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  • richardmitnick 1:37 pm on January 11, 2019 Permalink | Reply
    Tags: , , , , ESA Integral, , Host galaxy CGCG 137-068, , , Supernova explosion AT2018cow, Team of telescopes finds X-ray engine inside mysterious supernova   

    From European Space Agency: “Team of telescopes finds X-ray engine inside mysterious supernova” 

    ESA Space For Europe Banner

    From European Space Agency

    10 January 2019

    Raffaella Margutti
    Department of Physics and Astronomy
    Northwestern University
    Evanston, IL, USA
    Email: raffaella.margutti@northwestern.edu

    Indrek Vurm
    Tartu Observatory
    University of Tartu, Estonia
    Email: indrek.vurm@ut.ee

    Volodymyr Savchenko
    Department of Astronomy
    University of Geneva, Switzerland
    Email: Volodymyr.Savchenko@unige.ch

    Carlo Ferrigno
    Department of Astronomy
    University of Geneva, Switzerland
    Email: Carlo.Ferrigno@unige.ch

    Giulia Migliori
    INAF–Institute of Radioastronomy
    University of Bologna, Italy
    Email: g.migliori@ira.inaf.it

    Erik Kuulkers
    ESA Integral Project Scientist
    European Space Agency
    Email: ekuulker@sciops.esa.int

    Norbert Schartel
    ESA XMM-Newton Project Scientist
    European Space Agency
    Email: norbert.schartel@sciops.esa.int

    Markus Bauer








    ESA Science Communication Officer









    Tel: +31 71 565 6799









    Mob: +31 61 594 3 954









    Email: markus.bauer@esa.int

    1
    An image of supernova explosion AT2018cow and its host galaxy, CGCG 137-068, which is located some 200 million light years away. The image was obtained on 17 August 2018 using the DEep Imaging and Multi-Object Spectrograph (DEIMOS) on the W. M. Keck Observatory in Hawaii.

    Keck/DEIMOS on Keck 2


    Keck Observatory, Maunakea, Hawaii, USA.4,207 m (13,802 ft), above sea level, showing also NASA’s IRTF and NAOJ Subaru

    Credit: R. Margutti/W. M. Keck Observatory

    The supernova was first spotted on 16 June 2018 with the ATLAS telescope, also in Hawaii. Further observations performed with a large team of telescopes – including ESA’s high-energy space telescopes Integral and XMM-Newton – revealed a source of powerful X-rays at the centre of this unprecedentedly bright and rapidly evolving stellar explosion, suggesting that it could either be a nascent black hole or neutron star with a powerful magnetic field, sucking in the surrounding material. Credit: R. Margutti/W. M. Keck Observatory

    ESA’s high-energy space telescopes Integral and XMM-Newton have helped to find a source of powerful X-rays at the centre of an unprecedentedly bright and rapidly evolving stellar explosion that suddenly appeared in the sky earlier this year.

    ESA/XMM Newton

    ESA/Integral

    The ATLAS telescope in Hawaii first spotted the phenomenon, since then named AT2018cow, on 16 June.

    ATLAS is an asteroid impact early warning system of two telescopes being developed by the University of Hawaii and funded by NASA


    ATLAS telescope, First Asteroid Terrestrial-impact Last Alert system (ATLAS) fully operational 8/15/15 Haleakala , Hawaii, USA, Altitude 4,205 m (13,796 ft)

    They soon realised this was something completely new. In only two days the object exceeded the brightness of any previously observed supernova – a powerful explosion of an aging massive star that expels most of its material into the surrounding space, sweeping up the interstellar dust and gases in its vicinity.

    A new paper, accepted for publication in The Astrophysical Journal, presents the observations from the first 100 days of the object’s existence, covering the entire electromagnetic spectrum of the explosion from radio waves to gamma rays.

    The analysis, which includes observations from ESA’s Integral and XMM-Newton, as well as NASA’s NuSTAR and Swift space telescopes, found a source of high-energy X-rays sitting deep inside the explosion.

    NASA NuSTAR X-ray telescope

    NASA Neil Gehrels Swift Observatory

    The behaviour of this source, or engine, as revealed in the data, suggests that the strange phenomenon could either be a nascent black hole or neutron star with a powerful magnetic field, sucking in the surrounding material.

    “The most exciting interpretation is that we might have seen for the first time the birth of a black hole or a neutron star,” says Raffaella Margutti of Northwestern University, USA, lead author of the paper.

    “We know that black holes and neutron stars form when stars collapse and explode as a supernova, but never before have we seen one right at the time of birth,” adds co-author Indrek Vurm of Tartu Observatory, Estonia, who worked on modelling the observations.

    2
    An image of supernova explosion AT2018cow and its host galaxy, CGCG 137-068, which is located some 200 million light years away. The image was obtained on 17 August 2018 using the DEep Imaging and Multi-Object Spectrograph (DEIMOS) on the W. M. Keck Observatory in Hawaii. The insert in the top left shows a zoom onto the galaxy, indicating the location of the supernova. The supernova was first spotted on 16 June 2018 with the ATLAS telescope, also in Hawaii. Further observations performed with a large team of telescopes – including ESA’s high-energy space telescopes Integral and XMM-Newton – revealed a source of powerful X-rays at the centre of this unprecedentedly bright and rapidly evolving stellar explosion, suggesting that it could either be a nascent black hole or neutron star with a powerful magnetic field, sucking in the surrounding material. Credit: R. Margutti/W. M. Keck Observatory

    The AT2018cow explosion was not only 10 to 100 times brighter than any other supernova previously observed: it also reached peak luminosity much faster than any other previously known event – in only a few days compared to the usual two weeks.

    Integral made its first observations of the phenomenon about five days after it had been reported and kept monitoring it for 17 days. Its data proved crucial for the understanding of the strange object.

    “Integral covers a wavelength range which is not covered by any other satellite,” says Erik Kuulkers, Integral project scientist at ESA. “We have a certain overlap with NuSTAR in the high-energy X-ray part of the spectrum but we can see higher energies, too.”

    So while data from NuSTAR revealed the hard X-ray spectrum in great detail, with Integral the astronomers were able to see the spectrum of the source entirely, including its upper limit at soft gamma-ray energies.

    “We saw a kind of a bump with a sharp cut-off in the spectrum at the high-energy end,” says Volodymyr Savchenko, an astronomer at the University of Geneva, Switzerland, who worked on the Integral data. “This bump is an additional component of the radiation released by this explosion, shining through an opaque, or optically thick, medium.”

    “This high-energy radiation most likely came from an area of very hot and dense plasma surrounding the source,” adds Carlo Ferrigno, also of the University of Geneva.

    3
    The evolution of supernova explosion AT2018cow as observed at soft X-rays with NASA’s Swift (red circles) and ESA’s XMM-Newton (red triangles) space observatories, and at hard X-rays with NASA’s NuSTAR (orange circles) and ESA’s INTEGRAL (yellow circles) satellites. The supernova was first spotted on 16 June 2018 with the ATLAS telescope in Hawaii. The data shown in this animation were collected between 22 June and 22 July. These observations revealed a source of powerful X-rays at the centre of this unprecedentedly bright and rapidly evolving stellar explosion, suggesting that it could either be a nascent black hole or neutron star with a powerful magnetic field, sucking in the surrounding material. Credit: R. Margutti et al (2019)

    Because Integral kept monitoring the AT2018cow explosion over a longer period of time, its data was also able to show that the high-energy X-ray signal was gradually fading.

