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  • richardmitnick 1:53 pm on August 9, 2017 Permalink | Reply
    Tags: , , , , , ESO Paranal VLT, The star S2   

    From ESO: “First Evidence for Relativity Effects in Stars Orbiting Supermassive Black Hole at Centre of Galaxy” 

    ESO 50 Large

    European Southern Observatory

    9 August 2017
    Marzieh Parsa
    I. Physikalisches Institut, Universität zu Köln
    Köln, Germany
    Tel: +49(0)221/470-3495
    Email: parsa@ph1.uni-koeln.de

    Andreas Eckart
    I. Physikalisches Institut, Universität zu Köln
    Köln, Germany
    Tel: +49(0)221/470-3546
    Email: eckart@ph1.uni-koeln.de

    Vladimir Karas
    Astronomical Institute, Academy of Science
    Prague, Czech Republic
    Tel: +420-226 258 420
    Email: vladimir.karas@cuni.cz

    Richard Hook
    ESO Public Information Officer
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    1
    A new analysis of data from ESO’s Very Large Telescope and other telescopes [I have asked ESO repeatedly to credit all telscopes used in any project, as they are all supported by public money. They apparently prefer to leave us in the dark.] they reveals for the first time that the orbits of stars around the supermassive black hole at the centre of the Milky Way show the subtle effects predicted by Einstein’s general theory of relativity. The orbit of the star S2 is found to be deviating slightly from the path calculated using classical physics. This tantalising result is a prelude to much more precise measurements and tests of relativity that will be made using the GRAVITY instrument as star S2 passes very close to the black hole in 2018.

    ESO GRAVITY insrument on The VLT

    This artist’s impression shows the orbits of three of the stars very close to the supermassive black hole at the centre of the Milky Way. Analysis of data from ESO’s Very Large Telescope and other telescopes has revealed that the orbits of these stars show the subtle effects predicted by Einstein’s general theory of relativity. The orbit of the star called S2 is found to be deviating slightly from the path calculated using classical physics.
    The position of the supermassive black hole is marked with a white circle with a blue halo. Credit: ESO/M. Parsa/L. Calçada


    The orbit of the star S2 is found to be deviating slightly from the path calculated using classical physics. This tantalising result is a prelude to much more precise measurements and tests of relativity that will be made using the GRAVITY instrument as star S2 passes very close to the black hole in 2018.

    At the centre of the Milky Way, 26 000 light-years from Earth, lies the closest supermassive black hole, which has a mass four million times that of the Sun. This monster is surrounded by a small group of stars orbiting at high speed in the black hole’s very strong gravitational field. It is a perfect environment in which to test gravitational physics, and particularly Einstein’s general theory of relativity.

    A team of German and Czech astronomers have now applied new analysis techniques to the very rich set of existing observations of the stars orbiting the black hole, accumulated using ESO’s Very Large Telescope (VLT) in Chile and others over the last twenty years [1]. They compare the measured star orbits to predictions made using classical Newtonian gravity as well as predictions from general relativity.

    The team found evidence for a small change in the motion of one of the stars, known as S2, that is consistent with the predictions of general relativity [2]. The change due to relativistic effects amounts to only a few percent in the shape of the orbit, as well as only about one sixth of a degree in the orientation of the orbit [3]. This is the first time that a measurement of the strength of the general relativistic effects has been achieved for stars orbiting a supermassive black hole.

    Marzieh Parsa, PhD student at the University of Cologne, Germany and lead author of the paper [The Astropysical Journel], is delighted: “The Galactic Centre really is the best laboratory to study the motion of stars in a relativistic environment. I was amazed how well we could apply the methods we developed with simulated stars to the high-precision data for the innermost high-velocity stars close to the supermassive black hole.”

    3
    The central parts of our Galaxy, the Milky Way, as observed in the near-infrared with the NACO instrument on ESO’s Very Large Telescope. The position of the centre, which harbours the (invisible) black hole known as Sgr A*,with a mass 4 million times that of the Sun, is marked by the orange cross.

    The star S2 will make a close pass around the black hole in 2018 when it will be used as a unique probe of the strong gravity and act as a test of Einstein’s general theory of relativity. Credit: ESO/MPE/S. Gillessen et al.

    The high accuracy of the positional measurements, made possible by the VLT’s near-infrared adaptive optics instruments, was essential for the success of the study [4]. These were vital not only during the star’s close approach to the black hole, but particularly during the time when S2 was further away from the black hole. The latter data allowed an accurate determination of the shape of the orbit and how it is changing under the influence of relativity.

    “During the course of our analysis we realised that to determine relativistic effects for S2 one definitely needs to know the full orbit to very high precision,” comments Andreas Eckart, team leader at the University of Cologne.

