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  • richardmitnick 5:44 am on September 3, 2014 Permalink | Reply
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    From ESO- “Cosmic Forecast: Dark Clouds Will Give Way to Sunshine 


    European Southern Observatory

    3 September 2014

    Contacts
    Richard Hook
    ESO education and Public Outreach Department
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    Lupus 4, a spider-shaped blob of gas and dust, blots out background stars like a dark cloud on a moonless night in this intriguing new image. Although gloomy for now, dense pockets of material within clouds such as Lupus 4 are where new stars form and where they will later burst into radiant life. The Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile captured this new picture.

    black

    ESO Wide Field Imager 2.2m LaSilla
    WFI
    ESO 2.2 meter telescope
    ESO 2.2 meter telescope interior
    ESO 2.2 meter telescope

    ESO LaSilla Long View
    ESO/LaSilla

    Lupus 4 is located about 400 light-years away from Earth, straddling the constellations of Lupus (The Wolf) and Norma (The Carpenter’s Square). The cloud is one of several affiliated dark clouds found in a loose star cluster called the Scorpius–Centaurus OB association. An OB association is a relatively young, yet widely dispersed grouping of stars [1]. The stars likely had a common origin in a gigantic cloud of material.

    Because the association, and its Lupus clouds, form the closest such grouping to the Sun, they are a prime target for studying how stars grow up together before going their separate ways. The Sun, along with most stars in our galaxy, is thought to have started out in a similar environment.

    American astronomer Edward Emerson Barnard is credited with the earliest descriptions of the Lupus dark clouds in the astronomical literature, back in 1927. Lupus 3, neighbour to Lupus 4, is the best studied, thanks to the presence of at least 40 fledgling stars formed over the last three million years, and which are on the cusp of igniting their fusion furnaces (eso1303). The main energy source in these adolescent stars, known as T Tauri stars, is the heat generated by their gravitational contraction. That is in contrast to the fusion of hydrogen and other elements which powers mature stars such as the Sun.

    Observations of the cold darkness of Lupus 4 have turned up only a few T Tauri stars. Yet promisingly for Lupus 4 in terms of future star formation is a dense, starless core of material in the cloud. Given a few million years, that core should develop into T Tauri stars. Comparing Lupus 3 and Lupus 4 in this way suggests that the former is older than the latter, because its contents have had more time to develop into stars.

    How many stars might eventually start to shine within Lupus 4? It is hard to say, as mass estimates for Lupus 4 vary. Two studies agree on a figure of around 250 times the mass of the Sun, though another, using a different method, arrives at a figure of around 1600 solar masses. Either way, the cloud contains ample material to give rise to plenty of bright new stars. Rather as earthly clouds make way for sunshine, so, too, shall this cosmic dark cloud eventually dissipate and give way to brilliant starlight.

    Notes
    [1] The “OB” refers to the hot, bright, short-lived stars of spectral types O and B that are still shining brilliantly within the widely dispersed cluster as it travels through the Milky Way galaxy.

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  • richardmitnick 10:08 am on August 31, 2014 Permalink | Reply
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    From ESO: “Possible Planetary System Photographed Around Nearby Star” 1987 A Good Piece of ESO History 


    European Southern Observatory

    5 January 1987
    Contacts
    Richard West
    ESO
    Garching, Germany
    Tel: +49 89 3200 6276
    Email: information@eso.org

    Based on observations obtained at the European Southern Observatory (ESO), astronomers at the Space Telescope Science Institute (STScI) have uncovered the strongest evidence yet for the presence of a giant planetary or protoplanetary system accompanying a nearby star [1].

    image

    Using special observational and image analysis techniques, Francesco Paresce and Christopher Burrows, of STScI and the European Space Agency (ESA), have made the first visible light images of a large disc of material closely bound to the star Beta Pictoris. The disc is at least 80.000 million kilometres across, or more than three times the diameter of our solar system.

    bp
    The red dot shows the location of Beta Pictoris.

    The observations were made at the ESO La Silla observatory in the Atacama desert in Chile. The astronomers will present their findings at the 169th meeting of the American Astronomical Society in Pasadena, California on January 5th.

    ESO LaSilla
    ESO/LaSilla

    An unusual excess of infrared radiation, indicative of circumstellar matter, was initially detected around Beta Pictoris by the Infrared Astronomy Satellite (IRAS) in 1983. Subsequent ground-based observations revealed the presence of a disc-like feature at near-infrared wavelengths.

    Caltech IRAS
    Caltech IRAS

    When Paresce and Burrows made detailed observations of the disc at several regions of the visible light spectrum, they found that the reflectivity of the disc material was neutral, or wavelength independent. This means that the colour and spectral characteristics of light reflected from the disc almost exactly matched the spectrum of light emitted from the star itself.

    This observation offers the strongest indications yet that the disc is made up of relatively large solid particles. If it were extremely fine dust, which is commonly found in interstellar space, it would scatter only the bluer wavelengths of starlight. The observational data alone cannot establish the true size of the reflecting particles but does set a lower limit of about 0.001 millimetre (1 micron). At this diametre or greater, the particles found around Beta Pictoris are at least ten times larger than material normally observed in interstellar space.

    “The observations show unequivocally that an agglomeration process is in an advanced state, where fine interstellar grains stuck together to form larger clumps”, reports Dr. Paresce. It is believed that as such a ‘snowballing’ process continues, the disc material may eventually accrete into planet-sized objects, if they have not done so already. Our solar system may have condensed or accreted out of thick dust grains which formed a circumstellar nebula that accompanied the birth of our sun, approximately 4600 million years ago.

    The presently available observational data cannot determine the composition of the particles, though they likely contain silicates, carbonaceous materials, and water ice – common elements abundant within our own solar system.

    The evidence for planetary formation is also supported by the fact that the large dust particles are arranged in a flattened disc. The disc likely formed out of an immense, protostellar nebula that contracted and collapsed into the feature seen today. Most of the nebula’s gas and dust concentrated at the centre of the disc to form the star Beta Pictoris. The remaining material now continues to orbit the star.

    At present it is not known if planets already formed within the disc or if it is still in a protoplanetary stage. “All that can be said for sure is that the disc has progressed from a ‘fine sand’ stage into at least a ‘pebble’ stage”, says Dr. Paresce.

    Beta Pictoris is a relatively young star estimated to be no older than 1000 million years, or about one fifth the age of our sun. Approximately 50 light years away, it is a socalled ‘main-sequence dwarf‘, like our sun.

    Paresce and Burrows made their observations of Beta Pictoris, which is visible as a fourth magnitude star in the southern hemisphere, with the ESO 2.2 metre telescope. Attaching a coronograph of their own design and fabrication, the researchers blocked out the brilliant image of the star, so that the faint circumstellar features could be photographed with a CCD (Charge Coupled Device) detector. To allow analysis of the disc at various wavelengths of light, a series of exposures were then taken through bandpass filters across the visible spectrum. These difficult observations were facilitated by the excellent atmospheric conditions at the ESO La Silla observatory.

    ESO 2.2 meter telescope
    2.2
    ESO/ 2.2 meter telescope

    As a control, an identical observing sequence was performed on the stars Delta Hydrus and Alpha Pictoris which are not expected to have prominent circumstellar disc features visible from Earth.

    Through special data analysis techniques developed by Paresce and Burrows, the two stellar images were corrected for known instrumental effects, precisely registered, and differences between the two images were evaluated. This was an especially challenging task since the researchers were probing the near vicinity of Beta Pictoris and had to contend with intense scattered light from the star itself. They also had to be sure that they were seeing reflected light from a true disc feature and not contamination produced by the instrument optics.

    Their resulting data yields the first true, photometrically accurate image of the Beta Pictoris disc, down to about four arcseconds from the star. Never before has such a relatively faint feature been photographed within such close proximity to such a bright star.

    The resulting images reveal a highly flattened disc which extends symmetrically outward from Beta Pictoris, into a northeast and southwest direction on the sky. The disc’s apparent angular width may indicate that it is slightly tilted to our line of sight. The disc dramatically increases in brightness toward its center, though its structure closer to Beta Pictoris is not visible due to the occulting finger which blocks out most of the light from the star.

    Astronomers are eager to find evidence of extrasolar planetary systems to learn whether our own solar system was created out of very unique conditions, or whether it is the result of common and fundamental processes that accompany stellar formation. These questions can not be satisfactorily answered until astronomers have carefully studied examples of planetary formation other than our own solar system.

    Paresce and Burrows have images of planetary or protoplanetary around other stars to analyze. They also plan to make detailed observations of Beta Pictoris with the NASA/ESA Hubble Space Telescope, which is now scheduled for launch in late 1988. With its significant increase in resolution over present ground-based instruments, the Space Telescope will have the capability to provide a far more detailed view of the disc’s structure, closer to the star. It will also have the potential for detecting the extremely faint glow of planets which may accompany the star. It is also expected that this fascinating area of astronomical research will greatly benefit from future, giant telescopes on the ground, such as the ESO 16 metre Very Large Telescope (VLT), now in the final planning stage.

    NASA Hubble Telescope
    NASA/ESA Hubble

    ESO VLT
    ESO VLT Interior
    ESO/VLT

    Notes

    [1] The text of this Press Release is published simultaneously by STScI and ESO. A B/W picture is available on request from both organisations.
    More information

    The Hubble Space Telescope is a project of international collaboration between NASA and ESA. The Space Telescope Science Institute is operated for NASA by the Association of Universities for Research in Astronomy (AURA). It is located on the Johns Hopkins University Campus in Baltimore, Maryland, U.S.A.

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  • richardmitnick 8:02 am on August 20, 2014 Permalink | Reply
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    From ESO: “A Spectacular Landscape of Star Formation” 


    European Southern Observatory

    20 August 2014
    Richard Hook
    ESO Public Information Officer
    Garching bei München, Germany

    Tel: +49 89 3200 6655
    Email: rhook@eso.org

    This image, captured by the Wide Field Imager at ESO’s La Silla Observatory [on the 2.2 meter telescope] in Chile, shows two dramatic star formation regions in the southern Milky Way. The first is of these, on the left, is dominated by the star cluster NGC 3603, located 20 000 light-years away, in the Carina–Sagittarius spiral arm of the Milky Way galaxy. The second object, on the right, is a collection of glowing gas clouds known as NGC 3576 that lies only about half as far from Earth.

    scene

    ngc3603
    NASA/ESA Hubble

    ngc3576
    NGC 3576

    ESO Wide Field Imager 2.2m LaSilla
    WFI at LaSilla

    ESO 2.2 meter telescope
    2.2 meter telescope

    ESO LaSilla
    LaSilla

    NGC 3603 is a very bright star cluster and is famed for having the highest concentration of massive stars that have been discovered in our galaxy so far. At the centre lies a Wolf–Rayet multiple star system, known as HD 97950. Wolf–Rayet stars are at an advanced stage of stellar evolution, and start off with around 20 times the mass of the Sun. But, despite this large mass, Wolf–Rayet stars shed a considerable amount of their matter due to intense stellar winds, which blast the star’s surface material off into space at several million kilometres per hour, a crash diet of cosmic proportions.

    NGC 3603 is in an area of very active star formation. Stars are born in dark and dusty regions of space, largely hidden from view. But as the very young stars gradually start to shine and clear away their surrounding cocoons of material they become visible and create glowing clouds in the surrounding material, known as HII regions. HII regions shine because of the interaction of ultraviolet radiation given off by the brilliant hot young stars with the hydrogen gas clouds. HII regions can measure several hundred light-years in diameter, and the one surrounding NGC 3603 has the distinction of being the most massive in our galaxy.

    The cluster was first observed by John Herschel on 14 March 1834 during his three-year expedition to systematically survey the southern skies from near Cape Town. He described it as a remarkable object and thought that it might be a globular star cluster. Future studies showed that it is not an old globular, but a young open cluster, one of the richest known.

    NGC 3576, on the right of the image, also lies in the Carina–Sagittarius spiral arm of the Milky Way. But it is located only about 9000 light-years from Earth — much closer than NGC 3603, but appearing next to it in the sky.

    >NGC 3576 is notable for two huge curved objects resembling the curled horns of a ram. These odd filaments are the result of stellar winds from the hot, young stars within the central regions of the nebula, which have blown the dust and gas outwards across a hundred light-years. Two dark silhouetted areas known as Bok globules are also visible in this vast complex of nebulae. These black clouds near the top of the nebula also offer potential sites for the future formation of new stars.

    NGC 3576 was also discovered by John Herschel in 1834, making it a particularly productive and visually rewarding year for the English astronomer.

    See the full article here.

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  • richardmitnick 7:41 am on July 23, 2014 Permalink | Reply
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    From ESO: “Lives and Deaths of Sibling Stars” 


    European Southern Observatory

    23 July 2014
    Richard Hook
    ESO education and Public Outreach Department
    Garching bei München, Germany

    Tel: +49 89 3200 6655
    Email: rhook@eso.org

    In this striking new image from ESO’s La Silla Observatory in Chile young stars huddle together against a backdrop of clouds of glowing gas and lanes of dust. The star cluster, known as NGC 3293, would have been just a cloud of gas and dust itself about ten million years ago, but as stars began to form it became the bright group of stars we see here. Clusters like this are celestial laboratories that allow astronomers to learn more about how stars evolve.

    ngc3293

    ESO LaSilla
    LaSilla

    Star clusters like NGC 3293 contain stars that all formed at the same time, at the same distance from Earth and out of the same cloud of gas and dust, giving them the same chemical composition. As a result clusters like this are ideal objects for testing stellar evolution theory.

    Most of the stars seen here are very young, and the cluster itself is less than 10 million years old. Just babies on cosmic scales if you consider that the Sun is 4.6 billion years old and still only middle-aged. An abundance of these bright, blue, youthful stars is common in open clusters like NGC 3293, and, for example, in the better known Kappa Crucis cluster, otherwise known as the Jewel Box or NGC 4755.

    kcc
    The FORS1 instrument on the ESO Very Large Telescope (VLT) at ESO’s Paranal Observatory was used to take this exquisitely sharp close up view of the colourful Jewel Box cluster, NGC 4755. The telescope’s huge mirror allowed very short exposure times: just 2.6 seconds through a blue filter (B), 1.3 seconds through a yellow/green filter (V) and 1.3 seconds through a red filter (R).

    ESO FORS1
    FORS1 on VLT

    ESO VLT
    ESO VLT

    These open clusters each formed from a giant cloud of molecular gas and their stars are held together by their mutual gravitational attraction. But these forces are not enough to hold a cluster together against close encounters with other clusters and clouds of gas as the cluster’s own gas and dust dissipates. So, open clusters will only last a few hundred million years, unlike their big cousins, the globular clusters, which can survive for billions of years, and hold on to far more stars.

    Despite some evidence suggesting that there is still some ongoing star formation in NGC 3293, it is thought that most, if not all, of the nearly fifty stars in this cluster were born in one single event. But even though these stars are all the same age, they do not all have the dazzling appearance of a star in its infancy; some of them look positively elderly, giving astronomers the chance to explore how and why stars evolve at different speeds.

    Take the bright orange star at the bottom right of the cluster. This huge star, a red giant, would have been born as one of the biggest and most luminous of its litter, but bright stars burn out fast. As the star used up the fuel at its core its internal dynamics changed and it began to swell and cool, becoming the red giant we now observe. Red giants are reaching the end of their life cycle, but this red giant’s sister stars are still in what is known as the pre-main-sequence — the period before the long, stable, middle period in a star’s life. We see these stars in the prime of their life as hot, bright and white against the red and dusty background.

    This image was taken with the Wide Field Imager (WFI)ESO Wide Field Imager 2.2m LaSilla installed on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in northern Chile.

    ESO 2.2 meter telescope

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  • richardmitnick 6:22 am on July 2, 2014 Permalink | Reply
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    From ESO: “A Stellar Womb Shaped and Destroyed by its Ungrateful Offspring” 


    European Southern Observatory

    2 July 2014
    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 little-known cloud of cosmic gas and dust called Gum 15 is the birthplace and home of hot young stars. Beautiful and deadly, these stars mould the appearance of their mother nebula and, as they progress into adulthood, will eventually also be the death of her.

    gum

    This image was taken as part of the ESO Cosmic Gems programme using the Wide Field Imager on the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile. It shows Gum 15, located in the constellation of Vela (The Sails), some 3000 light-years from Earth. This glowing cloud is a striking example of an HII region. Such clouds form some of the most spectacular astronomical objects we can see; for example the Eagle Nebula (which includes the feature nicknamed “The Pillars of Creation”), the great Orion Nebula, and this less famous example, Gum 15.

    ESO Wide Field Imager 2.2m LaSilla
    ESO’s WFI

    ESO 2.2 meter telescope
    >MPG/ESO 2.2-metre telescope at the La Silla Observatory

    pillars
    Pillars of Creation
    Star forming pillars in the Eagle Nebula, as seen by the Hubble Space Telescope’s WFPC2. The picture is composed of 32 different images from four separate cameras in this instrument. The photograph was made with light emitted by different elements in the cloud and appears as a different colour in the composite image: green for hydrogen, red for singly-ionized sulphur and blue for double-ionized oxygen atoms.

    The missing part at the top right is because one of the four cameras has a magnified view of its portion, which allows astronomers to see finer detail. The images from this camera were scaled down in size to match those from the other three cameras.

    Orion
    Orion Nebula
    In one of the most detailed astronomical images ever produced, NASA/ESA’s Hubble Space Telescope captured an unprecedented look at the Orion Nebula. … This extensive study took 105 Hubble orbits to complete. All imaging instruments aboard the telescope were used simultaneously to study Orion. The Advanced Camera mosaic covers approximately the apparent angular size of the full moon.

    Hydrogen (H) is the most common element in the Universe, and can be found in virtually every environment investigated by astronomers. HII regions are different because they contain substantial amounts of ionised hydrogen — hydrogen atoms that have been stripped of their electrons through high energy interactions with ultraviolet photons — particles of light. As the ionised hydrogen nuclei recapture electrons they release light at different characteristic wavelengths. It is one of these that gives nebulae such as Gum 15 their reddish glow — a glow which astronomers call hydrogen alpha (Hα).

    In HII regions the ionising photons come from the young hot stars within the region, and Gum 15 is no exception. At the centre of this image you can see one of the culprits: the star HD 74804, the brightest member of a cluster of stars known as Collinder 197.

    The clumpy, irregular appearance that enhances this nebula’s beauty is not unusual for a HII region and is again a result of the stars within. HII regions have diverse shapes because the distribution of stars and gas inside them is so irregular. Adding to Gum 15’s interesting shape are the forked dark patch of obscuring dust visible in the centre of this image and some dim blue reflection structures crossing it. This dust feature makes the nebula resemble a larger and fainter version of the better known Trifid Nebula (Messier 20), although in this case the name Bifid Nebula might be more apposite.

    m20
    The Trifid nebula (M20, NGC NGC 6514) in pseudocolor.
    Image taken with the Palomar 1.5-m telescope.
    Caltech Palomar Observatory
    Palomar at Caltech

    An HII region like this one might give birth to thousands of stars over a period of several million years. Some of these stars cause it to glow and sculpt its shape, and it is these stars that will eventually destroy it. Once the newly minted stars have passed through their infant stages, strong winds of particles will stream away from these large stars, sculpting and dispersing the gases around them, and when the most massive of these stars begin to die, Gum 15 will die with them. Some stars are so large that they will go out with a bang, exploding as supernovae and dispersing the regions last traces of HII, leaving behind just a cluster of infant stars.

    See the full article,with notes, here.

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  • richardmitnick 11:40 am on June 17, 2014 Permalink | Reply
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    From ESO: “A Picture-perfect Pure-disc Galaxy” 2011 


    European Southern Observatory

    2 February 2011
    Richard Hook
    ESO, La Silla, Paranal, E-ELT and Survey Telescopes Press Officer
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Email: rhook@eso.org

    The bright galaxy NGC 3621, captured here using the Wide Field Imager on the 2.2-metre telescope at ESO’s La Silla Observatory in Chile, appears to be a fine example of a classical spiral. But it is in fact rather unusual: it does not have a central bulge and is therefore described as a pure-disc galaxy.

    ngc
    NGC3621

    ESO 2.2 meter telescope
    ESO 2.2m telescope at LaSilla

    ESO Wide Field Imager 2.2m LaSilla
    WFI

    NGC 3621 is a spiral galaxy about 22 million light-years away in the constellation of Hydra (The Sea Snake). It is comparatively bright and can be seen well in moderate-sized telescopes. This picture was taken using the Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile. The data were selected from the ESO archive by Joe DePasquale as part of the Hidden Treasures competition. Joe’s picture of NGC 3621 was ranked fifth in the competition.

    This galaxy has a flat pancake shape, indicating that it hasn’t yet come face to face with another galaxy as such a galactic collision would have disturbed the thin disc of stars, creating a small bulge in its centre. Most astronomers think that galaxies grow by merging with other galaxies, in a process called hierarchical galaxy formation. Over time, this should create large bulges in the centres of spirals. Recent research, however, has suggested that bulgeless, or pure-disc, spiral galaxies like NGC 3621 are actually fairly common.

    This galaxy is of further interest to astronomers because its relative proximity allows them to study a wide range of astronomical objects within it, including stellar nurseries, dust clouds, and pulsating stars called Cepheid variables, which astronomers use as distance markers in the Universe. In the late 1990s, NGC 3621 was one of 18 galaxies selected for a Key Project of the Hubble Space Telescope: to observe Cepheid variables and measure the rate of expansion of the Universe to a higher accuracy than had been possible before. In the successful project, 69 Cepheid variables were observed in this galaxy alone.

    NASA Hubble Telescope
    NASA/ESA Hubble

    Multiple monochrome images taken through four different colour filters were combined to make this picture. Images taken through a blue filter have been coloured blue in the final picture, images through a yellow-green filter are shown as green and images through a red filter as dark orange. In addition images taken through a filter that isolates the glow of hydrogen gas have been coloured red. The total exposure times per filter were 30, 40, 40 and 40 minutes respectively.

    See the full article, with notes, here.

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  • richardmitnick 5:48 am on May 21, 2014 Permalink | Reply
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    From ESO: “A Star Cluster in the Wake of Carina” 


    European Southern Observatory

    21 May 2014
    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

    This colourful new image from the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile shows the star cluster NGC 3590. These stars shine brightly in front of a dramatic landscape of dark patches of dust and richly hued clouds of glowing gas. This small stellar gathering gives astronomers clues about how these stars form and evolve — as well as giving hints about the structure of our galaxy’s pinwheeling arms.

    ngc3590

    NGC 3590 is a small open cluster of stars around 7500 light-years from Earth, in the constellation of Carina (The Keel). It is a gathering of dozens of stars loosely bound together by gravity and is roughly 35 million years old.

    This cluster is not just pretty; it is very useful to astronomers. By studying this particular cluster — and others nearby — astronomers can explore the properties of the spiral disc of our galaxy, the Milky Way. NGC 3590 is located in the largest single segment of a spiral arm that can be seen from our position in the galaxy: the Carina spiral feature.

    The Milky Way has multiple spiral arms, long curved streams of gas and stars stretching out from the galactic centre. These arms — two major star-filled arms, and two less populated minor arms — are each named after the constellations in which they are most prominent. The Carina spiral feature is seen from Earth as a patch of sky heavily populated with stars, in the Carina-Sagittarius minor arm.

    The name of this arm — Carina, or The Keel — is quite appropriate. These spiral arms are actually waves of piled up gas and stars sweeping through the galactic disc, triggering sparkling bursts of star formation and leaving clusters like NGC 3590 in their wake. By finding and observing young stars like those in NGC 3590, it is possible to determine the distances to the different parts of this spiral arm, telling us more about its structure.

    map
    Observed structure of the Milky Way’s spiral arms.

    Typical open clusters can contain anything from a few tens to a few thousands of stars, and provide astronomers with clues about stellar evolution. The stars in a cluster like NGC 3590 are born at around the same time from the same cloud of gas, making these clusters perfect test sites for theories on how stars form and evolve.