    Raffaella explains that this high-energy X-ray radiation that went away was the so-called reprocessed radiation – radiation from the source interacting with material ejected by the explosion. As the material travels away from the centre of the explosion, the signal gradually wanes and eventually disappears completely.

    In this signal, however, the astronomers were able to find patterns typical of an object that draws in matter from its surroundings – either a black hole or a neutron star.

    “This is the most unusual thing that we have observed in AT2018cow and it’s definitely something unprecedented in the world of explosive transient astronomical events,” says Raffaella.

    Meanwhile, XMM-Newton looked at this unusual explosion twice over the first 100 days of its existence. It detected the lower-energy part of its X-ray emission, which, according to the astronomers, comes directly from the engine at the core of the explosion. Unlike the high-energy X-rays coming from the surrounding plasma, the lower-energy X-rays from the source are still visible.

    The astronomers plan to use XMM-Newton to perform a follow-up observation in the future, which will allow them to understand the source’s behaviour over a longer period of time in greater detail.

    “We are continuing to analyse the XMM-Newton data to try to understand the nature of the source,” says co-author Giulia Migliori of University of Bologna, Italy, who worked on the X-ray data. “Accreting black holes leave characteristic imprints in X-rays, which we might be able to detect in our data.”

    “This event was completely unexpected and it shows that there is a lot of which we don’t completely understand,” says Norbert Schartel, ESA’s XMM-Newton project scientist. “One satellite, one instrument alone, would never be able to understand such a complex object. The detailed insights we were able to gather into the inner workings of the mysterious AT2018cow explosion were only achievable thanks to the broad cooperation and combination of many telescopes.”

    See the full article here .


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    Please help promote STEM in your local schools.

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    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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  • richardmitnick 12:20 pm on March 5, 2018 Permalink | Reply
    Tags: , , , , Donor star breathes life into zombie companion, , ESA Integral   

    From ESA: “Donor star breathes life into zombie companion” 

    ESA Space For Europe Banner

    European Space Agency

    5 March 2018

    Enrico Bozzo
    University of Geneva, Switzerland
    Email: enrico.bozzo@unige.ch

    Erik Kuulkers
    ESA Integral project scientist
    Email: erik.kuulkers@esa.int

    Markus Bauer








    ESA Science Communication Officer









    Tel: +31 71 565 6799









    Mob: +31 61 594 3 954









    Email: markus.bauer@esa.int

    1

    ESA’s Integral space observatory has witnessed a rare event: the moment that winds emitted by a swollen red giant star revived its slow-spinning companion, the core of a dead star, bringing it back to life in a flash of X-rays.

    ESA/Integral

    The X-ray flare was first detected by Integral on 13 August 2017 from an unknown source in the direction of the crowded centre of our Milky Way. The sudden detection triggered a slew of follow-up observations in the following weeks to pin down the culprit.

    The observations revealed a strongly magnetised and slowly rotating neutron star that had likely just begun to feed on material from a neighbouring red giant star.

    Stars the mass of our Sun, and up to eight times more massive, evolve into red giants towards the end of their lives. Their outer layers puff up and expand millions of kilometres, their dusty, gassy shells blown away from the central star in relatively slow winds up to few hundreds of km/s.

    2
    Stellar evolution
    Released 05/03/2018
    Copyright ESA
    Artist impression of some possible evolutionary pathways for stars of different initial masses. Some proto-stars, brown dwarfs, never actually get hot enough to ignite into fully-fledged stars, and simply cool off and fade away. Red dwarfs, the most common type of star, keep burning until they have transformed all their hydrogen into helium, turning into a white dwarf. Sun-like stars swell into red giants before puffing away their outer shells into colourful nebula while their cores collapse into a white dwarf. The most massive stars collapse abruptly once they have burned through their fuel, triggering a supernova explosion or gamma-ray burst, and leaving behind a neutron star or black hole.

    Even larger stars, up to 25–30 times more massive than the Sun, race through their fuel and explode in a supernova, sometimes leaving behind a spinning stellar corpse with a strong magnetic field, known as a neutron star. This tiny core packs the mass of nearly one and half Suns into a sphere only 10 km across, making them some of the densest celestial objects known.

    It is not uncommon to find stars paired together, but the new system of a neutron star and red giant is a particularly rare breed known as a ‘symbiotic X-ray binary’, with no more than 10 known.

    “Integral caught a unique moment in the birth of a rare binary system,” says Enrico Bozzo from University of Geneva and lead author of the paper that describes the discovery [Astronomy and Astrophysics]. “The red giant released a sufficiently dense slow wind to feed its neutron star companion, giving rise to high-energy emission from the dead stellar core for the first time.”

    The pairing is certainly peculiar. ESA’s XMM-Newton and NASA’s NuSTAR space telescopes showed that the neutron star spins almost every two hours – very slow compared with other neutron stars, which can spin up to many times per second.

    ESA/XMM Newton

    NASA NuSTAR X-ray telescope

    Then, the first measurement of the magnetic field of such a neutron star revealed it to be surprisingly strong.

    A strong magnetic field typically points to a young neutron star – the magnetic field is thought to fade over time – while a red giant is much older, making it a bizarre couple to have grown up together.

    “These objects are puzzling,” says Enrico. “It might be that either the neutron star magnetic field does not decay substantially with time after all, or the neutron star actually formed later in the history of the binary system. That would mean it collapsed from a white dwarf into a neutron star as a result of feeding off the red giant over a long time, rather than becoming a neutron star as a result of a more traditional supernova explosion of a short-lived massive star.”

    With a young neutron star and an old red giant, at some point the winds travelling from the puffed-up giant will begin to rain on to the smaller star, slowing its spin and emitting X-rays.

    “We haven’t seen this object before in the past 15 years of our observations with Integral, so we believe we saw the X-rays turning on for the first time,” says Erik Kuulkers, ESA’s Integral project scientist. “We’ll continue to watch how it behaves in case it is just a long ‘burp’ of winds, but so far we haven’t seen any significant changes.”

    The rapid response of the follow-up observations was enabled by the SmartNet community. This included important contributions from ESA’s XMM-Newton and NASA’s NuSTAR and Swift space telescopes, and the ground-based Southern Astrophysical Research Telescope, Faulkes Telescopes North and South and the Las Cumbres Observatory.

