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  • richardmitnick 10:22 am on July 23, 2017 Permalink | Reply
    Tags: Astro Watch, , , , , , , , FDM-Fuzzy Dark Matter, Lyman-alpha forest   

    From Astro Watch: “Flashes of Light on the Dark Matter” 

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    Astro Watch

    July 23, 2017
    No writer credit found

    1

    A web that passes through infinite intergalactic spaces, a dense cosmic forest illuminated by very distant lights and a huge enigma to solve. These are the picturesque ingredients of a scientific research – carried out by an international team composed of researchers from the International School for Adavnced Studies (SISSA) and the Abdus Salam International Center for Theoretical Physics (ICTP) in Trieste, the Institute of Astronomy of Cambridge and the University of Washington – that adds an important element for understanding one of the fundamental components of our Universe: the dark matter.

    In order to study its properties, scientists analyzed the interaction of the “cosmic web” – a network of filaments made up of gas and dark matter present in the whole Universe – with the light coming from very distant quasars and galaxies. Photons interacting with the hydrogen of the cosmic filaments create many absorption lines defined “Lyman-alpha forest”. This microscopic interaction succeeds in revealing several important properties of the dark matter at cosmological distances. The results further support the theory of Cold Dark Matter, which is composed of particles that move very slowly. Moreover, for the first time, they highlight the incompatibility with another model, i.e. the Fuzzy Dark Matter, for which dark matter particles have larger velocities. The research was carried out through simulations performed on international parallel supercomputers and has recently been published in Physical Review Letters.

    Although constituting an important part of our cosmos, the dark matter is not directly observable, it does not emit electromagnetic radiation and it is visible only through gravitational effects. Besides, its nature remains a deep mystery. The theories that try to explore this aspect are various. In this research, scientists investigated two of them: the so-called Cold Dark Matter, considered a paradigm of modern cosmology, and an alternative model called Fuzzy Dark Matter (FDM), in which the dark matter is deemed composed of ultralight bosons provided with a non-negligible pressure at small scales. To carry out their investigations, scientists examined the cosmic web by analyzing the so-called Lyman-alpha forest. The Lyman-alpha forest consists of a series of absorption lines produced by the light coming from very distant and extremely luminous sources, that passes through the intergalactic space along its way toward the earth’s telescopes. The atomic interaction of photons with the hydrogen present in the cosmic filaments is used to study the properties of the cosmos and of the dark matter at enormous distances.

    Through simulations carried out with supercomputers, researchers reproduced the interaction of the light with the cosmic web. Thus they were able to infer some of the characteristics of the particles that compose the dark matter. More in particular, evidence showed for the first time that the mass of the particles, which allegedly compose the dark matter according to the FDM model, is not consistent with the Lyman-alpha Forest observed by the Keck telescope (Hawaii, US) and the Very Large Telescope (European Southern Observatory, Chile).


    Keck Observatory, Maunakea, Hawaii, USA

    ESO/VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level

    Basically, the study seems not to confirm the theory of the Fuzzy Dark Matter. The data, instead, support the scenario envisaged by the model of the Cold Dark Matter.

    The results obtained – scientists say – are important as they allow to build new theoretical models for describing the dark matter and new hypotheses on the characteristics of the cosmos. Moreover, these results can provide useful indications for the realization of experiments in laboratories and can guide observational efforts aimed at making progress on this fascinating scientific theme.

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  • richardmitnick 5:30 pm on July 7, 2017 Permalink | Reply
    Tags: Astro Watch, , , , , Evidence Discovered for Two Distinct Giant Planet Populations   

    From Astro Watch: “Evidence Discovered for Two Distinct Giant Planet Populations” 

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    Astro Watch

    1

    In a paper highlighted by Astronomy & Astrophysics journal, a team of researchers from the Instituto de Astrofísica e Ciências do Espaço (IA) discovered observational evidence for the existence of two distinct populations of giant planets.

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    So far, more than 3500 planets have been detected orbiting solar type stars. Although recent results suggest that most planets in our Galaxy are rocky like Earth, a large population of giant planets, with masses that can go up to 10 or 20 times the mass of Jupiter (itself 320 times the mass of the Earth), was also discovered.

    A large amount of the information about how these planets are formed is coming from the analysis of the connection between the planets and their host star. Initial findings have shown, for example, that there is a tight connection between the metallicity of the star and the planet occurrence or frequency. Stellar mass has also been suggested to influence planet formation efficiency.

    State-of the art models of planet formation suggest that two main avenues exist for the formation of gas giants. The so called core-accretion process says that first you form a rocky/icy core, and then this core draws gas around it, giving origin to a giant planet. The other suggests that instabilities in the protoplanetary disk can lead to the formation of gas clumps, which then contract to form a giant planet.