    This image from the Wide Field Imager (WFI) on the MPG/ESO 2.2-metre telescope at La Silla, shows the cluster and the gas clouds surrounding it, which glow in orange and red hues due to the radiation coming from nearby hot stars. WFI’s large field of view also captures a colossal number of background stars.

    ESO LaSilla Long View
    ESO at LaSilla

    ESO Wide Field Imager 2.2m LaSilla
    ESO/WFI at MPG/ESO 2.2-metre telescope at La Silla

    To obtain this image, multiple observations were made using different filters to capture the different colours of the scene. This image was created by combining images taken in the visible and infrared parts of the spectrum, and a special filter that collected only light coming from glowing hydrogen.

    See the full article, with note, here.

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  • richardmitnick 8:56 pm on April 28, 2014 Permalink | Reply
    Tags: , , , , ESO La Silla, ESO Paranal   

    From ESO: “Watching a Cannibal Galaxy Dine” 2009 


    European Southern Observatory

    20 November 2009
    Contacts

    Jouni Kainulainen
    MPIA
    Germany
    Tel: +49-6221-528427
    Email: jtkainul@mpia-hd.mpg.de

    Yuri Beletsky
    ESO
    Chile
    Tel: +56 55 43 5311
    Email: ybialets@eso.org

    João Alves
    Calar Alto Observatory
    Spain
    Tel: +34 950 632 501
    Email: jalves@caha.es

    A new technique using near-infrared images, obtained with ESO’s 3.58-metre New Technology Telescope (NTT), allows astronomers to see through the opaque dust lanes of the giant cannibal galaxy Centaurus A, unveiling its “last meal” in unprecedented detail — a smaller spiral galaxy, currently twisted and warped. This amazing image also shows thousands of star clusters, strewn like glittering gems, churning inside Centaurus A.

    can

    ESO NTT
    ESO/NTT

    Centaurus A (NGC 5128) is the nearest giant, elliptical galaxy, at a distance of about 11 million light-years. One of the most studied objects in the southern sky, by 1847 the unique appearance of this galaxy had already caught the attention of the famous British astronomer John Herschel, who catalogued the southern skies and made a comprehensive list of nebulae.

    Herschel could not know, however, that this beautiful and spectacular appearance is due to an opaque dust lane that covers the central part of the galaxy. This dust is thought to be the remains of a cosmic merger between a giant elliptical galaxy and a smaller spiral galaxy full of dust.

    Between 200 and 700 million years ago, this galaxy is indeed believed to have consumed a smaller spiral, gas-rich galaxy — the contents of which appear to be churning inside Centaurus A’s core, likely triggering new generations of stars.

    First glimpses of the “leftovers” of this meal were obtained thanks to observations with the ESA Infrared Space Observatory , which revealed a 16 500 light-year-wide structure, very similar to that of a small barred galaxy. More recently, NASA’s Spitzer Space Telescope resolved this structure into a parallelogram, which can be explained as the remnant of a gas-rich spiral galaxy falling into an elliptical galaxy and becoming twisted and warped in the process. Galaxy merging is the most common mechanism to explain the formation of such giant elliptical galaxies.

    ESA ISO spacecraft
    ESA/ISO spacecraft (decommissioned)

    NASA Spitzer Telescope
    NASA/Spitzer spacecraft

    The new SOFI images, obtained with the 3.58-metre New Technology Telescope at ESO’s La Silla Observatory, allow astronomers to get an even sharper view of the structure of this galaxy, completely free of obscuring dust. The original images, obtained by observing in the near-infrared through three different filters (J, H, K) were combined using a new technique that removes the dark, screening effect of the dust, providing a clear view of the centre of this galaxy.

    ESO SOFI
    ESO SOFI infrared spectrograph

    What the astronomers found was surprising: “There is a clear ring of stars and clusters hidden behind the dust lanes, and our images provide an unprecedentedly detailed view toward it,” says Jouni Kainulainen, lead author of the paper reporting these results. “Further analysis of this structure will provide important clues on how the merging process occurred and what has been the role of star formation during it.”

    The research team is excited about the possibilities this new technique opens: “These are the first steps in the development of a new technique that has the potential to trace giant clouds of gas in other galaxies at high resolution and in a cost-effective way,” explains co-author João Alves. “Knowing how these giant clouds form and evolve is to understand how stars form in galaxies.”

    Looking forward to the new, planned telescopes, both on the ground and in space, “this technique is very complementary to the radio data ALMA will collect on nearby galaxies, and at the same time it poses interesting avenues of research for extragalactic stellar populations with the future European Extremely Large Telescope and the James Webb Space Telescope, as dust is omnipresent in galaxies,” says co-author Yuri Beletsky.

