Featured Research

from universities, journals, and other organizations

Something new on the sun: SDO spots a late phase in solar flares

Date:
September 8, 2011
Source:
NASA/Goddard Space Flight Center
Summary:
Analysis of 191 solar flares since May 2010 by NASA's Solar Dynamics Observatory (SDO) has recently shown a new piece in the pattern: some 15 percent of the flares have a distinct "late phase flare" some minutes to hours later that has never before been fully observed. This late phase of the flare pumps much more energy out into space than previously realized.

A compilation of solar data from various instruments on SDO recording a flare on May 5, 2010. The images on top show the initial magnetic loops of the flare, and a delayed brightening of additional magnetic loops above the originals showing the late phase flare. Along the bottom, graphs from EVE show the extreme ultraviolet light peaking both in time with the main flare and the late phase flare.
Credit: NASA/SDO/Tom Woods

The sun's surface dances. Giant loops of magnetized solar material burst up, twist, and fall back down. Some erupt, shooting radiation flares and particles out into space. Forced to observe this dance from afar, scientists use all the tools at their disposal to look for patterns and connections to discover what causes these great explosions. Mapping these patterns could help scientists predict the onset of space weather that bursts toward Earth from the sun, interfering with communications and Global Positioning System (GPS) signals.

Analysis of 191 solar flares since May 2010 by NASA's Solar Dynamics Observatory (SDO) has recently shown a new piece in the pattern: some 15 percent of the flares have a distinct "late phase flare" some minutes to hours later that has never before been fully observed. This late phase of the flare pumps much more energy out into space than previously realized.

"We're starting to see all sorts of new things," says Phil Chamberlin, deputy project scientist for SDO at NASA's Goddard Space Flight Center in Greenbelt, Md. "We see a large increase in emissions a half-hour to several hours later, that is sometimes even larger than the original, traditional phases of the flare. In one case on November 3, 2010, measuring only the effects of the main flare would mean underestimating the amount of energy shooting into Earth's atmosphere by 70 percent."

The entire space weather system, from the sun's surface to the outer edges of the solar system, is dependent on how energy transfers from one event to another -- magnetic reconnection near the sun transferred to movement energy barreling across space to energy deposited into Earth's atmosphere, for example. Better understanding of this late phase flare will help scientists quantify just how much energy is produced when the sun erupts.

The team found evidence for these late phases when SDO first began collecting data in May of 2010 and the sun decided to put on a show. In that very first week, in the midst of an otherwise fairly quiet time for the sun, there sprouted some nine flares of varying sizes. Flare sizes are divided into categories, named A, B, C, M and X, that have long been defined by the intensity of the X-rays emitted at the flare's peak as measured by the GOES (Geostationary Operational Environmental Satellite) satellite system. GOES is a NOAA-operated network of satellites that has been in geosynchronous orbit near Earth since 1976. One of the GOES satellites measures only X-ray emissions and is a crucial source of information on space weather that the sun sends our way.

That May 2010, however, SDO observed those flares with its multi-wavelength vision. It recorded data indicating that some other wavelengths of light weren't behaving in sync with the X-rays, but peaked at other times.

"For decades, our standard for flares has been to watch the x-rays and see when they peak," says Tom Woods, a space scientist at the University of Colorado, Boulder, Colo. who is first author on a paper on this subject that goes online Sept. 7 in the Astrophysical Journal. "That's our definition for when a flare goes off. But we were seeing peaks that didn't correspond to the X-rays." Woods says that at first they were worried the data were an anomaly or a glitch in the instruments. But as they confirmed the data with other instruments and watched the patterns repeat over many months, they began to trust what they were seeing. "And then we got excited," he says.

Over the course of a year, the team used the EVE (for Extreme ultraviolet Variability Experiment) instrument on SDO to record data from many more flares. EVE doesn't snap conventional images. Woods is the principal investigator for the EVE instrument and he explains that it collects all the light from the sun at once and then precisely separates each wavelength of light and measures its intensity. This doesn't produce pretty pictures the way other instruments on SDO do, but it provides graphs that map out how each wavelength of light gets stronger, peaks, and diminishes over time. EVE collects this data every 10 seconds, a rate guaranteed to provide brand new information about how the sun changes, given that previous instruments only measured such information every hour and a half or didn't look at all the wavelengths simultaneously -- not nearly enough information to get a complete picture of the heating and cooling of the flare.

Recording extreme ultraviolet light, the EVE spectra showed four phases in an average flare's lifetime. The first three have been observed and are well established. (Though EVE was able to measure and quantify them over a wide range of light wavelengths better than has ever been done.) The first phase is the hard X-ray impulsive phase, in which highly energetic particles in the sun's atmosphere rain down toward the sun's surface after an explosive event in the atmosphere known as magnetic reconnection. They fall freely for some seconds to minutes until they hit the denser lower atmosphere, and then the second phase, the gradual phase, begins. Over the course of minutes to hours, the solar material, called plasma, is heated and explodes back up, tracing its way along giant magnetic loops, filling the loops with plasma. This process sends off so much light and radiation that it can be compared to millions of hydrogen bombs.

