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  • richardmitnick 1:47 pm on October 20, 2018 Permalink | Reply
    Tags: , , , ,   

    From NASA Spaceflight: “Ariane 5 boosts BepiColombo mission enroute to Mercury” 

    NASA Spaceflight

    From NASA Spaceflight

    October 19, 2018
    Chris Bergin

    1

    ESA JAXA Bepicolumbo in flight illustration Artist’s impression of BepiColombo – ESA’s first mission to Mercury. ESA’s Mercury Planetary Orbiter (MPO) will be operated from ESOC, Germany

    Arianespace has conducted the opening part of the BepiColombo mission with the launch of the spacecraft on a flight to study Mercury. The launch was conducted by an Ariane 5 that lifted off at 01:45 UTC on Saturday from the European Spaceport at Kourou, French Guiana.

    BepiColombo is a joint mission of the European Space Agency [ESA] and the Japan Aerospace Exploration Agency [JAXA]. It was named in honor of Italian mathematician and engineer Giuseppe “Bepi” Colombo.

    The mission has been delayed by about five years, although that is not uncommon for major flagship missions.

    BepiColombo consists of two orbiters: Japan’s Mercury Magnetospheric Orbiter (MMO) and ESA’s Mercury Planetary Orbiter (MPO), both of which will be carried together by the Mercury Transport Module (MTM).

    ESA Bepicolumbo Mercury Planetary Orbiter

    JAXA BepiColombo Mercury Magnetosphere Orbiter

    While MPO will go into an approximately 400 x 1500 km mapping orbit around Mercury, MMO will enter a highly elliptical orbit to study the planet’s enigmatically strong magnetic field.

    A combination of spacecraft will be launched together, with the Mercury Composite Spacecraft (MCS) consisting of two orbiters: MMO, MPO; as well as two additional elements: MTM, the Magnetospheric Orbiter Sunshield and Interface Structure (MOSIF).

    The mission will undertake a seven year cruise to Mercury, using a combination of solar electric propulsion and nine gravity assist flybys at Earth, Venus and Mercury.

    The opening element of that journey involved a ride on the Ariane 5 rocket.

    This interplanetary mission comes hot on the heels of Ariane 5’s 100th flight, placing two telecommunications satellites into orbit in the process – which are the bread and butter missions for this launch vehicle.

    Designated VA245 in Arianespace’s launcher family numbering system, this was the 23rd major scientific mission performed by the company to date.

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    Launch profile via ESA

    The launch window for BepiColombo opened on 5 October and would have closed on 29 November 2018 – a window designed to ensure the trajectory and multiple planetary flybys and gravity assists needed to eventually insert BepiColombo into the orbit of Mercury can be achieved via planetary alignments of Earth, Venus, and Mercury.

    Based on an October 2018 launch, BepiColombo will perform the following flyby / planetary encounter sequence leading to orbit insertion at Mercury on 5 December 2025:

    Date Milestone
    6 April 2020 First (and only) Earth flyby
    12 October 2020 First Venus flyby
    11 August 2021 Second (and final) Venus flyby
    2 October 2021 First Mercury flyby
    23 June 2022 Second Mercury flyby
    20 June 2023 Third Mercury flyby
    5 September 2024 Fourth Mercury flyby
    2 December 2024 Fifth Mercury flyby
    9 January 2025 Sixth Mercury flyby
    5 December 2025 Mercury orbit insertion

    Ariane 5 lofted estimated payload mass of 4,241 kg from ELA-3, with spacecraft separation occurring 27 minutes into the flight.

    The carrier spacecraft will use a combination of electric propulsion – which has undergone steering tests on the ground – along with multiple gravity-assists to complete the 7.2 year journey to the Solar System’s mysterious innermost planet.

    The 22 cm-diameter T6 thruster was designed for ESA by QinetiQ in the UK, whose expertise in electric propulsion stretches back to the 1960s. The spacecraft built was led by Airbus, but involves numerous companies and countries.

    After arriving at Mercury, the modules will separate and from their respective orbits the science orbiters will make complementary measurements of Mercury’s interior, surface, exosphere and magnetosphere, following up on many of the open questions raised by NASA’s Messenger mission.

    BepiColombo will investigate properties of the innermost planet of our Solar System that are still mysterious, such as its high density, the fact that it is the only planet with a magnetic field similar to Earth’s, the much higher than expected amount of volatile elements detected by NASA’s Messenger probe and the nature of water ice that may exist in the permanently shadowed areas at the poles.

    NASA’s MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft ended its mission in 2015 with a dramatic, but planned, event – crashing into the surface of the planet that it had been studying for over four years.

    NASA/Messenger satellite, ended its mission in 2015 with a dramatic, but planned, event – crashing into the surface of the planet that it had been studying for over four years.


    NASA Messenger satellite schematic, ended its mission in 2015 with a dramatic, but planned, event – crashing into the surface of the planet that it had been studying for over four years.


    NASA Messenger satellite, ended its mission in 2015 with a dramatic, but planned, event – crashing into the surface of the planet that it had been studying for over four years.

    The follow on information from BepiColombo will provide more data about the origin and evolution of a planet close to its parent star, providing a better understanding of the overall evolution of our own Solar System. The two orbiters will be providing a huge amount of data to scientists on Earth.

    MTM is equipped with three monitoring cameras, which provide black-and-white snapshots in 1024 x 1024 pixel resolution. One of the monitoring cameras is positioned on the MTM with a field of view looking up towards the Mercury Planetary Orbiter (MPO), which sits above.

    The MTM’s solar arrays are currently folded for launch, resulting in the presented image, but after their deployment the camera will have a clearer view. In particular, the MPO’s high-gain antenna will be in the field of view of the camera around one day after launch.

    The other two cameras are placed on the other side of the module: one will look down the extended solar array of the MTM, the other towards the MPO, capturing glimpses of the medium-gain antenna once deployed and, later, of the magnetometer boom.

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    MTM cameras via ESA

    The actual deployment of the solar arrays and antenna will be confirmed by telemetry data sent by the spacecraft after launch. Later, the monitoring cameras will be switched on. The first sets of images are planned to be taken around 12 hours and 1.5 days after launch and returned to Earth shortly after.

    The monitoring cameras will be used ad-hoc during the cruise phase, notably during the flybys of Earth, Venus and Mercury.