    ALMA Array
    ALMA

    ESO E-ELT
    ESO E-ELT

    NASA Webb Telescope
    NASA/Webb

    Previous observations done with ISAAC on the VLT have revealed that a supermassive black hole lurks inside Centaurus A. Its mass is about 200 million times the mass of our Sun, or 50 times more massive than the one that lies at the centre of our Milky Way. In contrast to our own galaxy, the supermassive black hole in Centaurus A is continuously fed by material falling onto into it, making the giant galaxy a very active one. Centaurus A is in fact one of the brightest radio sources in the sky (hence the “A” in its name). Jets of high energy particles from the centre are also observed in radio and X-ray images.

    ESO ISAAC
    ESO ISAAC (since decommissioned)

    ESO VLT
    ESO VLT

    The new image of Centaurus A is a wonderful example of how frontier science can be combined with aesthetic aspects. Fine images of Centaurus A have been obtained in the past with ESO’s Very Large Telescope and with the Wide Field Imager on the MPG/ESO 2.2-metre telescope at La Silla and the FORS2 instrument on the Very Large Telescope (VLT) at Paranal.

    ESO Wide Field Imager 2.2m LaSilla
    ESO WFI on MPG/ESO 2.2-metre telescope at LaSilla

    ESO 2.2 meter telescope
    MPG/ESO 2.2-metre telescope

    ESO LaSilla
    ESO LaSilla Observatory

    See the full article here.

    Another ESO image of Centaurus A
    centa
    ESO/WFI (Optical); MPIfR/ESO/APEX/A.Weiss et al. (Submillimetre); NASA/CXC/CfA/R.Kraft et al. (X-ray)
    Colour composite image of Centaurus A, revealing the lobes and jets emanating from the active galaxy’s central black hole. This is a composite of images obtained with three instruments, operating at very different wavelengths. The 870-micron submillimetre data, from LABOCA on APEX, are shown in orange. X-ray data from the Chandra X-ray Observatory are shown in blue. Visible light data from the Wide Field Imager (WFI) on the MPG/ESO 2.2 m telescope located at La Silla, Chile, show the background stars and the galaxy’s characteristic dust lane in close to “true colour”.

    ESO APEX
    ESO APEX

    ESO LABOCA
    ESO LABOCA

    NASA Chandra Telescope
    NASA/Chandra spacecraft

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  • richardmitnick 7:21 pm on April 21, 2014 Permalink | Reply
    Tags: , , , , ESO La Silla,   

    From ESO: “A Look into the Hellish Cradles of Suns and Solar Systems” 2009 


    European Southern Observatory

    19 August 2009
    Contacts

    Dieter Nürnberger
    ESO
    Chile
    Tel: +56 2 463 3080
    Email: dnuernbe@eso.org

    New images released today [date above] by ESO delve into the heart of a cosmic cloud, called RCW 38, crowded with budding stars and planetary systems. There, young stars bombard fledgling suns and planets with powerful winds and blazing light, helped in their task by short-lived, massive stars that explode as supernovae. In some cases, this onslaught cooks away the matter that may eventually form new solar systems. Scientists think that our own Solar System emerged from such an environment.

    rcw38

    The dense star cluster RCW 38 glistens about 5500 light years away in the direction of the constellation Vela (the Sails). Like the Orion Nebula Cluster, RCW 38 is an “embedded cluster”, in that the nascent cloud of dust and gas still envelops its stars. Astronomers have determined that most stars, including the low mass, reddish ones that outnumber all others in the Universe, originate in these matter-rich locations. Accordingly, embedded clusters provide scientists with a living laboratory in which to explore the mechanisms of star and planetary formation.

    “By looking at star clusters like RCW 38, we can learn a great deal about the origins of our Solar System and others, as well as those stars and planets that have yet to come”, says Kim DeRose, first author of the new study that appears in the Astronomical Journal. DeRose did her work on RCW 38 as an undergraduate student at the Harvard-Smithsonian Center for Astrophysics, USA.

    Using the NACO adaptive optics instrument on ESO’s Very Large Telescope, astronomers have obtained the sharpest image yet of RCW 38. They focused on a small area in the centre of the cluster that surrounds the massive star IRS2, which glows in the searing, white-blue range, the hottest surface colour and temperatures possible for stars. These dramatic observations revealed that IRS2 is actually not one, but two stars — a binary system consisting of twin scorching stars, separated by about 500 times the Earth–Sun distance.

    ESO NACO
    NACO

    ESOVLTI
    VLT

    In the NACO image, the astronomers found a handful of protostars — the faintly luminous precursors to fully realised stars — and dozens of other candidate stars that have eked out an existence here despite the powerful ultraviolet light radiated by IRS2. Some of these gestating stars may, however, not get past the protostar stage. IRS2’s strong radiation energises and disperses the material that might otherwise collapse into new stars, or that has settled into so-called protoplanetary discs around developing stars. In the course of several million years, the surviving discs may give rise to the planets, moons and comets that make up planetary systems like our own.