The third phase is characterized by the sun's atmosphere -- the corona --losing brightness, and so is known as the coronal dimming phase. This is often associated with what's known as a coronal mass ejection, in which a great cloud of plasma erupts off the surface of the sun.

But the fourth phase, the late phase flare, spotted by EVE was new. Anywhere from one to five hours later for several of the flares, they saw a second peak of warm coronal material that didn't correspond to another X-ray burst.

"Many observations have spotted an increased extreme ultraviolet peak just seconds to minutes after the main phase of the flare, and this behavior is considered a normal part of the flare process. But this late phase is different," says Goddard's Chamberlin, who is also a co-author on the paper. "These emissions happen substantially later. And it happens after the main flare exhibits that initial peak."

To try to understand what was happening, the team looked at the images collected from SDO's Advanced Imaging Assembly (AIA) as well. They could see the main phase flare eruption in the images and also noticed a second set of coronal loops far above the original flare site. These extra loops were longer and become brighter later than the original set (or the post-flare loops that appeared just minutes after that). These loops were also physically set apart from those earlier ones.

"The intensity we're recording in those late phase flares is usually dimmer than the X-ray intensity," says Woods. "But the late phase goes on much longer, sometimes for multiple hours, so it's putting out just as much total energy as the main flare that typically only lasts for a few minutes." Because this previously unrealized extra source of energy from the flare is equally important to impacting Earth's atmosphere, Woods and his colleagues are now studying how the late phase flares can influence space weather.

The late phase flare is, of course, just one piece of the puzzle as we try to understand the star with which we live. But keeping track of the energy, measuring all the different wavelengths of light, using all the instruments NASA has at its disposal, such information helps us map out all the steps of the sun's great dance.


Story Source:

The above story is based on materials provided by NASA/Goddard Space Flight Center. Note: Materials may be edited for content and length.


Journal Reference:

  1. Thomas N. Woods, Rachel Hock, Frank Eparvier, Andrew R. Jones, Phillip C. Chamberlin, James A. Klimchuk, Leonid Didkovsky, Darrell Judge, John Mariska, Harry Warren, Carolus J. Schrijver, David F. Webb, Scott Bailey, W. Kent Tobiska. New Solar Extreme-ultraviolet Irradiance Observations during Flares. The Astrophysical Journal, 2011; 739 (2): 59 DOI: 10.1088/0004-637X/739/2/59

Cite This Page:

NASA/Goddard Space Flight Center. "Something new on the sun: SDO spots a late phase in solar flares." ScienceDaily. ScienceDaily, 8 September 2011. <www.sciencedaily.com/releases/2011/09/110908091413.htm>.
NASA/Goddard Space Flight Center. (2011, September 8). Something new on the sun: SDO spots a late phase in solar flares. ScienceDaily. Retrieved September 18, 2014 from www.sciencedaily.com/releases/2011/09/110908091413.htm
NASA/Goddard Space Flight Center. "Something new on the sun: SDO spots a late phase in solar flares." ScienceDaily. www.sciencedaily.com/releases/2011/09/110908091413.htm (accessed September 18, 2014).

Share This



More Space & Time News

Thursday, September 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Boeing, SpaceX to Send Astronauts to Space Station

Boeing, SpaceX to Send Astronauts to Space Station

AFP (Sep. 17, 2014) — NASA selected Boeing and SpaceX on Tuesday to build America's next spacecraft to carry astronauts to the International Space Station (ISS) by 2017, opening the way to a new chapter in human spaceflight. Duration: 01:13 Video provided by AFP
Powered by NewsLook.com
East Coast Treated To Rare Meteor Sighting

East Coast Treated To Rare Meteor Sighting

Newsy (Sep. 16, 2014) — Numerous residents along the East Coast reported seeing a bright meteor flash through the sky Sunday night. Video provided by Newsy
Powered by NewsLook.com
Space Race Pits Bezos Vs Musk

Space Race Pits Bezos Vs Musk

Reuters - Business Video Online (Sep. 16, 2014) — Amazon CEO Jeff Bezos' startup will team up with Boeing and Lockheed to develop rocket engines as Elon Musk races to have his rockets certified. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
NASA Picks Boeing and SpaceX to Ferry Astronauts

NASA Picks Boeing and SpaceX to Ferry Astronauts

AP (Sep. 16, 2014) — NASA is a giant step closer to launching Americans again from U.S. soil. It has announced it has picked Boeing and SpaceX to transport astronauts to the International Space Station in the next few years. (Sept. 16) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

More Coverage


Space Instrument Observes New Characteristics of Solar Flares; Findings May Lead to Improved Space Weather Forecasting

Sep. 7, 2011 — NASA's Solar Dynamics Observatory, which is carrying a suite of instruments, has provided scientists with new information that energy from some solar flares is stronger and lasts longer than ... read more
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins