 3, 2017 Permalink | Reply
    Tags: , , , , Lambda Cold Dark Matter paradigm, Seeker,   

    From Seeker: “Elusive Dwarf Galaxies Found Hidden Away in Tiny Clusters” 

    Seeker bloc

    SEEKER

    Jan 23, 2017 [Where has this been hiding?]
    IRENE KLOTZ

    The discovery of these bite-sized galaxy clusters provides a key piece of evidence for how galaxies evolve — and how dark matter might be in the middle of it all.

    1
    Photo: Robert Gendler/NASA/ESA/Hubble Heritage Team

    Computer simulations and theoretical models have shown that clusters of miniature galaxies, some 10- to 1,000 times smaller than the Milky Way, should exist, but proof has been elusive. Detections of dwarf galaxy clusters would provide key evidence that the current theory for how the universe evolved structures is correct.

    The so-called Lambda Cold Dark Matter paradigm is the prediction that smaller things merge to form bigger things, University of Virginia astronomer Sabrina Stierwalt told Seeker. But there has been scant observational evidence of this process for low-mass galaxies despite the fact that small galaxies greatly outnumber bigger ones like the Milky Way, she added.

    In paper published in this week’s Nature Astronomy, Stierwalt and colleagues describe a new hunt for dwarf galaxy clusters using data from the Sloan Digital Sky Survey.

    4
    SDSS Galaxy Map – Gallery – SDSS-III

    The team first looked for pairs of interacting dwarf galaxies, then studied those pairs to see if they could be part of a bigger group.

    Follow-up observations with the Magellan Telescope in Chile, the Apache Point Observatory in New Mexico and the Gemini North Telescope in Hawaii provided optical images and spectroscopy of additional suspected group members.

    Carnegie 6.5 meter Magellan  Baade and Clay Telescopes located at Carnegie’s Las Campanas Observatory, Chile.
    Carnegie 6.5 meter Magellan Baade and Clay Telescopes located at Carnegie’s Las Campanas Observatory, Chile

    SDSS Telescope at Apache Point Observatory, NM, USA
    SDSS Telescope at Apache Point Observatory, NM, USA

    Gemini/North telescope at Mauna Kea, Hawaii, USA
    Gemini/North telescope at Mauna Kea, Hawaii, USA

    In all, the scientists found seven groups of dwarf galaxies, each with three- to five members.

    “We suspect these groups are gravitationally bound and thus will eventually merge to form one larger, intermediate-mass galaxy,” Stierwalt said.

    The galaxies are located between 200 million and 650 million light-years from Earth.

    “That sounds like a lot but it is relatively nearby given the vast size of the universe. Dwarf galaxies are fainter and smaller than more massive galaxies like the Milky Way we reside in, and so they are harder to detect at farther distances,” Stierwalt said.

    The number of clusters matches predictions, which builds confidence in the computer models.

    “Such groups are predicted to be rare theoretically and found to be rare observationally at the current epoch,” the astronomers noted in the paper.

    The newly found dwarf galaxy groups “provide direct probes of hierarchical structure formation in action at the low mass end, giving us a new window into a process expected to be common at earlier times, but nearly impossible to observe at such redshifts,” the paper said.

    “Redshifts” is a cosmic yardstick for measuring distance and time. It refers to the lengthening of wavelengths of light as a radiating object moves farther away, similar to how the sound of a train shifts as it recedes.

    See the full article here .

    Please help promote STEM in your local schools.

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  • richardmitnick 7:38 am on October 24, 2016 Permalink | Reply
    Tags: , , Computer Glitch Nixes Juno's Run at Jupiter, , Seeker   

    From Seeker: “Computer Glitch Nixes Juno’s Run at Jupiter” 

    Seeker bloc

    SEEKER

    Oct 21, 2016
    Irene Klotz

    NASA/Juno
    NASA/Juno at Jupiter

    After a potential engine problem derailed plans for the Juno spacecraft to a tighten up its orbit as it passed close to Jupiter this week, flight controllers decided instead to use the flyby for some early science observations.

    But that plan fell apart too when an unrelated computer problem shut down Juno’s science instruments 13 hours before Wednesday’s close encounter.

    “It did exactly what it was supposed to do when it detects a condition that is not expected,” Scott Bolton, the project’s lead scientist, said at the American Astronomical Society meeting in Pasadena, Calif.

