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  • richardmitnick 11:51 am on March 28, 2020 Permalink | Reply
    Tags: "From the ground to the sky", , , , , Cosmology, , María Díaz Trigo, X-ray binary systems, XRISM is a JAXA/NASA collaborative mission with participation from the European Space Agency (ESA).   

    From ESOblog: “From the ground to the sky” 

    ESO 50 Large

    From ESOblog

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    27 March 2020. People@ESO.

    As well as being an Operations Astronomer at the ESO ALMA Regional Centre, María Díaz Trigo is a world-renowned expert in high-energy astrophysics and lends her expertise to X-ray space missions. In this week’s blog post, we find out what Maria does on a daily basis, how she fits everything in, and why she thinks it’s important that ground- and space-based astronomy evolve in parallel.

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    María Díaz Trigo

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    Artist”s impression of the black holes studied by the astronomers, using ULTRACAM attached to ESO’s Very Large Telescope [below]. The systems — designated Swift J1753.5-0127 and GX 339-4 — each contain a black hole and a normal star separated by a few million kilometres. That’s less than 10 percent of the distance between Mercury and our Sun. Because the two objects are so close to each other, a stream of matter spills from the normal star toward the black hole and forms a disc of hot gas around it. As matter collides in this so-called accretion disc, it heats up to millions of degrees. Near the black hole, intense magnetic fields in the disc accelerate some of this hot gas into tight jets that flow in opposite directions away from the black hole. The orbital period of Swift J1753.5-0127 — just 3.2 hours — is the fastest found for a black hole. The orbital period of GX 339-4, by contrast, is about 1.7 days. Credit: ESO/L. Calçada.

    Q. Firstly, could you tell us a bit about your role at ESO? What do you do on a daily basis?

    A. I’m an ALMA astronomer, meaning half of my time is dedicated to ALMA Observatory duties.

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

    This spans a range of activities, including scheduling different projects to happen at the right time, under the right conditions.

    The other half of my time is spent on my own research, where I am really free to work on whatever I want. So I focus on X-ray binary systems, which consist of either a small black hole (by which I mean around ten times the mass of the Sun!) or a neutron star, as well as a normal star. The black hole or neutron star pulls matter from the normal star. This process, called accretion, powers the most energetic phenomena in the Universe and releases a lot of X-rays. These X-rays can be observed using dedicated space telescopes, and I look at these X-ray observations together with observations of the same systems in other wavelengths of light made by telescopes on the ground. This gives me a lot of information about what’s going on in different parts of the system.

    Q. What first got you interested in astronomy?

    A. At university I specialised in particle physics, but after my master’s degree, particle physics seemed to be at the stage where the most exciting science had already been done. It is also difficult to work on your own research in particle physics; everything needs big expensive particle accelerators and extensive collaborations. So I switched to astronomy because of the amazing number of things that can be done with telescopes — both by collecting new data and by analysing data that already exist.

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    This artist’s impression shows the surroundings of a supermassive black hole, typical of that found at the heart of many galaxies. The black hole itself is surrounded by a brilliant accretion disc of very hot, infalling material and, further out, a dusty torus. There are also often high-speed jets of material ejected at the black hole’s poles that can extend huge distances into space. Observations with ALMA have detected a very strong magnetic field close to the black hole at the base of the jets and this is probably involved in jet production and collimation. Credit: ESO/L. Calçada.

    Q. And you are now an expert in high-energy astrophysics. Could you tell us a bit more about your research and why it inspires you?

    A. When a black hole or neutron star in a binary system pulls matter from a companion star, a disc forms around the black hole or neutron star, consisting of matter dragged off of the companion star, and this is what feeds the heavier object. At some point this disc is heated so much that the upper layers evaporate and matter flies away from the system in the form of winds. These winds have speeds of the order of 1000 km/s and are detected predominantly in X-rays and sometimes with telescopes that observe optical light. However, these winds are “slow” compared to the very narrow, collimated, extremely high-speed jets that are also expelled from the system and detected from radio to infrared wavelengths.

    I study these winds and jets and try to figure out how they fit in with the rest of the system. One of the biggest mysteries is how to feed black holes so that they get as big as those found at the centres of galaxies, which weigh as much as millions of Suns. Even if black holes are attracting matter from gas and stars, it seems as if a significant part of that matter is ejected in winds and possibly jets before it even gets to the black hole, so we’re still wondering how matter actually reaches the black hole so it can grow.

    Q. How does this research fit in with being a European Participating Scientist for JAXA’s X-ray Imaging and Spectroscopy Mission (XRISM)? Why did you choose to take on this role?

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    Artist’s impression of the JAXA/NASA X-ray Imaging and Spectroscopy Mission (XRISM).
    Credit: JAXA

    A. Well, I wanted to contribute to making the mission a success in getting us to the next stage of X-ray instrumentation! XRISM is a JAXA/NASA collaborative mission, with participation from the European Space Agency (ESA). It will carry a revolutionary micro-calorimeter providing a spectral resolution higher than conventional X-ray imaging spectrometers by a factor of 30. A micro-calorimeter will also be flown on ESA’s next large X-ray space mission Athena and we hope to learn lots of lessons from XRISM!

    I was selected by ESA around two years ago to represent the European scientific community on XRISM, and I mostly contribute scientific expertise in the area of X-ray binaries. I meet with a whole group of participating scientists every six months in person and monthly remotely, and we form part of the mission’s science team. We are currently considering which X-ray-emitting objects we should observe during the first six months after XRISM is launched in 2022, which will be the performance verification phase. During this period we will use the telescope to observe lots of different sources to check how the instrument fares — where it works well and where it works less well — so that the science community can prepare their own observations for the operational phase.

    Q. Do you think it’s important that ground-based astronomy and space-based astronomy evolve in parallel, with astronomers from both areas working together? If so, why?

