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  • richardmitnick 9:45 am on February 18, 2022 Permalink | Reply
    Tags: "New 'black widow' millisecond pulsar discovered", , Green Bank Observatory (US), , The newfound pulsar designated PSR J1555−2908 turns out to be one of the so-called "black widow" MSPs   

    From Green Bank Observatory (US) via phys.org: “New ‘black widow’ millisecond pulsar discovered” 

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    From Green Bank Observatory (US)

    via

    phys.org

    February 17, 2022
    Tomasz Nowakowski

    1
    Multi-band radio pulse profiles of PSR J1555−2908. Credit: Ray et al., 2022.

    An international team of astronomers reports the detection of a new millisecond pulsar (MSP) using the Green Bank Telescope (GBT). The newfound pulsar designated PSR J1555−2908 turns out to be one of the so-called “black widow” MSPs. The finding is detailed in a paper published February 10 for The Astrophysical Journal.

    The most rapidly rotating pulsars, those with rotation periods below 30 milliseconds, are known as MSPs. Researchers assume that they are formed in binary systems when the initially more massive component turns into a neutron star that is then spun up due to accretion of matter from the secondary star.

    A class of extreme binary pulsars with semi-degenerate companion stars is dubbed “spider pulsars.” These objects are further categorized as “black widows” if the companion has extremely low mass (less than 0.1 solar masses), while they are called “redbacks” if the secondary star is heavier.

    PSR J1555−2908 was initially identified as a gamma-ray point source by NASA’s Fermi spacecraft.

    National Aeronautics and Space Administration(US) Fermi Gamma-Ray Large Area Telescope.

    National Aeronautics and Space Administration(US)/Fermi Gamma Ray Space Telescope.

    Given that a large number of point sources in the GeV gamma-ray sky are known to be powered by pulsars, PSR J1555−2908 was perceived as a promising target to search for pulsations. Therefore, a team of astronomers led by Paul S. Ray of the U.S. Naval Research Laboratory in Washington, DC, has investigated this source with GBT, which resulted in the detection of radio pulsations.

    “This fast and energetic millisecond pulsar was first detected as a gamma-ray point source in Fermi Large Area Telescope (LAT) sky survey observations. Guided by a steep spectrum radio point source in the Fermi error region, we performed a search at 820 MHz with the Green Bank Telescope that first discovered the pulsations,” the researchers explained.

    GBT observations identified radio pulsations of PSR J1555−2908 with a 1.79 ms period. Afterward a 5-minute GBT observation at S-band confirmed the discovery and determined the pulse width at 559.4 Hz to be very narrow—about 3%. By analyzing the Fermi data, gamma-ray pulsations have been also detected from this source.

    According to the study, PSR J1555−2908 is an interacting binary system with an orbital period of approximately 0.23 days. The neutron star’s mass is estimated to be some 1.4 solar masses, while the minimum mass of the companion star was calculated to be about 0.052 solar masses. These results indicate the “black widow” class of this MSP.

    PSR J1555−2908 has a relatively high spin-down power—at a level of 310 decillion erg/s. Such a high value makes it a good candidate to search for X-ray pulsations, as other MSPs with comparable spin-down power are known to exhibit bright non-thermal pulsations. However, the team analyzed the available data from the Neutron Star Interior Composition ExploreR (NICER) but, so far, has not found any significant X-ray pulsations from this pulsar.

    This may change as the researchers continue their monitoring of PSR J1555−2908 using ground-based facilities.

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

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    Mission Statement

    Green Bank Observatory (US) enables leading edge research at radio wavelengths by offering telescope, facility and advanced instrumentation access to the astronomy community as well as to other basic and applied research communities. With radio astronomy as its foundation, the Green Bank Observatory is a world leader in advancing research, innovation, and education.

    Green Bank Observatory campus

    History

    60 years ago, the trailblazers of American radio astronomy declared this facility their home, establishing the first ever National Radio Astronomy Observatory within the United States and the first ever national laboratory dedicated to open access science. Today their legacy is alive and well.