    As well as more precise information about the orbit of the star S2, the new analysis also gives the mass of the black hole and its distance from Earth to a higher degree of accuracy [5].

    Co-author Vladimir Karas from the Academy of Sciences in Prague, the Czech Republic, is excited about the future: “It is very reassuring that S2 shows relativistic effects as expected on the basis of its proximity to the extreme mass concentration at the centre of the Milky Way. This opens up an avenue for more theory and experiments in this sector of science.”

    This analysis is a prelude to an exciting period for observations of the Galactic Centre by astronomers around the world. During 2018 the star S2 will make a very close approach to the supermassive black hole. This time the GRAVITY instrument, developed by a large international consortium led by the Max-Planck-Institut für extraterrestrische Physik in Garching, Germany [6], and installed on the VLT Interferometer [7], will be available to help measure the orbit much more precisely than is currently possible. Not only is this expected to reveal the general relativistic effects very clearly, but also it will allow astronomers to look for deviations from general relativity that might reveal new physics.
    Notes

    [1] Data from the near-infrared NACO camera now at VLT Unit Telescope 1 (Antu) and the near-infrared imaging spectrometer SINFONI at the Unit Telescope 4 (Yepun) were used for this study. Some additional published data obtained at the Keck Observatory were also used.

    ESO/NACO

    ESO/SINFONI


    Keck Observatory, Maunakea, Hawaii, USA

    [2] S2 is a 15-solar-mass star on an elliptical orbit around the supermassive black hole. It has a period of about 15.6 years and gets as close as 17 light-hours to the black hole — or just 120 times the distance between the Sun and the Earth.

    [3] A similar, but much smaller, effect is seen in the changing orbit of the planet Mercury in the Solar System. That measurement was one of the best early pieces of evidence in the late nineteenth century suggesting that Newton’s view of gravity was not the whole story and that a new approach and new insights were needed to understand gravity in the strong-field case. This ultimately led to Einstein publishing his general theory of relativity, based on curved spacetime, in 1915.

    When the orbits of stars or planets are calculated using general relativity, rather than Newtonian gravity, they evolve differently. Predictions of the small changes to the shape and orientation of orbits with time are different in the two theories and can be compared to measurements to test the validity of general relativity.

    [4] An adaptive optics system compensates for the image distortions produced by the turbulent atmosphere in real time and allows the telescope to be used at much angular resolution (image sharpness), in principle limited only by the mirror diameter and the wavelength of light used for the observations.

    [5] The team finds a black hole mass of 4.2 × 106 times the mass of the Sun, and a distance from us of 8.2 kiloparsecs, corresponding to almost 27 000 light-years.

    [6] The University of Cologne is part of the GRAVITY team (http://www.mpe.mpg.de/ir/gravity) and contributed the beam combiner spectrometers to the system.

    [7] GRAVITY First Light was in early 2016 and it is already observing the Galactic Centre.

    The team is composed of Marzieh Parsa, Andreas Eckart (I.Physikalisches Institut of the University of Cologne, Germany; Max Planck Institute for Radio Astronomy, Bonn, Germany), Banafsheh Shahzamanian (I.Physikalisches Institut of the University of Cologne, Germany), Christian Straubmeier (I.Physikalisches Institut of the University of Cologne, Germany), Vladimir Karas (Astronomical Institute, Academy of Science, Prague, Czech Republic), Michal Zajacek (Max Planck Institute for Radio Astronomy, Bonn, Germany; I.Physikalisches Institut of the University of Cologne, Germany) and J. Anton Zensus (Max Planck Institute for Radio Astronomy, Bonn, Germany).

    See the full article here .

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

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

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

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

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

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

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

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

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

    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)

     
  • richardmitnick 9:19 am on August 2, 2017 Permalink | Reply
    Tags: AOF- Adaptive Optics Facility, , , , , Cutting-edge Adaptive Optics Facility Sees First Light, , ESO Paranal VLT   

    From ESO: “Cutting-edge Adaptive Optics Facility Sees First Light” 

    ESO 50 Large

    European Southern Observatory

    2 August 2017
    Harald Kuntschner
    ESO, AOF Project Scientist
    Garching bei München, Germany
    Tel: +49 89 3200 6465
    Email: hkuntsch@eso.org

    Richard Hook
    ESO Public Information Officer
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    Joël Vernet
    ESO MUSE and GALACSI Project Scientist
    Garching bei München, Germany
    Tel: +49 89 3200 6579
    Email: jvernet@eso.org

    1
    The Unit Telescope 4 (Yepun) of ESO’s Very Large Telescope (VLT) has now been transformed into a fully adaptive telescope. After more than a decade of planning, construction and testing, the new Adaptive Optics Facility (AOF) has seen first light with the instrument MUSE, capturing amazingly sharp views of planetary nebulae and galaxies. The coupling of the AOF and MUSE forms one of the most advanced and powerful technological systems ever built for ground-based astronomy.