    Vardan Adibekyan (IA & Universidade do Porto) comments: “Our team, using public exoplanet data, obtained an interesting observational evidence that giant planets such us Jupiter and its larger mass cousins, several thousand times more massive than the Earth (of which we do not have an example in the Solar System) form in different environments, and make two distinct populations.”

    While objects smaller than about 4 Jupiter masses show a strong preference for metal-rich stars, in the 4 to 20 Jupiter mass range, host stars tend to be more metal-poor and more massive, suggesting that these massive giant planets form with a different mechanism than their lower mass brothers. Nuno Cardoso Santos (IA & Faculdade de Ciências da Universidade do Porto) adds: “The result now published suggests that both mechanisms may be at play, the first forming the lower mass planets, and the other one responsible for the formation of the higher mass ones.”

    On one side, the lower mass giant planets (mass below 4 Jupiter masses) seem to be formed by the core-accretion process, around more metal-rich stars, while more massive planets seem to be formed mainly through gravitational instability. But Adibekyan adds that: “Although this discovery was a large and important step towards a complete understanding of planet formation, it is not the last and final one. Our team will enthusiastically continue addressing many still open questions.”

    Observations with GAIA (ESA), whose sensitivity will allow the detection of thousands of giant exoplanets in long period orbits around stars of different masses, may shed some light into this. In the near future, missions like ESA’s CHEOPS and PLATO, or NASA’s TESS, which will allow for the study of mass-radius relation, along with studies of their atmospheric composition using instruments such as ESO’s ESPRESSO at the VLT and HIRES at the ELT, or the James Webb Space Telescope (JWST), may also bring new constraints about the processes of planet formation.

    ESA/GAIA satellite

    ESA/CHEOPS

    ESA/PLATO

    NASA/TESS

    ESO/Espresso on the VLT

    NASA/ESA/CSA Webb Telescope annotated

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  • richardmitnick 4:27 pm on May 21, 2017 Permalink | Reply
    Tags: , Astro Watch, , , , , DeeDee,   

    From Astro Watch: “The Mysteries of DeeDee: One of the Solar System’s Most Distant Object Studied by Astronomers” 

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    Astro Watch

    May 21, 2017
    No writer credit found

    1
    Artist concept of the planetary body 2014 UZ224, more informally known as DeeDee. ALMA was able to observe the faint millimeter-wavelength “glow” emitted by the object, confirming it is roughly 635 kilometers across. At this size, DeeDee should have enough mass to be spherical, the criteria necessary for astronomers to consider it a dwarf planet, though it has yet to receive that official designation.
    Credit: Alexandra Angelich (NRAO/AUI/NSF)

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    Lurking somewhere beyond Neptune, the planetary body 2014 UZ224, nicknamed DeeDee, is one of the most distant objects in the solar system. Although DeeDee was lately studied by astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, this faraway dim object still holds many mysteries waiting to be uncovered.

    2014 UZ224 is a 635-kilometer-wide trans-Neptunian object (TNO), orbiting the sun every 1,136 years. The object was detected by a team of astronomers led by David Gerdes of the University of Michigan, using the 4-meter Blanco telescope at the Cerro Tololo Inter-American Observatory in Chile as part of ongoing observations for the Dark Energy Survey.


    Dark Energy Camera [DECam], built at FNAL


    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam

    They announced their discovery in October 2016 and informally dubbed the newly found TNO DeeDee, which is short for Distant Dwarf.

    Recent observations of DeeDee conducted with ALMA allowed Gerdes and his team to reveal the object’s fundamental orbital parameters as well as its size and albedo. Based on the new findings, the researchers assume that 2014 UZ224 is most likely a dwarf planet with a mixed ice-rock composition. However, more observations are needed in order to draw final conclusions about the real nature of this distant TNO.

    “We expect to make further optical observations of DeeDee with the Blanco 4-meter telescope during the Dark Energy Survey’s upcoming observing season, from August 2017 to February 2018. These observations will help refine DeeDee’s orbital parameters,” Gerdes told Astrowatch.net.

    DeeDee’s orbital and physical properties could reveal important insights about the formation of planets, including Earth. Such objects are leftovers from the formation of the solar system, thus could be real treasure troves of information regarding the history and evolution of celestial bodies.

    DeeDee is currently about 92 astronomical units (AU) away from the sun. This is roughly three times Pluto’s current distance. The object will reach it’s perihelion distance of about 38 AU in the year 2142, when due to its proximity it could be studied by a dedicated probe. Hence, the only opportunity now available to study this TNO is to employ ground-based telescopes or space observatories flying in Earth’s orbit.