    A. Absolutely! Astronomy is a complex science and one telescope observing one wavelength of light is not enough to have a full picture of what’s going on out there in the Universe. For example, one mystery surrounding black holes is that the supermassive black holes at the centre of galaxies emit X-rays, and so do the little black holes that I observe in binary systems, but medium-sized black holes don’t emit any X-rays! We didn’t even know whether these medium-sized black holes existed until gravitational waves allowed us to detect them for the first time. Now we can find out more about them and figure out why we don’t see any X-rays from them.

    Q. And what about collaboration between different scientific organisations? Why is this important?

    A. Knowledge sharing is always important. ESO and ESA have an ongoing collaboration to share knowledge and experience in the areas of science, technology and operations. This is mostly done through a working group for each of the three areas. I am part of the science working group in which we try to see where we can collaborate to advance scientific projects. For example, for some ESA space missions to achieve their full science goals, their observations are followed up by ESO’s ground-based telescopes.

    ALMA itself is a partnership between ESO, the US National Science Foundation, and Japan’s National Institute of Natural Sciences in cooperation with the Republic of Chile. So representatives from most continents are involved and the telescope is showing what can be achieved through a global collaboration. It’s hard work but very, very rewarding.

    Space missions are also becoming more complex and expensive, making it difficult for one agency alone to build and fund them. Costs and expertise have to be shared; this is demonstrated in XRISM where expertise comes from scientists around the world.

    Q. It sounds like you’ve got a lot on your plate! How do you fit everything in?

    A. (María laughs) I do what I can! It is a lot, but it’s one of the challenges that comes with working in science. The 50% of time many scientists have available to spend on “‘science” is not really all “own research time” in the end. We have to do a lot of work for the community otherwise the community can’t move forward. Being involved in advisory committees or selecting proposals from other scientists for observations with a given telescope indeed leaves less time for research, but it means that we extend and share our expertise.

    For example, for XRISM I contribute my knowledge about X-ray binaries, but there are so many other objects out there that emit X-rays. I’ve recently been learning from cosmological experts who work on very, very distant X-ray-emitting clusters of galaxies.

    Q. Finally, you’ve also got a degree in philosophy. How does that fit in with your interests in physics and understanding the Universe?

    A. Aside from being influenced by a fantastic teacher, I was always very attracted by philosophy because it’s at the core of thinking. Centuries ago, philosophers were the physicists of their times – their aim was to understand the Universe. Nowadays unfortunately we’re locked into small areas of expertise making it difficult to see the bigger picture. I found this very unsatisfactory; I can do many things to better understand my little black holes but in the end our aim is to discover why we are here and where we go now. I can’t answer these questions with my data alone.

    Seeing the bigger picture gives us a direction, something to aim for. Fortunately, we are now moving in the direction of multidisciplinary work; people from different areas are working together and combining their knowledge to solve bigger problems.

    See the full article here .


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    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 VLT at Cerro Paranal in the Atacama Desert, •ANTU (UT1; The Sun ),
    •KUEYEN (UT2; The Moon ),
    •MELIPAL (UT3; The Southern Cross ), and
    •YEPUN (UT4; Venus – as evening star).
    elevation 2,635 m (8,645 ft) from above Credit J.L. Dauvergne & G. Hüdepohl atacama photo,

    Glistening against the awesome backdrop of the night sky above ESO_s Paranal Observatory, four laser beams project out into the darkness from Unit Telescope 4 UT4 of the VLT, a major asset of the Adaptive Optics system


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

    ESO VLT 4 lasers on Yepun


    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.

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

    ESO/E-ELT,to be on top of Cerro Armazones in the Atacama Desert of northern Chile. located at the summit of the mountain at an altitude of 3,060 metres (10,040 ft).


    ESO APEXESO/MPIfR APEX high on the Chajnantor plateau in Chile’s Atacama region, at an altitude of over 4,800 m (15,700 ft)at the Llano de Chajnantor Observatory in the Atacama desert.

    A novel gamma ray telescope under construction on Mount Hopkins, Arizona. a large project known as the Cherenkov Telescope Array, composed of hundreds of similar telescopes to be situated in the Canary Islands and Chile. The telescope on Mount Hopkins will be fitted with a prototype high-speed camera, assembled at the University of Wisconsin–Madison, and capable of taking pictures at a billion frames per second. Credit: Vladimir Vassiliev

     
  • richardmitnick 11:37 am on March 27, 2020 Permalink | Reply
    Tags: , , , , , Cosmology, , ,   

    From AAS NOVA: ” Signals from Neutron Star Binaries” 

    AASNOVA

    From AAS NOVA

    27 March 2020
    Tarini Konchady

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    Artist’s illustration of a binary star system consisting of two highly magnetized neutron stars. [John Rowe Animations]

    Fast radio bursts (FRBs) are brief radio signals that last on the order of milliseconds. They appear to be extragalactic, coming from small, point-like areas on the sky. Some FRBs are one-off events, while others are periodic or “repeating”. The sources of FRBs are still unknown, but binary neutron star systems might be a piece of the puzzle.

    Wanted: A Reliable Source of Repeating Fast Radio Bursts

    Any proposed model for a repeating FRB must explain a number of observed behaviors. Among them are the following:

    Repeating bursts from a given FRB source are consistent in frequency and overall intensity on the timescale of years.
    Bursts exhibit small-scale variations in measures of the source’s magnetic environment.
    FRBs seem to be preferentially hosted in massive, Milky-Way-like galaxies.

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    Example of an FRB from a repeating source, showing the intensity and various frequencies contained in a single burst (darker means more intense, lighter means less intense). The red lines just below and above 550 MHz and those near 450 MHz and 650 MHz indicate frequencies that were unused due to other radio signals interfering [adapted from the CHIME/FRB Collaboration, Andersen et al. 2019].

    CHIME Canadian Hydrogen Intensity Mapping Experiment -A partnership between the University of British Columbia, the University of Toronto, McGill University, Yale and the National Research Council in British Columbia, at the Dominion Radio Astrophysical Observatory in Penticton, British Columbia, CA Altitude 545 m (1,788 ft)

    Binary neutron stars (BNSs) have been considered as possible solutions to the repeating FRB puzzle. Specifically, binary neutron star mergers might produce FRBs, along with gamma-ray bursts and gravitational waves. But how could BNSs produce repeating, consistent FRBs?