    While the MPO is equipped with a high-resolution scientific camera, this can only be operated after separating from the MTM upon arrival at Mercury in late 2025 because, like several of the 11 instrument suites, it is located on the side of the spacecraft fixed to the MTM during the cruise phase.

    Nonetheless, it will be possible to operate or partially operate as many as eight of the 11 instruments on the MPO during the flybys, along with three of the five instrument packages onboard JAXA’s Mercury Magnetospheric Orbiter. This will afford some unique data collection opportunities at Venus, for example.

    BepiColombo carries enough propellant to potentially be extended for an additional year, resulting in two Earth years of observation around Mercury – or 8.2 Mercurian years.

    The follow on information from BepiColombo will provide more data about the origin and evolution of a planet close to its parent star, providing a better understanding of the overall evolution of our own Solar System. The two orbiters will be providing a huge amount of data to scientists on Earth.

    MTM is equipped with three monitoring cameras, which provide black-and-white snapshots in 1024 x 1024 pixel resolution. One of the monitoring cameras is positioned on the MTM with a field of view looking up towards the Mercury Planetary Orbiter (MPO), which sits above.

    The MTM’s solar arrays are currently folded for launch, resulting in the presented image, but after their deployment the camera will have a clearer view. In particular, the MPO’s high-gain antenna will be in the field of view of the camera around one day after launch.

    The other two cameras are placed on the other side of the module: one will look down the extended solar array of the MTM, the other towards the MPO, capturing glimpses of the medium-gain antenna once deployed and, later, of the magnetometer boom.

    See the full article here .

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    NASASpaceFlight.com, now in its eighth year of operations, is already the leading online news resource for everyone interested in space flight specific news, supplying our readership with the latest news, around the clock, with editors covering all the leading space faring nations.

    Breaking more exclusive space flight related news stories than any other site in its field, NASASpaceFlight.com is dedicated to expanding the public’s awareness and respect for the space flight industry, which in turn is reflected in the many thousands of space industry visitors to the site, ranging from NASA to Lockheed Martin, Boeing, United Space Alliance and commercial space flight arena.

    With a monthly readership of 500,000 visitors and growing, the site’s expansion has already seen articles being referenced and linked by major news networks such as MSNBC, CBS, The New York Times, Popular Science, but to name a few.

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  • richardmitnick 4:43 pm on October 19, 2018 Permalink | Reply
    Tags: A Feasibility Study on the Photometric Detection of Quiescent Black Hole X-ray Binaries, , , , ,   

    From Isaac Newton Group of Telescopes: “A Feasibility Study on the Photometric Detection of Quiescent Black Hole X-ray Binaries” 

    Isaac Newton Group of Telescopes Logo
    From Isaac Newton Group of Telescopes

    19 October, 2018

    Black hole X-ray binaries (BHXBs) are essential to our understanding of extreme physics across the universe, such as accretion/ejection processes, supernova explosions, long gamma-ray bursts and gravitational-wave sources. About 60 BHXBs have been discovered to date in the Galaxy through transient outbursts but, unfortunately, only 17 are confirmed dynamically (i.e. have a mass function greater than ~3 solar masses), owing to difficulties in measuring the spectrum of the companion star at very faint quiescent luminosities.

    Our knowledge of the fundamental parameters of BHXBs and thus of their formation and evolution as a population, is clearly jeopardized by limited statistics. Therefore, there is pressing need for new strategies to discover the hidden population of quiescent BHXBs.

    Jorge Casares and Manuel A.P. Torres from the Instituto de Astrofísica de Canarias (IAC) have tested a novel photometric technique that can help unveil new quiescent BHXBs to unprecedented depths. They used an allocation of (IAC) Director’s Discretionary Time with the instrument ACAM on the William Herschel Telescope (WHT)[shown below]…

    ING ACAM mounted on the William Herschel Telescope

    …equipped with an OASIS r-band filter MR661 and two Halpha filters, kindly loaned by the Nordic Optical Telescope (NOT), to observe four dynamical BHXBs


    Nordic Optical telescope, at Roque de los Muchachos Observatory, La Palma in the Canary Islands, Spain, Altitude 2,396 m (7,861 ft)

    This filter combination allowed them to place the observed BHXBs in a colour-colour diagram. They appear conveniently detached from the locus occupied by normal field stars. Furthermore, their colours contain information on the equivalent width (EW) and full-width-at-half-maximum (FWHM) of the Halpha emission line, formed in the accretion disc around the black hole.

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    Colour-colour diagram produced with the r-band MR661 filter and the two Halpha NOT filters. Black and cyan crosses on the left represent standard stars and field stars respectively. Red and blue circles indicate photometric and spectroscopic (synthetic) colours for the 4 BHXBs. The magenta circle depicts a test observation (i.e. short integration time) of another BHXB, without simultaneous spectroscopy. Lines of constant EW in the range 10-400 Å and constant FWHM betwteen 1200-5400 km/s are overploted for reference. Credit: J. Casares and M.A.P. Torres.

    The photometric FWHM determinations were compared with spectroscopic FWHM values measured from near-simultaneous spectra, obtained with the instrument OSIRIS on the Gran Telescopio Canarias (GTC) using (IAC) Director’s Discretionary Time. The results agree within 10%, thus proving that the FWHM of the Halpha lines in BHXBs can be recovered using photometric techniques.

    IAC Gran Telescopio Canarias OSIRIS spectrograph

    Gran Telescopio Canarias at the Roque de los Muchachos Observatory on the island of La Palma, in the Canaries, Spain, sited on a volcanic peak 2,267 metres (7,438 ft) above sea level

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    GTC spectra of the 4 BHXBs, obtained simultaneously with the WHT observations. The transmission curves of the r-band and Halpha filters are plotted in red. Credit: J. Casares and M.A.P. Torres.

    This research opens the door to efficient selection of BHXBs since very deep gravitational wells are required to produce Halpha lines broader than FWHM > 2200 km/s. Monte Carlo simulations have shown that a cut-off at FWHM > 2200 km/s would allow selection of half of the BHXBs while rejecting other (dominant) populations of Halpha sources.

    It is estimated that a survey of ~1000 square degrees of the Galactic plane at signal-to-noise-ratio SNR~50 and depth r~22, using this filter strategy, would unveil around 50 new BHXBs, a three-fold improvement over the current population. Such a survey would also provide a detailed census of other Galactic populations of interest, most notably short-period (eclipsing) cataclysmic variables, neutron star X-ray binaries and ultra-compact binaries.