    “A dedicated mission to study this object from close range is not feasible at this time. DeeDee will reach its perihelion distance of 38 AU in the year 2142. Perhaps at that point in the distant future a dedicated mission will be both practical and scientifically interesting,” Gerdes noted.

    TNOs are icy bodies in orbit beyond Neptune. Observations of these objects could provide better understanding of accretion and evolution processes that governed planetary formation in our solar system as well as in other dusty star discs. Currently, NASA’s New Horizons spacecraft, after completing its flyby of Pluto, is on its way to study such celestial body designated 2014 MU69.

    NASA/New Horizons spacecraft

    This object is about 44 AU away from the sun. New Horizons is expected to arrive there in January 2019.

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  • richardmitnick 1:56 pm on April 18, 2017 Permalink | Reply
    Tags: , Astro Watch, , , , LHCb Finds New Hints of Possible Deviations from the Standard Model, ,   

    From Astro Watch: “LHCb Finds New Hints of Possible Deviations from the Standard Model” 

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    Astro Watch

    April 18, 2017
    CERN

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    CERN LHCb

    The LHCb experiment finds intriguing anomalies in the way some particles decay. If confirmed, these would be a sign of new physics phenomena not predicted by the Standard Model of particle physics. The observed signal is still of limited statistical significance, but strengthens similar indications from earlier studies. Forthcoming data and follow-up analyses will establish whether these hints are indeed cracks in the Standard Model or a statistical fluctuation.

    Today, in a seminar at CERN, the LHCb collaboration presented new long-awaited results on a particular decay of B0 mesons produced in collisions at the Large Hadron Collider. The Standard Model of particle physics predicts the probability of the many possible decay modes of B0 mesons, and possible discrepancies with the data would signal new physics.

    In this study, the LHCb collaboration looked at the decays of B0 mesons to an excited kaon and a pair of electrons or muons. The muon is 200 times heavier than the electron, but in the Standard Model its interactions are otherwise identical to those of the electron, a property known as lepton universality. Lepton universality predicts that, up to a small and calculable effect due to the mass difference, electron and muons should be produced with the same probability in this specific B0 decay. LHCb finds instead that the decays involving muons occur less often.

    While potentially exciting, the discrepancy with the Standard Model occurs at the level of 2.2 to 2.5 sigma, which is not yet sufficient to draw a firm conclusion. However, the result is intriguing because a recent measurement by LHCb involving a related decay exhibited similar behavior.

    While of great interest, these hints are not enough to come to a conclusive statement. Although of a different nature, there have been many previous measurements supporting the symmetry between electrons and muons. More data and more observations of similar decays are needed in order to clarify whether these hints are just a statistical fluctuation or the first signs for new particles that would extend and complete the Standard Model of particles physics. The measurements discussed were obtained using the entire data sample of the first period of exploitation of the Large Hadron Collider (Run 1). If the new measurements indeed point to physics beyond the Standard Model, the larger data sample collected in Run 2 will be sufficient to confirm these effects.

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  • richardmitnick 9:06 am on March 4, 2017 Permalink | Reply
    Tags: Astro Watch,   

    From Astro Watch: “ESO Remains World’s Most Productive Ground-based Observatory” 

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    Astro Watch

    1

    A survey of peer-reviewed scientific papers published in 2016 and using data from ESO’s telescopes and instruments has shown that ESO remains the world’s most productive ground-based observatory. Astronomers used observational data from ESO facilities to produce an all-time high of 936 refereed papers last year.

    There were 565 papers credited to ESO in 2016 that used data acquired with either the Very Large Telescope (VLT) or the VLT Interferometer facilities on Cerro Paranal. The three most productive VLT instruments in terms of papers are UVES, FORS2 and VIMOS, which featured in 123, 109 and 75 papers, respectively. The MUSE and SPHERE instruments also saw large increases from the previous year. Data from the VISTA and VST survey telescopes on Cerro Paranal led to 93 and 18 papers, respectively.

    Facilities located at La Silla provided data for almost 200 papers in total. HARPS remains La Silla’s most productive instrument, with 80 papers to its name.

    European observing time with the Atacama Large Millimeter/submillimeter Array (ALMA) accounted for 129 papers in 2016, bringing to 305 the total number of such papers by the end of 2016. Observations made with the Atacama Pathfinder Experiment telescope (APEX) in ESO-APEX observing time led to 46 papers in 2016, taking the total of such papers to 301 by the end of 2016. The continued success of ALMA and APEX contributed significantly to ESO’s record-high number of publications. APEX is a collaboration between the Max Planck Institute for Radio Astronomy, the Onsala Space Observatory and ESO, and is operated by ESO on the Chajnantor Plateau in Chile’s Atacama region.