    In a recent study, Bing Zhang (University of Nevada Las Vegas; Kyoto University, Japan) attempts to explain repeating FRBs using BNSs in a novel way. Instead of considering the neutron-star merger itself, Zhang examined whether the years leading up to the merger could produce repeating FRBs.

    A Magnetic Dance

    Repeating FRBs put out an enormous amount of energy over a few milliseconds — at least as much energy as the Sun puts out over three days. To put constraints on the average FRB-producing BNS, Zhang used the double-pulsar system PSR J0737-3039A/B (pulsars are fast-rotating neutron stars with strong magnetic fields), which is very well characterized in terms of its component stars and overall structure.

    Aside from having enormous amounts of rotational energy intrinsically and in their orbits, BNSs also have strong magnetic fields. These magnetic fields are key to the production of FRBs in Zhang’s scenario — as the neutron stars orbit each other, their magnetic fields interact, possibly triggering a flow of particles that would produce FRBs.

    On the scale of centuries or even decades pre-merger, these triggers could occur repeatedly and consistently, satisfying a key requirement for repeating FRBs. This picture of interacting magnetic fields would also explain the small-scale variations in the magnetic environment measures, and there is an overlap between the sorts of galaxies that host FRBs and those that host the gamma-ray bursts that could be associated with BNS mergers.

    By Way of Gravitational Waves

    An observational test for this scenario is the detection of gravitational waves from an FRB source. Space-based gravitational wave detectors, such as the Laser Interferometer Space Antenna, would be well-suited for this.

    Gravity is talking. Lisa will listen. Dialogos of Eide

    ESA/NASA eLISA space based, the future of gravitational wave research

    Ground-based detectors would also play a role, picking up waves from the BNSs actually merging.

    MIT /Caltech Advanced aLigo


    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    And of course, the more FRBs we observe, the more we can narrow down their properties and sources. Fortunately, the Canadian Hydrogen Intensity Mapping Experiment (CHIME) is predicted to detect 2 to 50 FRBs per day, and other radio telescopes are hard at work as well. So maybe this FRB mystery will be solved sooner than we think!

    Citation

    “Fast Radio Bursts from Interacting Binary Neutron Star Systems,” Bing Zhang 2020 ApJL 890 L24.

    https://iopscience.iop.org/article/10.3847/2041-8213/ab7244

    See the full article here .


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    AAS Mission and Vision Statement

    The mission of the American Astronomical Society is to enhance and share humanity’s scientific understanding of the Universe.

    The Society, through its publications, disseminates and archives the results of astronomical research. The Society also communicates and explains our understanding of the universe to the public.
    The Society facilitates and strengthens the interactions among members through professional meetings and other means. The Society supports member divisions representing specialized research and astronomical interests.
    The Society represents the goals of its community of members to the nation and the world. The Society also works with other scientific and educational societies to promote the advancement of science.
    The Society, through its members, trains, mentors and supports the next generation of astronomers. The Society supports and promotes increased participation of historically underrepresented groups in astronomy.
    The Society assists its members to develop their skills in the fields of education and public outreach at all levels. The Society promotes broad interest in astronomy, which enhances science literacy and leads many to careers in science and engineering.

    Adopted June 7, 2009

     
  • richardmitnick 10:48 am on March 27, 2020 Permalink | Reply
    Tags: "ALMA Resolves Gas Impacted by Young Jets from Supermassive Black Hole", , , , , Cosmology,   

    From ALMA: “ALMA Resolves Gas Impacted by Young Jets from Supermassive Black Hole” 

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

    From ALMA

    Nicolás Lira
    Education and Public Outreach Coordinator
    Joint ALMA Observatory, Santiago – Chile
    Phone: +56 2 2467 6519
    Cell phone: +56 9 9445 7726
    Email: nicolas.lira@alma.cl

    Masaaki Hiramatsu
    Education and Public Outreach Officer, NAOJ Chile
    Observatory
, Tokyo – Japan
    Phone: +81 422 34 3630
    Email: hiramatsu.masaaki@nao.ac.jp

    Bárbara Ferreira
    ESO Public Information Officer
    Garching bei München, Germany
    Phone: +49 89 3200 6670
    Email: pio@eso.org

    Iris Nijman
    Public Information Officer
    National Radio Astronomy Observatory Charlottesville, Virginia – USA
    Cell phone: +1 (434) 249 3423
    Email: alma-pr@nrao.edu

    1
    Reconstructed images of what MG J0414+0534 would look like if gravitational lensing effects were turned off. The emissions from dust and ionized gas around a quasar are shown in red. The emissions from carbon monoxide gas are shown in green, which have a bipolar structure along the jets. Credit: ALMA (ESO/NAOJ/NRAO), K. T. Inoue et al.

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    ALMA image of MG J0414+0534 (emissions from dust and ionized gas shown in red and emissions from carbon monoxide gas shown in green). Credit: ALMA (ESO/NAOJ/NRAO), K. T. Inoue at al.

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    Artist’s impression of MG J0414+0534. The central supermassive black hole has just emitted powerful jets, which are disturbing the surrounding gas in the host galaxy. Credit: Kindai University

    Astronomers obtained the first resolved image of disturbed gaseous clouds in a galaxy 11 billion light-years away by using the Atacama Large Millimeter/submillimeter Array (ALMA). The team found that the disruption is caused by young powerful jets ejected from a supermassive black hole residing at the center of the host galaxy. This result will cast light on the mystery of the evolutionary process of galaxies in the early Universe.

    It is commonly known that black holes exert strong gravitational attraction on surrounding matter. However, it is less well known that some black holes have fast-moving streams of ionized matter, called jets. In some nearby galaxies, evolved jets blow off galactic gaseous clouds, resulting in suppressed star formation. Therefore, to understand the evolution of galaxies, it is crucial to observe the interaction between black hole jets and gaseous clouds throughout cosmic history. However, it had been difficult to obtain clear evidence of such interaction, especially in the early Universe.