    NASA Neil Gehrels Swift Observatory

    SART telescope (SOAR) situated on Cerro Pachón, just to the southeast of Cerro Tololo on the AURA site at an altitude of 2,700 meters (8,775 feet) above sea level

    Faulkes North telescope located at Haleakala Observatory in the U.S. state of Hawaii Altitude 3,052 m (10,013 ft)

    The Faulkes SouthTelescope is a clone of the Liverpool Telescope and is located at Siding Spring Observatory in New South Wales, Australia Altitude 1,165 m (3,822 ft)

    LCOGT Las Cumbres Observatory Global Telescope Network, Haleakala Hawaii, USA

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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  • richardmitnick 4:34 am on October 17, 2017 Permalink | Reply
    Tags: , , , , , ESA Integral, ,   

    From ESA: “Integral sees blast travelling with gravitational waves” 

    ESA Space For Europe Banner

    European Space Agency

    16 October 2017
    Erik Kuulkers
    ESA Integral Project Scientist
    European Space Agency
    Tel: +31 71 565 8470
    Mob: +31 6 30249526
    Email: Erik.Kuulkers@esa.int

    Volodymyr Savchenko
    Integral Science Data Centre
    University of Geneva, Switzerland
    Email: Volodymyr.Savchenko@unige.ch

    Carlo Ferrigno
    Integral Science Data Centre
    University of Geneva, Switzerland
    Tel: +41 7979 67782
    Email: Carlo.Ferrigno@unige.ch

    Paul McNamara
    LISA Study Scientist
    European Space Agency
    Tel: +31 71 565 8239
    Email: paul.mcnamara@esa.int

    Markus Bauer








    ESA Science Communication Officer









    Tel: +31 71 565 6799









    Mob: +31 61 594 3 954









    Email: markus.bauer@esa.int

    1
    Colliding neutron stars. No image credit [and not the best I have ever seen, but their choice, not mine].

    ESA’s Integral satellite recently played a crucial role in discovering the flash of gamma rays linked to the gravitational waves released by the collision of two neutron stars.

    1
    Integral gamma-ray observatory. No image credit

    On 17 August, a burst of gamma rays lit up in space for almost two seconds. It was promptly recorded by Integral and NASA’s Fermi satellite.

    NASA/Fermi Telescope


    NASA/Fermi LAT

    Such short gamma-ray bursts are not uncommon: Integral catches about 20 every year. But this one was special: just seconds before the two satellites saw the blast, an entirely different instrument was triggered on Earth.

    One of the two detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) experiment, in the USA, recorded the passage of gravitational waves – fluctuations in the fabric of spacetime caused by powerful cosmic events.


    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-Zib

    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)

    “This is a ground-breaking discovery, revealing for the first time gravitational waves and highly energetic light released by the same cosmic source,” says Erik Kuulkers, Integral project scientist at ESA.

    Before this finding, gravitational waves had been confirmed on four occasions: in all cases, they were traced back to pairs of merging black holes as they spiralled towards each other.

    The two LIGO detectors had seen the first in September 2015, followed by two more in late 2015 and early 2017. Recently, on 14 August, the fourth observation of gravitational waves also involved Europe’s Virgo instrument in Italy.

    These detections won the LIGO founding scientists the Nobel Prize in physics earlier this month.

    Gravitational waves are the only ‘messenger’ expected when black holes collide. Following these four measurements, scientists across the world began searching with ground and space telescopes for possible luminous bursts linked to the gravitational waves.

    “We had contributed to these earlier searches with Integral, looking for gamma- or X-ray emission and finding none, as expected from the vast majority of theories,” says Volodymyr Savchenko from the Integral Science Data Centre in Geneva, Switzerland.

    This time, however, the story took a different turn.

    Other cosmic clashes are suspected to release not only gravitational waves but also light across the electromagnetic spectrum. This can happen, for example, when the collision involves one or more neutron stars – like black holes, they are compact remnants of what were once massive stars.

    Merging neutron stars have also been thought to be the long-sought sources of short gamma-ray bursts, though no observational proof had yet been found.

    Until August.

    “We realised that we were witnessing something historic when we saw the notification of Fermi’s and LIGO’s detections appear on our internal network almost at the same time, and soon after we saw the confirmation in the data from Integral’s SPI instrument, too,” says Carlo Ferrigno, from the Integral Science Data Centre.

    “Nothing like this had happened before: it was clearly the signature of a neutron star merger,” adds Volodymyr.

    3
    Gamma-ray burst after gravitational waves. No image credit.

    Ordinarily, an alert from only one of the three gravitational-wave detectors would not awaken curiosity so suddenly, but the coincidence with the gamma-ray blast detected from space prompted the LIGO/Virgo scientists to look again.

    It later appeared that both LIGO detectors had recorded the gravitational waves. Owing to its lower sensitivity and different orientation, Virgo produced a smaller response, but combining all three sets of measurements was crucial to locating the source.

    The data pointed to a 28 square degree patch in the sky, equivalent to a square spanning roughly 10 times the diameter of the full Moon on each side. The gravitational wave signal indicated that the source lies only about 130 millions light-years away.

    Without further delay, a large number of ground and space telescopes turned to this portion of the sky.

    About half a day after the detections, scientists at various optical observatories, including the European Southern Observatory’s telescopes in Chile, spotted something new near the core of galaxy NGC 4993. Sitting at just the distance indicated by LIGO/Virgo, it was just what you would expect to see in visible light as neutron stars merged.

    “This is the closest short gamma-ray burst detected among the ones for which we’ve measured the distance, and by far the dimmest one – nearly a million times less bright than average,” says Volodymyr.

    “We think that the unusual properties of this source indicate that the powerful jets that arise in the cosmic clash of the neutron stars are not pointing straight towards us, as happens in the majority of gamma-ray bursts detected.”

    With the position of the source known, a large number of observatories and other sensors continued looking at it for several days and, in some cases, weeks, searching for light and particles emitted in the aftermath of the collision. Many are still observing it.

    After the initial detection of the blast, Integral observed it for five and a half days. No further gamma rays were detected, an important fact in understanding how the neutron stars merged.

    The extensive follow-up campaign revealed signals across the spectrum, first in the ultraviolet, visible and infrared bands, then in X-rays and, eventually, radio wavelengths.

    “What we are witnessing is clearly a kilonova: the neutron-rich material released in the merger is impacting its surroundings, forging a wealth of heavy elements in the process,” explains Carlo.

    “This amazing discovery was made possible by a terrific collaboration of thousands of people working in different observatories and experiments worldwide,” says Erik.

    “We are thrilled that Integral could provide a crucial contribution to confirming the nature of such a rare phenomenon that scientists have been seeking for decades.”

    With high sensitivity to gamma rays and almost full-sky coverage for brief events, Integral is amongst the best astronomical facilities for keeping an eye on gamma-ray bursts.

    When the LIGO/Virgo sensors start their observations again, with improved sensitivity, in late 2018, it is crucial that as many gamma-ray satellites as possible are active to check on the gravitational wave detections.

    Meanwhile, ESA is working on the next generation of gravitational-wave experiments, taking the quest to space with LISA, the Laser Interferometer Space Antenna.

    Planned for launch in 2034, LISA will be sensitive to gravitational waves of lower frequency than those detected with terrestrial instruments. These are released by the clashes of even more exotic cosmic objects: supermassive black holes, which sit at the centre of galaxies and have masses millions to billions of times larger than that of the stellar-mass black holes detected by LIGO and Virgo.

    “LISA will broaden the study of gravitational waves much like the first observations at infrared and radio wavelengths have revolutionised astronomy,” says Paul McNamara, LISA study scientist at ESA.

    “Until then, we are excited that ESA’s high-energy satellites are contributing to the growing field of gravitational-wave astronomy.”