    J. Casares, M.A.P. Torres, 2018, “A feasibility study on the photometric detection of quiescent black hole X-ray binaries”, MNRAS 481, 4372

    J. Casares, 2018, “Hibernating black holes revealed by photometric mass functions”, MNRAS, 473, 5195

    See the full article here .

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    Isaac Newton Group telescopes
    Isaac Newton Group telescopes


    ING 4 meter William Herschel Telescope at Roque de los Muchachos Observatory on La Palma in the Canary Islands, 2,396 m (7,861 ft)


    ING Isaac Newton 2.5m telescope at Roque de los Muchachos Observatory on La Palma in the Canary Islands, Spain, Altitude 2,344 m (7,690 ft)

     
  • richardmitnick 3:46 pm on October 19, 2018 Permalink | Reply
    Tags: , , , Christine Desbordes- Head of the Logistics and Facilities Management at Paranal Observatory, , , Towards an Ecological and Sustainable ESO   

    From ESOblog: “Towards an Ecological and Sustainable ESO” 

    ESO 50 Large

    From ESOblog

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    19 October 2018, On the Ground

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    Interview with:
    Christine Desbordes

    ESO designs, constructs and operates the most powerful ground-based telescopes in the world, which places significant demands on resources, including energy. ESO’s observatories are located in Chile’s isolated Atacama Desert, and in such a location, limiting the impact on the surroundings while ensuring effective and efficient observations can be extremely difficult. Christine Desbordes, Head of the Logistics and Facilities Management at Paranal Observatory, tell us more about the environmental challenges ESO faces and its impact-reduction policies.

    Q: What are you responsible for here at Paranal?

    A: I am currently the Head of Logistics and Facilities Management at Paranal Observatory. I lead the management of the Residencia, which is where astronomers sleep and eat when they observe here. I also oversee the fleet of 75 vehicles and the maintenance of the civil infrastructure, including the basecamp — it’s like operating a small town!

    Q: Tell us a little about your background and how you joined ESO.

    A: I was born in France in the mid-60s before being raised in West Africa, where I caught the globetrotting virus. As soon as I finished my studies, I left France to start an international career, first in the private sector and later in the public sector. From 2014 to 2016, I held a challenging post as the Head of Administration for both the Kenya and Somalia delegations based in Nairobi, the second biggest representation of the European Union. When my oldest daughter finished high school and went off to university in the United Kingdom, I felt it was time to do something else. An ESO position at Paranal was exactly what I was looking for: a challenging task in a quiet region of a beautiful country.

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    Paranal Observatory is situated in the vast Atacama Desert, far from other civilisation. In this image, the telescopes are in the foreground with the Residencia to their right. Credit: ESO/M. Tarenghi

    Q: Paranal sits in the hostile Atacama Desert, 130 km from the nearest city of Antofagasta, so keeping people fed and watered must take a lot of resources. How do you reduce ESO’s ecological footprint?

    A: Indeed, as Paranal is so remote, food, water and other consumables have to either be produced on-site or trucked in from nearby cities. Paranal has always been wary of the impact of its presence in the Atacama Desert. Before my arrival in August 2016, a member of staff investigated the impact of the flights that bring people to the observatory. And the Maintenance, Software and Engineering Department had already started a recycling procedure for things like oil, batteries and pneumatics. But more certainly needed to be done; my department realised we had to contribute to the “three Rs” (reduce, reuse and recycle).

    We started with small projects such as monitoring food waste, reducing plastic and increasing our use of biodegradable products — we have replaced plastic laundry bags with fabric bags and standard bulbs with LED bulbs. We also reduced the number of big shuttle buses to and from Antofagasta by designing a better rotation distribution during the weekdays. Furthermore, we now organise most of the weekend transfers with more energy efficient vehicles.

    We also have plans for bigger projects which will take more time, for example we plan to install an osmosis plant in 2020 that will recycle up to one third of our waste water. This will avoid having to bring an additional water truck when we host the workers who will be assembling the Extremely Large Telescope in the near future.

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    The Residencia gives astronomers the chance to relax.
    Credit: N. Blind/ESO

    Q: The osmosis plant sounds intriguing — could you explain more about how it will work?

    A: We will launch the concept study next year for the upgrade of the existing sewage treatment plant to include the osmosis technology which is the one most used in Chile. The purpose is to be able to recycle up to 30 cubic metres of waste water per day, which will be used in a separate circuit in the toilets and gardens.

    Q: One of your initiatives was to reduce the number of plastic bottles used at Paranal. How did you approach the problem, and was it a success?

    A: Indeed, we started with the most obvious problem which was not only a polluting factor but also a logistics challenge: in 2016, Paranal Observatory disposed of more than 120 000 plastic bottles. To reduce this number, we replaced the individual water bottles with reusable 10-litre and 20-litre containers and we give our staff and visitors individual reusable bottles to refill. We also replaced the individual fizzy drinks bottles by drinks distributors. In 2018, Paranal will dispose of fewer than 12 000 individual bottles — ten times fewer than we used in 2016 — and we will recycle all of these.

    The process was definitely challenging! We had some logistical hiccups with the new suppliers and some resistance to the change on site, but in the end we have a simpler and more reliable water supply system. And I think the onsite staff have come round to the more eco-friendly system!

    Q: Paranal was recently connected to the Chilean electrical grid, which works on mainly renewable energy. What does this mean for ESO and how has the change affected Paranal’s ecological footprint?

    A: Before being connected to the grid, we created power using a gas turbine backed up by a generator which were both terrible for the environment. After being connected in December 2017, our ecological footprint has been considerably reduced as we don’t burn any fossil fuels. Additionally, the connection will allow us to further replace energy consuming items like the gas water boilers at the basecamp with solar-powered boilers and the petrol- and diesel-fueled vehicles with cars that run completely on electricity.

    5
    A hotel room with a view. Credit: Y. Beletsky (LCO)/ESO

    Q: Yes, we’ve actually heard that Paranal will receive its first electric cars this year! Will the whole fleet eventually be electric cars?

    A: We estimate that, depending on the availability of funds, in the next 10–15 years up to 75% of the fleet could be electric sedans and small vans. Unfortunately, it will not be possible to only have electric cars; due to the nature of our activities, we need pick-ups and small trucks on site and, although Chile is promoting the industry, we will not have those specialised electric vehicles available anytime soon.