    ESO MUSE on the VLT

    2
    The planetary nebula NGC 6369 seen with natural seeing (left) and when the AOF is providing ground layer correction of the turbulent atmosphere (right). The AOF provides much sharper view of celestial objects and enables access to much finer and fainter structures. Credit: ESO/P. Weilbacher.

    The Adaptive Optics Facility (AOF) is a long-term project on ESO’s Very Large Telescope (VLT) to provide an adaptive optics system for the instruments on Unit Telescope 4 (UT4), the first of which is MUSE (the Multi Unit Spectroscopic Explorer) [1]. Adaptive optics works to compensate for the blurring effect of the Earth’s atmosphere, enabling MUSE to obtain much sharper images and resulting in twice the contrast previously achievable. MUSE can now study even fainter objects in the Universe.

    4
    The Adaptive Optics Facility works to remove the blurring effect of Earth’s atmosphere. When used one can see much finer details in the faint planetary nebula NGC 6563 as compared to the natural sky quality. Credit: ESO.

    “Now, even when the weather conditions are not perfect, astronomers can still get superb image quality thanks to the AOF,” explains Harald Kuntschner, AOF Project Scientist at ESO.

    Following a battery of tests on the new system, the team of astronomers and engineers were rewarded with a series of spectacular images. Astronomers were able to observe the planetary nebulae IC 4406, located in the constellation Lupus (The Wolf), and NGC 6369, located in the constellation Ophiuchus (The Serpent Bearer). The MUSE observations using the AOF showed dramatic improvements in the sharpness of the images, revealing never before seen shell structures in IC 4406 [2].

    5
    The AOF + MUSE at work. Inside the UT4 of the Very Large Telescope, part of the Adaptive Optics Facility, the four Laser Guide Stars Facility, point to the skies during the first observations using the MUSE instrument. The sharpness and dynamic range of images using the AOF equipped MUSE instrument will dramatically improve future observations. Credit: Roland Bacon.

    The AOF, which made these observations possible, is composed of many parts working together. They include the Four Laser Guide Star Facility (4LGSF) and the very thin deformable secondary mirror of UT4 [3] [4]. The 4LGSF shines four 22-watt laser beams into the sky to make sodium atoms in the upper atmosphere glow, producing spots of light on the sky that mimic stars. Sensors in the adaptive optics module GALACSI (Ground Atmospheric Layer Adaptive Corrector for Spectroscopic Imaging) use these artificial guide stars to determine the atmospheric conditions.

    GALACSI Adaptive Optics System for VLT

    6
    Inside the UT4 of the Very Large Telescope, part of the Adaptive Optics Facility, the four Laser Guide Stars Facility, point to the skies during the first observations using the MUSE instrument. The AOF system is composed of many parts working together to create sharp images of astronomical objects. Credit: Roland Bacon.

    One thousand times per second, the AOF system calculates the correction that must be applied to change the shape of the telescope’s deformable secondary mirror to compensate for atmospheric disturbances. In particular, GALACSI corrects for the turbulence in the layer of atmosphere up to one kilometre above the telescope. Depending on the conditions, atmospheric turbulence can vary with altitude, but studies have shown that the majority of atmospheric disturbance occurs in this “ground layer” of the atmosphere.

    “The AOF system is essentially equivalent to raising the VLT about 900 metres higher in the air, above the most turbulent layer of atmosphere,” explains Robin Arsenault, AOF Project Manager. “In the past, if we wanted sharper images, we would have had to find a better site or use a space telescope — but now with the AOF, we can create much better conditions right where we are, for a fraction of the cost!”

    7
    UT4 and the AOF at work. The four Laser Guide Stars Facility points to the skies during the first observations using the AOF-equipped MUSE instrument. Adaptive optics assist ground-based telescopes by compensating for the blurring effect of the Earth’s atmosphere on starlight. Credit: Roland Bacon.

    The corrections applied by the AOF rapidly and continuously improve the image quality by concentrating the light to form sharper images, allowing MUSE to resolve finer details and detect fainter stars than previously possible. GALACSI currently provides a correction over a wide field of view, but this is only the first step in bringing adaptive optics to MUSE. A second mode of GALACSI is in preparation and is expected to see first light early 2018. This narrow-field mode will correct for turbulence at any altitude, allowing observations of smaller fields of view to be made with even higher resolution.