    From ESA

    Published on Oct 16, 2017

    This artist’s impression video shows how two tiny but very dense neutron stars merge and explode as a kilonova. Such a very rare event is expected to produce both gravitational waves and a short gamma-ray burst, both of which were observed on 17 August 2017 by LIGO–Virgo and Fermi/INTEGRAL respectively. Subsequent detailed observations with the NASA/ESA Hubble Space Telescope and other telescopes all over the world have confirmed that this object, seen in the galaxy NGC 4993 about 130 million light-years from the Earth, is indeed a kilonova. These objects are the main source of very heavy chemical elements, such as gold and platinum, in the Universe.
    Credit: ESO/L. Calçada. Music: Johan B. Monell (www.johanmonell.com)

    From NASA
    Published on Oct 16, 2017

    For the first time, NASA scientists have detected light tied to a gravitational-wave event, thanks to two merging neutron stars in the galaxy NGC 4993, located about 130 million light-years from Earth in the constellation Hydra.

    Shortly after 8:41 a.m. EDT on Aug. 17, NASA’s Fermi Gamma-ray Space Telescope picked up a pulse of high-energy light from a powerful explosion, which was immediately reported to astronomers around the globe as a short gamma-ray burst. The scientists at the National Science Foundation’s Laser Interferometer Gravitational-wave Observatory (LIGO) detected gravitational waves dubbed GW170817 from a pair of smashing stars tied to the gamma-ray burst, encouraging astronomers to look for the aftermath of the explosion. Shortly thereafter, the burst was detected as part of a follow-up analysis by ESA’s (European Space Agency’s) INTEGRAL satellite.

    NASA’s Swift, Hubble, Chandra and Spitzer missions, along with dozens of ground-based observatories, including the NASA-funded Pan-STARRS survey, later captured the fading glow of the blast’s expanding debris.

    NASA/SWIFT Telescope

    NASA/ESA Hubble Telescope

    NASA/Chandra Telescope

    NASA/Spitzer Infrared Telescope

    Neutron stars are the crushed, leftover cores of massive stars that previously exploded as supernovas long ago. The merging stars likely had masses between 10 and 60 percent greater than that of our Sun, but they were no wider than Washington, D.C. The pair whirled around each other hundreds of times a second, producing gravitational waves at the same frequency. As they drew closer and orbited faster, the stars eventually broke apart and merged, producing both a gamma-ray burst and a rarely seen flare-up called a “kilonova.”

    Neutron star mergers produce a wide variety of light because the objects form a maelstrom of hot debris when they collide. Merging black holes — the types of events LIGO and its European counterpart, Virgo, have previously seen — very likely consume any matter around them long before they crash, so we don’t expect the same kind of light show.

    Within hours of the initial Fermi detection, LIGO and the Virgo detector at the European Gravitational Observatory near Pisa, Italy, greatly refined the event’s position in the sky with additional analysis of gravitational wave data. Ground-based observatories then quickly located a new optical and infrared source — the kilonova — in NGC 4993.

    To Fermi, this appeared to be a typical short gamma-ray burst, but it occurred less than one-tenth as far away as any other short burst with a known distance, making it among the faintest known. Astronomers are still trying to figure out why this burst is so odd, and how this event relates to the more luminous gamma-ray bursts seen at much greater distances.

    NASA’s Swift, Hubble and Spitzer missions followed the evolution of the kilonova to better understand the composition of this slower-moving material, while Chandra searched for X-rays associated with the remains of the ultra-fast jet.

    NASA/SWIFT Telescope

    This animation captures phenomena observed over the course of nine days following the neutron star merger known as GW170817. They include gravitational waves (pale arcs), a near-light-speed jet that produced gamma rays (magenta), expanding debris from a kilonova that produced ultraviolet (violet), optical and infrared (blue-white to red) emission, and, once the jet directed toward us expanded into our view from Earth, X-rays (blue).
    Credit: NASA’s Goddard Space Flight Center/CI Lab

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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  • richardmitnick 11:09 am on March 30, 2016 Permalink | Reply
    Tags: , , ESA Integral, ,   

    From ESA: “Integral sets limits on gamma rays from merging black holes” 

    ESA Space For Europe Banner

    European Space Agency

    30 March 2016

    Markus Bauer








    ESA Science Communication Officer









    Tel: +31 71 565 6799









    Mob: +31 61 594 3 954









    Email: markus.bauer@esa.int

    Volodymyr Savchenko
    François Arago Center
    APC – Astroparticule et Cosmologie
    Université Paris Diderot, CNRS/IN2P3, CEA/Irfu, Observatoire De Paris, Sorbonne Paris Cité
    Paris, France
    Email: savchenk@apc.in2p3.fr

    Carlo Ferrigno
    Integral Science Data Centre
    University of Geneva, Switzerland
    Email: Carlo.Ferrigno@unige.ch

    Erik Kuulkers
    ESA Integral Project Scientist
    Email: Erik.Kuulkers@esa.int

    Black holes merging Swinburne Astronomy Productions
    Black holes merging Swinburne Astronomy Productions
    Cornell SXS team. Two merging black holes simulation
    Cornell SXS team. Two merging black holes simulation

    Following the discovery of gravitational waves from the merging of two black holes, ESA’s Integral satellite has revealed no simultaneous gamma rays, just as models predict.

    ESA/Integral
    ESA/Integral

    On 14 September, the terrestrial Laser Interferometer Gravitational-wave Observatory (LIGO) detected gravitational waves – fluctuations in the fabric of spacetime – produced by a pair of black holes as they spiralled towards each other before merging.

    MIT/Caltech Advanced aLIGO Hanford Washington USA installation
    MIT/Caltech Advanced aLIGO Hanford Washington USA installation

    The signal lasted less than half a second.

    The discovery was the first direct observation of gravitational waves, predicted by Albert Einstein a century ago.

    Two days after the detection, the LIGO team alerted a number of ground- and space-based astronomical facilities to look for a possible counterpart to the source of gravitational waves. The nature of the source was unclear at the time, and it was hoped that follow-up observations across the electromagnetic spectrum might provide valuable information about the culprit.

    Gravitational waves are released when massive bodies are accelerated, and strong emission should occur when dense stellar remnants such as neutron stars or black holes spiral towards each other before coalescing.

    Models predict that the merging of two stellar-mass black holes would not produce light at any wavelength, but if one or two neutron stars were involved in the process, then a characteristic signature should be observable across the electromagnetic spectrum.

    Another possible source of gravitational waves would be an asymmetric supernova explosion, also known to emit light over a range of wavelengths.

    It was not possible to pinpoint the LIGO source – its position could only be narrowed down to a very long strip across the sky.

    Observatories searched their archives in case data had been serendipitously collected anywhere along this strip around the time of the gravitational wave detection. They were also asked to point their telescopes to the same region in search for any possible ‘afterglow’ emission.

    Integral is sensitive to transient sources of high-energy emission over the whole sky, and thus a team of scientists searched through its data, seeking signs of a sudden burst of hard X-rays or gamma rays that might have been recorded at the same time as the gravitational waves were detected.