    In order to obtain such clear evidence, the team used ALMA to observe an interesting object known as MG J0414+0534. A distinctive feature of MG J0414+0534 is that the paths of light traveling from it to Earth are significantly distorted by the gravity of another ‘lensing’ galaxy between MG J0414+0534 and us, causing significant magnification.

    “This distortion works as a ‘natural telescope’ to enable a detailed view of distant objects,” says Takeo Minezaki, an associate professor at the University of Tokyo.

    Another feature is that MG J0414+0534 has a supermassive black hole with bipolar jets at the center of the host galaxy. The team was able to reconstruct the ‘true’ image of gaseous clouds as well as the jets in MG J0414+0534 by carefully accounting for the gravitational effects exerted by the intervening lensing galaxy.

    “Combining this cosmic telescope and ALMA’s high-resolution observations, we obtained exceptionally sharp vision, that is 9,000 times better than human eyesight,” adds Kouichiro Nakanishi, a project associate professor at the National Astronomical Observatory of Japan/SOKENDAI. “With this extremely high resolution, we were able to obtain the distribution and motion of gaseous clouds around jets ejected from a supermassive black hole.”

    Thanks to such a superior resolution, the team found that gaseous clouds along the jets have violent motion with speeds as high as 600 km/s, showing clear evidence of impacted gas. Moreover, it turned out that the size of the impacted gaseous clouds and the jets are much smaller than the typical size of a galaxy at this age.

    “We are perhaps witnessing the very early phase of jet evolution in the galaxy,” says Satoki Matsushita, a research fellow at Academia Sinica Institute of Astronomy and Astrophysics. “It could be as early as several tens of thousands of years after the launch of the jets.”

    “MG J0414+0534 is an excellent example because of the youth of the jets,” summarizes Kaiki Inoue, a professor at Kindai University, Japan, and the lead author of the research paper which appeared in the Astrophysical Journal Letters. “We found telltale evidence of significant interaction between jets and gaseous clouds even in the very early evolutionary phase of jets. I think that our discovery will pave the way for a better understanding of the evolutionary process of galaxies in the early Universe.”
    Additional Information

    These observation results are presented in K. T. Inoue et al. “ALMA 50-parsec resolution imaging of jet-ISM interaction in the lensed quasar MG J0414+0534” appeared in The Astrophysical Journal Letters on March 27, 2020.

    The research team members are Kaiki T. Inoue (Kindai University), Satoki Matsushita (Academia Sinica Institute of Astronomy and Astrophysics), Kouichiro Nakanishi (National Astronomical Observatory of Japan/SOKENDAI), and Takeo Minezaki (The University of Tokyo).

    See the full article here .

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    The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan.

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

    NRAO Small
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  • richardmitnick 11:01 am on March 25, 2020 Permalink | Reply
    Tags: , , , Chaos in the Universe is a feature not a bug., Cosmology, It takes as few as three gravitationally interacting bodies to break time-reversal symmetry., , The movement of the three black holes can be so enormously chaotic that something as small as the Planck length will influence the movements., The n-body problem is a famous problem in astrophysics. It arises as you add more bodies to a gravitationally interacting system., Time-reversal symmetry.   

    From Science Alert: “Just Three Orbiting Black Holes Can Break Time-Reversal Symmetry, Physicists Find” 

    ScienceAlert

    From Science Alert

    25 MARCH 2020
    MICHELLE STARR

    1
    (wragg/Getty Images)

    Most of the laws of physics don’t care which direction time is travelling. Forwards, backwards… either way, the laws work exactly the same. Newtonian physics, general relativity – time is irrelevant to the mathematics: This is called time-reversal symmetry.

    In the real Universe, things get a bit messier. And now a team of scientists led by astronomer Tjarda Boekholt of the University of Aveiro in Portugal have shown that it takes as few as three gravitationally interacting bodies to break time-reversal symmetry.

    “Hitherto, a quantitative relation between chaos in stellar dynamical systems and the level of irreversibility remained undetermined,” they wrote in their paper.

    “In this work we study chaotic three-body systems in free fall initially using the accurate and precise n-body code Brutus, which goes beyond standard double-precision arithmetic. We demonstrate that the fraction of irreversible solutions decreases as a power law with numerical accuracy.”

    The n-body problem is a famous problem in astrophysics. It arises as you add more bodies to a gravitationally interacting system.

    The movements of two bodies of comparable size in orbit around a central point are relatively simple to mathematically predict, according to Newton’s laws of motion and Newton’s law of universal gravitation.

    However, once you add another body, things become tricky. The bodies start to gravitationally perturb each others’ orbits, introducing an element of chaos into the interaction. This means that, although solutions exist for special cases, there is no one formula – under Newtonian physics or general relativity – that describes these interactions with complete accuracy.

    Even within the Solar System, which we understand pretty well, we can only predict a few million years into the future. Chaos in the Universe is a feature, not a bug.

    When running n-body simulations, physicists sometimes return time-irreversibility in their results – in other words, running the simulations backwards doesn’t get them to the original starting point.

    What has been unclear is whether this is a result of the chaos of these systems, or problems with the simulations, leading to uncertainty over their reliability.

    So, Boekholt and his colleagues designed a test to figure this out. He and computational astrophysicist Simon Portegies Zwart of Leiden University in the Netherlands previously wrote an n-body simulation code called Brutus that uses brute-force computing power to reduce the magnitude of numerical errors.

    Now, they have used it to test the time-reversibility of a three-body system.

    “Since Newton’s equations of motion are time reversible, a forward integration followed by a backward integration of the same time should recover the initial realisation of the system (albeit with a sign difference in the velocities),” they wrote in their paper.

    “The outcome of a reversibility test is thus exactly known.”

    The three bodies in the system are black holes, and they were tested in two scenarios. In the first, the black holes started from rest, moving towards each other into complicated orbits, before one of the black holes is kicked out of the system.

    The second scenario starts where the first one ends, and is run backwards in time, trying to restore the system to its initial state.

