Studying the Sun From Far Away Like a Star to Understand Stellar Flares and Exoplanets

New Look Sunspots

Sunspots and active regions on the sun’s surface influence its overall emissions, causing variations in brightness across different types of emissions. Understanding these changes helps in characterizing stars and improves the search for exoplanets.

New research shows that sunspots and other active regions can change the overall solar emissions. The sunspots cause some emissions to dim and others to brighten; the timing of the changes also varies between different types of emissions. This knowledge will help astronomers characterize the conditions of stars, which has important implications for finding exoplanets around those stars.

An international research team led by Shin Toriumi at the Japan Aerospace Exploration Agency added up the different types of emissions observed by a fleet of satellites including “Hinode” and the “Solar Dynamics Observatory” to see what the Sun would look like if observed from far away as a single dot of light like other stars.

The team investigated how features like sunspots change the overall picture. They found that when a sunspot is near the middle of the side of the Sun facing us, it causes the total amount of visible light to dim. In contrast, when the sunspots are near the edge of the Sun the total visible light brightens because at that viewing angle bright structures known as faculae surrounding the sunspots are more visible than the dark centers.

Various Solar Emissions

(Foreground) The time evolution of the total brightness of various solar emissions as a group of sunspots rotated across the surface of the Sun. (Background) Images of the Sun taken in the different kinds of emissions when the group of sunspots was near the middle of the Sun.Credit: ISAS/NAOJ

In addition, X-rays that are produced in the corona above the solar surface grow brighter when a sunspot is visible. The coronal loops extending above the sunspots are magnetically heated, so this brightening appears before the sunspot itself rotates into view and persists even after the sunspot has rotated out of view.

Because the changes in the overall solar emissions and their timings carry information about the location and structure of features on the surface of the Sun, astronomers hope to be able to deduce the surface features of other stars such as starspots and magnetic fields. This will help astronomers to better recognize dimming caused by the shadow of an exoplanet. With better knowledge about the effects of starspots, we can estimate the parameters, such as the radii and orbits, of exoplanets more accurately.

As in-depth investigations into the Sun proceed, a better understanding of the detailed mechanisms of atmospheric heating and flare eruptions will be gained. Toriumi comments, “To this end, the next-generation solar-observing satellite Solar-C(EUVST), being developed by Japan in close collaboration with US and European partners, aims to observe the Sun in emissions that probe the chromosphere, transition region, and corona as a single system.”

For more on this research, read A New Look at Sunspots is Helping NASA Understand Life Around Other Stars.

Reference: “Sun-as-a-star Spectral Irradiance Observations of Transiting Active Regions” by Shin Toriumi, Vladimir S. Airapetian, Hugh S. Hudson, Carolus J. Schrijver, Mark C. M. Cheung and Marc L. DeRosa, 8 October 2020, Astrophysical Journal.
DOI: 10.3847/1538-4357/abadf9

3 Comments on "Studying the Sun From Far Away Like a Star to Understand Stellar Flares and Exoplanets"

  1. doctor mehrdad kesiri1389 | February 6, 2024 at 10:27 pm | Reply

    Hello, doesn’t the earth rotate from left to right, and actually the earth rotates from west to east, so why is the sun rotating from left to right in the six images on this page, and in the images you posted on this page, the sun rotates like the earth? It rotates around itself, while the sun should not rotate in the direction of the earth, stars and planets always rotate opposite each other, of course, several planets collided with Venus, and Venus rotates in the direction of the sun, which rotates around itself, and Venus also rotates in the direction of the sun, and Venus rotates opposite each other. The planets turn, this is also due to the impact of meteorites that came from a disintegrated planet that hit the sun from the arm of the galaxy and when it hit the sun after the fragments of the said planet collided with Venus and caused the reverse rotation of Venus. I have explained about Venus and the slow rotation of Mercury, please refer to the following address, I have explained everything in those addresses doctor mehrdad kesiti1389 9:57 am

    • doctor mehrdad kesiri1389 | February 8, 2024 at 1:13 am | Reply

      Basically, the sun turns both to the left and to the right, that’s why the stars and planets of the two arms of the galaxy came towards the sun and collided with the sun and solar bodies over tens of billions of years. They gave rise to solar bodies, inner and outer belts, moons and rocky planets in the solar system Time 12:43 pm

    • doctor mehrdad kesiri1389 | February 8, 2024 at 1:35 am | Reply

      Why did the scientists in the media, after all the research on solar objects, not notice that hundreds or thousands of star systems collided with solar objects and the sun, and how NASA scientists did not notice that the continents and seas of the earth were created by humans tens of millions of years ago. It was shaped in the form of humans, animals, and birds, and a civilization on earth with hundreds of thousands of years of history was destroyed, and a planet collided with the sun and exploded, and the elements inside the said planet fell to the surface of the moon, Venus, and Mercury, and shattered shards on the surface of the earth. That planet hit the surface of the oceans and the earth and the fish died and were buried under two thousand meters of soil and turned into oil.

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