    “We searched through all the available Integral data, but did not find any indication of high-energy emission associated with the LIGO detection,” says Volodymyr Savchenko of the François Arago Centre in Paris, France. Volodymyr is the lead author of a paper reporting the results, published today in Astrophysical Journal Letters.

    The team analysed data from the Anti-Coincidence Shield on Integral’s SPI instrument. The shield helps to screen out radiation and particles coming from directions other than that where the instrument is pointing, as well as to detect transient high-energy sources across the whole sky.

    The team also looked at data from Integral’s IBIS instrument, although at the time it was not pointing at the strip where the source of gravitational waves was thought to be located.

    “The source detected by LIGO released a huge amount of energy in gravitational waves, and the limits set by the Integral data on a possible simultaneous emission of gamma rays are one million times lower than that,” says co-author Carlo Ferrigno from the Integral Science Data Centre at the University of Geneva, Switzerland.

    Subsequent analysis of the LIGO data has shown that the gravitational waves were produced by a pair of coalescing black holes, each with a mass roughly 30 times that of our Sun, located about 1.3 billion light years away. Scientists do not expect to see any significant emission of light at any wavelength from such events, and thus Integral’s null detection is consistent with this scenario.

    Similarly, nothing was seen by the great majority of the other astronomical facilities making observations from radio and infrared to optical and X-ray wavelengths.

    The only exception was the Gamma-Ray Burst Monitor on NASA’s Fermi Gamma-Ray Space Telescope, which observed what appears to be a sudden burst of gamma rays about 0.4 seconds after the gravitational waves were detected.

    NASA/Fermi Telescope
    NASA/Fermi Telescope

    The burst lasted about one second and came from a region of the sky that overlaps with the strip identified by LIGO.

    This detection sparked a bounty of theoretical investigations, proposing possible scenarios in which two merging black holes of stellar mass could indeed have released gamma rays along with the gravitational waves.

    However, if this gamma-ray flare had had a cosmic origin, either linked to the LIGO gravitational wave source or to any other astrophysical phenomenon in the Universe, it should have been detected by Integral as well. The absence of any such detection by both instruments on Integral suggests that the measurement from Fermi could be unrelated to the gravitational wave detection.

    “This result highlights the importance of synergies between scientists and observing facilities worldwide in the quest for as many cosmic messengers as possible, from the recently-detected gravitational waves to particles and light across the spectrum,” says Erik Kuulkers, Integral project scientist at ESA.

    This will become even more important when it becomes possible to observe gravitational waves from space. This has been identified as the goal for the L3 mission in ESA’s Cosmic Vision programme, and the technology for building it is currently being tested in space by ESA’s LISA Pathfinder mission.

    ESA/LISA Pathfinder
    ESA/LISA Pathfinder

    Such an observatory will be capable of detecting gravitational waves from the merging of supermassive black holes in the centres of galaxies for months prior to the final coalescence, making it possible to locate the source much more accurately and thus provide astronomical observatories with a place and a time to look out for associated electromagnetic emission.

    “We are looking forward to further collaborations and discoveries in the newly-inaugurated era of gravitational astronomy,” concludes Erik.

    Integral Upper Limits On Gamma-Ray Emission Associated With The Gravitational Wave Event GW150914, by V. Savchenko et al. is published in Astrophysical Journal Letters.

    The science team:
    V. Savchenko1, C. Ferrigno2, S. Mereghetti3, L. Natalucci4, A. Bazzano4, E. Bozzo2, S. Brandt5, T. J.-L. Courvoisier2, R. Diehl6, L. Hanlon7, A. von Kienlin6, E. Kuulkers8, P. Laurent9,10, F. Lebrun9, J. P. Roques11, P. Ubertini4, and G. Weidenspointner6,12

    Author affiliations

    1 François Arago Centre, APC, Université Paris Diderot, CNRS/IN2P3, CEA/Irfu, Observatoire de Paris, Sorbonne Paris Cité, 10 rue Alice Domon et Léonie Duquet, F-75205 Paris Cedex 13, France

    2 ISDC, Department of astronomy, University of Geneva, chemin d’Écogia, 16 CH-1290 Versoix, Switzerland

    3 INAF, IASF-Milano, via E.Bassini 15, I-20133 Milano, Italy

    4 INAF-Institute for Space Astrophysics and Planetology, Via Fosso del Cavaliere 100, I-00133-Rome, Italy

    5 DTU Space—National Space Institute Elektrovej—Building 327 DK-2800 Kongens Lyngby, Denmark

    6 Max-Planck-Institut für Extraterrestrische Physik, Garching, Germany

    7 Space Science Group, School of Physics, University College Dublin, Belfield, Dublin 4, Ireland

    8 European Space Astronomy Centre (ESA/ESAC), Science Operations Department E-28691, Villanueva de la Cañada, Madrid, Spain

    9 APC, AstroParticule et Cosmologie, Université Paris Diderot, CNRS/IN2P3, CEA/Irfu, Observatoire de Paris, Sorbonne Paris Cité, 10 rue Alice Domont et Léonie Duquet, F-75205 Paris Cedex 13, France

    10 DSM/Irfu/Service d’Astrophysique, Bat. 709 Orme des Merisiers CEA Saclay, F-91191 Gif-sur-Yvette Cedex, France

    11 Université Toulouse; UPS-OMP; CNRS; IRAP; 9 Av. Roche, BP 44346, F-31028 Toulouse, France

    12 European XFEL GmbH, Albert-Einstein-Ring 19, D-22761, Hamburg, Germany

    See the full article here .

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    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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  • richardmitnick 7:09 am on January 26, 2016 Permalink | Reply
    Tags: , , , ESA Integral   

    From ESA: “Integral X-rays Earth’s aurora” 

    ESASpaceForEuropeBanner
    European Space Agency

    26 January 2016
    Erik Kuulkers
    Integral Project Scientist
    Directorate of Science and Robotic Exploration
    European Space Agency
    Tel: +34 918 131 358
    Email: erik.Kuulkers@sciops.esa.int

    Markus Bauer







    ESA Science and Robotic Exploration Communication Officer








    Tel: +31 71 565 6799








    Mob: +31 61 594 3 954








    Email: markus.bauer@esa.int

    1
    Integral’s X-ray view of Earth’s aurora
    Cool .gif, if it disappears from this post, do not be surprised, WordPress has been screwing these up. Just access it in the full article, see link below.

    Normally busy with observing high-energy black holes, supernovas and neutron stars, ESA’s Integral space observatory recently had the chance to look back at our own planet’s aurora.

    ESA Integral
    Integral

    Auroras from around the world
    Auroras from around the world.

    Auroras are well known as the beautiful light shows at polar latitudes as the solar wind interacts with Earth’s magnetic field.

    As energetic particles from the Sun are drawn along Earth’s magnetic field, they collide with different molecules and atoms in the atmosphere to create dynamic, colourful light shows in the sky, typically in green and red.

    But what may be less well known is that auroras also emit X-rays, generated as the incoming particles decelerate.

    Integral detected high-energy auroral X-rays on 10 November 2015 as it turned to Earth – although it was looking for something else at the time.

    Its task was to measure the diffuse cosmic X-ray background that arises naturally from supermassive black holes that are gobbling up material at the centres of some galaxies.