    “Sixteen years ago, when we proposed building the revolutionary MUSE instrument, our vision was to couple it with another very advanced system, the AOF,” says Roland Bacon, project lead for MUSE. “The discovery potential of MUSE, already large, is now enhanced still further. Our dream is becoming true.”

    One of the main science goals of the system is to observe faint objects in the distant Universe with the best possible image quality, which will require exposures of many hours. Joël Vernet, ESO MUSE and GALACSI Project Scientist, comments: “In particular, we are interested in observing the smallest, faintest galaxies at the largest distances. These are galaxies in the making — still in their infancy — and are key to understanding how galaxies form.”

    Furthermore, MUSE is not the only instrument that will benefit from the AOF. In the near future, another adaptive optics system called GRAAL will come online with the existing infrared instrument HAWK-I, sharpening its view of the Universe. That will be followed later by the powerful new instrument ERIS.

    ESO Graal

    ESO HAWK-I the ESO Very Large Telescope at the Paranal Observatory in Chile, with an elevation of 2,635 metres (8,645 ft) above sea level

    ESO is driving the development of these adaptive optics systems, and the AOF is also a pathfinder for ESO’s Extremely Large Telescope,” adds Arsenault. “Working on the AOF has equipped us — scientists, engineers and industry alike — with invaluable experience and expertise that we will now use to overcome the challenges of building the ELT.”
    Notes

    [1] MUSE is an integral-field spectrograph, a powerful instrument that produces a 3D data set of a target object, where each pixel of the image corresponds to a spectrum of the light from the object. This essentially means that the instrument creates thousands of images of the object at the same time, each at a different wavelength of light, capturing a wealth of information.

    [2] IC 4406 has previously been observed with the VLT (eso9827a).

    [3] At just over one metre in diameter, this is the largest adaptive optics mirror ever produced and demanded cutting-edge technology. It was mounted on UT4 in 2016 (ann16078) to replace the telescope’s original conventional secondary mirror.

    [4] Other tools to optimise the operation of the AOF have been developed and are now operational. These include an extension of the Astronomical Site Monitor software that monitors the atmosphere to determine the altitude at which the turbulence is occurring, and the Laser Traffic Control System (LTCS) that prevents other telescopes looking into the laser beams or at the artificial stars themselves and potentially affecting their observations.

    7
    ESO 338-4 is a starburst galaxy located in Sagittarius, the Archer. It is currently in the process of merging, with several smaller galaxies colliding to form the final galaxy. The new AOF+MUSE data clearly resolve several bright knots where intense star formation, induced by the merging, is occurring, as well as filaments of glowing hydrogen gas. Credit: ESO/P. Weilbacher.

    See the full article here .

    Please help promote STEM in your local schools.
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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
    VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.

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

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

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

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

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

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

    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)

     
  • richardmitnick 2:24 pm on August 1, 2017 Permalink | Reply
    Tags: , , , , ESO Paranal VLT, Tau Boötis b revealed   

    From ESO via Manu: “New Way of Probing Exoplanet Atmospheres” 2012 


    Manu Garcia, a friend from IAC.

    The universe around us.
    Astronomy, everything you wanted to know about our local universe and never dared to ask.

    ESO 50 Large

    European Southern Observatory

    27 June 2012
    Ignas Snellen
    Leiden Observatory, Leiden University
    Leiden, The Netherlands
    Tel: +31 715 275838
    Email: snellen@strw.leidenuniv.nl

    Matteo Brogi
    Leiden Observatory, Leiden University
    Leiden, The Neherlands
    Tel: +31 715 278434
    Email: brogi@strw.leidenuniv.nl

    Jayne Birkby
    Leiden Observatory, Leiden University
    Leiden, The Netherlands
    Tel: +31 715 275832
    Email: birkby@strw.leidenuniv.nl

    Richard Hook
    ESO, La Silla, Paranal, E-ELT & Survey Telescopes Press Officer
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    Remco de Kok
    Space Research Organization Netherlands (SRON)
    Utrecht, The Netherlands
    Tel: +31 88 777 5725
    Email: R.J.de.Kok@sron.nl

    Tau Boötis b revealed.

    1
    For the first time a clever new technique has allowed astronomers to study the atmosphere of an exoplanet in detail — even though it does not pass in front of its parent star. An international team has used ESO’s Very Large Telescope to directly catch the faint glow from the planet Tau Boötis b. They have studied the planet’s atmosphere and measured its orbit and mass precisely for the first time — in the process solving a 15-year old problem. Surprisingly, the team also finds that the planet’s atmosphere seems to be cooler higher up, the opposite of what was expected. The results will be published in the 28 June 2012 issue of the journal Nature.