    Q: How could ESO reduce its ecological footprint in future?

    A: At the moment we are quite heavily restricted by the fact that the Chilean industry has not yet reached a particularly eco-friendly level, so we struggle to find companies who can help us. Hopefully this will change over the next few years!

    Otherwise, the two biggest pollution factors are also the most challenging to tackle. One of these polluters is travel to bring astronomers and support staff to the observatory to carry out their work. Currently, the majority of Paranal observations are made without flying in visiting astronomers, but we are still responsible for more than 10 000 domestic flights per year! To reduce this number, we could look into reducing the number of shifts per year and/or limiting any increase in staff members.

    The other big polluter is the transportation of water and waste, which involves two or three lorries per day. To reduce the impact of this, we could limit our own water use on site even more, and make more of our own water, for example with a desalination plant. We could also further reduce our waste, for example with an organic waste disposal system.

    Even though those possible measures seem like extreme changes that would involve serious financial investment, we are trying our best to continue implementing reduction, recycling and reuse as much as we can at our observatories.

    See the full article here .


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    Visit ESO in Social Media-

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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 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.

    ALMA Array
    ALMA on the 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 APEX
    APEX Atacama Pathfinder 5,100 meters above sea level, at the Llano de Chajnantor Observatory in the Atacama desert.

    Leiden MASCARA instrument, La Silla, located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

    Leiden MASCARA cabinet at ESO Cerro la Silla located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

    ESO Next Generation Transit Survey at Cerro Paranel, 2,635 metres (8,645 ft) above sea level

    SPECULOOS four 1m-diameter robotic telescopes 2016 in the ESO Paranal Observatory, 2,635 metres (8,645 ft) above sea level

    ESO TAROT telescope at Paranal, 2,635 metres (8,645 ft) above sea level

    ESO ExTrA telescopes at Cerro LaSilla at an altitude of 2400 metres

     
  • richardmitnick 3:20 pm on October 19, 2018 Permalink | Reply
    Tags: , , , Blazar PG 1553+113, , ,   

    From Discover Magazine: “In a First, Astronomers Find a Blazar That Cycles Every Two Years” 

    DiscoverMag

    From Discover Magazine

    October 19, 2018
    Chelsea Gohd

    1
    A visualization of the blazar being observed while emitting gamma rays. (Credit: Stefano Ciprini)

    Blazar Brightness

    After 10 years of observations, scientists have confirmed a two-year cycle in the gamma-ray brightness of a blazar, or a galaxy with supermassive black holes that consume mass and produce high-energy jets as a result. Blazars are the most energetic and luminous objects that we have identified so far in the known universe.

    “This is the first time that a gamma-ray period has been confirmed in an active galaxy,” Stefano Ciprini, a researcher at the INFN Tor Vergata division of the Italian Space Agency’s Space Science Data Center in Rome, said in a press statement. Gamma rays are some of the most energetic electromagnetic emissions, and powerful objects like blazars produce them in large quantities.

    Finding that the emissions increase and decrease in a predictable cycle, though, hints to researchers that there might be more than one supermassive black hole at the center of this galaxy.

    The confirmation, the first of its kind, could help to support new investigations and provide new insight into what really happens close to supermassive black holes.

    2
    An animation of emissions from the blazar showing how they vary predictably. (Credit: NASA)

    Exploring Black Holes

    One of the most exciting things about this work and this blazar, named PG 1553+113, is that scientists think that the galaxy may have a pair of supermassive black holes in its center, instead of just one. This could explain the cyclical nature of the blazar, the researchers say. One black hole would be emitting a jet of gamma rays and other material, and the other might be interfering with the stream as it orbits, causing the jet to wobble.

    In 2015, this research team found hints of this gamma-ray cycle inPG 1553+113. They suspected that this distant blazar might be producing the first observed years-long gamma-ray emission cycle. And, after a few more years of observations, the team has confirmed these previous inklings.

    “This result has been achieved after 10 years of continuous monitoring by Fermi’s Large Area Telescope (LAT),” Sara Cutini, a researcher at the Italian Institute for Nuclear Physics (INFN) in Perugia, said in the statement.

    A paper detailing this analysis and conclusions is in the works and the findings were announced yesterday (Oct. 17) at the Eighth International Fermi Symposium meeting in Baltimore.

    See the full article here .

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  • richardmitnick 2:51 pm on October 19, 2018 Permalink | Reply
    Tags: , , , , , NASA’s Fermi Mission Energizes the Sky With Gamma-ray Constellations   

    From NASA Fermi: “NASA’s Fermi Mission Energizes the Sky With Gamma-ray Constellations” 

    NASA Fermi Banner

    NASA/Fermi Telescope
    From NASA Fermi

    Oct. 17, 2018

    Francis Reddy
    francis.j.reddy@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    Long ago, sky watchers linked the brightest stars into patterns reflecting animals, heroes, monsters and even scientific instruments into what is now an official collection of 88 constellations. Now scientists with NASA’s Fermi Gamma-ray Space Telescope have devised a set of modern constellations constructed from sources in the gamma-ray sky to celebrate the mission’s 10th year of operations.

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    To explore all Fermi’s Gamma-ray Constellations, visit: https://fermi.gsfc.nasa.gov/science/constellations/

    The new constellations include a few characters from modern myths. Among them are the Little Prince, the time-warping TARDIS from “Doctor Who,” Godzilla and his heat ray, the antimatter-powered U.S.S. Enterprise from “Star Trek: The Original Series” and the Hulk, the product of a gamma-ray experiment gone awry.

    “Developing these unofficial constellations was a fun way to highlight a decade of Fermi’s accomplishments,” said Julie McEnery, the Fermi project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “One way or another, all of the gamma-ray constellations have a tie-in to Fermi science.”

    New, unofficial animated constellations appear in this image of the sky mapped by NASA’s Fermi Gamma-ray Space Telescope. Fermi scientists devised the constellations to highlight the mission’s 10th year of operations. Fermi has mapped about 3,000 gamma-ray sources — 10 times the number known before its launch and comparable to the number of bright stars in the traditional constellations.
    Credits: NASA

    Since July 2008, Fermi’s Large Area Telescope (LAT) has been scanning the entire sky each day, mapping and measuring sources of gamma rays, the highest-energy light in the universe. The emission may come from pulsars, nova outbursts, the debris of supernova explosions and giant gamma-ray bubbles located in our own galaxy, or supermassive black holes and gamma-ray bursts — the most powerful explosions in the cosmos — in others.

