Astrophysicists measure precise rotation pattern of sun-like stars for the first time

Posted: September 21, 2018 by oldbrew in Astrophysics, modelling, research
Tags: ,

Artist’s impression of an exoplanetary system [credit: NASA]


…and don’t get the answers their models led them to expect. Could the close proximity to their star of most exoplanets so far observed be a factor?

Sun-like stars rotate up to two and a half times faster at the equator than at higher latitudes, a finding by researchers at NYU Abu Dhabi that challenges current science on how stars rotate, reports Phys.org.

Until now, little was known about the precise rotational patterns of Sun-like stars, only that the equator spins faster than at higher latitudes, similar to the Sun.

Scientists at the NYU Abu Dhabi Center for Space Science used observations from NASA’s Kepler mission and asteroseismology—the study of sound waves traveling inside stars—to determine with precision how Sun-like stars rotate, which no other scientific method has been able to achieve.

Their study found that Sun-like stars, characterized as being like the Sun in mass and age, do indeed rotate in a similar manner as the Sun in that their equatorial regions rotate more rapidly than at mid- to high latitudes. But there’s a key difference.

The equator of the Sun rotates about 10 percent faster than its mid latitudes, while equators of Sun-like stars spin up to two and a half times faster than their mid latitudes.

“This is very unexpected, and challenges current numerical simulations, which suggest that stars like these should not be able to sustain differential rotation of this magnitude,” said Othman Benomar, research associate at the NYU Abu Dhabi Center for Space Science and lead author of the study published in Science.

Continued here.

Comments
  1. Curious George says:

    They derive deep conclusions from loosely related data.

  2. pochas94 says:

    I’d like to know how the spin axis of these suns are oriented. All parallel and pointing in the same direction? Perpendicular to the disk axis of their galaxy? Random? Is the universe rotating?

  3. oldbrew says:

    pochas says: is the universe rotating?

    Relative to what? 😎
    – – –
    The velocities were calculated based on the effects of acoustic oscillations generated by convective cells in the stars’ outer layers. The frequencies of those oscillations were used to determine how fast different latitude zones were rotating.

    “Using observations from NASA’s Kepler mission, we can now probe the interior of stars with asteroseismology and determine their rotational profiles at different latitudes and depths,” said Laurent Gizon, director at MPS.

    “Modes of oscillation that propagate in the direction of rotation move faster than the modes that propagate in the opposite direction, thus their frequencies are slightly different,” he said. “Our best measurements all reveal stars with solar-like rotation.”

    The research shows the potential of asteroseismology for probing stellar interiors.

    https://astronomynow.com/2018/09/21/astronomers-surprised-how-fast-a-sampling-of-sun-like-stars-rotate/

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