    The planet Tau Boötis b [1] was one of the first exoplanets to be discovered back in 1996, and it is still one of the closest exoplanets known. Although its parent star is easily visible with the naked eye, the planet itself certainly is not, and up to now it could only be detected by its gravitational effects on the star. Tau Boötis b is a large “hot Jupiter” planet orbiting very close to its parent star.

    Planet transit. NASA/Ames

    Like most exoplanets, this planet does not transit the disc of its star (like the recent transit of Venus). Up to now such transits were essential to allow the study of hot Jupiter atmospheres: when a planet passes in front of its star it imprints the properties of the atmosphere onto the starlight. As no starlight shines through Tau Boötis b’s atmosphere towards us, this means the planet’s atmosphere could not be studied before.

    But now, after 15 years of attempting to study the faint glow that is emitted from hot Jupiter exoplanets, astronomers have finally succeeded in reliably probing the structure of the atmosphere of Tau Boötis b and deducing its mass accurately for the first time. The team used the CRIRES [2] instrument on the Very Large Telescope (VLT) at ESO’s Paranal Observatory in Chile.

    ESO CRIRES on the VLT

    They combined high quality infrared observations (at wavelengths around 2.3 microns) [3] with a clever new trick to tease out the weak signal of the planet from the much stronger one from the parent star [4].

    Lead author of the study Matteo Brogi (Leiden Observatory, the Netherlands) explains: “Thanks to the high quality observations provided by the VLT and CRIRES we were able to study the spectrum of the system in much more detail than has been possible before. Only about 0.01% of the light we see comes from the planet, and the rest from the star, so this was not easy”.

    The majority of planets around other stars were discovered by their gravitational effects on their parent stars, which limits the information that can be gleaned about their mass: they only allow a lower limit to be calculated for a planet’s mass [5]. The new technique pioneered here is much more powerful. Seeing the planet’s light directly has allowed the astronomers to measure the angle of the planet’s orbit and hence work out its mass precisely. By tracing the changes in the planet’s motion as it orbits its star, the team has determined reliably for the first time that Tau Boötis b orbits its host star at an angle of 44 degrees and has a mass six times that of the planet Jupiter in our own Solar System.

    “The new VLT observations solve the 15-year old problem of the mass of Tau Boötis b. And the new technique also means that we can now study the atmospheres of exoplanets that don’t transit their stars, as well as measuring their masses accurately, which was impossible before”, says Ignas Snellen (Leiden Observatory, the Netherlands), co-author of the paper. “This is a big step forward.”

    As well as detecting the glow of the atmosphere and measuring Tau Boötis b’s mass, the team has probed its atmosphere and measured the amount of carbon monoxide present, as well as the temperature at different altitudes by means of a comparison between the observations and theoretical models. A surprising result from this work was that the new observations indicated an atmosphere with a temperature that falls higher up. This result is the exact opposite of the temperature inversion — an increase in temperature with height — found for other hot Jupiter exoplanets [6] [7].

    The VLT observations show that high resolution spectroscopy from ground-based telescopes is a valuable tool for a detailed analysis of non-transiting exoplanets’ atmospheres. The detection of different molecules in future will allow astronomers to learn more about the planet’s atmospheric conditions. By making measurements along the planet’s orbit, astronomers may even be able to track atmospheric changes between the planet’s morning and evening.

    “This study shows the enormous potential of current and future ground-based telescopes, such as the E-ELT. Maybe one day we may even find evidence for biological activity on Earth-like planets in this way”, concludes Ignas Snellen.
    Notes

    [1] The name of the planet, Tau Boötis b, combines the name of the star (Tau Boötis, or τ Bootis, τ is the Greek letter “tau”, not a letter “t” ) with the letter “b” indicating that this is the first planet found around this star. The designation Tau Boötis a is used for the star itself.

    [2] CRyogenic InfraRed Echelle Spectrometer

    [3] At infrared wavelengths, the parent star emits less light than in the optical regime, so this is a wavelength regime favorable for separating out the dim planet’s signal.

    [4] This method uses the velocity of the planet in orbit around its parent star to distinguish its radiation from that of the star and also from features coming from the Earth’s atmosphere. The same team of astronomers tested this technique before on a transiting planet, measuring its orbital velocity during its crossing of the stellar disc.

    [5] This is because the tilt of the orbit is normally unknown. If the planet’s orbit is tilted relative to the line of sight between Earth and the star then a more massive planet causes the same observed back and forth motion of the star as a lighter planet in a less tilted orbit and it is not possible to separate the two effects.

    [6] Thermal inversions are thought to be characterised by molecular features in emission in the spectrum, rather than in absorption, as interpreted from photometric observations of hot Jupiters with the Spitzer Space Telescope.

