• A young, sun-like star may hold warnings

    From ScienceDaily@1:317/3 to All on Thu Dec 9 21:30:44 2021
    A young, sun-like star may hold warnings for life on Earth

    Date:
    December 9, 2021
    Source:
    University of Colorado at Boulder
    Summary:
    Last year, scientists looked on as a star called EK Draconis ejected
    a massive burst of energy and charged particles many times more
    powerful than anything recorded on Earth's sun. Such explosive
    events may have been common in the early years of our solar system,
    the researchers say.



    FULL STORY ========================================================================== Astronomers spying on a stellar system located dozens of lightyears from
    Earth have, for the first time, observed a troubling fireworks show: A
    star, named EK Draconis, ejected a massive burst of energy and charged particles much more powerful than anything scientists have seen in our
    own solar system.


    ==========================================================================
    The researchers, including astrophysicist Yuta Notsu of the University
    of Colorado Boulder, will publish their results Dec. 9 in the journal
    Nature Astronomy.

    The study explores a stellar phenomenon called a "coronal mass ejection," sometimes known as a solar storm. Notsu explained that the sun shoots out
    these sorts of eruptions on a regular basis -- they're made up of clouds
    of extremely-hot particles, or plasma, that can hurtle through space at
    speeds of millions of miles per hour. And they're potentially bad news:
    If a coronal mass ejection hit Earth dead on, it could fry satellites
    in orbit and shut down the power grids serving entire cities.

    "Coronal mass ejections can have a serious impact on Earth and human
    society," said Notsu, a research associate at the Laboratory for
    Atmospheric and Space Physics (LASP) at CU Boulder and the U.S. National
    Solar Observatory.

    The new study, led by Kosuke Namekata of the National Astronomical
    Observatory of Japan and formerly a visiting scholar at CU Boulder,
    also suggests that they can get a lot worse.

    In that research, Namekata, Nostu and their colleagues used telescopes
    on the ground and in space to peer at EK Draconis, which looks like a
    young version of the sun. In April 2020, the team observed EK Draconis
    ejecting a cloud of scorching-hot plasma with a mass in the quadrillions
    of kilograms -- more than 10 times bigger than the most powerful coronal
    mass ejection ever recorded from a sun-like star.



    ==========================================================================
    The event may serve as a warning of just how dangerous the weather in
    space can be.

    "This kind of big mass ejection could, theoretically, also occur on our
    sun," Notsu said. "This observation may help us to better understand
    how similar events may have affected Earth and even Mars over billions
    of years." Superflares erupt Notsu explained that coronal mass ejections
    often come right after a star lets loose a flare, or a sudden and bright
    burst of radiation that can extend far out into space.

    Recent research, however, has suggested that on the sun, this sequence
    of events may be relatively sedate, at least so far as scientists have observed.

    In 2019, for example, Notsu and his colleagues published a study that
    showed that young sun-like stars around the galaxy seem to experience
    frequent superflares -- like our own solar flares but tens or even
    hundreds of times more powerful.



    ==========================================================================
    Such a superflare could, theoretically, also happen on Earth's sun but
    not very often, maybe once every several thousand years. Still, it got
    Notsu's team curious: Could a superflare also lead to an equally super
    coronal mass ejection? "Superflares are much bigger than the flares
    that we see from the sun," Notsu said. "So we suspect that they would
    also produce much bigger mass ejections.

    But until recently, that was just conjecture." Danger from above To find
    out, the researchers set their sights on EK Draconis. The curious star,
    Notsu explained, is about the same size as our sun, but, at just 100
    million years old, it's a relative youngster in a cosmic sense.

    "It's what our sun looked like 4.5 billion years ago," Notsu said.

    The researchers observed the star for 32 nights in winter and spring
    2020 using NASA's Transiting Exoplanet Survey Satellite (TESS) and Kyoto University's SEIMEI Telescope. On April 5, Notsu and his colleagues got
    lucky: The researchers looked on as EK Draconis erupted into a superflare,
    a really big one. About 30 minutes later, the team observed what appeared
    to be a coronal mass ejection flying away from the star's surface. The researchers were only able to catch the first step in that ejection's
    life, called the "filament eruption" phase. But even so, it was a monster, moving at a top speed of roughly 1 million miles per hour.

    It may also not bode well for life on Earth: The team's findings hint
    that the sun could also be capable of such violent extremes. But don't
    hold your breath -- like superflares, super coronal mass ejections are
    probably rare around our getting-on-in-years sun.

    Still, Notsu noted that huge mass ejections may have been much more common
    in the early years of the solar system. Gigantic coronal mass ejections,
    in other words, could have helped to shape planets like Earth and Mars
    into what they look like today.

    "The atmosphere of present-day Mars is very thin compared to Earth's,"
    Notsu said. "In the past, we think that Mars had a much thicker
    atmosphere. Coronal mass ejections may help us to understand what
    happened to the planet over billions of years." Co-authors on the new
    study include researchers from the National Astronomical Observatory
    of Japan, University of Hyogo, Kyoto University, Kobe University, Tokyo Institute of Technology, The University of Tokyo and Doshisha University.

    ========================================================================== Story Source: Materials provided by
    University_of_Colorado_at_Boulder. Original written by Daniel
    Strain. Note: Content may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Kosuke Namekata, Hiroyuki Maehara, Satoshi Honda, Yuta Notsu, Soshi
    Okamoto, Jun Takahashi, Masaki Takayama, Tomohito Ohshima, Tomoki
    Saito, Noriyuki Katoh, Miyako Tozuka, Katsuhiro L. Murata, Futa
    Ogawa, Masafumi Niwano, Ryo Adachi, Motoki Oeda, Kazuki Shiraishi,
    Keisuke Isogai, Daikichi Seki, Takako T. Ishii, Kiyoshi Ichimoto,
    Daisaku Nogami, Kazunari Shibata. Probable detection of an eruptive
    filament from a superflare on a solar-type star. Nature Astronomy,
    2021; DOI: 10.1038/ s41550-021-01532-8 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2021/12/211209124244.htm

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