    They found that, 5 percent of the time, the simulation could not be reversed. All it took was a disturbance to the system the size of a Planck length, which, at 0.000000000000000000000000000000000016 metres, is the smallest length possible.

    “The movement of the three black holes can be so enormously chaotic that something as small as the Planck length will influence the movements,” Boekholt said. “The disturbances the size of the Planck length have an exponential effect and break the time symmetry.”

    Five percent may not seem like much, but since you can never predict which of your simulations will fall within that five percent, the researchers have concluded that n-body systems are therefore “fundamentally unpredictable”.

    And they have shown that the problem is not with the simulations after all.

    “Not being able to turn back time is no longer just a statistical argument,” Portegies Zwart said. “It is already hidden in the basic laws of nature. Not a single system of three moving objects, big or small, planets or black holes, can escape the direction of time.”

    The research has been published in the Monthly Notices of the Royal Astronomical Society.

    See the full article here .


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  • richardmitnick 9:23 am on March 25, 2020 Permalink | Reply
    Tags: "Mizar and Alcor- famous double star" easy to spot in the Big Dipper’s handle., , , , Cosmology,   

    From EarthSky: “Mizar and Alcor, famous double star” 

    1

    From EarthSky

    March 25, 2020
    Bruce McClure

    Mizar and its fainter companion star Alcor are easy to spot in the Big Dipper’s handle.

    1
    Mizar and Alcor. Image via F. Espenak/astropixels.

    Mizar and its fainter companion star Alcor are one of the most famous double stars in the sky. You’ll spot Mizar first, as the middle star of the Big Dipper’s handle. Look closely, and you’ll see Alcor right next to Mizar.

    Mizar and Alcor appear so closely linked in our sky’s dome that they’re often said to be a test of eyesight. But in fact even people with less than perfect eyesight can see the two stars, especially if they’re looking in a dark clear sky. This pair of stars in the Big Dipper’s handle is famously called “the horse and rider.” If you can’t see fainter Alcor with the unaided eye, use binoculars to see Mizar’s nearby companion.

    2
    Located in the handle of the Big Dipper, Mizar (brighter) and Alcor (fainter) are one of the most famous visual double stars in the sky. Image via ESO Online Digitized Sky Survey.

    Mizar is perhaps the Big Dipper’s most famous star, glorified in the annals of astronomy many times over. Apart from Alcor, Mizar in itself became known a double star in 1650. In fact, it was the first double star to be seen through a telescope.

    Few, if any, astronomers back then even dreamed that double stars were anything other than chance alignments of physically unrelated stars. Yet, in 1889, an instrument called a spectroscope revealed that Mizar’s brighter telescopic component consisted of two stars – making Mizar the first binary star ever discovered by spectroscopic means.

    At a later date, Mizar’s dimmer telescopic component also showed itself to be a spectroscopic binary, meaning that Mizar consists of two sets of binaries – making it a quadruple star.

    As for Alcor, it was long believed that Mizar and Alcor were not gravitationally bound and did not form a true binary star system. In 2009, though, two groups of astronomers independently reported that Alcor actually is itself a binary, consisting of Alcor A and Alcor B. Astronomers now believe that the Alcor binary system is gravitationally bound to the Mizar quadruple system – making six stars in all, where we see only two with the eye.

    Thus Mizar and Alcor not only test eyesight, but the limits of our technological vision as well.

    Bottom line: Famous double stars Mizar and Alcor are easy to find in the handle of the Big Dipper. Mizar is really four stars, and Alcor is really two stars. So what we see as two stars are really six in one!

    See the full article here .


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    Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. “Being an EarthSky editor is like hosting a big global party for cool nature-lovers,” she says.

     
  • richardmitnick 9:00 am on March 25, 2020 Permalink | Reply
    Tags: "Chinese astronomers detect gamma-ray emission from two star-forming galaxies", , , , Cosmology,   

    From phys.org: “Chinese astronomers detect gamma-ray emission from two star-forming galaxies” 


    From phys.org

    March 24, 2020
    Tomasz Nowakowski

    1
    Test statistic map in the energy band 0.3 − 500 GeV around M33. Credit: Xi et al., 2020.

    Astronomers from Nanjing University in China have detected gamma ray emission from two star-forming galaxies designated Messier 33 and Arp 299. The finding, which is detailed in a paper published March 17 on arXiv.org [https://arxiv.org/abs/2003.07830], could be helpful in improving knowledge about the origin of very high-energy emission in galaxies.

    It is believed that gamma rays in galaxies are the result of interaction of cosmic rays with the interstellar gas. Star-forming galaxies are huge reservoirs of cosmic rays and therefore could be crucial for studies of extragalactic gamma ray emission. However, the list of known star-forming galaxies detected in gamma rays is still relatively short, hence finding new ones and studying them in detail is of high importance for astronomers.

    Now, a team of astronomers led by Shao-Qiang Xi reports the detection of two star-forming galaxies in gamma rays. The discovery was made as part of a systematic search for possible gamma ray emission from galaxies in the IRAS Revised Bright Galaxies Sample, using data from NASA’s Fermi spacecraft.

    NASA/Fermi LAT


    NASA/Fermi Gamma Ray Space Telescope

    “We selected our sample galaxies from the IRAS Revised Bright Galaxies Sample, excluding the 15 IR-bright galaxies that have been detected in gamma rays with Fermi–LAT and listed in Fermi–LAT Fourth Source Catalog. We performed the standard sequence of analysis steps for each galaxies, resulting in the detection of two new gamma ray sources that are, respectively, spatially coincident with M33 and Arp 299,” the astronomers wrote in the paper.

    Messier 33 (also known as the Triangulum Galaxy) is the third largest galaxy in the Local Group.

    Local Group. Andrew Z. Colvin 3 March 2011

    It is located some 2.73 million light years from the Earth in the constellation Triangulum. The researchers measured a flux of approximately 1.28 perg/cm2/s in the energy range 0.1 − 100 GeV. This value indicates a luminosity of about 1.1 duodecillion erg/s.