    NASA/Spitzer Infrared Telescope

    The exoplanet HD209458b is the best-studied example of thermal inversions in the exoplanet atmospheres.

    [7] This observation supports models in which strong ultraviolet emission associated to chromospheric activity — similar to the one exhibited by the host star of Tau Boötis b — is responsible for the inhibition of the thermal inversion.
    More information

    This research was presented in a paper The signature of orbital motion from the dayside of the planet τ Boötis b to appear in the journal Nature on 28 June 2012.

    The team is composed of Matteo Brogi (Leiden Observatory, the Netherlands), Ignas A. G. Snellen (Leiden Observatory), Remco J. de Kok (SRON, Utrecht, the Netherlands), Simon Albrecht (Massachusetts Institute of Technology, Cambridge, USA), Jayne Birkby (Leiden Observatory) and Ernst J. W. de Mooij (University of Toronto, Canada; Leiden Observatory).

    See the full article here .
    Thanks, Manu.

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

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

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

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

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

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

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

    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)

     
  • richardmitnick 4:37 pm on April 4, 2014 Permalink | Reply
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    FRom ESO: “Two Galaxies for a Unique Event” 2009 


    European Southern Observatory

    4 April 2009
    Contacts

    Henri Boffin
    ESO
    Garching, Germany
    Tel: +49 89 3200 6222
    Email: hboffin@eso.org

    Valentina Rodriguez
    ESO
    Chile
    Tel: +56 2 463 3123
    Email: vrodrigu@eso.org

    To celebrate the 100 Hours of Astronomy, ESO is sharing two stunning images of unusual galaxies, both belonging to the Sculptor group of galaxies. The images, obtained at two of ESO’s observatories at La Silla and Paranal in Chile, illustrate the beauty of astronomy.

    par
    Image of the irregular galaxy NGC 55 obtained with the Wide Field Imager on the 2.2-metre MPG/ESO telescope at ESO La Silla Observatory. The galaxy is about 7.5 million light-years away and 70,000 light-years across. The image is based on data obtained through B, V, and H-alpha filters. North is up, East to the left. The field of view is 30 arcminutes wide.

    ESO Wide Field Imager 2.2m LaSilla
    WFI

    ESO 2.2 meter telescope
    2.2-metre MPG/ESO telescope

    ESO LaSilla
    LaSilla

    par
    Image of the chaotic spiral galaxy NGC 7793, observed with the FORS instrument attached to ESO’s Very Large Telescope at Paranal. The image is based on data obtained through B, V, I and H-alpha filters

    ESO FORS1
    FORS

    ESO VLT
    VLT at Paranal

    As part of the International Year of Astronomy 2009 Cornerstone project, 100 Hours of Astronomy, the ambitious “Around the World in 80 Telescopes” event is a unique live webcast over 24 hours, following night and day around the globe to some of the most advanced observatories on and off the planet. To provide a long-lasting memory of this amazing world tour, observatories worldwide are revealing wonderful, and previously unseen, astronomical images. For its part, ESO is releasing outstanding pictures of two galaxies, observed with telescopes at the La Silla and Paranal observatories.

    The first of these depicts the irregular galaxy NGC 55, a member of the prominent Sculptor group of galaxies in the southern constellation of Sculptor. The galaxy is about 70 000 light-years across, that is, a little bit smaller than our own Milky Way. NGC 55 actually resembles more our galactic neighbour, the Large Magellanic Cloud (LMC), although the LMC is seen face-on, whilst NGC 55 is edge-on.

    By studying about 20 planetary nebulae in this image, a team of astronomers found that NGC 55 is located about 7.5 million light-years away. They also found that the galaxy might be forming a bound pair with the gorgeous spiral galaxy NGC 300 . Planetary nebulae are the final blooming of Sun-like stars before their retirement as white dwarfs.

    This striking image of NGC 55, obtained with the Wide Field Imager on the 2.2-metre MPG/ESO telescope at La Silla, is dusted with a flurry of reddish nebulae, created by young, hot massive stars. Some of the more extended ones are not unlike those seen in the LMC, such as the Tarantula Nebula. The quality of the image is clearly demonstrated by the remarkable number of background galaxies seen, as well as the huge numbers of individual stars that can be counted within NGC 55.

    The second image shows another galaxy belonging to the Sculptor group. This is NGC 7793, which has a chaotic spiral structure, unlike the class of grand-design spiral galaxies to which our Milky Way belongs. The image shows how difficult it is to identify any particular spiral arm in these chaotic structures, although it is possible to guess at a general rotating pattern. NGC 7793 is located slightly further away than NGC 55, about 12.5 million light-years from us, and is about half the size of NGC 55.

