• New insights into seasons on a planet ou

    From ScienceDaily@1:317/3 to All on Thu Jan 13 21:30:36 2022
    New insights into seasons on a planet outside our solar system
    Observations of a hot Jupiter may also advance our understanding of
    planet origins and evolution

    Date:
    January 13, 2022
    Source:
    McGill University
    Summary:
    Imagine being in a place where the winds are so strong that they
    move at the speed of sound. That's just one aspect of the atmosphere
    on XO-3b, one of a class of exoplanets (planets outside our solar
    system), known as hot Jupiters. The eccentric orbit of the planet
    also leads to seasonal variations hundreds of times stronger than
    what we experience on Earth.



    FULL STORY ========================================================================== Imagine being in a place where the winds are so strong that they move at
    the speed of sound. That's just one aspect of the atmosphere on XO-3b,
    one of a class of exoplanets (planets outside our solar system), known
    as hot Jupiters.

    The eccentric orbit of the planet also leads to seasonal variations
    hundreds of times stronger than what we experience on Earth. In a recent
    paper, a McGill- led research team, provides new insight into what
    seasons looks like on a planet outside our solar system. The researchers
    also suggest that the oval orbit, extremely high surface temperatures
    (2,000 degrees C- hot enough to vaporize rock) and "puffiness" of XO-3b
    reveal traces of the planet's history.

    The findings will potentially advance both the scientific understanding
    of how exoplanets form and evolve and give some context for planets in
    our own solar system.


    ==========================================================================
    Hot Jupiters are massive, gaseous worlds like Jupiter, that orbit
    closer to their parent stars than Mercury is to the Sun. Though not
    present in our own solar system, they appear to be common throughout
    the galaxy. Despite being the most studied type of exoplanet, major
    questions remain about how they form.

    Could there be subclasses of hot Jupiters with different formation
    stories? For example, do these planets take shape far from their parent
    stars -- at a distance where it's cold enough for molecules such as
    water to become solid - - or closer. The first scenario fits better with theories about how planets in our own solar system are born, but what
    would drive these types of planets to migrate so close to their parent
    stars remains unclear.

    To test those ideas, the authors of a recent McGill-led study used data
    from NASA's retired Spitzer Space Telescope to look at the atmosphere
    of exoplanet XO-3b. They observed eccentric seasons and measured wind
    speeds on the planet by obtaining a phase curve of the planet as it
    completed a full revolution about its host star.

    Looking at atmospheric dynamics and interior evolution "This planet is an extremely interesting case study for atmospheric dynamics and interior evolution, as it lies in an intermediate regime of planetary mass where processes normally neglected for less massive hot Jupiters may come into
    play," says Lisa Dang, the first author of a paper published recently in
    The Astronomical Journal, a PhD student at McGill University's Department
    of Physics. "XO-3b has an oval orbit rather than the circular orbit
    of almost all other known hot Jupiters. This suggests that it recently
    migrated toward its parent star; if that's the case, it will eventually
    settle into a more circular orbit." The eccentric orbit of the planet
    also leads to seasonal variations hundreds of times stronger than what
    we experience on Earth. Nicolas Cowan, a McGill professor explains: "The
    entire planet receives three times more energy when it is close to its
    star during a brief sort of summer, than when it is far from the star."
    The researchers also re-estimated the planet's mass and radius and found
    that the planet was surprisingly puffier than expected. They suggest
    and that the possible source of this heating could be due to leftover
    nuclear fusion.

    Excess warmth and puffiness due to tidal heating? Observations by
    Gaia, an ESA (European Space Agency) mission, found that the planet is
    puffier than expected which indicate its interior may be particularly energetic. Spitzer observations also hints that the planet produces
    much of its own heat as XO-3b's excess thermal emission isn't seasonal
    -- it's observed throughout the year on XO-3b. It's possible that the
    excess warmth is coming from the planet's interior, through a process
    called tidal heating. The star's gravitational squeeze on the planet
    oscillates as the oblong orbit takes the planet farther and then closer
    to the star. The resulting changes in interior pressure produce heat.

    For Dang, this unusual hot Jupiter provides an opportunity to test ideas
    about which formation processes may producer certain characteristics
    in these exoplanets. For example, could tidal heating in other hot
    Jupiters also be a sign of recent migration? XO-3b alone won't unlock
    the mystery, but it serves as an important test for emerging ideas about
    these scorching giants.

    ========================================================================== Story Source: Materials provided by McGill_University. Note: Content
    may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Lisa Dang, Taylor J. Bell, Nicolas B. Cowan, Daniel Thorngren,
    Tiffany
    Kataria, Heather A. Knutson, Nikole K. Lewis, Keivan G. Stassun,
    Jonathan J. Fortney, Eric Agol, Gregory P. Laughlin, Adam Burrows,
    Karen A.

    Collins, Drake Deming, Diana Jovmir, Jonathan Langton,
    Sara Rastegar, Adam P. Showman. Thermal Phase Curves of
    XO-3b: An Eccentric Hot Jupiter at the Deuterium Burning
    Limit. The Astronomical Journal, 2021; 163 (1): 32 DOI:
    10.3847/1538-3881/ac365f ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/01/220113120739.htm
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