    A comparison of the number of papers produced using facilities at major observatories worldwide puts ESO’s observatories at the top of the list. Note that the methods used to obtain these numbers differ from one observatory to another, so the figures cannot be compared precisely. Nevertheless, it is clear that ESO continues to significantly surpass any other ground-based observatory and on the available figures has increased its lead over the NASA/ESA Hubble Space Telescope since 2015.

    These results highlight ESO’s major contribution to astronomical research. The publication statistics give an idea of how much scientific work is carried out with data from the individual observatories, but do not address the wider impact they have on science.

    The figures are published in the annual Basic ESO Publication Statistics published by ESO’s Library and calculated using the ESO Telescope Bibliography (telbib), a database containing refereed publications that use ESO data. ESO makes extensive efforts to identify all refereed papers that use ESO data and considers telbib essentially complete. In 2016, the 13 000th paper was added to telbib, published by a former ESO student and using data from the X-shooter and UVES instruments on the VLT.

    Interactive graphs of selected statistics are also available online. These graphs display the entire content of the telbib database, which contains records for publications from the year 1996 to the present. They can be used to explore many aspects of the publication history, including the development of science papers using data from ESO instruments and the use of archival data.

    ESO Bloc Icon

    ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

    ESO LaSilla
    ESO/Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres

    ESO VLT
    VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level

    ESO Vista Telescope
    ESO/Vista Telescope at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level

    ESO NTT
    ESO/NTT at Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres

    ESO VLT Survey telescope
    VLT Survey Telescope at Cerro Paranal with an elevation of 2,635 metres (8,645 ft) above sea level

    ALMA Array
    ALMA on the Chajnantor plateau at 5,000 metres

    ESO E-ELT
    ESO/E-ELT to be built at Cerro Armazones at 3,060 m

    ESO APEX
    APEX Atacama Pathfinder 5,100 meters above sea level, at the Llano de Chajnantor Observatory in the Atacama desert

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  • richardmitnick 11:36 am on June 4, 2016 Permalink | Reply
    Tags: Astro Watch, ,   

    From Astro Watch: “At the Cradle of Oxygen: Brand-new Detector to Reveal the Interiors of Stars” 

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    Astro Watch

    June 4, 2016
    No writer credit found

    1
    No image caption. No image credit

    The most intense source of gamma radiation constructed to date will soon become operational at the ELI Nuclear Physics research facility. It will be possible to study reactions that reveal the details of many processes occurring within stars, in particular those leading to the formation of oxygen. An important part of the equipment will rely on a particle detector built by physicists at the University of Warsaw, Poland. A prototype has recently concluded the first round of testing.

    Oxygen is essential for life: we are immersed in it yet none of it actually originates from our own planet. All oxygen was ultimately formed through thermonuclear reactions deep inside stars. Laboratory studies of the astrophysical processes leading to the formation of oxygen are extremely important. A big step forward in these studies will be possible when work commences in 2018 at the Extreme Light Infrastructure – Nuclear Physics (ELI-NP) facility near Bucharest, using a state-of-the-art source of intense gamma radiation. High energy protons will be intercepted using a specially-designed particle detector acting as a target. A demonstrator version of the detector, constructed at the Faculty of Physics, University of Warsaw (FUW), has recently completed the first round of tests in Romania.

    In terms of mass, the most abundant elements in the Universe are hydrogen (74%) and helium (24%). The percentage by mass of other, heavier elements is significantly lower: oxygen comprises just 0.85% and carbon 0.39% (in contrast, oxygen comprises 65% of the human body and carbon 18% by mass). In nature, conditions supporting the formation of oxygen are present only within evolutionarily-advanced stars which have converted almost all their hydrogen into helium. Helium becomes then their main fuel. At this stage, three helium nuclei start combining into a carbon nucleus. By adding another helium nucleus, this in turn forms an oxygen nucleus and emits one or more gamma photons.

    “Oxygen can be described as the ‘ash’ from the thermonuclear ‘combustion’ of carbon. But what mechanism explains why carbon and oxygen are always formed in stars at more or less the same proportion of 6 to 10?” asks Dr. Chiara Mazzocchi (FUW). She goes on to explain: “Stars evolve in stages. During the first stage, they convert hydrogen into helium, then helium into carbon, oxygen and nitrogen, with heavier elements formed in subsequent stages. Oxygen is formed from carbon during the helium-burning phase. The thing is that, in theory, oxygen could be produced at a faster rate. If the star were to run out of helium and shift to the next stage of its evolution, the proportions between carbon and oxygen would be different.”