    To achieve this, Integral records the X-ray brightness with and without the Earth in the way, blocking the background. These types of measurements help astronomers estimate how many distant supermassive black holes there are in the Universe.

    Unfortunately, on this occasion, the X-rays from Earth’s aurora drowned out the cosmic background – but the observations were not a waste.

    They also help us to understand the distribution of electrons raining into Earth’s upper atmosphere, and they reveal interactions between the solar wind and Earth’s protective magnetic bubble, or magnetosphere.

    “Auroras are transient, and cannot be predicted on the timeframe that satellite observations are planned, so it was certainly an unexpected observation,” comments Erik Kuulkers, Integral project scientist.

    “It’s also quite unusual for us to point the spacecraft at Earth: it requires innovative planning by the operations teams to coordinate such a dedicated set of manoeuvres to ensure it can operate safely with Earth inside the instruments’ field of view and then return to its standard observing programme.

    “Although the original background X-ray measurements didn’t go quite to plan this time, it was exciting to capture such intense auroral activity by chance.”

    See the full article here .

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    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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  • richardmitnick 9:31 am on June 25, 2015 Permalink | Reply
    Tags: , , ESA Integral   

    From ESA: “Monster black hole wakes up after 26 years” 

    ESASpaceForEuropeBanner
    European Space Agency

    1
    Black hole with stellar companion

    25 June 2015
    No Writer Credit

    Over the past week, ESA’s Integral satellite has been observing an exceptional outburst of high-energy light produced by a black hole that is devouring material from its stellar companion.

    ESA Integral
    Integral

    X-rays and gamma rays point to some of the most extreme phenomena in the Universe, such as stellar explosions, powerful outbursts and black holes feasting on their surroundings.

    In contrast to the peaceful view of the night sky we see with our eyes, the high-energy sky is a dynamic light show, from flickering sources that change their brightness dramatically in a few minutes to others that vary on timescales spanning years or even decades.

    On 15 June 2015, a long-time acquaintance of X-ray and gamma ray astronomers made its comeback to the cosmic stage: V404 Cygni, a system comprising a black hole and a star orbiting one another. It is located in our Milky Way galaxy, almost 8000 light-years away in the constellation Cygnus, the Swan.

    In this type of binary system, material flows from the star towards the black hole and gathers in a disc, where it is heated up, shining brightly at optical, ultraviolet and X-ray wavelengths before spiralling into the black hole.

    First signs of renewed activity in V404 Cygni were spotted by the Burst Alert Telescope on NASA’s Swift satellite, detecting a sudden burst of gamma rays, and then triggering observations with its X-ray telescope.

    NASA SWIFT Telescope
    NASA/Swift

    Soon after, MAXI (Monitor of All-sky X-ray Image), part of the Japanese Experiment Module on the International Space Station, observed an X-ray flare from the same patch of the sky.

    These first detections triggered a massive campaign of observations from ground-based telescopes and from space-based observatories, to monitor V404 Cygni at many different wavelengths across the electromagnetic spectrum. As part of this worldwide effort, ESA’s Integral gamma-ray observatory started monitoring the out-bursting black hole on 17 June.

    2
    Integral image before and after the outburst

    “The behaviour of this source is extraordinary at the moment, with repeated bright flashes of light on time scales shorter than an hour, something rarely seen in other black hole systems,” comments Erik Kuulkers, Integral project scientist at ESA.

    “In these moments, it becomes the brightest object in the X-ray sky – up to fifty times brighter than the Crab Nebula, normally one of the brightest sources in the high-energy sky.”

    The V404 Cygni black hole system has not been this bright and active since 1989, when it was observed with the Japanese X-ray satellite Ginga and high-energy instruments on board the Mir space station.

    “The community couldn’t be more thrilled: many of us weren’t yet professional astronomers back then, and the instruments and facilities available at the time can’t compare with the fleet of space telescopes and the vast network of ground-based observatories we can use today. It is definitely a ‘once in a professional lifetime’ opportunity,” adds Kuulkers.

    2
    Integral light curve

    The 1989 outburst of V404 Cygni was crucial in the study of black holes. Until then, astronomers knew only a handful of objects that they thought could be black holes, and V404 Cygni was one of the most convincing candidates.

    A couple of years after the 1989 outburst, once the source had returned to a quieter state, the astronomers were able to see its companion star, which had been outshone by the extreme activity. The star is about half as massive as the Sun, and by studying the relative motion of the two objects in the binary system, it was determined that the companion must be a black hole, about twelve times more massive than the Sun.

    At the time, the astronomers also looked back at archival data from optical telescopes over the twentieth century, finding two previous outbursts, one in 1938 and another one in 1956.

    These peaks of activity, which occur every two to three decades, are likely caused by material slowly piling up in the disc surrounding the black hole, until eventually reaching a tipping point that dramatically changes the black hole’s feeding routine for a short period.

    “Now that this extreme object has woken up again, we are all eager to learn more about the engine that powers the outburst we are observing,” says Carlo Ferrigno from the Integral Science Data Centre at the University of Geneva, Switzerland.

    “As coordinators of Integral operations, Enrico Bozzo and I received a text message at 01:30 am on 18 June from our burst alert system, which is designed to detect gamma-ray bursts in the Integral data. In this case, it turned out to be ‘only’ an exceptional flare since Integral was observing this incredible black hole: definitely a good reason to be woken up in the middle of the night!”

    Since the first outburst detection on 15 June by the Swift satellite, V404 Cygni has remained very active, keeping astronomers extremely busy. Over the past week, several teams around the world published over twenty Astronomical Telegrams and other official communications, sharing the progress of the observations at different wavelengths.

    This exciting outburst has also been discussed by astronomers attending the European Week of Astronomy and Space Science conference this week in Tenerife, sharing information on observations that have been made in the past few days.

    Integral too has been observing this object continuously since 17 June, except for some short periods when it was not possible for operational reasons. The X-ray data show huge variability, with intense flares lasting only a couple of minutes, as well as longer outbursts over time scales of a few hours. Integral also recorded a huge emission of gamma rays from this frenzied black hole.

    Because different components of a black-hole binary system emit radiation at different wavelengths across the spectrum, astronomers are combining high-energy observations with those made at optical and radio wavelengths in order to get a complete view of what is happening in this unique object.

    “We have been observing V404 Cygni with the Gran Telescopio Canarias, which has the largest mirror currently available for optical astronomy,” explains Teo Muñoz-Darias from the Instituto de Astrofísica de Canarias in Tenerife, Spain.

    Grand Telescope de Canaries
    Gran Telescope de Canaries interior
    Gran Telescopio Canarias

    Using this 10.4-m telescope located on La Palma, the astronomers can quickly obtain high quality spectra, thus probing what happens around the black hole on short time scales.

    “There are many features in our spectra, showing signs of massive outflows of material in the black hole’s environment. We are looking forward to testing our current understanding of black holes and their feeding habits with these rich data,” adds Muñoz-Darias.

    Radio astronomers all over the world are also joining in this extraordinary observing campaign. The first detection at these long wavelengths was made shortly after the first Swift alert on 15 June with the Arcminute Microkelvin Imager from the Mullard Radio Astronomy Observatory near Cambridge, in the UK, thanks to the robotic mode of this telescope.