    NGC 7793 was observed with one of the workhorses of the ESO Paranal Observatory, the FORS instrument, attached to the Very Large Telescope.
    Notes

    ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe. It is supported by 14 countries: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. 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 plays also a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in the Atacama Desert region of Chile: La Silla, Paranal and Chajnantor.

    See the full article here.

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    ESO Main

    ESO, European Southern Observatory, builds and operates a suite of the world’s most advanced ground-based astronomical telescopes.


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  • richardmitnick 6:06 pm on December 4, 2013 Permalink | Reply
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    From ESO: “A Galaxy Full of Surprises — NGC 3621 is bulgeless but has three central black holes” 


    European Southern Observatory

    This image, from ESO’s Very Large Telescope (VLT), shows a truly remarkable galaxy known as NGC 3621. To begin with, it is a pure-disc galaxy. Like other spirals, it has a flat disc permeated by dark lanes of material and with prominent spiral arms where young stars are forming in clusters (the blue dots seen in the image). But while most spiral galaxies have a central bulge — a large group of old stars packed in a compact, spheroidal region — NGC 3621 doesn’t. In this image, it is clear that there is simply a brightening to the centre, but no actual bulge like the one in NGC 6744 (eso1118), for example.

    ngc3621
    NGC3621 by ESO’s VLT

    las
    Another view, this one taken by the Wide Field Imager (WFI) at ESO’s La Silla Observatory

    NGC 3621 is also interesting as it is believed to have an active supermassive black hole at its centre that is engulfing matter and producing radiation. This is somewhat unusual because most of these so-called active galactic nuclei exist in galaxies with prominent bulges. In this particular case, the supermassive black hole is thought to have a relatively small mass, of around 20 000 times that of the Sun.

    Another interesting feature is that there are also thought to be two smaller black holes, with masses of a few thousand times that of the Sun, near the nucleus of the galaxy. Therefore, NGC 3621 is an extremely interesting object which, despite not having a central bulge, has a system of three black holes in its central region.

    This galaxy is located in the constellation of Hydra (The Sea Snake) and can be seen with a moderate-sized telescope. This image, taken using B, V, and I filters with the FORS1 instrument on the powerful VLT, shows striking detail in this odd object and also reveals a multitude of background galaxies. A number of bright foreground stars that belong to our own Milky Way are also visible.

    ESO VLT
    ESO’s Very Large Telescope (VLT)

    ESO LaSilla
    ESO at La Silla

    See the full article here.

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  • richardmitnick 1:04 pm on November 28, 2013 Permalink | Reply
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    From ESO: “The Topsy-Turvy Galaxy NGC 1313” 


    European Southern Observatory

    The central parts of the starburst galaxy NGC 1313.

    ngc1313

    The very active state of this galaxy is very evident from the image, showing many star formation regions. A great number of supershell nebulae, that is, cocoon of gas inflated and etched by successive bursts of star formation, are visible. The green nebulosities are regions emitting in the ionised oxygen lines and may harbour clusters with very hot stars. This colour-composite is based on images obtained with the FORS1 instrument on one of the 8.2-m Unit Telescope of ESO’s Very Large Telescope, located at Cerro Paranal. The data were obtained in the night of 16 December 2003, through different broad- (R, B, and z) and narrow-band filters (H-alpha, OI, and OIII).

    fors
    Instrument-Control-Software for FoRS

    See the full article here.

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  • richardmitnick 8:55 am on November 27, 2013 Permalink | Reply
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    From ESO: “A Fiery Drama of Star Birth and Death” 


    European Southern Observatory

    27 November 2013
    Contacts

    Richard Hook
    ESO Public Information Officer
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    The Large Magellanic Cloud is one of the closest galaxies to our own. Astronomers have now used the power of ESO’s Very Large Telescope to explore one of its lesser known regions. This new image shows clouds of gas and dust where hot new stars are being born and are sculpting their surroundings into odd shapes. But the image also shows the effects of stellar death — filaments created by a supernova explosion.

    lmc
    Large Magellanic Cloud

    ESO VLT
    ESO’s VLT

    Located only about 160 000 light-years from us (eso1311) in the constellation of Dorado (The Swordfish), the Large Magellanic Cloud is one of our closest galactic neighbours. It is actively forming new stars in regions that are so bright that some can even be seen from Earth with the naked eye, such as the Tarantula Nebula (eso1033). This new image, taken by ESO’s Very Large Telescope at the Paranal Observatory in Chile, explores an area called NGC 2035 (right), sometimes nicknamed the Dragon’s Head Nebula.

    tran
    The Tarantula Nebula, first light image of the TRAPPIST national telescope at La Silla Observatory

    NGC 2035 is an HII region, or emission nebula, consisting of clouds of gas that glow due to the energetic radiation given off by young stars. This radiation strips electrons from atoms within the gas, which eventually recombine with other atoms and release light. Mixed in with the gas are dark clumps of dust that absorb rather than emit light, creating weaving lanes and dark shapes across the nebula.

