Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Why are sunspots a source of radio emissions?

26.08.2010
NJIT researcher explains more

Why sunspots are a strong source of radio emissions and what information those emissions carry will be the focus of an invited talk by NJIT Research Professor Jeongwoo Lee tomorrow at the International Astronomical Union Symposium on the Physics of Sun and Star Spots in Ventura, CA. http://www.csun.edu/physicsandastronomy/IAUS273/ The event numbers among the top gatherings in the U.S. for people studying sunspots and related phenomena.

Lee, who will speak Aug. 26, 2010, will highlight Owens Valley Solar Array (OVSA), one of the two unique frequency-agile radio telescopes in the world. NJIT has managed and operated the facility since 1997. Research opportunities there coupled with Lee's earlier article-- "Radio Emissions from Solar Active Regions" Space Science Reviews, Vol. 133, 73-102 http://www.springerlink.com/content/6533674378432313/ --will be the foundation for the talk.

Owens Valley Solar Array features an unusually large number of frequencies (up to 86) in the range of 1—18 GHz, which can exploit the unique sensitivity of the gyroresonant spectrum to coronal magnetic fields. The imaging spectroscopy (a technique for constructing spectrum in every spatial point of interest) of sunspots implemented with the OVSA is one of the best examples for unambiguous observational determination of the coronal magnetic field and temperature.

Why are sunspots such strong sources of radio emission? "The solar corona is of tenuous plasma which is generally too faint to be detected by ground-based observations," he said. "Sunspots, though, appear to be very bright at centimeter wavelengths because hot electrons (which are millions of degrees) gyrate in the coronal magnetic field. As they gyrate, they produce an efficient radiation called gyroresonant emission. This emission can serve as an excellent indicator of the magnetic field and temperature in the coronae above sunspots. The ability to measure these quantities without the complications arising in other solar radiations is a particular advantage for studying sunspot radio emissions."

The lecture will also look at the contributions of the premier radio array for astronomical observations operated by the National Radio Astronomy Observatory known as the "Very Large Array" (VLA). This facility is capable of high-quality imaging at a few wavelengths in the centimeter range. VLA solar images have been used to perform many studies of sunspot physics. Highlights of the VLA's scientific achievements include findings of inhomogeneous structures of plasma and magnetic fields, and the presence of electric currents and waves in the sunspot coronae.

The Nobeyama Radioheliograph (NoRH), a solar-dedicated radio heliograph in Japan, will also be covered. This facility has made an important contribution to understanding the evolving nature of sunspot emissions. The radio synoptic map and butterfly diagram constructed with the eighteen-year measurement of the solar full disk provides an important clue to understanding the nature of the solar cycle.

The talk concludes with a plea to support a new generation of radio telescopes, a dream that Lee and his NJIT colleagues, as well as NRAO, is already pursuing.

"Such an array should feature as many frequencies as Owens Valley Solar Array offers and as high-resolution imaging as the VLA performs," Lee said. "It will advance the study of three-dimensional structures of temperature and magnetic fields above sunspots. And, it will allow scientists to continue monitoring time-dependent solar radio activity, such as rapid transient heating, sunspot oscillations, and solar cycle dependence of coronal temperature."

NJIT, New Jersey's science and technology university,enrolls more than 8,800 students pursuing bachelor's, master's and doctoral degrees in 120 programs. The university consists of six colleges: Newark College of Engineering, College of Architecture and Design, College of Science and Liberal Arts, School of Management, College of Computing Sciences and Albert Dorman Honors College. U.S. News & World Report's 2010 Annual Guide to America's Best Colleges ranked NJIT in the top tier of national research universities. NJIT is internationally recognized for being at the edge in knowledge in architecture, applied mathematics, wireless communications and networking, solar physics, advanced engineered particulate materials, nanotechnology, neural engineering and e-learning. Many courses and certificate programs, as well as graduate degrees, are available online through the Office of Continuing Professional Education.

Sheryl Weinstein | EurekAlert!
Further information:
http://www.njit.edu

More articles from Physics and Astronomy:

nachricht NASA laser communications to provide Orion faster connections
30.03.2017 | NASA/Goddard Space Flight Center

nachricht Pinball at the atomic level
30.03.2017 | Max-Planck-Institut für Struktur und Dynamik der Materie

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

'On-off switch' brings researchers a step closer to potential HIV vaccine

30.03.2017 | Health and Medicine

Penn studies find promise for innovations in liquid biopsies

30.03.2017 | Health and Medicine

An LED-based device for imaging radiation induced skin damage

30.03.2017 | Medical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>