Published on June 22nd, 2013 | by James Ayre0
Solar Eruption Sheds New Light On Growth Processes Of Young Stars
On June 7, 2011, the Sun erupted, blowing large masses of hot plasma out into space; some of this plasma then fell back down onto the Sun, setting off bright flashes of ultraviolet light. This eruption was captured in great detail by the Solar Dynamics Observatory (SDO) spacecraft — and as a result has provided us with great insight into the processes by which young stars suck up the gas near them and use it to grow.
The SDO spacecraft has its expensive cameras trained on the Sun 24 hours a day, every day — providing us with images possessing better-than-HD resolution. Its Atmospheric Imaging Assembly instrument was designed and developed by researchers at the Harvard-Smithsonian Center for Astrophysics.
“We’re getting beautiful observations of the Sun. And we get such high spatial resolution and high cadence that we can see things that weren’t obvious before,” states CfA astronomer Paola Testa.
The movies take by the SDO spacecraft of the June 7th eruption “show dark filaments of gas blasting outward from the Sun’s lower right. Although the solar plasma appears dark against the Sun’s bright surface, it actually glows at a temperature of about 18,000 degrees Fahrenheit. When the blobs of plasma hit the Sun’s surface again, they heat up by a factor of 100 to a temperature of almost 2 million degrees F. As a result, those spots brighten in the ultraviolet by a factor of 2 — 5 over just a few minutes.”
The enormous release of energy was the result of the falling blobs traveling at very high speeds, up to 900,000 miles per hour. “Those speeds are similar to the speeds reached by material falling onto young stars as they grow via accretion. Therefore, observations of this solar eruption provide an ‘up close’ view of what happens on distant stars.”
“We often study young stars to learn about our Sun when it was an ‘infant.’ Now we’re doing the reverse and studying our Sun to better understand distant stars,” says Testa.
The new observations — when in combination with computer modeling — have provided researchers with a means of resolving a “decade-long argument over how to measure the accretion rates of growing stars. Astronomers calculate how fast a young star is gathering material by observing its brightness at various wavelengths of light, and how that brightness changes over time. However, they got higher estimates from optical and ultraviolet light than from X-rays.”
The researchers “discovered that the ultraviolet flashes they observed came from the in falling material itself, not the surrounding solar atmosphere. If the same is true for distant, young stars, then by analyzing the ultraviolet light they emit, we can learn about the material they are accreting.”
“By seeing the dark spots on the Sun, we can learn about how young stars accrete material and grow.” explains Testa.
In semi-related news — the Supermoon will be visible tonight and tomorrow night. Make sure that you get out to see it.