Sunspots

Ionospheric Electron Content during Solar Cycle 23

Comparison of measured to modeled global total electron content
Tuesday, March 13, 2018

Solomon & Qian show that solar minima are not all the same, and may have implications for understanding the Sun during the extended periods of very low activity known as “grand minima” that have sometimes occurred in the past, the best known of which was the Maunder Minimum during 1650–1700.

The longitudinal evolution of equatorial coronal holes

The evolution of the total daily (black) and hemispheric sunspot numbers
Thursday, December 28, 2017

In 2011, three satellites—the Solar-Terrestrial RElations Observatory (STEREO) A & B, and the Solar Dynamics Observatory (SDO)—were in a unique spatial alignment that allowed a 360 degree view of the Sun. This alignment lasted until 2014, the peak of solar cycle 24.

Evershed and Counter-Evershed Flows In Sunspot MHD Simulations

Field line connectivity and associated pressure perturbation image
Wednesday, December 13, 2017

There have been a number of reports in the literature of counter-Evershed flows in well developed sunspot penumbrae, i.e. flows directed towards the umbra.

What causes the "seasons" in space weather?

Oscillation between differential rotation kinetic energy (solid red curve) and perturbation Rossby waves kinetic energy (red dashed curve)

It is widely known that the Sun has 'spots'--dark areas on its surface that are well known to contain strong magnetic fields, much stronger than the Earth's field. The number of spots seen on the Sun waxes and wanes with a period of roughly eleven years, the 'solar cycle'.

Magnetic Buoyancy and Rotational Instabilities in the Tachocline

Instability domains in low and middle latitudes
Wednesday, January 17, 2018

Peter Gilman presents results from an analytical model for magnetic buoyancy and ro­tational instabilities in a full spherical shell tachocline that includes rotation. differential rotation close to that observed helioseismicly, and toroidal field.

Origins of the Ambient Solar Wind: Implication for Space Weather

Carrington rotation stack plots
Thursday, September 7, 2017

The Sun’s outer atmosphere is heated to temperatures of millions of degrees, and solar plasma flows out into interplanetary space at supersonic speeds. This paper reviews our current understanding of these interrelated problems: coronal heating and the acceleration of the ambient solar wind.

Deciphering Solar Magnetic Activity: Spotting Solar Cycle 25

Comparing the evolution of the daily hemispheric sunspot number and a data-inspired representation of activity band polarity and migration image
Friday, June 9, 2017

We present observational signatures of solar cycle 25 onset. Those signatures are visibly following a migratory path from high to low latitudes.

Beyond sunspots: Studies using the McIntosh Archive of global solar magnetic

Thursday, December 15, 2016

In 1964 (Solar Cycle 20; SC 20), Patrick McIntosh began creating hand-drawn synoptic maps of solar magnetic features, based on H-alpha images.

Annie Maunder, A Pioneer of Solar Astronomy

If you have visited the High Altitude Observatory, you may recall seeing the Maunder’s original butterfly diagram. The chart resembles three butterflies traveling west. Drawn by Annie S.D. Maunder and E.

Azaymi Siu investigates the penumbra of sunspots

Azaymi Litzi Siu Tapia

Azaymi Litzi Siu Tapia is a PhD student in Solar Physics at Max Planck Institute for Solar System Research and the University of Gottingen in Germany, since August 2014. She is working with Andreas Lagg and Sami K.

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