    The experiments planned for ELI-NP will not actually recreate thermonuclear reactions converting carbon into oxygen and photons gamma. In fact, researchers are hoping to observe the reverse reaction: collisions between high-energy photons with oxygen nuclei to produce carbon and helium nuclei. Registering the products of this decay should make it possible to study the characteristics of the reaction and fine-tune existing theoretical models of thermonuclear synthesis.

    “We are preparing an eTPC detector for the experiments at ELI-NP. It is an electronic-readout time-projection chamber, which is an updated version of an earlier detector built at the Faculty’s Institute of Experimental Physics. The latter was successfully used by our researchers for the world’s first observations of a rare nuclear process: two-proton decay,” says Dr. Mikolaj Cwiok (FUW).

    The main element of the eTPC detector is a chamber filled with gas comprising many oxygen nuclei (e.g. carbon dioxide). The gas acts as a target. The gamma radiation beam passes through the gas, with some of the photons colliding with oxygen nuclei to produce carbon and helium nuclei. The nuclei formed through the reaction, which are charged particles, ionize the gas. In order to increase their range, the gas is kept at a reduced pressure, around 1/10 of the atmospheric one. The released electrons are directed using an electric field towards the Gas Electron Multiplier (GEM) amplification structures followed by readout electrodes. The paths of the particles are registered electronically using strip electrodes. Processing the data using specialized FPGA processors makes it possible to reconstruct the 3D paths of the particles.

    The active region of the detector will be 35x20x20 cm3, and at nominal intensity of the photon beam it should register up to 70 collisions of gamma photons with oxygen nuclei per day. Tests at ELI-NP used a demonstrator:a smaller but fully functional version of the final detector, named mini-eTPC. The device was tested with a beam of alpha particles (helium nuclei).

    “We are extremely pleased with the results of the tests conducted thus far. The demonstrator worked as we expected and successfully registered the tracks of charged particles. We are certain to use it in future research as a fully operational measuring device. In 2018, ELI-NP will be equipped with a larger detector which we are currently building at our laboratories,” adds Dr. Mazzocchi.

    The project is carried out in collaboration with researchers from ELI-NP/IFIN-HH (Magurele, Romania) and the University of Connecticut in the US. The Warsaw team, led by Prof. Wojciech Dominik, brings together physicists and engineers from the Division of Particles and Fundamental Interactions and the Nuclear Physics Division and students from the University of Warsaw: Jan Stefan Bihalowicz, Jerzy Manczak, Katarzyna Mikszuta and Piotr Podlaski.

    Extreme Light Infrastructure (ELI) is a research project valued at 850 million euro, conducted as part of the European Strategy Forum on Research Infrastructures roadmap. The ELI scientific consortium will encompass three centers in the Czech Republic, Romania and Hungary, focusing on research into the interactions between light and matter under the conditions of the most powerful photon beams and at a wide range of wavelengths and timescales measured in attoseconds (a billionth of a billionth of a second). The Romanian ELI – Nuclear Physics center, in Magurele near Bucharest, conducts research into two sources of radiation: high-intensity radiation lasers (of the order of a 1023 watts per square centimeter), and high-intensity sources of monochromatic gamma radiation. The gamma beam will be formed by scattering laser light off the electrons accelerated by a linear accelerator to speeds nearing the speed of light.

    Credit: fuw.edu.pl
    Dr. Chiara Mazzocchi
    Institute of Experimental Physics, Faculty of Physics, University of Warsaw
    tel. +48 22 5532666
    email: chiara.mazzocchi@fuw.edu.pl

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  • richardmitnick 2:47 pm on May 27, 2016 Permalink | Reply
    Tags: Astro Watch, , , Mysterious Changes in the Bright Spots on Ceres   

    From Astro Watch: “Life on Ceres? Mysterious Changes in the Bright Spots Still Baffle Scientists” 

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    Astro Watch

    May 26, 2016

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    No image caption. No image credit.

    Bright spots on the dwarf planet Ceres continue to puzzle researchers. When recently a team of astronomers led by Paolo Molaro of the Trieste Astronomical Observatory in Italy, conducted observations of these features, they found out something unexpected. The scientists were surprised to detect that the spots brighten during the day and also show other variations. This variability still remains a mystery.

    The bright features have been discovered by NASA’s Dawn spacecraft which is orbiting this dwarf planet, constantly delivering substantial information about it.

    NASA/Dawn Spacescraft
    NASA/Dawn Spacescraft

    These spots reflect far more light than their much darker surroundings. The composition of these features is discussed as the scientists debate if they are made of water ice, of evaporated salts, or something else.

