Behind howls of solar wind, quiet chirps reveal its origins

Posted: January 17, 2020 by oldbrew in research, Solar physics, solar system dynamics
Tags: , ,

Here we learn that the solar wind ‘has a sort of internal heater’, which may be short on scientific explanation but sounds interesting as far as it goes.
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There’s a wind that emanates from the sun, and it blows not like a soft whistle but like a hurricane’s scream, says

Made of electrons, protons, and heavier ions, the solar wind courses through the solar system at roughly 1 million miles per hour, barreling over everything in its path.

Yet through the wind’s roar, NASA’s Parker Solar Probe can hear small chirps, squeaks, and rustles that hint at the origins of this mysterious and ever-present wind.

Now, the team at the Johns Hopkins Applied Physics Laboratory, which designed, built, and manages the Parker Solar Probe for NASA, is getting their first chance to hear those sounds, too.

“We are looking at the young solar wind being born around the sun,” says Nour Raouafi, mission project scientist for the Parker Solar Probe. “And it’s completely different from what we see here near Earth.”

Scientists have studied the solar wind for more than 60 years, but they’re still puzzled over many of its behaviors.

For example, while they know it comes from the sun’s million-degree outer atmosphere called the corona, the solar wind doesn’t slow down as it leaves the sun—it speeds up, and it has a sort of internal heater that keeps it from cooling as it zips through space.

With growing concern about the solar wind’s ability to interfere with GPS satellites and disrupt power grids on Earth, it’s imperative to better understand it.

Just 17 months since the probe’s launch and after three orbits around the sun, Parker Solar Probe has not disappointed in its mission.

“We expected to make big discoveries because we’re going into uncharted territory,” Raouafi says. “What we’re actually seeing is beyond anything anybody imagined.”

Researchers suspected that plasma waves within the solar wind could be responsible for some of the wind’s odd characteristics.

Just as fluctuations in air pressure cause winds that force rolling waves on the ocean, fluctuations in electric and magnetic fields can cause waves that roll through clouds of electrons, protons, and other charged particles that make up the plasma racing away from the sun. Particles can ride these plasma waves much like the way a surfer rides an ocean wave, propelling them to higher speeds.

“Plasma waves certainly play a part in heating and accelerating the particles,” Raouafi says.

Scientists just don’t know how much of a part. That’s where Parker Solar Probe comes in.

Full article here.

  1. oldbrew says:

    A lot of dust from ex-asteroids around…

    “We protected almost everything from the dust,” Kinnison says. And although the dust is denser than expected, nothing right now points to dust impacts being a concern for the mission, he adds.

    Gravity obviously hasn’t led to the Sun collecting it all 🤔

  2. JB says:

    The first of the converted solar waves sounds very much like the “birdie” of a heterodyne radio receiver.

  3. oldbrew says:

    ‘The interplanetary magnetic field (IMF), now more commonly referred to as the heliospheric magnetic field (HMF),[2] is the component of the solar magnetic field that is dragged out from the solar corona by the solar wind flow to fill the Solar System.

    The coronal and solar wind plasmas are highly electrically conductive, meaning the magnetic field lines and the plasma flows are effectively “frozen” together[3] and the magnetic field cannot diffuse through the plasma on time scales of interest.’

    Sounds like electricity everywhere. But we mostly hear about its partner, magnetism 🤔

  4. oldbrew says:

    Milky Way gas halo up to 10x hotter than expected…

    “We thought that gas temperatures in galactic halos ranged from around 10 000 to one million degrees—but it turns out that some of the gas in the Milky Way’s halo can hit a scorching 10 million degrees,” said Sanskriti Das, a graduate student at The Ohio State University, U.S., and lead author of the new study.

    “While we think that gas gets heated to around one million degrees as a galaxy initially forms, we’re not sure how this component got so hot. It may be due to winds emanating from the disc of stars within the Milky Way.”
    . . .
    “These observations provide new insights into the thermal and chemical history of the Milky Way and its halo, and challenge our knowledge of how galaxies form and evolve,” said ESA XMM project scientist Norbert Schartel.

    we’re not sure how this component got so hot – we just don’t know?

    challenge our knowledge – our theories don’t work?