    “By 2015, the number of different sources mapped by Fermi’s LAT had expanded to about 3,000 — 10 times the number known before the mission,” said Goddard’s Elizabeth Ferrara, who led the constellation project. “For the first time ever, the number of known gamma-ray sources was comparable to the number of bright stars, so we thought a new set of constellations was a great way to illustrate the point.”

    The 21 gamma-ray constellations include famous landmarks — such as Sweden’s recovered warship, Vasa, the Washington Monument and Mount Fuji in Japan — in countries contributing to Fermi science. Others represent scientific ideas or tools, from Schrödinger’s Cat — both alive and dead, thanks to quantum physics — to Albert Einstein, Radio Telescope and Black Widow Spider, the namesake of a class of pulsars that evaporate their unfortunate companion stars.

    Ferrara and Daniel Kocevski, an astrophysicist now at NASA’s Marshall Space Flight Center in Huntsville, Alabama, developed a web-based interactive to showcase the constellations, with artwork from Aurore Simonnet, an illustrator at Sonoma State University in Rohnert Park, California, and a map of the whole gamma-ray sky from Fermi. Clicking on a constellation turns on its artwork and name, which includes a link to a page with more information. Other controls switch on the visible sky and selected traditional constellations.

    “Fermi is still going strong, and we are now preparing a new all-sky LAT catalog,” said Jean Ballet, a Fermi team member at the French Atomic Energy Commission in Saclay. “This will add about 2,000 sources, many varying greatly in brightness, further enriching these constellations and enlivening the high-energy sky!”

    To explore Fermi’s Gamma-ray Constellations, visit:

    https://fermi.gsfc.nasa.gov/science/constellations/

    For more about NASA’s Fermi mission, visit:

    https://www.nasa.gov/fermi

    See the full article here .


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    The Fermi Gamma-ray Space Telescope , formerly referred to as the Gamma-ray Large Area Space Telescope (GLAST), is a space observatory being used to perform gamma-ray astronomy observations from low Earth orbit. Its main instrument is the Large Area Telescope (LAT), with which astronomers mostly intend to perform an all-sky survey studying astrophysical and cosmological phenomena such as active galactic nuclei, pulsars, other high-energy sources and dark matter. Another instrument aboard Fermi, the Gamma-ray Burst Monitor (GBM; formerly GLAST Burst Monitor), is being used to study gamma-ray bursts. The mission is a joint venture of NASA, the United States Department of Energy, and government agencies in France, Germany, Italy, Japan, and Sweden.

     
  • richardmitnick 2:29 pm on October 19, 2018 Permalink | Reply
    Tags: , , , , , , Scientists Map Out 21 New Constellations, Using Gamma Rays   

    From Discover Magazine: “Using Gamma Rays, Scientists Map Out 21 New Constellations” 

    DiscoverMag

    From Discover Magazine

    October 19, 2018
    Chelsea Gohd

    1
    The Godzilla constellation in the gamma-ray sky — a new set of constellations based off of gamma-ray emissions observed with NASA’s Fermi Gamma-ray Space Telescope. (Credit: NASA)

    NASA/Fermi LAT


    NASA/Fermi Gamma Ray Space Telescope

    Gamma-Ray Sky

    For countless years, humans have gazed up at the sky and made sense of the stars by finding shapes in them — constellations of heroes, animals, and well-worn tales. Now, to celebrate the 10th mission year of NASA’s Fermi Gamma-ray Space Telescope, scientists have used the telescope to develop a new set of constellations that correspond with gamma-ray emissions [Future post].

    Gamma rays are the most powerful in the electromagnetic spectrum, and they’re typically only produced by very powerful objects. Supermassive black holes at the center of galaxies emit gamma rays, and gamma rays can also spring from explosive gamma-ray bursts, pulsars, the debris of supernova explosions, and more. The Fermi telescope has spent the last decade scanning the sky to compile list of gamma ray sources in the observable universe. That’s given them an array of points, similar to the stars we see shining in the visible spectrum.

    In what is known as the “gamma-ray sky,” scientists have devised constellations inspired by many of the same things that inspired the starlight constellations our ancestors gazed at.

    The “original” constellations primarily fall into three categories: myths and legends, meaningful topics and common creatures and items, NASA Goddard’s Elizabeth Ferrara, who led the constellation project, explained in a teleconference. The Fermi constellations from the gamma-ray sky are also derived from three categories: modern legends, team partners, and Fermi science. To make sure they didn’t look too much like stars, the team behind these constellations used artificial color to distinguish them.

    Familiar Shapes

    There are 21 Fermi constellations, including the Hulk (created from a gamma-ray mishap), Godzilla, the Starship Enterprise from “Star Trek: The Next Generation”, the TARDIS from “Doctor Who”, gamma-ray bursts, dark lightning, spider pulsars. Important landmarks from partner nations show up as well: Mt. Fuji for Japan, the Colosseum to represent Italy and more. The constellations even include a Saturn V rocket to represent Huntsville, Alabama where the gamma-ray burst monitor team is centered.

    2
    (Credit: NASA)
    The Godzilla constellation in the gamma-ray sky — a new set of constellations based off of gamma-ray emissions observed with NASA’s Fermi Gamma-ray Space Telescope. (Credit: NASA)
    Gamma-Ray Sky

    For countless years, humans have gazed up at the sky and made sense of the stars by finding shapes in them — constellations of heroes, animals, and well-worn tales. Now, to celebrate the 10th mission year of NASA’s Fermi Gamma-ray Space Telescope, scientists have used the telescope to develop a new set of constellations that correspond with gamma-ray emissions.

    Gamma rays are the most powerful in the electromagnetic spectrum, and they’re typically only produced by very powerful objects. Supermassive black holes at the center of galaxies emit gamma rays, and gamma rays can also spring from explosive gamma-ray bursts, pulsars, the debris of supernova explosions, and more. The Fermi telescope has spent the last decade scanning the sky to compile list of gamma ray sources in the observable universe. That’s given them an array of points, similar to the stars we see shining in the visible spectrum.