     
  • richardmitnick 10:23 am on November 8, 2021 Permalink | Reply
    Tags: "Green Bank Observatory a Catalyst for Next Decade of Astronomy Advancement", , , Green Bank Observatory (US), , The Observatory will be a partner for the Next Generation Very Large Array (ngVLA) project   

    From Green Bank Observatory (US) : “Green Bank Observatory a Catalyst for Next Decade of Astronomy Advancement” 

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    Green Bank Radio Telescope, West Virginia, USA, now the center piece of the Green Bank Observatory(US), being cut loose by the National Science Foundation(US), supported by Breakthrough Listen Project, West Virginia University, and operated by the nonprofit Associated Universities, Inc..

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    From Green Bank Observatory (US)

    2021-11-04
    Jill Malusky

    Green Bank Observatory campus
    The Green Bank Observatory is poised to support and advance the priorities of the National Academies Astro2020 Decadal Survey on Astronomy and Astrophysics.

    In addition to the work of the Green Bank Telescope (GBT), the largest fully steerable telescope in the world, the Observatory will be a partner for the Next Generation Very Large Array (ngVLA) project, which was highlighted as a priority by the Decadal Survey.

    ngVLA to be located near the location of the NRAO Karl G. Jansky Very Large Array (US) site on the plains of San Agustin, fifty miles west of Socorro, NM, USA, at an elevation of 6970 ft (2124 m) with additional mid-baseline stations currently spread over greater New Mexico, Arizona, Texas, and Mexico.

    The GBT is positioned to answer some of the most compelling scientific challenges and frontiers in astronomy and astrophysics. Over the coming decade, the unique capabilities of the GBT will allow for major advances in the study of pulsar timing and the detection of gravitational waves, time domain and multi-messenger astronomy, the search for the biochemical signatures of life, star formation, and the origins and evolution of galaxies.

    The Observatory will hold a special Zoom presentation on Wednesday November 17th at 1pm to discuss the results shared in the Astro2020 Decadal Survey. For more information on this presentation and our scientific working groups. Visit this page for more information on these activities.

    Beyond its impact to the astronomical sciences, Green Bank Observatory engages the public in dynamic educational programming to instill a greater appreciation for the value of radio astronomy, scientific discovery, and STEM in society. The Observatory uses student research opportunities, internships, apprenticeships, and co-ops to train the next generation of STEM workers, inclusive of traditionally underrepresented groups, to maximize the opportunities for diversity of future staff.

    See the full article here .


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

    Stem Education Coalition

    gbo-science-building

    Mission Statement

    Green Bank Observatory (US) enables leading edge research at radio wavelengths by offering telescope, facility and advanced instrumentation access to the astronomy community as well as to other basic and applied research communities. With radio astronomy as its foundation, the Green Bank Observatory is a world leader in advancing research, innovation, and education.

    History

    60 years ago, the trailblazers of American radio astronomy declared this facility their home, establishing the first ever National Radio Astronomy Observatory within the United States and the first ever national laboratory dedicated to open access science. Today their legacy is alive and well.

     
  • richardmitnick 11:47 am on June 19, 2021 Permalink | Reply
    Tags: "Massive Invisible Galactic Structure is Discovered – By Accident", , , , Green Bank Observatory (US), , The major component of the molecular gas in the interstellar medium is H2., The mysterious interstellar medium   

    From Green Bank Observatory (US) : “Massive Invisible Galactic Structure is Discovered – By Accident” 

    gbo-logo

    Green Bank Radio Telescope, West Virginia, USA, now the center piece of the GBO, Green Bank Observatory, being cut loose by the NSF, supported by Breakthrough Listen.

    Green Bank Radio Telescope, West Virginia, USA

    gbo-sign

    From Green Bank Observatory (US)

    2021-06-17
    Jill Malusky

    1
    1-4: Typical narrow-line emission from the OH molecule from spiral arms. 5: A new, broad, and faint structure from the OH molecule–in and between the spiral arms. Credit: P.Vosteen/ NSF/GBO/

    When it comes to the Universe, there is more than meets the eye. Astronomers using the National Science Foundation’s Green Bank Telescope (GBT) have discovered a massive, previously unknown structure in our Galaxy. This discovery was so unexpected, additional observations were taken using the Green Bank Observatory’s 20-meter Telescope to confirm the data.

