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  • richardmitnick 4:14 pm on August 18, 2014 Permalink | Reply
    Tags: Arecibo Observatory, , , , , , ,   

    From Astrobiology: ” SETI Searches Kepler Candidates for Signals of Life” 

    Astrobiology Magazine

    Astrobiology Magazine

    Aug 18, 2014
    Nola Taylor Redd

    A recent search by the Search for Extraterrestrial Intelligence (SETI) studied 86 candidates in the Kepler space observatory’s field for radio signals that could potentially indicate the presence of an intelligent civilization.

    Of course, no radio signals were found, but the search did identify the most promising Kepler objects for wide-band observations using the Green Bank Telescope in West Virginia.

    NRAO GBT
    NRAO Green Bank Telescope

    “The 86 target stars were selected because they hosted planets discovered by [the year] 2011 with properties that could be conducive to the development of life,” said Abhimat Gautam, of the University of California, Berkeley.

    Gautam, who just completed his senior undergratuate year at the University of California, Berkeley and was part of the Berkeley SETI Research Center, presented the results at the 224th summer meeting of the American Astronomical Society in Boston, Massachusetts in June.

    Widening the search

    By 2011, Kepler had revealed 1,235 planetary candidates (as of June 17, 2014, that number stands at 4,254, with 974 of them confirmed as planets). Gautam worked with Andrew Siemion and other scientists of the Berkeley SETI Research Center to select 86 planetary candidates that had surface temperatures between –50 and 100 degrees Celsius (-58 to 212 degrees Fahrenheit), a radius smaller than three times that of Earth, and an orbital period of more than 50 days. Such conditions placed the objects within the habitable zone around their stars, the region where liquid water can exist on the surface and where life might best be able to develop on a planet.

    k11
    Kepler-11, a sun-like star located approximately 2,000 light-years from Earth, hosts six transiting planets that were the target of a search for signals indicating advanced civilizations.

    The Green Bank Telescope (the world’s largest fully steerable radio telescope, located in Green Bank, West Virginia) targeted the parent stars using a wide-band signal. Scientists had performed previous searches of the Kepler field in the narrow-band with no success. Only 5 Hertz (Hz) wide on the radio spectrum, narrowband signals are only known to arise from artificial sources on Earth, Gautam said. The narrowband range is commonly used in SETI searches.

    By switching to wide-band, Gautam hoped for a number of benefits. Wide-band signals cover 2.5 Megahertz (MHz), which is half a billion times wider than previous searches. Increasing the region of the radio spectrum observed means that listening scientists can search for broader signals than those previously observed. The interstellar medium—the gas and dust between stars—can spread the signal out as it travels through the material, causing a delay that could provide a rough estimate of the distance to any detectable source and allowing SETI astronomers to track potential communications back to their origins.

    In addition, a wide-band signal may be more commonly used for intentional signaling, Gautam said.

    “An advanced alien civilization may even use a pulsar for signaling, which can be more easily and effectively detected in a wide-band search.”

    k22
    Located in the habitable zone around a sun-like star, Kepler-22b, shown in this artist’s interpretation, is 2.4 times the size of Earth. Credit: NASA/Ames/JPL-Caltech

    Gautam, who is pursuing a doctorate in astronomy at the University of California, Los Angeles, first took interest in SETI through theSETI@Home project while still in high school. He contacted Dan Werthimer, chief scientist for SETI@Home, in search of available research projects.

    SETI@home screensaver
    SETI @home

    “When UC Berkeley undergraduate students majoring in the physical sciences express an interest in continuing on for a graduate degree in their field, one of the first suggestions they receive is to seek out research opportunities,” SETI’s Andrew Siemion told Astrobiology Magazine in an email.

    Gautam presented the results while he was still an undergraduate student because“it was all his work,” Siemion said.

    “Abhimat [Gautam] was a fantastic member of our research group,” he said.

    Scanning the skies

    The SETI search focused both on active signals deliberately broadcast by a potential civilization, as well as passive signals such as those created by Earth’s television shows and airport radars.

    “We expect intentional, active signals to be brighter and easier to detect than non-intentional, passive signals,” Gautam said.

    With the Green Bank Telescope pointed at each target star, the radio beam would span approximately 4.2 light-years, wide enough to engulf the planetary system, including unknown bodies.