    Molaro and his colleagues studied the spots on Ceres in July and August 2015, using the High Accuracy Radial velocity Planet Searcher (HARPS), as was reported by the European Southern Observatory (ESO) earlier this year.

    ESO/HARPS
    ESO 3.6m telescope & HARPS at LaSilla
    ESO 3.6m telescope & HARPS at LaSilla

    This instrument, mounted on ESO’s 3.6m telescope at La Silla Observatory in Chile, enables measurements of radial velocities with the highest accuracy currently available.

    ESO 3.6 meter telescope interior
    ESO 3.6 meter telescope at LaSilla interior

    By utilizing HARPS, the researchers found out unexpected changes in the mysterious bright spots. However, at the beginning they thought that it was an instrumental problem. But after double checking, they had to conclude that the radial velocity anomalies were likely real. Then the team noticed that they were connected to periods of time when the bright spots in the Occator crater were visible from the Earth. So the scientists made an association between them.

    However, these detected variations still continue to perplex the astronomers as they haven’t found a plausible explanation for their occurrence.

    “We know nothing about these changes, really. And this increases the mystery of these spots,” Molaro told Astrowatch.net.

    One of the proposed hypotheses is that the observed changes could be triggered by the presence of volatile substances that evaporate due to solar radiation. When the spots are on the side illuminated by the sun they form plumes that reflect sunlight very effectively. The scientists suggest that these plumes then evaporate quickly, lose reflectivity and produce the observed changes.

    “It is already well known that a lot of water hides beneath the surface of Ceres, so water ice or clathrates hydrates are the most natural hypotheses. But a proper answer will be hopefully provided by scientists working in the Dawn team in the coming months,” Molaro said.

    He noted that the indication of variability needs to be confirmed by direct imaging of Occator’s bright spot at the highest available spatial resolution.

    “This kind of measurements are underway. I would say that the detection of a variability improves our ignorance rather than our understanding of this planetary body,” Molaro revealed.

    The team is currently applying for further observations by the end of this year to repeat in a more systematical way what they have done in their pilot project. An important aspect of their work is to have shown a new way to study Ceres from ground, which could turn out to be useful even after the end of the Dawn mission. However by now, they are eager to see the results from the Dawn spacecraft in the next months.

    If the team’s theory is confirmed, Ceres would seem to be internally active. While this dwarf planet is known to be rich in water, it is unclear whether this is related to the bright spots. It is also still debated if Ceres due to its vast reservoir of water, could be a suitable place to host microbial life.

    “Life as we know it on Earth needs liquid water, biogenic elements and a stable source of energy. Is Ceres a good place to have these things simultaneously and for a substantial amount of time, like billions of years? Nobody knows at the moment,” Molaro concluded.

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  • richardmitnick 8:33 pm on May 12, 2016 Permalink | Reply
    Tags: Astro Watch, , , Leoncino - Small Blue Galaxy   

    From Astro Watch: “Small Blue Galaxy Could Shed New Light on Big Bang” 

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    Astro Watch

    1

    May 12, 2016
    No writer credit found

    A faint blue galaxy about 30 million light-years from Earth and located in the constellation Leo Minor could shed new light on conditions at the birth of the universe. Astronomers at Indiana University recently found that a galaxy nicknamed Leoncino, or “little lion,” contains the lowest level of heavy chemical elements, or “metals,” ever observed in a gravitationally bound system of stars.

    The study* appears today in the Astrophysical Journal. The lead author on the paper is Alec S. Hirschauer, a graduate student in the IU Bloomington College of Arts and Sciences’ Department of Astronomy. Other IU authors on the paper are professor John J. Salzer and associate professor Katherine L. Rhode in the Department of Astronomy.

    “Finding the most metal-poor galaxy ever is exciting since it could help contribute to a quantitative test of the Big Bang,” Salzer said. “There are relatively few ways to explore conditions at the birth of the universe, but low-metal galaxies are among the most promising.”

    This is because the current accepted model of the start of the universe makes clear predictions about the amount of helium and hydrogen present during the Big Bang, and the ratio of these atoms in metal-poor galaxies provides a direct test of the model.

    In astronomy, any element other than hydrogen or helium is referred to as a metal. The elemental make-up of metal-poor galaxies is very close to that of the early universe.

    To find these low-metal galaxies, however, astronomers must look far from home. Our own Milky Way galaxy is a poor source of data due to the high level of heavier elements created over time by “stellar processing,” in which stars churn out heavier elements through nucleosynthesis and then distribute these atoms back into the galaxy when they explode as supernovae.