    As if intense ultraviolet rays were not enough, crowded stellar nurseries like RCW 38 also subject their brood to frequent supernovae when giant stars explode at the ends of their lives. These explosions scatter material throughout nearby space, including rare isotopes — exotic forms of chemical elements that are created in these dying stars. This ejected material ends up in the next generation of stars that form nearby. Because these isotopes have been detected in our Sun, scientists have concluded that the Sun formed in a cluster like RCW 38, rather than in a more rural portion of the Milky Way.

    “Overall, the details of astronomical objects that adaptive optics reveals are critical in understanding how new stars and planets form in complex, chaotic regions like RCW 38”, says co-author Dieter Nürnberger.

    The team is composed of K.L. DeRose, T.L. Bourke, R.A. Gutermuth and S.J. Wolk (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA), S.T. Megeath (Department of Physics and Astronomy, The University of Toledo, USA), J. Alves (Centro Astronómico Hispano Alemán, Almeria, Spain), and D. Nürnberger (ESO).

    Another view from ESO
    rcw38a
    The dense star cluster RCW 38 glistens about 5500 light years away in the direction of the constellation Vela (the Sails). RCW 38 is an “embedded” cluster, in that the nascent cloud of dust and gas still envelops its stars. This image was obtained with the Wide Field Imager instrument on the MPG/ESO 2.2-metre telescope at La Silla, using data collected through four filters (B, V, R and H-alpha). The field of view is about 10 arcminutes.

    ESO Wide Field Imager 2.2m LaSilla
    WFI

    ESO 2.2 meter telescope
    MPG/ESO 2.2-metre telescope

    ESO LaSilla
    LaSilla
    See the full article, with note, here.

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  • richardmitnick 7:53 pm on April 18, 2014 Permalink | Reply
    Tags: , , , , ESO La Silla,   

    From ESO: “Double Engine for a Nebula” 2009 


    European Southern Observatory

    5 August 2009
    Contacts

    Florentin Millour
    Max-Planck Institute for Radio Astronomy
    Bonn, Germany
    Tel: +49 228 525 188
    Email: fmillour@mpifr.de

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

    Valeria Foncea
    ESO
    Chile
    Tel: +56 2 463 3123
    Email: vfoncea@eso.org

    ESO has just [2009] released a stunning new image of a field of stars towards the constellation of Carina (the Keel). This striking view is ablaze with a flurry of stars of all colours and brightnesses, some of which are seen against a backdrop of clouds of dust and gas. One unusual star in the middle, HD 87643, has been extensively studied with several ESO telescopes, including the Very Large Telescope Interferometer (VLTI). Surrounded by a complex, extended nebula that is the result of previous violent ejections, the star has been shown to have a companion. Interactions in this double [binary star] system, surrounded by a dusty disc, may be the engine fuelling the star’s remarkable nebula.

    ds

    ESO VLT Interferometer
    ESO VLTI

    The new image, showing a very rich field of stars towards the Carina arm of the Milky Way, is centred on the star HD 87643, a member of the exotic class of B[e] stars. It is part of a set of observations that provide astronomers with the best ever picture of a B[e] star.

    mw
    Observed structure of the Milky Way’s spiral arms.

    The [above star field] image was obtained with the Wide Field Imager (WFI) attached to the MPG/ESO 2.2-metre telescope at the 2400-metre-high La Silla Observatory in Chile. The image shows beautifully the extended nebula of gas and dust that reflects the light from the star. The central star’s wind appears to have shaped the nebula, leaving bright, ragged tendrils of gas and dust. A careful investigation of these features seems to indicate that there are regular ejections of matter from the star every 15 to 50 years.

    ESO Wide Field Imager 2.2m LaSilla
    WFI on 2.2m telescope

    ESO 2.2 meter telescope
    2.2m telescope at LaSilla

    ESO LaSilla
    ESO at LaSilla

    A team of astronomers, led by Florentin Millour, has studied the star HD 87643 in great detail, using several of ESO’s telescopes. Apart from the WFI, the team also used ESO’s Very Large Telescope (VLT) at Paranal.

    At the VLT, the astronomers used the NACO adaptive optics instrument, allowing them to obtain an image of the star free from the blurring effect of the atmosphere. To probe the object further, the team then obtained an image with the Very Large Telescope Interferometer (VLTI)[above].

    ESO NACO
    NACO on ESO/VLT

    The sheer range of this set of observations, from the panoramic WFI image to the fine detail of the VLTI observations, corresponds to a zoom-in factor of 60 000 between the two extremes. The astronomers found that HD 87643 has a companion located at about 50 times the Earth–Sun distance and is embedded in a compact dust shell. The two stars probably orbit each other in a period between 20 and 50 years. A dusty disc may also be surrounding the two stars.

    The presence of the companion could be an explanation for the regular ejection of matter from the star and the formation of the nebula: as the companion moves on a highly elliptical orbit, it would regularly come very close to HD 87643, triggering an ejection.

    The work on HD 87643 has been published in a paper to appear in Astronomy and Astrophysics: A binary engine fueling HD 87643’s complex circumstellar environment using AMBER/VLTI imaging, by F. Millour et al.

    See the full article, with notes, 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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