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  • richardmitnick 1:51 pm on March 2, 2019 Permalink | Reply
    Tags: "Discovery of Many New Ultra-Diffuse Galaxies in Galaxy Clusters", , , , , Galaxies like our Milky Way can live in large groups with many others the so-called galaxy clusters, , KIWICS-The Kapteyn IAC WEAVE INT Clusters Survey, Laniakea supercluster,   

    From Isaac Newton Group of Telescopes: “Discovery of Many New Ultra-Diffuse Galaxies in Galaxy Clusters” 

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

    In preparation for the new multi-object survey spectrograph, WEAVE, on the 4.2m William Herschel Telescope, the astronomical community is working on deep imaging surveys to identify the astronomical objects which will be studied later in more detail with WEAVE.

    WEAVE will allow astronomers to take optical spectra of up to ~1000 targets at the same time in a single exposure, or to carry out integral-field spectroscopy using 20 deployable mini integral-field units or one large integral-field unit.

    Galaxies, like our Milky Way, can live in large groups with many others, the so-called galaxy clusters.

    Milky Way NASA/JPL-Caltech /ESO R. Hurt

    Local Group. Andrew Z. Colvin 3 March 2011

    Laniakea supercluster. From Nature The Laniakea supercluster of galaxies R. Brent Tully, Hélène Courtois, Yehuda Hoffman & Daniel Pomarède at http://www.nature.com/nature/journal/v513/n7516/full/nature13674.html. Milky Way is the red dot.

    Such associations contain a potpourri of galaxies with many different properties such as colours, ages, morphologies and brightness. Among this broad diversity there exists a bewildering population of large but extremely faint galaxies, called “ultra diffuse galaxies” (see e.g., news release “The Puzzle of Ultra-Diffuse Galaxies”), and understanding their properties is important to understand how the environment of galaxies affects their evolution. Since they are so faint, they are easily perturbed by the cluster environment, and therefore are ideal probes to study what happens with galaxies in the dense cluster environment.

    Using the capabilities of the WFC at the Isaac Newton Telescope (INT) to explore large areas of the sky and detect faint ultra-diffuse galaxies (UDGs), a collaboration of astronomers in the Netherlands and Spain performed a study to investigate these galaxies in detail, the Kapteyn IAC WEAVE INT Clusters Survey (KIWICS).

    ING Wide Field Camera on the Isaac Newton Telescope

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    Figure 1. Map of the sky showing the clusters surveyed in KIWICS, and the eight clusters that have been already analysed. Credit: Pavel Mancera Piña.

    When finished, the KIWICS survey will contain 48 X-ray selected clusters. The results for 8 clusters have recently been published in the journal Monthly Notices of the Royal Astronomical Society, and Monthly Notices of the Royal Astronomical Society

    By analysing the general properties of about 500 newly-found UDGs at different distances from the centres of the clusters the researchers found several signs of environmental effects. The first result was that the larger clusters show a lack of UDGs in their centres. This is proof that the enormous gravitational forces present there are tearing these fluffy galaxies apart.

    Moreover they also found that UDGs away from the cluster centre are generally younger and have less concentrated stellar distributions, showing that the gravitational potential of the cluster, which is stronger close to the cluster centre, is changing the structure of galaxies, and is removing the interstellar gas, so that no new stars are being formed in the centres of clusters.

    In addition, they see that, as UDGs approach the centres of their host clusters, their morphologies are transformed from irregular discs to more spheroidal systems. In fact, for dwarf galaxies, which are similar to UDGs, but much smaller, observations in the literature give the same results.

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    Figure 2. Left panel: Example of UDGs found in different clusters, the white lines show a scale of 5 arcsec. Upper right panel: The Sérsic index distribution (a measure of the light concentration of a galaxy) for central (red) and outer (blue) UDGs, showing that the galaxies in the central regions are more concentrated. Lower right panel: Axis ratio distribution of the two samples, showing that galaxies in the central regions are rounder. Credit: Pavel Mancera Piña.

    It is expected that the whole KIWICS survey will be finished at the end of 2019, just before WEAVE will be installed on the William Herschel Telescope.

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Isaac Newton Group of Telescopes located at Roque de los Muchachos Observatory on La Palma in the Canary Islands, Altitude 2,344 m (7,690 ft)

    Isaac Newton Group telescopes


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


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

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

     
  • richardmitnick 1:53 pm on December 16, 2018 Permalink | Reply
    Tags: , , , , Laniakea supercluster, , ,   

    From EarthSky: “What is the Local Group?” 

    1

    From EarthSky

    How many galaxies are now known to lie within our Local Group of galaxies? How does our Milky Way rank, size-wise? And what about the vast superclusters beyond?

    1
    One view of the Local Group- a bit to constricted.The 3 largest galaxies in the Local Group are, in descending order, Messier 31 the Andromeda galaxy, the Milky Way, and Messier 33 also known as the Triangulum Galaxy

    Iconic view of the Local Group. Andrew Z. Colvin 3 March 2011

    We know where our galaxy is located, but only locally speaking. The Milky Way galaxy is one of more than 54 galaxies known as the Local Group. The three largest members of the group are our Milky Way (second-biggest), the Andromeda galaxy (biggest) and the Triangulum Galaxy. The other galaxies in the Local Group are dwarf galaxies, and they’re mostly clustered around the three larger galaxies.

    The Local Group does have a gravitational center. It’s somewhere between the Milky Way and the Andromeda Galaxy.

    The Local Group has a diameter of about 10 million light-years.

    Astronomers have also discovered that our Local Group is on the outskirts of a giant supercluster of galaxies, known as the Virgo Supercluster.

    Virgo Supercluster NASA

    Virgo Supercluster, NASA, Wikipedia

    At least 100 galaxy groups and clusters are located within the Virgo Supercluster. Its diameter is thought to be about 110 million light-years.

    The Virgo Supercluster may be part of an even-larger structure that astronomers call the Laniakea Supercluster.

    Laniakea supercluster. From Nature The Laniakea supercluster of galaxies R. Brent Tully, Hélène Courtois, Yehuda Hoffman & Daniel Pomarède at http://www.nature.com/nature/journal/v513/n7516/full/nature13674.html. Milky Way is the red dot.

    It consists of perhaps 100,000 galaxies stretched out over some 520 million light-years.

    See the full article here .


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

    Stem Education Coalition

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

     
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