    According to Siemion’s SETI blog, the search also covered a region of the radio spectrum known as the “terrestrial microwave window,” which can travel through both interstellar space and Earth’s atmosphere with little distortion. Within that window, the SETI search covered the “water hole,” a region of the radio spectrum bounded by the two products of water — hydrogen and hydroxyl.

    “Some scientists have suggested that if an extraterrestrial intelligence were to deliberately signal other intelligent beings, they might chose this band,” Siemion wrote.

    The team found no sign of an intelligent civilization. They concluded that less than 1 percent of the stars in the region produce a radio signal greater than 60 times that of the Arecibo radio telescope in Puerto Rico.

    “The Arecibo Planetary Radar is the most powerful radio transmitter on Earth,” Gautam said.

    “This provides a good estimate for calculating estimates of the detectability of Earth-like technology in our search.”

    Arecibo
    Arecibo

    See the full article here.

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  • richardmitnick 7:20 am on August 8, 2014 Permalink | Reply
    Tags: Arecibo Observatory, , , , ,   

    From Royal Astronomical Society: “Astronomers find stream of gas – 2.6 million light years long” 

    Royal Astronomical Society

    Royal Astronomical Society

    07 August 2014
    Ruth E. Torres Hernández
    Public Relations Officer
    Arecibo Observatory
    Puerto Rico
    Tel: +1 787 878 2612 x615
    rutorres@suagm.edu

    Yvonne Guadalupe Negrón
    Director- Public Relations Office
    Universidad Metropolitana
    Puerto Rico
    Tel: +1 787 766 1717 x6405, +1 787 242 0806

    Erin Carver
    Media and Communications Manager
    Universities Space Research Association
    United States
    Tel: +1 410 227 7078
    ecarver@usra.edu

    Dr Robert Massey
    Royal Astronomical Society
    Tel: +44 (0)20 7734 3307 / 4582
    Mob: +44 (0)794 124 8035
    rm@ras.org.uk

    Astronomers and students have found a bridge of atomic hydrogen gas 2.6 million light years long between galaxies 500 million light years away. They detected the gas using the William E. Gordon Telescope at the Arecibo Observatory, a radio astronomy facility of the US National Science Foundation sited in Puerto Rico. The team publish their results today in a paper in Monthly Notices of the Royal Astronomical Society.

    Aracibo Observatory
    Arecibo

    bridge
    The bridge of gas (shown in green) stretches from the large galaxy at the bottom left to the group of galaxies at the top. A third nearby galaxy to the right also has a shorter stream of gas attached to it. The three insets show expanded views of the different galaxies and the green circle indicates the Arecibo telescope beam. Credit: Rhys Taylor/Arecibo Galaxy Environment Survey/The Sloan Digital Sky Survey Collaboration.

    The stream of atomic hydrogen gas is the largest known, a million light years longer than a gas tail found in the Virgo Cluster by another Arecibo project a few years ago. Dr Rhys Taylor, a researcher at the Czech Academy of Sciences and lead author of the paper, said “This was totally unexpected. We frequently see gas streams in galaxy clusters, where there are lots of galaxies close together, but to find something this long and not in a cluster is unprecedented.”

    It is not just the length of the stream that is surprising but also the amount of gas found in it. Roberto Rodriguez, a 2014 graduate from the University of Puerto Rico in Humacao who worked on the project as an undergraduate, explained “We normally find gas inside galaxies, but here half of the gas – 15 billion times the mass of the Sun – is in the bridge. That’s far more than in the Milky Way and Andromeda galaxies combined!”

    The team is still investigating the origin of the stream. One notion surmises that the large galaxy at one end of the stream passed close to the group of smaller galaxies at the other end in the past, and that the gas bridge was drawn out as they moved apart. A second notion suggests that the large galaxy plowed straight through the middle of the group, pushing gas out of it. The team plan to use computer simulations to find out which of these ideas can best match the shape of the bridge that is seen with the Arecibo Telescope.

    The project involved three undergraduate researchers: Roberto Rodriguez and Clarissa Vazquez from UPR Humacao, and Hanna Herbst, now a graduate student at the University of Florida. Dr Robert Minchin, a staff astronomer at Arecibo Observatory and the principal investigator on the project, said “Student involvement is very important to us. We are proud to be inspiring the next generation of astronomers, and particularly proud of the involvement of Puerto Rican students.”

    The bridge was found in data taken between 2008 and 2011 for the Arecibo Galaxy Environment Survey (AGES), which is using the power of the Arecibo Telescope to survey a large area of sky with a high level of sensitivity.

    See the full article here.

    The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science.

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