Scientists find elusive waves in sun's corona

Aug 30, 2007
The Sun

Scientists for the first time have observed elusive oscillations in the Sun's corona, known as Alfvén waves, that transport energy outward from the surface of the Sun. The discovery is expected to give researchers more insight into the fundamental behavior of solar magnetic fields, eventually leading to a fuller understanding of how the Sun affects Earth and the solar system.

The research, led by Steve Tomczyk of the National Center for Atmospheric Research (NCAR), is being published this week in Science.

"Alfvén waves can provide us with a window into processes that are fundamental to the workings of the Sun and its impacts on Earth," says Tomczyk, a scientist with NCAR's High Altitude Observatory.

Alfvén waves are fast-moving perturbations that emanate outward from the Sun along magnetic field lines, transporting energy. Although they have been detected in the heliosphere outside the Sun, they have never before been viewed within the corona, which is the outer layer of the Sun's atmosphere. Alfvén waves are difficult to detect partly because, unlike other waves, they do not lead to large-intensity fluctuations in the corona. In addition, their velocity shifts are small and not easily spotted.

"Our observations allowed us to unambiguously identify these oscillations as Alfvén waves," says coauthor Scott McIntosh of the Southwest Research Institute in Boulder. "The waves are visible all the time and they occur all over the corona, which was initially surprising to us."

Insights into the Sun

By tracking the speed and direction of the waves, researchers will be able to infer basic properties of the solar atmosphere, such as the density and direction of magnetic fields. The waves may provide answers to questions that have puzzled physicists for generations, such as why the Sun's corona is hundreds of times hotter than its surface.

The research also can help scientists better predict solar storms that spew thousands of tons of magnetized matter into space, sometimes causing geomagnetic storms on Earth that disrupt sensitive telecommunications and power systems. By learning more about solar disruptions, scientists may be able to better protect astronauts from potentially dangerous levels of radiation in space.

"If we want to go to the moon and Mars, people need to know what's going to happen on the Sun," Tomczyk says.

A powerful instrument

To observe the waves, Tomczyk and his coauthors turned to an instrument developed at NCAR over the last few years. The coronal multichannel polarimeter, or CoMP, uses a telescope at the National Solar Observatory in Sacramento Peak, New Mexico, to gather and analyze light from the corona, which is much dimmer than the Sun itself. It tracks magnetic activity around the entire edge of the Sun and collects data with unusual speed, making a measurement as frequently as every 15 seconds.

The instrument enabled the research team to simultaneously capture intensity, velocity, and polarization images of the solar corona. Those images revealed propagating oscillations that moved in trajectories aligned with magnetic fields, and traveled as fast as nearly 2,500 miles per second.

Source: National Center for Atmospheric Research

Explore further: 'Blockbuster' science images

add to favorites email to friend print save as pdf

Related Stories

Mystery of dwarf galaxy could be ejected black hole

Nov 19, 2014

An international team of researchers analyzing decades of observations from many facilities—including the W. M. Keck Observatory on Mauna Kea, the Pan-STARRS1 telescope on Haleakala and NASA's Swift satellite—has ...

Recommended for you

'Blockbuster' science images

20 hours ago

At this point, the blockbuster movie Interstellar has created such a stir that one would almost have to be inside a black hole not to know about it. And while the science fiction thriller may have taken some ...

Estimating the magnetic field of an exoplanet

Nov 20, 2014

Scientists developed a new method which allows to estimate the magnetic field of a distant exoplanet, i.e., a planet, which is located outside the Solar system and orbits a different star. Moreover, they ...

It's filamentary: How galaxies evolve in the cosmic web

Nov 20, 2014

How do galaxies like our Milky Way form, and just how do they evolve? Are galaxies affected by their surrounding environment? An international team of researchers, led by astronomers at the University of ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.