helioseismology Archives

August 12, 2024August 12, 2024 by David Dickinson

The Next Solar Cycle Has Started… But the Current One Hasn’t Finished Yet

We may be already seeing the makings of next solar cycle, peeking out through the current one.

It’s been a wild ride. Thus far, Solar Cycle Number 25 has been one of the strongest cycles in recent memory, producing several massive sunspot groups. The current large region turned Earthward (Active Region 3780) is now easily visible with eclipse glasses… no magnification needed. Cycle 25 started back in 2019.

November 29, 2023December 5, 2023 by David Dickinson

The Solar Radius Might Be Slightly Smaller Than We Thought

SDO Sol — NASA SDO's view, of our tempestuous host star. NASA/SDO

A pioneering method suggests that the size of our Sun and the solar radius may be due revision.

Our host star is full of surprises. Studying our Sun is the most essential facet of modern astronomy: not only does Sol provide us with the only example of a star we can study up close, but the energy it provides fuels life on Earth, and the space weather it produces impacts our modern technological civilization.

Now, a new study, titled The Acoustic Size of the Sun suggests that a key parameter in modern astronomy and heliophysics—the diameter of the Sun—may need a slight tweak.

July 30, 2023July 30, 2023 by Brian Koberlein

New Simulation Reveals the Churning Interiors of Giant Stars

A simulation of convection within a star. Credit: E.H. Anders et al

On a basic level, a star is pretty simple. Gravity squeezes the star trying to collapse it, which causes the inner core to get extremely hot and dense. This triggers nuclear fusion, and the heat and pressure from that pushes back against gravity. The two forces balance each other while a star is in its main sequence state. Easy peasy. But the details of how that works are extremely complex. Modeling the interior of a star accurately requires sophisticated computer models, and even then it can be difficult to match a model to what we see on the surface of a star. Now a new computer simulation is helping to change that.

May 15, 2021May 15, 2021 by Brian Koberlein

Massive Stars Mix Hydrogen in Their Cores, Causing Them to Pulse Every few Hours or Days

This illustration shows what the luminous blue variable star in the Kinman Dwarf galaxy could have looked like before its mysterious disappearance. Credit: ESO/L. Calçada

Main sequence stars fuse hydrogen in their cores. It’s how they produce the energy they need to shine and keeps them from collapsing under their own weight. As hydrogen is fused into helium, there is less hydrogen available in the core. This can pose a challenge for large stars. They need to fuse a tremendous amount of hydrogen to keep shining, and they can’t do that when core hydrogen is depleted. Fortunately, they can solve this problem by mixing more hydrogen into their core. A new study in Nature Astronomy shows us how this mixing happens.

November 25, 2020November 25, 2020 by Brian Koberlein

Solar astronomers can now predict future sunspots. There should be a big one in a couple of days

Sunspot image from the newly upgraded GREGOR Telescope

The surface of the Sun is a turbulent dance of gravity, plasma, and magnetic fields. Much like the weather on Earth, its behavior can seem unpredictable, but there are patterns to be found when you look closely.