    Located around 130 million light years away in the constellation Ursa Major, Arp 299 is one of the most powerful star-forming galaxies in the local universe. It is a pair of colliding galaxies in an advanced merging state, NGC 3690 to the west and IC 694 to the east, plus a small compact galaxy to the northwest. In the energy range 0.1 − 100 GeV, the flux was measured to be about 1.08 perg/cm2/s.

    What is interesting in the case of Arp 299 is that the study found evidence of flux variability in gamma ray emission from this galaxy. The astronomers explained that it may be partly due to the contribution from the obscured active galactic nuclei (AGN) in Arp 299.

    “If the variability is true, part of the emission should originate from the obscured AGN in this interacting galaxy system,” the paper reads.

    Summing up the results, the researchers concluded that the fluxes of Messier 33 and Arp 299 are consistent with the correlation between the gamma ray luminosity and the total infrared luminosity for star-forming galaxies. This supports the hypothesis that gamma ray emission from such sources is mainly due to cosmic rays interacting with the interstellar medium.

    See the full article here .

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    About Science X in 100 words
    Science X™ is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004 (Physorg.com), Science X’s readership has grown steadily to include 5 million scientists, researchers, and engineers every month. Science X publishes approximately 200 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Science X community members enjoy access to many personalized features such as social networking, a personal home page set-up, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.
    Mission 12 reasons for reading daily news on Science X Organization Key editors and writersinclude 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 8:29 am on March 24, 2020 Permalink | Reply
    Tags: "Featured Image: Evidence for Planets in Disks?", , , , , , Cosmology, Disk Substructures at High Angular Resolution (DSHARP) project   

    From AAS NOVA: “Featured Image: Evidence for Planets in Disks?” 

    AASNOVA

    From AAS NOVA

    23 March 2020
    Susanna Kohler

    1
    Disk Substructures at High Angular Resolution Project (DSHARP) ESO/ALMA

    Are baby planets responsible for the gaps and rings we’ve spotted in the disks that surround distant, young stars? A new study led by Christophe Pinte (Monash University, Australia; Univ. Grenoble Alpes, France) has found evidence supporting this theory in the images of eight circumstellar disks observed in the Disk Substructures at High Angular Resolution (DSHARP) project. DSHARP uses the Atacama Large Millimeter/submillimeter Array (ALMA) to explore the gas distributed within the disks around young stars.

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

    In the image above the left-most panel shows the 1.3-millimeter dust continuum images of five complex circumstellar disks. The panels to the right show gas measurements for each disk in different velocity channels, revealing “velocity kinks” — deviations from the normal Keplerian velocity expected from unperturbed, orbiting gas. According to Pinte and collaborators, the kinks signatures of planets that perturb the gas flow in their vicinity. For more information, check out the article below.

    Citation

    “Nine Localized Deviations from Keplerian Rotation in the DSHARP Circumstellar Disks: Kinematic Evidence for Protoplanets Carving the Gaps,” C. Pinte et al 2020 ApJL 890 L9.

    https://iopscience.iop.org/article/10.3847/2041-8213/ab6dda

    See the full article here .


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    1

    AAS Mission and Vision Statement

    The mission of the American Astronomical Society is to enhance and share humanity’s scientific understanding of the Universe.

    The Society, through its publications, disseminates and archives the results of astronomical research. The Society also communicates and explains our understanding of the universe to the public.
    The Society facilitates and strengthens the interactions among members through professional meetings and other means. The Society supports member divisions representing specialized research and astronomical interests.
    The Society represents the goals of its community of members to the nation and the world. The Society also works with other scientific and educational societies to promote the advancement of science.
    The Society, through its members, trains, mentors and supports the next generation of astronomers. The Society supports and promotes increased participation of historically underrepresented groups in astronomy.
    The Society assists its members to develop their skills in the fields of education and public outreach at all levels. The Society promotes broad interest in astronomy, which enhances science literacy and leads many to careers in science and engineering.

    Adopted June 7, 2009

     
  • richardmitnick 10:23 am on March 21, 2020 Permalink | Reply
    Tags: "Learning from LIGO’s Second Binary Neutron Star Detection", , , , , Cosmology, ,   

    From AAS NOVA: “Learning from LIGO’s Second Binary Neutron Star Detection” 

    AASNOVA

    From AAS NOVA

    20 March 2020
    Susanna Kohler

    1
    LIGO has discovered another likely binary neutron star merger — and this one has new, interesting implications. [NASA/Goddard Space Flight Center]

    In case you missed the news in January: the Laser Interferometer Gravitational-Wave Observatory (LIGO) has detected its second merger of two neutron stars — probably. In a recent publication, the collaboration details the interesting uncertainties and implications of this find.

    MIT /Caltech Advanced aLigo


    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    3
    Artist’s illustration of a binary neutron star merger. [National Science Foundation/LIGO/Sonoma State University/A. Simonnet]

    What We Saw and Why It’s Weird

    On April 25, 2019, the LIGO detector in Livingston, Louisiana, spotted a gravitational-wave signal from a merger roughly 520 million light-years away. This single-detector observation — LIGO Hanford was offline at the time, and the Virgo detector in Europe didn’t spot it — was nonetheless strong enough to qualify as a definite detection of a merger.

    Analysis of the GW190425 signal indicates that we saw the collision of a binary with a total mass of 3.3–3.7 times the mass of the Sun. While the estimated masses of the merging objects — between 1.1 and 2.5 solar masses — are consistent with the expected masses of neutron stars, that total mass measurement is much larger than any neutron star binary we’ve observed in our galaxy. We know of 17 galactic neutron star pairs with measured total masses, and these masses range from just 2.5 to 2.9 times that of the Sun. Why is GW190425 so heavy?

    What It Suggests For Formation Channels

    4
    Blue and orange curves show the estimated total mass of GW190425 under different spin assumptions. In either case, the estimated mass is dramatically different from the total masses for the known galactic population of binary neutron stars, indicated with the grey histogram bars and the dashed line. [Abbott et al. 2020]

    GW190425’s unusual mass may indicate that it formed differently from known galactic neutron star binaries.