    The filamentary shapes to the left in the image are the not the results of starbirth, but rather stellar death. It was created by one of the most violent events that can happen in the Universe — a supernova explosion. These explosions are so bright that they often briefly outshine their entire host galaxy, before fading from view over several weeks or months (also see eso1315 and potw1323a).

    From looking at this image, it may be difficult to grasp the sheer size of these clouds — they are several hundred light-years across. And they are not in our galaxy, but far beyond. The Large Magellanic Cloud is enormous, but when compared to our own galaxy it is very modest in extent, spanning just 14 000 light-years — about ten times smaller than the Milky Way.

    This image was acquired using the FOcal Reducer and low dispersion Spectrograph instrument attached to ESO’s Very Large Telescope, which is located at the Paranal Observatory in Chile, as part of the ESO Cosmic Gems programme.

    fors
    FORS at the VLT

    See the full article, with notes, links, and videos, here.

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  • richardmitnick 9:51 pm on October 25, 2013 Permalink | Reply
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    ESO VLT Brief: “Thor’s Helmet Nebula imaged on the occasion of ESO’s 50th Anniversary” 


    European Southern Observatory

    This VLT image of the Thor’s Helmet Nebula was taken on the occasion of ESO’s 50th Anniversary, 5 October 2012, with the help of Brigitte Bailleul — winner of the Tweet Your Way to the VLT! competition.

    th
    Credit: ESO/B. Bailleul
    Release date: 5 October 2012, 16:00

    The observations were broadcast live over the internet from the Paranal Observatory in Chile. This object, also known as NGC 2359, lies in the constellation of Canis Major (The Great Dog). The helmet-shaped nebula is around 15 000 light-years away from Earth and is over 30 light-years across. The helmet is a cosmic bubble, blown as the wind from the bright, massive star near the bubble’s centre sweeps through the surrounding molecular cloud.

    See the full article here.

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    ESO, European Southern Observatory, builds and operates a suite of the world’s most advanced ground-based astronomical telescopes.


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  • richardmitnick 10:28 am on October 19, 2013 Permalink | Reply
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    ESO VLT Brief: “The smoky pink core of the Omega Nebula” 


    European Southern Observatory

    omega
    Release date: 4 January 2012, 12:00

    This image of the Omega Nebula (Messier 17), captured by ESO’s Very Large Telescope (VLT), is one of the sharpest of this object ever taken from the ground. It shows the dusty, rosy central parts of the famous star-forming region in fine detail.

    See the full article here.

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    ESO, European Southern Observatory, builds and operates a suite of the world’s most advanced ground-based astronomical telescopes.


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  • richardmitnick 11:19 am on October 15, 2013 Permalink | Reply
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    From ESO: “Nebulae Near the Hot Wolf-Rayet Star BAT99-2 in the LMC” 


    European Southern Observatory

    Three-colour composite image of the highly excited nebula near the Wolf-Rayet (WR) star BAT99-2 in the Large Magellanic Cloud (LMC), obtained in January 2002 with the FORS1 multi-mode instrument at the 8.2-m VLT MELIPAL telescope at the Paranal Observatory (Chile).

    bat
    Release date: 9 April 2003

    It is based on three exposures through narrow-band optical (interference) filters that isolate the light from specific atoms and ions. In this rendering, the blue colour represents the light from singly ionized Helium (He II; wavelength 468.6 nm; exposure time 60 min), green corresponds to doubly ionized oxygen ([O III]; 495.7 + 500.7 nm; 5 min) and red to hydrogen atoms (H; H-alpha line at 656.2 nm; 5 min). Of these three ions, He II is the tracer of high excitation, i.e. the bluest areas of the nebula are the hottest. The sky field measures 400 x 400 square arcsec; the original pixel size on the 2k x 2k CCD is 0.23 arcsec. North is up and east to the left. Before combination, the CCD frames were flat-fielded and cleaned of cosmic-rays. Moreover, the stars in the blue (He II) image were removed in order to provide a clearer view of the surrounding nebular emission. The reproduced brightness is proportional to the square-root of the actual intensity; this increases the “dynamical range” of the image, i.e. it shows better areas of very different brightness.

    See the full article here.

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    ESO, European Southern Observatory, builds and operates a suite of the world’s most advanced ground-based astronomical telescopes.


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