    “Low metal abundance is essentially a sign that very little stellar activity has taken place compared to most galaxies,” Hirschauer said.

    Leoncino is considered a member of the “local universe,” a region of space within about 1 billion light years from Earth and estimated to contain several million galaxies, of which only a small portion have been cataloged. A galaxy previously recognized to possess the lowest metal abundance was identified in 2005; however, Leoncino has an estimated 29 percent lower metal abundance.

    The abundance of elements in a galaxy is estimated based upon spectroscopic observations, which capture the light waves emitted by these systems. These observations allow astronomers to view the light emitted by galaxies like a rainbow created when a prism disperses sunlight.

    Regions of space that form stars, for example, emit light that contains specific types of bright lines, each indicating the atoms from various gases: hydrogen, helium, oxygen, nitrogen and more. In the light of the star-forming region in Leoncino, IU scientists detected lines from these elements, after which they used the laws of atomic physics to calculate the abundance of specific elements.

    “A picture is worth a thousand words, but a spectrum is worth a thousand pictures,” Salzer said. “It’s astonishing the amount of information we can gather about places millions of light years away.”

    The study’s observations were made by spectrographs on two telescopes in Arizona: the Mayall 4-meter telescope at the Kitt Peak National Observatory and the Multiple Mirror Telescope at the summit of Mount Hopkins near Tucson.

    NOAO Mayall 4 m telescope exterior
    NOAO Mayall 4 m telescope interior
    NOAO Mayall 4 m telescope at Kitt Peak, Arizona, USA

    MMT Telescope at the summit of Mount Hopkins near Tucson, Arizona, USA
    MMT Telescope interior
    MMT Telescope at the summit of Mount Hopkins near Tucson, Arizona, USA

    The galaxy was originally discovered by Cornell University’s Arecibo Legacy Fast ALFA, or ALFALFA, radio survey project.

    NAIC/Arecibo Observatory, Puerto Rico, USA
    NAIC/Arecibo Observatory, Puerto Rico, USA

    Officially, the “little lion” is named AGC 198691. The scientists who conducted the metal abundance analysis nicknamed the galaxy Leoncino in honor of both its constellation location and in recognition of the Italian-born radio astronomer, Riccardo Giovanelli, who led the group that first identified the galaxy.

    Aside from low levels of heavier elements, Leoncino is unique in several other ways. A so-called “dwarf galaxy,” it’s only about 1,000 light years in diameter and composed of several million stars. The Milky Way, by comparison, contains an estimated 200 billion to 400 billion stars. Leoncino is also blue in color, due to the presence of recently formed hot stars, but surprisingly dim, with the lowest luminosity level ever observed in a system of its type.

    “We’re eager to continue to explore this mysterious galaxy,” said Salzer, who is pursuing observing time on other telescopes, including the Hubble Space Telescope, to delve deeper into this fascinating object. “Low-metal-abundance galaxies are extremely rare, so we want to learn everything we can.”

    NASA/ESA Hubble Telescope
    NASA/ESA Hubble Telescope

    Other authors on the paper are Evan D. Skillman of the University of Minnesota; Danielle Berg of the University of Wisconsin Milwaukee; Kristen B.W. McQuinn of the University of Texas at Austin; John M. Cannon and Alex J.R. Gordon of Macalester College in St. Paul, Minn.; Martha P. Haynes and Riccardo Giovanelli of Cornell University; Elizabeth A.K. Adams of the Netherlands Institute for Radio Astronomy; Steven Janowiecki of the University of Western Australia; Richard W. Pogge and Kevin V. Croxall of The Ohio State University; and Erik Aver of Gonzaga University.

    This research was supported in part by the National Science Foundation, the National Aeronautics and Space Administration and the Brinson Foundation.

    Credit: indiana.edu

    *Science paper:
    ALFALFA DISCOVERY OF THE MOST METAL-POOR GAS-RICH GALAXY KNOWN: AGC 198691

    See the full article here .

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  • richardmitnick 9:46 am on May 2, 2016 Permalink | Reply
    Tags: Astro Watch, , ,   

    From Astro Watch: “NASA’s WFIRST Spacecraft Expected to Be a Huge Step Forward in Our Understanding of Dark Matter” 

    Astro Watch bloc

    Astro Watch

    NASA/WFIRST telescope
    NASA/WFIRST telescope

    NASA’s Wide Field Infrared Survey Telescope (WFIRST) could be a space observatory of the future, destined for great discoveries in the field of astrophysics. With a view about 100 times bigger than that of the iconic Hubble Space Telescope, WFIRST is expected to yield crucial results about the still-elusive dark matter and dark energy.

