Featured Research

from universities, journals, and other organizations

How to look into the solar interior

Date:
March 25, 2014
Source:
Lomonosov Moscow State University
Summary:
Scientists have proposed the first ever quantitative description of the mechanism responsible for sunspot formation and underlying the solar activity cycle. Magnetic field helicity is one of the so-called motion invariants in magneto-hydrodynamics. It is a conserved quantity, like energy, describing the degree to which the field lines are "wrapped around themselves". During the last 20 years, scientists realized that conservation of this quantity is even more influential upon magnetic field evolution than energy conservation.

An international group including one professor from the Moscow State University proposed the first ever quantitative description of the mechanism responsible for sunspot formation and underlying the solar activity cycle.

Magnetic field helicity is one of the so-called motion invariants in magneto-hydrodynamics. It is a conserved quantity, like energy, describing the degree to which the field lines are "wrapped around themselves." During the last 20 years, scientists realized that conservation of this quantity is even more influential upon magnetic field evolution than energy conservation.

Chinese researches lead by Hongqi Zhang considered magnetic helicity monitoring results for Solar active regions. Using the data from the Solar Dynamics Observatory (SDO), they considered one particular active region (one area containing a number of sunspots) in the Southern hemisphere of the Sun. "These active regions do not emerge from nowhere but float up from the Solar interior and carry important information about the magnetic fields there. Considering these regions we literally look into the bowels of the star," explains Dmitry Sokoloff, professor of the Physics Department of the Moscow State University.

Until recently, magnetic helicity spectrum (meaning the percentage of smaller and larger vortices found in active regions) successfully evaded all the scientists' attempts to measure it. "Axel Brandenburg and I understood how this spectrum may be calculated by scientific techniques, and Axel used a standard code to reconstruct the magnetic helicity spectrum using Fourier transforms," tells Sokoloff. Observing a single active region on several different dates using different magnetogram types has shown this spectrum to be really stable, in consistence with the scientists' expectations.

Authors say that magnetic helicity measurements on the Sun is an achievement of the recent several years. Disentangling the processes of helicity distribution establishment is important to understand the mechanisms controlling the 11-year Solar activity cycle. "Ohm's law for Solar matter includes the components absent in "earthbound" electrodynamics. This is because Solar convection lacks reflectional symmetry, hence local currents become parallel to magnetic fields rather than perpendicular to them. This is not of mere but of key importance. And helicity itself is the measure of chiral, or reflectional, asymmetry," explains Sokoloff. Results of the paper accepted to Astrophysical Journal Letters are expected to facilitate prediction of Solar activity variations in future.

Besides, understanding the role of magnetic helicity in Solar activity will help the astronomers explain the nature of such phenomena as Maunder Minimum -- a prolonged period in the end of XVIIth century characterized by very low sunspot numbers. "Helicity is definitely involved here, but it is difficult to check now because the data available for this period are only sunspot numbers, we do not possess any XVIIth century helicity measurements," says the Russian researcher.


Story Source:

The above story is based on materials provided by Lomonosov Moscow State University. Note: Materials may be edited for content and length.


Journal Reference:

  1. Hongqi Zhang, Axel Brandenburg, D. D. Sokoloff. MAGNETIC HELICITY AND ENERGY SPECTRA OF A SOLAR ACTIVE REGION. The Astrophysical Journal, 2014; 784 (2): L45 DOI: 10.1088/2041-8205/784/2/L45

Cite This Page:

Lomonosov Moscow State University. "How to look into the solar interior." ScienceDaily. ScienceDaily, 25 March 2014. <www.sciencedaily.com/releases/2014/03/140325133538.htm>.
Lomonosov Moscow State University. (2014, March 25). How to look into the solar interior. ScienceDaily. Retrieved July 29, 2014 from www.sciencedaily.com/releases/2014/03/140325133538.htm
Lomonosov Moscow State University. "How to look into the solar interior." ScienceDaily. www.sciencedaily.com/releases/2014/03/140325133538.htm (accessed July 29, 2014).

Share This




More Space & Time News

Tuesday, July 29, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Russia Saves Gecko Sex Satellite, Media Has Some Fun With It

Russia Saves Gecko Sex Satellite, Media Has Some Fun With It

Newsy (July 27, 2014) The satellite is back under ground control after a tense few days, but with a gecko sex experiment on board, the media just couldn't help themselves. Video provided by Newsy
Powered by NewsLook.com
NASA EDGE: OCO-2 Launch

NASA EDGE: OCO-2 Launch

NASA (July 25, 2014) NASA EDGE webcasts live from Vandenberg AFB for the launch of the Oribiting Carbon Observatory-2 (OCO) launch. Video provided by NASA
Powered by NewsLook.com
This Week @ NASA, July 25, 2014

This Week @ NASA, July 25, 2014

NASA (July 25, 2014) Apollo 11 celebration, Next Giant Leap anticipation, ISS astronauts appear in the House and more... Video provided by NASA
Powered by NewsLook.com
Space to Ground: Coming and Going

Space to Ground: Coming and Going

NASA (July 25, 2014) One station cargo ship leaves, another arrives, aquatic research and commercial spinoffs. Questions or comments? Use #spacetoground to talk to us. Video provided by NASA
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:
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