    How do astronomers miss a structure like this? This research used the radio spectrum, which is not visible to the naked eye. The GBT is the world’s largest fully steerable radio telescope, and thanks to its high level of sensitivity, it was able to detect this massive structure, made of molecular gas not just present in more recognizable celestial objects, but in the vast spaces between these structures, throughout the disk of our Galaxy. Researchers believe that this gaseous structure extends far into the outskirts of our Galaxy.

    The Universe is composed of a mysterious interstellar medium, which scientists are still learning more about. The major component of the molecular gas in the interstellar medium is H2, but the H2 is usually undetectable! To map it out, radio astronomers look for “tracers” in the form of signals from other molecules mixed with the H2 in smaller quantities, and the standard tracer is carbon monoxide (CO). However, depending on how diffuse and cold the H2 and CO gases are, they still might not be seen. In 2005, astronomers (Grenier et al. Science) found an excess of cosmic rays, of unknown origin, emanating from the disk of our Galaxy. Was it possible that these rays were a clue to large reserves of molecular gas not yet been detected, and was there another method to trace this gas and confirm its existence?

    In 2012, astronomer Ron Allen, a professor with the Physics and Astronomy Department of Johns Hopkins University (US), unexpectedly found OH emission without corresponding CO emission while working on an unrelated project. As OH is also a gas molecule that occurs in clouds of molecular H2, this finding hinted that there might be an abundant portion of H2 not traced by CO, also referred to as “CO-dark” molecular gas.

    Allen worked with Dave Hogg of National Radio Astronomy Observatory (US) to create a new research program using the GBT to observe OH as an alternative tracer of H2. Philip Engelke, a new Ph.D. student at Johns Hopkins University, joined the project soon after. In 2015, the first results of this research were published, showing that OH indeed traces the “CO-Dark” component of H2 remarkably well. While it required long exposure times, the OH observations began filling in the gaps between previous CO observations, showing molecular gas as a major component in the structure of our Galaxy.

    Later in 2015, while reviewing data, Engelke noticed a bump-like feature, which he initially thought corresponded to the Outer Arm of our Milky Way Galaxy. Follow-up observations revealed a large, faint, broad feature in the entire line of sight. Allen and team were intrigued, but suspected that this feature could be an instrumental by-product of the GBT itself, rather than an actual feature in the Galaxy. The researchers came up with a test: observe the feature with a completely independent telescope.

    In 2018, 100 hours of independent observations were conducted using the Observatory’s 20-meter Telescope.

    3
    GBO 20-meter Telescope.

    Johns Hopkins PhD student Michael Busch joined Allen’s team and played a major role in this work. The 20-meter, a much smaller and older instrument, is primarily used in educational projects including the University of North Carolina’s SkyNet.

    The 20-meter observed the signal from the massive structure. Engelke commented, “To be even more sure, we tried several different independent signal processing techniques on the GBT and 20-meter results to attempt to remove the feature as if it were from the instrumental background, rather than a real signal, and none of these methods managed to remove it.” In 2019, another 100 hours of GBT observations at additional points along the disk of the Galaxy revealed that the feature follows the extent and shape of other known components of Galactic structure. At this point the researchers were convinced that the massive structure was actually real!

    What impact will this new discovery have on astronomy? The existence of this massive structure has implications for star formation theories, as well as the structure, make-up, and total mass of the interstellar medium.

    Professor Allen passed away in August of 2020, as this research was drafted by his former PhD students for publication in The Astrophysical Journal. Busch shared, “Ron was an incredible mentor, a brilliant astronomer, and a great friend to me… I will miss him dearly.” Adds Engelke, who completed his doctorate in 2019, “We were very lucky to have known him. Ron was truly excited about this discovery, and I know he would have been proud of the result. Michael and I look forward to continued research inspired by this discovery.”

    See the full article here .


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

    Stem Education Coalition

    gbo-science-building

    Mission Statement

    Green Bank Observatory (US) enables leading edge research at radio wavelengths by offering telescope, facility and advanced instrumentation access to the astronomy community as well as to other basic and applied research communities. With radio astronomy as its foundation, the Green Bank Observatory is a world leader in advancing research, innovation, and education.

    History

    60 years ago, the trailblazers of American radio astronomy declared this facility their home, establishing the first ever National Radio Astronomy Observatory within the United States and the first ever national laboratory dedicated to open access science. Today their legacy is alive and well.

     
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