    In what is known as the “gamma-ray sky,” scientists have devised constellations inspired by many of the same things that inspired the starlight constellations our ancestors gazed at.

    The “original” constellations primarily fall into three categories: myths and legends, meaningful topics and common creatures and items, NASA Goddard’s Elizabeth Ferrara, who led the constellation project, explained in a teleconference. The Fermi constellations from the gamma-ray sky are also derived from three categories: modern legends, team partners, and Fermi science. To make sure they didn’t look too much like stars, the team behind these constellations used artificial color to distinguish them.

    Familiar Shapes

    There are 21 Fermi constellations, including the Hulk (created from a gamma-ray mishap), Godzilla, the Starship Enterprise from “Star Trek: The Next Generation”, the TARDIS from “Doctor Who”, gamma-ray bursts, dark lightning, spider pulsars. Important landmarks from partner nations show up as well: Mt. Fuji for Japan, the Colosseum to represent Italy and more. The constellations even include a Saturn V rocket to represent Huntsville, Alabama where the gamma-ray burst monitor team is centered.

    “The hope, of course, is to make the gamma-ray sky more acceptable,” Ferrara said. “By creating constellations that tie into themes that people already know and think about, we hope to bring gamma-ray science into their thoughts.”

    Ferrara and Daniel Kocevski, from NASA’s Marshall Space Flight Center, have developed an interactive webpage so that the public can easily engage with these constellations. The interactive site uses a map of the gamma-ray sky from Fermi and artwork from Aurore Simonnet, an illustrator at Sonoma State University in Rohnert Park, California.

    Users on the site can explore the gamma-ray sky themselves and learn about the name, artwork, and details behind each constellation.

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

     
  • richardmitnick 1:30 pm on October 19, 2018 Permalink | Reply
    Tags: , , , , , NASA ACE Solar Observatory, Screening for the Slow Solar Wind,   

    From AAS NOVA: “Screening for the Slow Solar Wind” 

    AASNOVA

    From AAS NOVA

    19 October 2018
    Kerry Hensley

    1
    This artist’s impression of the solar wind shows a constant torrent of particles filling the heliosphere and streaming past Earth. [NASA Goddard’s Conceptual Image Lab/Greg Shirah]

    The solar wind extends outward from the solar corona, suffusing interplanetary space with plasma and magnetic fields. While the solar wind has traditionally been designated as either “fast” or “slow” based on its velocity, a new study suggests that there may be a better way to characterize this highly variable plasma flow.

    2
    Coronal holes, like the one clearly visible as a dark region in this X-ray image of the Sun from Solar Dynamics Observatory, are thought to be the source of the fast solar wind. [NASA/AIA]

    NASA/SDO

    Slow vs. Fast

    The fast solar wind is thought to originate from coronal holes — regions of open solar magnetic field lines. The slow solar wind has been associated with streams of coronal plasma emitted from near the Sun’s equator, but this source location for the slow solar wind is still up for debate.

    The formation mechanism for the slow solar wind is also uncertain; one of the persistent questions of solar physics is whether the slow and fast solar wind form in fundamentally different ways.

    Solving the mysteries of where and how the slow solar wind forms may rely on first finding a better definition of what constitutes the slow and fast solar wind. While regions of slow and fast solar wind have traditionally been separated based only on velocity, the parameters of the solar wind — such as the density, temperature, and ionization state — vary broadly for a given solar wind speed.

    3
    Comparison of solar wind proton speed, components of the proton velocity, and standard deviation in the components of the proton velocity. HCS and PS mark the times of heliospheric current sheet and pseudostreamer crossings, respectively. Low proton speeds are associated with low fluctuations in the proton velocity, while high speeds are associated with high fluctuations in the proton velocity. [Ko, Roberts & Lepri 2018]

    An ACE up Their Sleeve

    Yuan-Kuen Ko of the Naval Research Laboratory and collaborators argue that there is a better way to distinguish between the different states of the solar wind.

    By analyzing data from NASA’s Advanced Composition Explorer (ACE), a solar and space exploration mission launched more than two decades ago, Ko and collaborators found that the slow and fast solar wind may be better distinguished by the magnitude of their velocity fluctuations rather than their absolute velocities.

    NASA ACE Solar Observatory

    To demonstrate this, the authors compared the velocity fluctuation, δvT, to other observed solar wind properties. With the exception of the plasma beta — the ratio of the thermal pressure to the magnetic pressure — δvT correlates well with all observed solar wind properties.

    Ko and collaborators also explored the effect the phase of the solar cycle has on solar wind parameters by comparing data from two time intervals: one from the period during which solar activity is declining, and one near solar minimum. The authors found that while the absolute values of the solar wind parameters during epochs of low δvT varied between the two phases, their overall behavior did not; parameters that increased with increasing δvT did so during both the declining phase of the solar cycle and solar minimum.

    3
    The three slow-solar-wind formation scenarios implied by the results. [Ko, Roberts & Lepri 2018]

    More Solar Data Headed Our Way

    What does this mean for the formation of the slow solar wind? Ko and collaborators derive three potential slow-solar-wind formation scenarios from their findings, none of which are mutually exclusive.

    Distinguishing between these scenarios will have to wait — but not for long. Luckily, the next decade brings two highly anticipated spacecraft that will increase our understanding of the solar corona and solar wind, including the formation of the slow solar wind: NASA’s Parker Solar Probe, which started its journey to the Sun in August 2018, and ESA’s Solar Orbiter, which is scheduled to launch in February 2020.

    Citation

    “Boundary of the Slow Solar Wind,” Yuan-Kuen Ko, D. Aaron Roberts, and Susan T. Lepri 2018 ApJ 864 139.
    http://iopscience.iop.org/article/10.3847/1538-4357/aad69e/meta

    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 12:51 pm on October 19, 2018 Permalink | Reply
    Tags: , , , , ,   

    From Science Magazine: “Chemists find a recipe that may have jump-started life on Earth’ 

    AAAS
    From Science Magazine

    1
    New research spells out the simple chemical steps that may have launched the RNA World. Mark Garlick/Science Source

    Oct. 18, 2018
    Robert F. Service

    In the molecular dance that gave birth to life on Earth, RNA appears to be a central player. But the origins of the molecule, which can store genetic information as DNA does and speed chemical reactions as proteins do, remain a mystery. Now, a team of researchers has shown for the first time that a set of simple starting materials, which were likely present on early Earth, can produce all four of RNA’s chemical building blocks.

