astrophysics

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How big is a neutron star?

    While we’ve known about neutron stars for the better part of a century, astrophysicists still aren’t entirely sure how large they are. That uncertainty is related to two other unanswered questions: What’s in the middle of neutron stars, and how massive can they grow? Astrophysicists are combining multiple methods to reveal the secrets of some of the weirdest objects in the universe.

    We don’t know how fast the universe is expanding, and that’s a problem

      From New Scientist, July 15, 2020: Two sets of measurements to estimate the rate of expansion of the universe — described by the Hubble constant — conflict with one another, which may be a sign that our basic understanding of the cosmos is wrong. Two new attempts by astronomers to solve this problem have complicated things further. Fermilab scientist Antonella Palmese and her colleagues have used measurements of gravitational waves to calculate an independent value of the Hubble constant.

      Five thousand eyes on the skies: Scientists choreograph robots to observe distant galaxies

      Scientists have begun operating the Dark Energy Spectroscopic Instrument, or DESI, to create a 3-D map of over 30 million galaxies and quasars that will help them understand the nature of dark energy. The new instrument is the most advanced of its kind, with 5,000 robotic positioners that will enable scientists to gather more than 20 times more data than previous surveys. Researchers at Fermilab helped develop the software that will direct these positioners to focus on galaxies several billion light-years away and are currently in the process of fine-tuning the programs used before the last round of testing later this year.

      Satellite galaxies can help us understand dark matter’s nature

        From Nature World News, May 20, 2020: Two studies have shown evidence of how a larger satellite galaxy can draw smaller ones into them as they get “trapped” into orbiting the Milky Way. Such an arrangement can inform astronomers and researchers about the nature of the formation of galaxies as well as insights into dark matter and its nature. Fermilab scientist Alex Drlica-Wagner is featured.