    Theory suggests that massive, fast-merging neutron-star pairs like GW190425 could potentially result from especially low-metallicity stars evolving in close binary systems. Under the right conditions, the energetic kicks caused by supernova explosions might be suppressed, allowing the objects to stay together in the close binary even after their evolution into neutron stars.

    If this is the case, GW190425 could represent a population of binary neutron stars that we haven’t observed before. These binaries have remained invisible due to their ultra-tight orbits with sub-hour periods; the rapid accelerations of these objects would obscure their signals in pulsar surveys. The shortest-period neutron star binary we’ve detected with pulsar surveys has a period of 1.88 hours, and it won’t merge for another 46 million years. GW190425 could represent a very different binary neutron star population that’s just as common as the galactic population we know.

    What If It’s Not Neutron Stars?

    Unfortunately, the single-detector observation of GW190425 means we couldn’t pin down the gravitational-wave source’s location well — so follow-up observations haven’t yet spotted an electromagnetic counterpart like the one we had for GW170817, the first binary neutron star merger LIGO observed.

    5
    GW190425’s signal was localized to an unfortunately large area of ~16% of the sky, providing a challenge for electromagnetic and neutrino observatories hoping to discover counterparts. [Abbott et al. 2020]

    This means we’re missing outside information confirming that this was a neutron star binary; it’s therefore possible that one or both of the merging objects was actually a black hole. If so, this would be smaller than any black holes we’ve detected so far, and we would need to significantly revamp our models of black hole binary formation.

    There are clearly still a lot of open questions, but it’s early days yet! With the many recent upgrades to the LIGO and Virgo detectors, we can hope for more binary neutron star detections soon — and every new signal brings us a wealth of information in this rapidly developing field.

    Citation

    “GW190425: Observation of a Compact Binary Coalescence with Total Mass ~ 3.4 M⊙,” B. P. Abbott et al 2020 ApJL 892 L3.
    https://iopscience.iop.org/article/10.3847/2041-8213/ab75f5

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    1

    AAS Mission and Vision Statement

    The mission of the American Astronomical Society is to enhance and share humanity’s scientific understanding of the Universe.

    The Society, through its publications, disseminates and archives the results of astronomical research. The Society also communicates and explains our understanding of the universe to the public.
    The Society facilitates and strengthens the interactions among members through professional meetings and other means. The Society supports member divisions representing specialized research and astronomical interests.
    The Society represents the goals of its community of members to the nation and the world. The Society also works with other scientific and educational societies to promote the advancement of science.
    The Society, through its members, trains, mentors and supports the next generation of astronomers. The Society supports and promotes increased participation of historically underrepresented groups in astronomy.
    The Society assists its members to develop their skills in the fields of education and public outreach at all levels. The Society promotes broad interest in astronomy, which enhances science literacy and leads many to careers in science and engineering.

    Adopted June 7, 2009

     
  • richardmitnick 9:17 am on March 21, 2020 Permalink | Reply
    Tags: "Gemini Telescope Images “Minimoon” Orbiting Earth - in Color!", , , , Cosmology,   

    From Gemini Observatory: “Gemini Telescope Images “Minimoon” Orbiting Earth – in Color!” 


    Gemini Observatory
    From Gemini Observatory

    February 27, 2020

    Peter Michaud
    Public Information Officer
    NSF’s National Optical-Infrared Astronomy Research Laboratory
    Tel: +1 808 974-2510
    Cell: +1 808 936-6643
    Email: pmichaud@gemini.edu

    Grigori Fedorets
    Queen’s University Belfast
    Email: g.fedorets@qub.ac.uk

    1
    International Gemini Observatory image of 2020 CD3 (center, point source) obtained with the 8-meter Gemini North telescope [below] on Hawaii’s Maunakea. The image combines three images each obtained using different filters to produce this color composite. 2020 CD3 remains stationary in the image since it was being tracked by the telescope as it appears to move relative to the background stars, which appear trailed due to the object’s motion. Credit: The international Gemini Observatory/NSF’s National Optical-Infrared Astronomy Research Laboratory/AURA

    Gemini Observatory Image Release

    Mysterious object could be natural or human-made, more observations needed to tell the full story.

    Astronomers using the international Gemini Observatory, on Hawaii’s Maunakea, have imaged a very small object in orbit around the Earth, thought to be only a few meters across. According to Grigori Fedorets, the lead astronomer for the observations, the object could be a rare natural rocky object, or it could be something humans put into space decades ago — essentially space debris. “Either way this is a very compelling object and needs more data to determine what it is,” said Fedorets.

    The newly discovered orbiting object has been assigned the provisional designation 2020 CD3 by the International Astronomical Union’s Minor Planet Center. If it is natural in origin, such as an asteroid, then it is only the second known rocky satellite of the Earth ever discovered in space other than the Moon. The other body, discovered in 2006, has since been ejected out of Earth orbit. 2020 CD3 was discovered on the night of 15 February 2020 by Kacper Wierzchos and Teddy Pruyne at the Catalina Sky Survey operating out of the University of Arizona’s Lunar and Planetary Laboratory in Tucson Arizona.

    The image, obtained on 24 February 2020, shows simply a tiny pinpoint of light against trailing stars. “The stars are trailing because this object is moving relative to the background stars and the 8-meter Gemini North telescope was tracking on this object,” said Fedorets, adding that it is challenging to follow moving objects like this with a big telescope like Gemini. John Blakeslee, Head of Science at the international Gemini Observatory comments, “Obtaining the images was a scramble for the Gemini team because the object is quickly becoming fainter as it moves away from Earth. It is expected to be ejected from Earth’s orbit altogether in April.”

    Fedorets, an astronomer at Queen’s University Belfast, and his team are “pulling out all of the stops” to obtain more data on the object to determine its nature. “Additional observations to refine its position will help us determine this mystery object’s orbit and its possible origin,” said Fedorets, adding that its reflectivity is also an important characteristic, as rocky bodies tend to have relatively low reflectivity compared to things like spent rocket boosters.