    Those building blocks—cytosine, uracil, adenine, and guanine—have previously been re-created in the lab from other starting materials. In 2009, chemists led by John Sutherland at the University of Cambridge in the United Kingdom devised a set of five compounds likely present on early Earth that could give rise to cytosine and uracil, collectively known as pyrimidines. Then, 2 years ago, researchers led by Thomas Carell, a chemist at Ludwig Maximilian University in Munich, Germany, reported that his team had an equally easy way to form adenine and guanine [Nature], the building blocks known as purines. But the two sets of chemical reactions were different. No one knew how the conditions for making both pairs of building blocks could have occurred in the same place at the same time.

    Now, Carell says he may have the answer. On Tuesday, at the Origins of Life Workshop here, he reported that he and his colleagues have come up with a simple set of reactions that could have given rise to all four RNA bases.

    Carell’s story starts with only six molecular building blocks—oxygen, nitrogen, methane, ammonia, water, and hydrogen cyanide, all of which would have been present on early Earth. Other research groups had shown that these molecules could react to form somewhat more complex compounds than the ones Carell used.

    To make the pyrimidines, Carell started with compounds called cyanoacetylene and hydroxylamine, which react to form compounds called amino-isoxazoles. These, in turn, react with another simple molecule, urea, to form compounds that then react with a sugar called ribose to make one last set of intermediate compounds.

    Finally, in the presence of sulfur-containing compounds called thiols and trace amounts of iron or nickel salts, these intermediates transform into the pyrimidines cytosine and uracil. As a bonus, this last reaction is triggered when the metals in the salts harbor extra positive charges, which is precisely what occurs in the final step in a similar molecular cascade that produces the purines, adenine and guanine. Even better, the step that leads to all four nucleotides works in one pot, Carell says, offering for the first time a plausible explanation of how all of RNA’s building blocks could have arisen side by side.

    “It looks pretty good to me,” says Steven Benner, a chemist with the Foundation for Applied Molecular Evolution in Alachua, Florida. The process provides a simple way to produce all four bases under conditions consistent with those believed present on early Earth, he says.

    The process doesn’t solve all of RNA’s mysteries. For example, another chemical step still needs to “activate” each of RNA’s four building blocks to link them into the long chains that form genetic material and carry out chemical reactions. But making RNA under conditions like those present on early Earth now appears within reach.

    See the full article here .


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    Please help promote STEM in your local schools.

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    • stewarthoughblog 11:31 pm on October 19, 2018 Permalink | Reply

      Some interesting science here, but mostly wildly speculative naturalism. The “molecular dance” is a myth, like Darwin’s “warm little ponds,” Oparin-Haldane primordial soup or Miller-Urey test tube goo. There are no naturalistic processes capable of any appreciable assembly of abiotic chemicals at any level that approach the basic, elemental level of assembly required for the origin of life.

      RNA, in particular, is an intermediate molecule that is easily mutated, easily contaminated, highly reactive, composed of homochiral AGCU that does not develop naturalistically and does not function at any level that produces metabolic processes or reproduce.

      The intelligently designed, highly orchestrated lab experiments are biogeochemically irrelevant to primordial Earth conditions and do no demonstrate any significant achievement relative to the origin of life.

      Like

  • richardmitnick 10:26 am on October 19, 2018 Permalink | Reply
    Tags: A low amplitude 'J-phase' seismic wave that passes through the planet's core, , For The First Time We Have Confirmation That Earth's Core Is Actually Solid, , It's also a bit squishy, , Seismic wave science   

    From Australian National University via Science Alert: “For The First Time, We Have Confirmation That Earth’s Core Is Actually Solid” 

    ANU Australian National University Bloc

    From Australian National University

    via

    Science Alert

    19 OCT 2018
    MIKE MCRAE

    1
    (forplayday/iStock)

    It’s also a bit squishy.

    For the first time, geologists have confirmed that our planet’s inner core is indeed solid – although not quite as firm as previous models have suggested.

    Thanks to a new method for detecting soft whispers of seismic waves, analysis of an elusive type of earthquake ripple has revealed key properties of our planet’s deepest layer.

    Researchers from the Australian National University (ANU) zeroed in on a low amplitude ‘J-phase’ seismic wave that passes through the planet’s core, allowing them to finally put constraints on its solidity.

    As the planet’s crust grinds and groans on the surface, waves of energy are sent rippling their way through its gooey insides.

    These come in various forms. Some, described as compressional waves, push back and forth through the planet’s body like a series of jittering train carriages. Others, called shear waves, surge up and down like the ocean’s surf along surfaces.

    How one converts into the other according to various phase changes can tell you a lot about the properties of the material it’s passing through.

    One particular variation called a J-phase should pass through the planet’s inner core, picking up details of the layer’s elasticity. That’s always been the theory, at least. The only problem is they’re rather quiet, making them virtually impossible to detect, so geologists have seen their measurement as something of a ‘Holy Grail’ of seismology.

    Two ANU Earth scientists have now worked out a clever way to listen to these incredibly faint waves in the hum of earthquake vibrations echoing through our planet.

    The method relies on taking any two seismic receivers on the planet’s surface and comparing notes several hours after the loudest rumbles have died away. With enough pairs of signals, a pattern can emerge.

    “Using a global network of stations, we take every single receiver pair and every single large earthquake – that’s many combinations – and we measure the similarity between the seismograms,” says researcher Hrvoje Tkalčić.

    “That’s called cross correlation, or the measure of similarity. From those similarities we construct a global correlogram – a sort of fingerprint of the Earth.”

    A similar process was recently used [Journal of Geophysical Research:Solid Earth] to accurately measure the thickness of ice in Antarctica, providing a novel way to determine not just the properties of Earth’s layers, but potentially of other worlds as well.

    Getting a grip on the nature of our planet’s guts is no easy task. We can barely dig more than 12 kilometres (about 7.5 miles) into the crust, which hardly scratches the surface, let alone reveals what’s thousands of kilometres underfoot.

    A century ago, it was thought our planet had a thick crunchy outer coating and a gooey centre made of molten metals.

    That all changed in the 1930s [American Museum of Natural History], following seismic readings of a large earthquake in New Zealand, which threw up signs of compression waves that shouldn’t have been there. A Danish seismologist by the name of Inge Lehmann suggested these patterns were most likely an echo bouncing off a solid centre.