    Flight directors at NASA’s Jet Propulsion Laboratory in Pasadena are still analyzing why Juno went into what is known as “safe mode.”

    “Early indications are a software performance monitor induced a reboot of the spacecraft’s onboard computer. The spacecraft … restarted successfully and is healthy,” NASA said in a statement.

    Juno, which remains in a looping, 53-day orbit around Jupiter, won’t pass close by the planet until Dec. 11. At that time, if the engine issue is resolved, Juno could be commanded to trim its orbit so that passes close to Jupiter every 14 days.

    If the problem persists, Juno could conduct its mission from its present orbit, since the primary science observations are made when the spacecraft is closest to Jupiter — whenever that occurs.

    “A 53-day orbit has the same value that a 14-day orbit would have … The difference is how far away you get from Jupiter,” Bolton said. “The worst-case scenario is I have to be patient and get the science slowly.”

    Since arriving at Jupiter on July 4, Juno has had just one previous close encounter, an Aug. 27 flyby allowed the science team to calibrate instruments and cameras.

    That work went better than expected, giving scientists some early insights into the planet’s magnetic fields and aurora, both bigger and more powerful than previously estimated. They also got a first glimpse of what is happening beneath Jupiter’s thick clouds.

    “We are seeing that those beautiful belts and bands of orange and white we see at Jupiter’s cloud tops extend in some version as far down as our instruments can see, but seem to change with each layer,” Bolton said in a statement.

    See the full article here .

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  • richardmitnick 3:02 pm on August 28, 2016 Permalink | Reply
    Tags: , , , , , , Seeker   

    From SEEKER: “The Race to See Our Supermassive Black Hole” 

    Seeker bloc

    SEEKER

    May 26, 2016 [Article brought forward by ESO]
    No writer credit found

    Using the power of interferometry, two astronomical projects are, for the first time, close to directly observing the black hole in the center of the Milky Way.

    Sag A*  NASA Chandra X-Ray Observatory 23 July 2014, the supermassive black hole at the center of the Milky Way
    Sag A* NASA Chandra X-Ray Observatory 23 July 2014, the supermassive black hole at the center of the Milky Way

    There’s a monster living in the center of the galaxy.

    We know the supermassive black hole is there by tracking the motions of stars and gas clouds that orbit an invisible point. That point exerts an overwhelming tidal influence on all objects that get trapped in its gravitational domain and this force can be measured through stellar orbits to calculate its mass.

    It certainly isn’t the biggest black hole in the universe, but it isn’t the smallest either, it “weighs in” at an incredible 4 million times the mass of our sun.

    But this black hole behemoth, called Sagittarius A*, is over 20,000 light-years from Earth making direct observations, before now, nigh-on impossible. Despite its huge mass, the black hole is minuscule when seen from Earth; a telescope with an unprecedented angular resolution is needed.

    Though we already know a lot about Sagittarius A* from indirect observations, seeing is believing and there’s an international race, using the world’s most powerful observatories and sophisticated astronomical techniques, to zoom-in on the Milky Way’s black hole. This won’t only prove it’s really there, but it will reveal a region where space-time is so warped that we will be able to make direct tests of general relativity in the strongest gravity environment known to exist in the universe.

    The Event Horizon Telescope and GRAVITY

    A huge global effort is currently under way to link a network of global radio telescopes to create a virtual telescope that will span the width of our planet. Using the incredible power of interferometry, astronomers can combine the light from many distant radio antennae and collect it at one point, to mimic one large radio antenna spanning the globe.

    Event Horizon Telescope Array

    Event Horizon Telescope map
    Event Horizon Telescope map

    Arizona Radio Observatory
    Arizona Radio Observatory/Submillimeter-wave Astronomy (ARO/SMT)

    ESO/APEX
    Atacama Pathfinder EXperiment (APEX)

    CARMA Array no longer in service
    Combined Array for Research in Millimeter-wave Astronomy (CARMA)

    Atacama Submillimeter Telescope Experiment (ASTE)
    Atacama Submillimeter Telescope Experiment (ASTE)

    Caltech Submillimeter Observatory
    Caltech Submillimeter Observatory (CSO)

    IRAM NOEMA interferometer
    Institut de Radioastronomie Millimetrique (IRAM) 30m

    James Clerk Maxwell Telescope interior, Mauna Kea, Hawaii, USA
    James Clerk Maxwell Telescope interior, Mauna Kea, Hawaii, USA