    NASA/ESA Hubble Telescope
    NASA/ESA Hubble Telescope

    Perplexing astronomers for years, dark matter and dark energy could soon reveal their real nature. WFIRST is currently being designed to address the most baffling questions about these mysterious substances, together accounting for about 95 percent of the mass-energy of the universe. The spacecraft could provide a major improvement in our understanding of this subject.

    “WFIRST will survey large areas of the sky measuring the effects of dark matter on the distribution of galaxies in the universe. It will also observe distant Type Ia supernovae to use them as tracers of dark matter and dark energy. It will provide a huge step forward in our understanding of dark matter and dark energy,” Brooke Hsu of NASA’s Goddard Space Flight Center in Greenbelt, Md. told Astrowatch.net.

    WFIRST is managed at Goddard, with participation by the Jet Propulsion Laboratory (JPL) in Pasadena, California, the Space Telescope Science Institute in Baltimore, the Infrared Processing and Analysis Center, also in Pasadena, and a science team comprised of members from U.S. research institutions across the country.

    The spacecraft is currently in Phase A of preparations. The purpose of this phase is to develop the mission requirements and architecture necessary to meet the programmatic requirements and constraints on the project and to develop the plans for the Preliminary Design phase. The preparations are on track for a mid-2020 launch. After liftoff, the telescope will travel to a gravitational balance point known as Earth-Sun L2, located about one million miles from Earth in a direction directly opposite the Sun.

    LaGrange Points map
    LaGrange Points map

    Operating at L2, WFIRST will study dark matter and dark energy with several techniques. The High Latitude Spectroscopic Survey will measure accurate distances and positions of a very large number of galaxies. It will measure the growth of large structure of the universe, testing theory of Einstein’s General Relativity.

    “It will perform large surveys of galaxies and galaxy clusters to see the effects of dark matter and energy on their shapes and distributions in the universe. All told, more than a billion galaxies will be observed by WFIRST,” Hsu revealed.

    The spacecraft will conduct the Type Ia Supernovae (SNe) Survey which will use type Ia SNe as “standard candles” to measure absolute distances. Calculating the distance to and redshift of the SNe provides another means of measuring the evolution of dark energy over time, providing a cross-check with the high latitude surveys.

    “It will observe Type Ia supernovae to determine their distance and properties. More than 2,000 supernovae will be observed,” Hsu said.

    WFIRST will also carry out the High Latitude Imaging Survey that will measure the shapes and distances of a very large number of galaxies and galaxy clusters. This survey is expected to determine both the evolution of dark energy over time as well as provide another independent measurement of the growth of large structure of the universe.

    But WFIRST is not only about astrophysics. The infrared telescope will also have a chance to prove its usefulness as an exoplanet hunter. It will use microlensing techniques to expand our catalog of known extrasolar planets and will directly characterize these alien worlds using coronagraphy.

    “WFIRST will study exoplanets with two very different techniques: microlensing and coronagraph. The mission will stare at the a dense star region toward the direction of the center of our Milky Way galaxy to observe microlensing events. These brightenings caused when two stars exactly align and also provide a tally of the exoplanets around the stars. Over 2,000 exoplanets will be detected this way,” Hsu noted.

    To fulfill its scientific goals, WFIRST will be equipped in a 2.4-meter telescope hosting two instruments: the Wide-Field Instrument (WFI) and a high contrast coronagraph. WFI will provide the wide-field imaging and slitless spectroscopic capabilities required to perform the Dark Energy, Exoplanet Microlensing, and near-infrared (NIR) surveys while the coronagraph instrument is being designed for the exoplanet high contrast imaging and spectroscopic science.

    “The Wide Field Instrument provides wide-field imaging and spectroscopy in support of the dark energy and microlensing surveys and integral field spectroscopy in support of the supernova survey,” Hsu said.

    The coronagraph will be able to detect more than 50 exoplanets and observe their properties.

    “It will be a huge leap forward compared to current instruments. Most exciting will be spectral observations of the light from the planets to see what the properties are of the atmospheres and possibly surfaces. Searches will be made for signatures of life on the planets,” Hsu said.

    By operating WFIRST, NASA hopes to make major discoveries in the areas of dark matter and energy, exoplanets and general astrophysics. The agency expects to learn the nature of dark matter and energy to determine what they are.

    “We will survey the sky to find the most exotic and interesting galaxies, black holes, and stars. We will take a census of exoplonets that are beyond on astronomical unit from their stars, a region that Kepler is not able to survey. We will make the first sensitive direct observation of nearby exoplanets and find what their nature is and if there are signatures of life,” Hsu concluded.

    See the full article here .

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