    This inner core has been firmly established in geological models of our planet’s structure. It’s about three quarters the size of our Moon, made of iron and nickel, and sizzles at a temperature roughly as hot as the Sun’s surface.

    There might even be a complexity to its structure, with differences in how its iron crystals align giving the inner core its own ‘inner core’.

    But even if all that is already established in geological models, it’s nice to now get firm evidence that scientists have been on the right track – besides, we got a bit of a surprise, too.

    “We found the inner core is indeed solid, but we also found that it’s softer than previously thought,” says Tkalčić.

    “It turns out – if our results are correct – the inner core shares some similar elastic properties with gold and platinum.”

    All of this information is vital if we’re to build a firm understanding of phenomena like planetary formation, or how magnetic fields work.

    Our own protective bubble of magnetism reverses regularly [PNAS], for example, and we still haven’t nailed down exactly how this happens.

    “The understanding of the Earth’s inner core has direct consequences for the generation and maintenance of the geomagnetic field, and without that geomagnetic field there would be no life on the Earth’s surface,” says Tkalčić.

    With a new way to listen to our planet’s rumbling, we’re almost certain to learn more about what its soft heart is telling us.

    This research was published in Science.

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    ANU Campus

    ANU is a world-leading university in Australia’s capital city, Canberra. Our location points to our unique history, ties to the Australian Government and special standing as a resource for the Australian people.

    Our focus on research as an asset, and an approach to education, ensures our graduates are in demand the world-over for their abilities to understand, and apply vision and creativity to addressing complex contemporary challenges.

     
  • richardmitnick 9:23 am on October 19, 2018 Permalink | Reply
    Tags: , , , , , Cosmic microwave background radiation. Stephen Hawking Center for Theoretical Cosmology U Cambridge, , Measuring the Age of the Universe   

    From Harvard-Smithsonian Center for Astrophysics: “Measuring the Age of the Universe” 

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    Inflationary Universe. NASA/WMAP


    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

    1

    October 17, 2018

    Tyler Jump
    Public Affairs
    Harvard-Smithsonian Center for Astrophysics
    +1 617-495-7462
    tyler.jump@cfa.harvard.edu

    The single most important puzzle in today’s cosmology (the study of the universe as a whole) can be summarized in one question: How old is it? For nearly a century — since the discoveries by Einstein, Hubble, LeMaitre and others led to the big bang model of creation — we have known the answer. It is about 13.8 billion years old (using current data). But in just the past decade the two alternative measurement methods have narrowed the uncertainties in their results to a few percent to reach a stunning conclusion: The two do not agree with each other. Since both methods are based on exactly the same model and equations, our understanding of the universe is somehow wrong — perhaps fundamentally so.

    Enter the most exciting technical achievement in astronomy for decades, the detection of gravitational waves (GW) caused by the mergers of black holes or neutron stars with each other by LIGO-Virgo, soon to be joined by other similar GW detection facilities in other countries.


    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger

    ESA/eLISA the future of gravitational wave research

    1
    Skymap showing how adding Virgo to LIGO helps in reducing the size of the source-likely region in the sky. (Credit: Giuseppe Greco (Virgo Urbino group)

    The solution to the cosmological dilemma is likely to be settled soon by these instruments according to a new Nature paper by Hsin-Yu Chen of Harvard’s Black Hole Initiative, Maya Fishbach and Daniel E. Holz of the University of Chicago. The authors describe how upcoming detections of GW will have enough statistics to settle the question of age, forcing either one or the other (or perhaps even both) methods to re-think their basic understanding, or possibly even forcing a new variation of the When and How of the creation.

    The two currently conflicting methods rely on observations of vastly different parts of the cosmic order. The first method measures and models the cosmic microwave background radiation (the CMBR method) produced by the universe when, after about 380,000 years, it cooled down and allowed neutral hydrogen atoms to form and light to propagate without scattering.

    Cosmic microwave background radiation. Stephen Hawking Center for Theoretical Cosmology U Cambridge

    The second method, the one used by Hubble and interpreted by LeMaitre, measures galaxies. This method takes advantage of the expansion of the universe to correlate a galaxy’s distance with its recession velocity, the so-called Hubble-LeMaitre Law, and to derive the Hubble-LeMaitre parameter which describes how long these galaxies have been in motion, related to the age of the universe. All astronomers today rely on this expression to obtain the distances to galaxies too far away to measure directly but whose velocities are easily seen in the Doppler shifts (the redshift) of their spectral lines. While the most familiar use of the parameter is to obtain the age of the universe, its value influences all the other parameters in the cosmological model (about nine of them) which together also explain the shape and expansion character of the universe.

    Hubble calibrated his set of distances with nearby galaxies, but today we are capable of seeing galaxies so remote their light has been traveling to us for over ten billion years. Supernovae (SN), or at least those whose brightness is thought to be well understood, can be seen at great distances and so have been used to bootstrap the distance scale calibration outward from Hubble’s original neighborhood. There are subtle complexities in SN that are not well understood, however, resulting in an uncertainty that has been getting smaller as our understanding of them has improved. Today those uncertainties are small enough to exclude the comparable result from CMBR measurements.

    The GW method of distance measurement is completely independent of both galaxy and CMBR methods. General relativity alone provides the intrinsic strength of the GW signal from its peculiar ringing signal, and its observed strength provides a direct measure of its distance. (The velocity information is obtained from the redshift of atomic lines in the host galaxy). Dr. Chen and her colleagues simulated 90,000 merger events in binary black hole or binary neutron star systems, including the host galaxy properties, and included likely selection effects and other complexities. The GW strength, for example, depends on our viewing angle of inclination of the merger, while the number of events to expect is only roughly constrained by the detections so far. Including these and similar uncertainties, the astronomers conclude that within the next five years it is likely that the GW method will fix the Hubble-LeMaitre parameter (that is, the age of the universe) to a precision of 2%, and to 1% in a decade, good enough to exclude one or even both of the other methods. The new paper’s conclusions are bolstered by the fact that one paper using the GW method to estimate an age has already appeared. It had an uncertainty of between 11.9 billion years to 15.7 billion years, spanning both the current CMBR and galaxy values. But the new paper shows that in five years another roughly fifty GW events will be detected and these should be enough to settle the matter … and usher in a new era in precision cosmology.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    The Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy.

     
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