    See the full article here .


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    Please help promote STEM in your local schools.


    Stem Education Coalition

    NOAO Gemini North on MaunaKea, Hawaii, USA, Altitude 4,213 m (13,822 ft)


    Gemini South telescope, Cerro Tololo Inter-American Observatory (CTIO) campus near La Serena, Chile, at an altitude of 7200 feet


    Gemini’s mission is to advance our knowledge of the Universe by providing the international Gemini Community with forefront access to the entire sky.

    The Gemini Observatory is an international collaboration with two identical 8-meter telescopes. The Frederick C. Gillett Gemini Telescope is located on Mauna Kea, Hawai’i (Gemini North) and the other telescope on Cerro Pachón in central Chile (Gemini South); together the twin telescopes provide full coverage over both hemispheres of the sky. The telescopes incorporate technologies that allow large, relatively thin mirrors, under active control, to collect and focus both visible and infrared radiation from space.

    The Gemini Observatory provides the astronomical communities in six partner countries with state-of-the-art astronomical facilities that allocate observing time in proportion to each country’s contribution. In addition to financial support, each country also contributes significant scientific and technical resources. The national research agencies that form the Gemini partnership include: the US National Science Foundation (NSF), the Canadian National Research Council (NRC), the Chilean Comisión Nacional de Investigación Cientifica y Tecnológica (CONICYT), the Australian Research Council (ARC), the Argentinean Ministerio de Ciencia, Tecnología e Innovación Productiva, and the Brazilian Ministério da Ciência, Tecnologia e Inovação. The observatory is managed by the Association of Universities for Research in Astronomy, Inc. (AURA) under a cooperative agreement with the NSF. The NSF also serves as the executive agency for the international partnership.

     
  • richardmitnick 5:05 pm on March 19, 2020 Permalink | Reply
    Tags: "New telescope design could capture distant celestial objects with unprecedented detail", , , , Cosmology, The Optical Society   

    From The Optical Society: “New telescope design could capture distant celestial objects with unprecedented detail” 

    From The Optical Society

    18 March 2020

    Upgraded hypertelescope could image multiple stars simultaneously and aid in search for life in other solar systems.

    1
    A new multi-field hypertelescope design could image multiple stars at once with high resolution. Hypertelescopes use large arrays of mirrors with space between them. The multi-field design could be incorporated into the hypertelescope prototype being tested in the Alps (pictured).
    Credit: Antoine Labeyrie, Collège de France and Observatoire de la Cote d’Azur

    Researchers have designed a new camera that could allow hypertelescopes to image multiple stars at once. The enhanced telescope design holds the potential to obtain extremely high-resolution images of objects outside our solar system, such as planets, pulsars, globular clusters and distant galaxies.

    “A multi-field hypertelescope could, in principle, capture a highly detailed image of a star, possibly also showing its planets and even the details of the planets’ surfaces,” said Antoine Labeyrie, emeritus professor at the Collège de France and Observatoire de la Cote d’Azur, who pioneered the hypertelescope design. “It could allow planets outside of our solar system to be seen with enough detail that spectroscopy could be used to search for evidence of photosynthetic life.”

    In The Optical Society’s (OSA) journal Optics Letters, Labeyrie and a multi-institutional group of researchers report optical modeling results that verify that their multi-field design can substantially extend the narrow field-of-view coverage of hypertelescopes developed to date.

    Making the mirror larger

    Large optical telescopes use a concave mirror to focus light from celestial sources. Although larger mirrors can produce more detailed pictures because of their reduced diffractive spreading of the light beam, there is a limit to how large these mirrors can be made. Hypertelescopes are designed to overcome this size limitation by using large arrays of mirrors, which can be spaced widely apart.

    Researchers have previously experimented with relatively small prototype hypertelescope designs, and a full-size version is currently under construction in the French Alps. In the new work, researchers used computer models to create a design that would give hypertelescopes a much larger field of view. This design could be implemented on Earth, in a crater of the moon or even on an extremely large scale in space.

    Building a hypertelescope in space, for example, would require a large flotilla of small mirrors spaced out to form a very large concave mirror. The large mirror focuses light from a star or other celestial object onto a separate spaceship carrying a camera and other necessary optical components.

    “The multi-field design is a rather modest addition to the optical system of a hypertelescope, but should greatly enhance its capabilities,” said Labeyrie. “A final version deployed in space could have a diameter tens of times larger than the Earth and could be used to reveal details of extremely small objects such as the Crab pulsar, a neutron star believed to be only 20 kilometers in size.”

    Expanding the view

    Hypertelescopes use what is known as pupil densification to concentrate light collection to form high-resolution images. This process, however, greatly limits the field of view for hypertelescopes, preventing the formation of images of diffuse or large objects such as a globular star cluster, exoplanetary system or galaxy.

    The researchers developed a micro-optical system that can be used with the focal camera of the hypertelescope to simultaneously generate separate images of each field of interest. For star clusters, this makes it possible to obtain separate images of each of thousands of stars simultaneously.

    The proposed multi-field design can be thought of as an instrument made of multiple independent hypertelescopes, each with a differently tilted optical axis that gives it a unique imaging field. These independent telescopes focus adjacent images onto a single camera sensor.

    The researchers used optical simulation software to model different implementations of a multi-field hypertelescope. These all provided accurate results that confirmed the feasibility of multi-field observations.

    Incorporating the multi-field addition into hypertelescope prototypes would require developing new components, including adaptive optics components to correct residual optical imperfections in the off-axis design. The researchers are also continuing to develop alignment techniques and control software so that the new camera can be used with the prototype in the Alps. They have also developed a similar design for a moon-based version.

    See the full article here .

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    The Optical Society (OSA) is a professional association of individuals and companies with an interest in optics and photonics. It publishes journals, and organizes conferences and exhibitions. In 2019 it had about 22,000 members in more than 100 different countries, including some 300 companies

     
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