    Large Millimeter Telescope Alfonso Serrano
    Large Millimeter Telescope Alfonso Serrano

    CfA Submillimeter Array Hawaii SAO
    Submillimeter Array Hawaii SAO

    Future Array/Telescopes

    ESO/NRAO/NAOJ ALMA Array
    ESO/NRAO/NAOJ ALMA Array, Chile

    Plateau de Bure interferometer
    Plateau de Bure interferometer

    South Pole Telescope SPTPOL
    South Pole Telescope SPTPOL

    This effort is known as the Event Horizon Telescope (EHT) and it is hoped the project will be able to attain the angular resolution and spatial definition required to soon produce its first radio observations of the bright ring just beyond Sagittarius A*’s event horizon — the point surrounding a black hole where nothing, not even light, can escape.

    However, another project has the same goal in mind, but it’s not going to observe in radio wavelengths, it’s going to stare deep into the galactic core to seek out optical and infrared light coming from Sagittarius A* and it just needs one observatory to make this goal a reality.

    1
    The ESO Very Large Telescope located atop Cerro Paranal in Chile. Ian O’Neill

    The GRAVITY instrument is currently undergoing commissioning at the ESO’s Very Large Telescope at Paranal Observatory high in the Atacama Desert in Chile (at an altitude of over 2,600 meters or 8,300 ft) and it will also use the power of interferometry to resolve our supermassive black hole. But rather than connecting global observatories like the EHT, GRAVITY will combine the light of the four 8 meter telescopes of the VLT Interferometer (collectively known as the VLTI) to create a “virtual” telescope measuring the distance between each individual telescope.

    ESO GRAVITY insrument
    ESO GRAVITY insrument

    “By doing this you can reach the same resolution and precision that you would get from a telescope that has a size, in this case, of roughly a hundred meters, simply because these eight meter-class telescopes are separated by roughly one hundred meters,” astronomer Oliver Pfuhl, of Max Planck Institute for Extraterrestrial Physics, Germany, told DNews. “If you combine the light from those you reach the same resolution as a virtual telescope of a hundred meters would have.”

    Strong Gravity Environment

    When GRAVITY is online it will be used to track features just outside Sagittarius A*’s event horizon.

    “For about ten years, we’ve known that this black hole is actually not black. Once in awhile it flares, so we see it brightening and darkening,” he said. This flaring is matter falling into the event horizon, generating a powerful flash of energy. The nature of these flares are poorly understood, but the instrument should be able to track this flaring material as it rapidly orbits the event horizon and fades away. These flares will also act as tracers, helping us see the structure of space-time immediately surrounding a black hole for the first time.

    2
    One of the four Very Large Telescope domes fires its new four-laser adaptive optics system. GRAVITY will make use of adaptive optics to improve observations of Sagittarius A* by compensating for the effects of atmospheric turbulence. ESO

    “Our goal is to measure these motions. We think that what we see as this flaring is actually gas which spirals into the black hole. This brightening and darkening is essentially the gas, when it comes too close to the black hole, the strong tidal forces make it heat up,” said Pfuhl.

    “If we can study these motions which happen so close to the black hole, we have a direct probe of the space time close to the black hole. In this way we have a direct test of general relativity in one of the most extreme environments which you can find in the universe.”

    While GRAVITY will be able to track these flaring events very close to the black hole, the Event Horizon Telescope will see the shadow, or silhouette, of the dark event horizon surrounded by radio wave emissions. Both projects will be able to measure different components of the region directly surrounding the event horizon, so combined observations in optical and radio wavelengths will complement one other.

    It just so happens that the Atacama Large Millimeter/submillimeter Array (ALMA), the largest radio observatory on the planet — also located in the Atacama Desert — will also be added to the EHT.

    “The Event Horizon Telescope will combine ALMA with telescopes around the world like Hawaii and other locations, and with that power you can look at really fine details especially in the black hole in the center of our galaxy and perhaps in some really nearby other galaxies that also have black holes in their centers,” ESO astronomer Linda Watson told DNews.

    3
    The ALMA antenna in a clustered formation on Chajnantor plateau during the #MeetESO event on May 11, 2016. The extreme location of the observatory can produce unpredictable weather and, as depicted here, a blizzard descended on the plateau cutting the visit short.
    Ian O’Neill

    ALMA itself is an interferometer combining the collecting power of 66 radio antennae located atop Chajnantor plateau some 5,000 meters (16,400 ft) in altitude. Watson uses ALMA data to study the cold dust in interstellar space, but when added to the EHT, its radio-collecting power will help us understand the dynamics of the environment surrounding Sagittarius A*.