    Arcminute Microkelvin Imager
    Arcminute Microkelvin Imager

    Like the data at other wavelengths, these radio observations also exhibit a continuous series of extremely bright flares. Astronomers will exploit them to investigate the mechanisms that give rise to powerful jets of particles, moving away at velocities close to the speed of light, from the black hole’s accretion disc.

    There are only a handful of black-hole binary systems for which data have been collected simultaneously at many wavelengths, and the current outburst of V404 Cygni offers the rare chance to gather more observations of this kind. Back in space, Integral has a full-time job watching the events unfold.

    “We have been devoting all of Integral’s time to observe this exciting source for the past week, and we will keep doing so at least until early July,” comments Peter Kretschmar, ESA Integral mission manager.

    “The observations will soon be made available publicly, so that astronomers across the world can exploit them to learn more about this unique object. It will also be possible to use Integral data to try and detect polarisation of the X-ray and gamma ray emission, which could reveal more details about the geometry of the black hole accretion process. This is definitely material for the astrophysics textbooks for the coming years.”

    Notes for Editors

    The International Gamma-ray Astrophysics Laboratory Integral was launched on 17 October 2002. It is an ESA project with the instruments and a science data centre funded by ESA Member States (especially the Principal Investigator countries: Denmark, France, Germany, Italy, Spain and Switzerland), and with the participation of Russia and the USA. The mission is dedicated to spectroscopy (E/∆E = 500) and imaging (angular resolution: 12 arcmin FWHM) of celestial gamma-ray sources in the energy range 15 keV to 10 MeV with concurrent source monitoring in the X-ray (3–35 keV) and optical (V-band, 550 nm) wavelengths.

    See the full article here.

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  • richardmitnick 5:56 pm on January 23, 2015 Permalink | Reply
    Tags: , , ESA Integral   

    From ESA: “Integral Maneuvers for the Future” 

    ESASpaceForEuropeBanner
    European Space Agency

    23 January 2015
    No Writer Credit

    1
    Integral: gamma-ray observatory

    23 January 2015

    Since 2002, ESA’s Integral spacecraft has been observing some of the most violent events in the Universe, including gamma-ray bursts and black holes. While it still has years of life ahead, its fuel will certainly run out one day.

    Integral, one of ESA’s longest-serving and most successful space observatories, has begun a series of four thruster burns carefully designed to balance its scientific life with a safe reentry in 2029.

    That seems far off, but detailed planning and teamwork now will ensure that the satellite’s eventual entry into the atmosphere will meet the Agency’s guidelines for minimising space debris.

    Making these disposal manoeuvres so early will also minimises fuel usage, allowing ESA to exploit the valuable satellite’s lifetime to the fullest.

    This is the first time that a spacecraft’s orbit is being adjusted, after 12 years in space, to achieve a safe reentry 15 years in the future, while maximising valuable science return for the subsequent seven to eight years.

    “Our four burns will use about half of the estimated 96 kg of fuel available,” says Richard Southworth, spacecraft operations manager at ESA’s Space Operations Centre, ESOC, in Darmstadt, Germany.

    “This will influence how Integral’s orbit evolves, so that even after we run out of propellant we will still have a safe reentry in February 2029 as a result of natural orbit decay.

    “No further manoeuvres are required between now and then and Integral can continue to operate.”

    2
    Protected orbital regions

    The latest ESA debris guidelines require that a satellite must be disposed of in such a way that it poses no risk to other satellites in protected orbital regions for more than 25 years.

    Although Integral’s early launch date, in 2002, means it is not required to stick to the guidelines, they were followed for planning the disposal.

    “We have done a great deal of modelling for Integral’s reentry in 2029,” says Klaus Merz of ESA’s Space Debris Office.

    “We’re confident that this month’s manoeuvres will put it on track for a future safe reentry at latitudes in the far south, reducing risk far below guideline levels.”

    Without these firings, the fuel supply would run out in perhaps 12–16 more years, after other essentials such as power end Integral’s working life. But the satellite would not reenter for up to 200 years, which would present a hazard to other missions.

    The first of the four burns was performed on 12–13 January, and ran for 16 minutes.

    It delivered a small change in orbital velocity, and hence size and shape of the orbit, so that ESA’s Perth, Australia, ground tracking station would become usable for the satellite for all future manoeuvres.

    3
    Supernova explosion 2014
    INTEGRAL detetced gamma rays from the supernova

    This is important because it allows the Integral team to execute subsequent firings exactly at perigee – the point of closest approach to Earth’s surface – which is the optimum point in its orbit to execute manoeuvres, leading to the most efficient use of fuel.

    The second and largest burn is set for Saturday, 24 January, and will run for about 32 minutes to provide about half of the overall required change in velocity.

    The third manoeuvre is planned for 4 February, followed by a possible fourth on 12 February to trim the orbit in order to provide favourable tracking coverage for the rest of the mission from ESA’s Kiruna ground station in Sweden.

    Developing the complex plan has taken years of teamwork by the mission operations and science operations teams, but it will set Integral onto a sustainable course for the rest of its mission.

    “At first glance, it looked like the goals of space debris mitigation and maximising science were incompatible considering the limited amount of fuel available,” explained Claudia Dietze and Gerald Ziegler, flight dynamics specialists working on Integral at ESOC.

    5
    ESA’s flight dynamics team works from a specialised control room at ESOC, Darmstadt

    “However, after detailed analysis, a sequence was developed that meets both goals. Moreover, additional considerations of attitude constraints and ground station coverage had to be taken into account, making it a highly interesting and challenging undertaking.”

    With the burns complete, Integral will continue scientific observations until its fuel runs out in the early 2020s.

    The normal degradation of the solar panels by radiation will begin to limit observations anyway until, at some point probably in the mid-2020s, science operations would need to stop regardless of fuel.

    “However, we are also looking into ways to reduce routine fuel usage by applying techniques developed for other missions, such as our sister satellite, XMM-Newton,” says Richard Southworth.

    “This is a robust, doable, safe and complete plan,” says Peter Kretschmar, Integral’s mission manager.

    “It’s allowing us to maximise the precious scientific return from this satellite, while fully meeting end-of-life and debris mitigation guidelines,” adds Erik Kuulkers, Integral’s project scientist.

    The mission celebrated its 10th anniversary in orbit in 2012, and is currently extended until December 2016.

    Integral enables scientists to study our Universe at gamma-ray wavelengths, and it has discovered amazing objects including one of the fastest spinning neutron stars as well as gamma-rays from a supernova.

    See the full article here.

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  • richardmitnick 2:03 pm on August 27, 2014 Permalink | Reply
    Tags: , , , , ESA Integral   

    From ESA: “INTEGRAL Catches a Dead Star Exploding in a Blaze of Glory” 

    ESASpaceForEuropeBanner
    European Space Agency

    27 August 2014

    Markus Bauer
    ESA Science and Robotic Exploration Communication Officer
    Phone: +31 71 565 6799
    Mobile: +31 61 594 3 954
    Email: markus.bauer@esa.int

    Eugene Churazov
    Space Research Institute (IKI), Moscow, Russia
    Phone: +7-495-3333377
    Email: churazov@hea.iki.rssi.ru
    and Max Planck Institute for Astrophysics, Germany
    Phone: +49-89-30000-2219
    Email: churazov@mpa-garching.mpg.de

    Roland Diehl
    Max Planck Institute for Extraterrestrial Physics, Germany
    Phone: +49-89-30000-3850
    Email: rodmpe.mpg.de

    Erik Kuulkers
    INTEGRAL Project Scientist
    Directorate of Science and Robotic Exploration
    European Space Agency
    Phone: +34-91-8131-358
    Email: Erik.Kuulkers@sciops.esa.int

    exp
    White dwarfs are inert stars that contain up to 1.4 times the mass of the Sun squeezed into a volume about the same size as the Earth. Being inert, they can’t simply blow themselves up. Instead, astronomers believe that they leech matter from a companion star, which builds up on the surface until a critical total mass is reached. At that point, the pressure in the heart of the white dwarf triggers a catastrophic thermonuclear detonation.

    27 August 2014

    Astronomers using ESA’s INTEGRAL gamma-ray observatory have demonstrated beyond doubt that dead stars known as white dwarfs can reignite and explode as supernovae. The finding came after the unique signature of gamma rays from the radioactive elements created in one of these explosions was captured for the first time.

    ESA Integral
    ESA/INTEGRAL

    The explosions in question are known as Type Ia supernovae, long suspected to be the result of a white dwarf star blowing up because of a disruptive interaction with a companion star. However, astronomers have lacked definitive evidence that a white dwarf was involved until now. The ‘smoking gun’ in this case was evidence for radioactive nuclei being created by fusion during the thermonuclear explosion of the white dwarf star.

    “INTEGRAL has all the capabilities to detect the signature of this fusion, but we had to wait for more than ten years for a once-in-a-lifetime opportunity to catch a nearby supernova,” says Eugene Churazov, from the Space Research Institute (IKI) in Moscow, Russia and the Max Planck Institute for Astrophysics,in Garching, Germany.

    Although Type Ia supernovae are expected to occur frequently across the Universe they are rare occurrences in any one galaxy, with typical rates of one every few hundred years.

    <img src="http://www.esa.int/var/esa/storage/images/esa_multimedia/images/2014/08/supernova_sn2014j_in_nearby_galaxy_m82/14745137-1-eng-GB
    Supernova SN2014J in nearby galaxy M82

    INTEGRAL’s chance came on 21 January 2014, when students at the University College London’s teaching observatory at Mill Hill, UK detected a type Ia supernova, later named SN2014J, in the nearby galaxy M82.

    University of London Mill Hill Observatory
    University of London Mill Hill Observatory interior
    Mill HIll

    According to the theory of such explosions, the carbon and oxygen found in a white dwarf should be fused into radioactive nickel during the explosion. This nickel should then quickly decay into radioactive cobalt, which would itself subsequently decay, on a somewhat longer timescale, into stable iron.

    Because of its proximity – at a distance of about 11.5 million light-years from Earth, SN2014J is the closest of its type to be detected in decades – INTEGRAL stood a good chance of seeing the gamma rays produced by the decay. Within one week of the initial discovery, an observing plan to use INTEGRAL had been drawn-up and approved.

    Using INTEGRAL to study the aftermath of the supernova explosion, scientists looked for the signature of cobalt decay – and they found it, in exactly the quantities that the models predicted.

    “The consistency of the spectra, obtained by INTEGRAL 50 days after the explosion, with that expected from cobalt decay in the expanding debris of the white dwarf was excellent,” says Churazov, who is lead author of a paper describing this study and reported in the journal Nature.

    With that confirmation in hand, other astronomers could begin to look into the details of the process. In particular, how the white dwarf is detonated in the first place.

    White dwarfs are inert stars that contain up to 1.4 times the mass of the Sun squeezed into a volume about the same size as the Earth. Being inert, they can’t simply blow themselves up. Instead, astronomers believe that they leech matter from a companion star, which builds up on the surface until a critical total mass is reached. At that point, the pressure in the heart of the white dwarf triggers a catastrophic thermonuclear detonation.

    Early INTEGRAL observations of SN2014J tell a somewhat different story, and have been the focus of a separate study, reported online in Science Express by Roland Diehl from the Max Planck Institute for Extraterrestrial Physics, Germany, and colleagues.

    Diehl and his colleagues detected gamma rays from the decay of radioactive nickel just 15 days after the explosion. This was unexpected, because during the early phase of a Type Ia supernova, the explosion debris is thought to be so dense that the gamma rays from the nickel decay should be trapped inside.

    “We were puzzled by this surprising signal, and some from the group even thought it must be wrong,” says Diehl. “We had long and ultimately very fruitful discussions about what might explain these data.”

    A careful examination of the theory showed that the signal would have been hidden only if the explosion had begun in the heart of the white dwarf. Instead, Diehl and colleagues think that what they are seeing is evidence for a belt of gas from the companion star that must have built up around the equator of the white dwarf. This outer layer detonated, forming the observed nickel and then triggering the internal explosion that became the supernova.

    “Regardless of the fine details of how these supernovae are triggered, INTEGRAL has proved beyond doubt that a white dwarf is involved in these stellar cataclysms,” says Erik Kuulkers, ESA’s INTEGRAL Project Scientist. “This clearly demonstrates that even after almost twelve years in operation, INTEGRAL is still playing a crucial role in unraveling some of the mysteries of the high-energy Universe.”

    See the full article here.

    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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  • richardmitnick 2:36 pm on March 4, 2013 Permalink | Reply
    Tags: , , , , , ESA Integral   

    From ESA: “High mass X-ray binaries trace the Milky Way’s spiral arms” 

    ESASpaceForEuropeBanner
    European Space Agency

    04 Mar 2013

    “Our Galaxy is littered with pairs of massive stars, many of which contain the remnants of supernova explosions. A new study of these X-ray emitting binary systems, using data from ESA’s INTEGRAL space observatory, has made it possible to reconstruct the locations of the Milky Way’s spiral arms many millions of years ago.

    ESA Integral
    Integral

    mw
    Milky Way with legends

    High mass X-ray binaries (HMXBs) contain stars which consume their hydrogen and helium fuel so quickly that they explode as supernovas within a few tens of millions of years – the blink of an eye in the history of the Universe.

    These short-lived stellar systems comprise an extremely dense, compact object (a neutron star or a black hole) which is pulling in matter ejected from a massive companion – a process known as accretion. The stellar companion is usually either a main sequence Be star or an evolved supergiant which is nearing the end of its life.

    star chart

    Be stars are rapidly rotating objects which are surrounded by a disc of gas that is ejected by the stars themselves. When the neutron star passes periodically through this disc, gas is strongly heated during accretion onto its surface, creating a blast of X-rays. In the case of supergiant X-ray binaries, the accreted material is derived from the massive companions ejecting large amounts of material in their stellar winds.

    Dedicated X-ray observations of the sky, particularly with the INTEGRAL spacecraft, have quintupled the known population of high mass supergiant X-ray binaries in the Galaxy. Some 35 supergiant HMXBs are currently catalogued, out of a total of more than 200 HMXBs.”

    See the full article here.

    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

    ESA Technology


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