    “ALMA’s an interferometer with 66 antennas, (the EHT) will treat ALMA as just one telescope and will combine it with other telescopes around the world to be another interferometer,” she added.

    Black Hole Mysteries

    Many black holes are thought to possess an accretion disk of swirling gas and dust. ALMA, when combined with the EHT, will be able to measure this disk’s structure, speed and direction of motion. Lacking direct observations, many of these characteristics have only been modeled by computer simulations or inferred from indirect observations. We’re about to enter an era when we can truly get to answer some of the biggest mysteries surrounding black hole dynamics.

    “The first thing we want to see is we want to understand how accretion works close to the black hole,” said Pfuhl. “This is also true for the Event Horizon Telescope. Another thing we want to learn is does our black hole have spin? That means, does it rotate?”

    Though the EHT and GRAVITY are working at different wavelengths, observing phenomena around Sagittarius A* will reveal different things about the closest supermassive black hole to Earth. By extension it is hoped that we may observe smaller black holes in our galaxy and other supermassive black holes in neighboring galaxies.

    3
    Computer simulation of what theoretical physiicists expect to see with the EHT — a round, dark disk surrounded by radio emissions.
    Avery E. Broderick/Univ. of Waterloo/Perimeter Institute (screenshot from the Convergence meeting)

    But as we patiently wait for the first direct observations of the black hole monster lurking in the center of our galaxy, an event that some scientists say will be as historic as the “Pale Blue Dot” photo of Earth as captured by Voyager 1 in 1990, it’s hard not to wonder which project will get there first.

    “I think it’s a very tight race,” said Pfuhl. “Let’s see.”

    See the full article here .

    Please help promote STEM in your local schools.

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  • richardmitnick 11:20 am on September 27, 2015 Permalink | Reply
    Tags: , , Nomads, Seeker   

    From Seeker via Discovery: “Documenting The World’s Last Nomadic Tribes” 

    Discovery News
    Discovery News

    Seeker from Discovery
    Seeker

    9.13.15
    Taylor Kubota

    Download mp4 video here.

    Native nomadic tribes are disappearing across the world. See how some photographers are trying to preserve their endangered legacies.

    1
    The Tuareg (Twareg or Touareg; endonym Imuhagh) are group of largely matrilineal semi-nomadic, pastoralist people of Berber extraction residing in the Saharan interior of North-Western Africa. The Tuaregs who are mostly Sunni Muslims descended from the Berber (“Amazigh branch”) ancestors who lived in North Africa many years ago. Migdalovitz (1989) aver that “Garamante is believed to be the origin of Tuaregs and it was the predominant tribe in the south west of Libya some time before 1000 BC.”

    We talk a lot about endangered species and disappearing environments but parts of life that are more difficult to categorize can be threatened with extinction as well. Language, customs, and traditional practices are often passed down from generation to generation but some fall by the wayside. Just because a cultural tradition is going away doesn’t mean it’s valueless. This is part of the sentiment of UNESCO’s List of Intangible Cultural Heritage in Need of Urgent Safeguarding.

    The List of Intangible Cultural Heritage in Need of Urgent Safeguarding holds 314 elements from countries all around the world. You may have heard of some of the list items -such as Chinese shadow puppetry, French horseback riding, and Colombian Marimba music – but you are unlikely to be familiar with everything on this list. For example, Jultagi (Korean tightrope walking), the Ifa divination system from Nigeria, and the silent circle dance of the Dalmatian hinterland of Croatia are just a few “intangibles” that may hold some mystery for the majority of us.

    With all the impact humans have on the natural world, it may feel misguided to focus on preserving pieces of human culture. Particularly considering these are often simply the victims of progress and modernization. But, as we all know and have each probably said ourselves, it’s vital that we learn from our history, so that we can attempt to avoid past mistakes. Attempts to preserve culture can help us in this, through the maintenance and study of oral history, unique craftsmanship, and traditional wisdoms. Studying cultural heritage can also provide us with colorful, diverse, rich experiences that can be difficult to find in the modern era.

    See the full article here .

    Please help promote STEM in your local schools.

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