Astronomy and Astrophysics – Astrophysics
Scientific paper
May 2002
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2002agusmsh21d..02l&link_type=abstract
American Geophysical Union, Spring Meeting 2002, abstract #SH21D-02
Astronomy and Astrophysics
Astrophysics
7500 Solar Physics, Astrophysics, And Astronomy, 7534 Radio Emissions, 7871 Waves And Instabilities
Scientific paper
Solar ZEBRA radio bursts are one of the least understood solar radio emissions. They occur irregularly during solar Type IV radio bursts covering a relatively wide frequency range from 0.5-4 GHz. Their instantaneous total bandwidth is narrow of the order of a fraction of 1 GHz. As the name suggests, they consist of a limited but sometimes large number of emission lines which are about equally spaced in frequency. The spacing is of the same order as the width of each line emission. Their connection with type IV bursts suggests that they occur in relatively strong magnetic field regions in the source region of the type IV and are related to the generation of emission by the trapped electron component in magnetic loop configurations. We propose a mechanism which is based on trapping of the upper hybrid mode in plasma density fluctuations in the loop plasma. Upper hybrid waves are readily excited by the trapped electron populations in the loop, whose distribution functions are characterized by loss cones. Trapping causes a discrete spectrum of such modes and nearly constant frequency spacing with the number of quasi-harmonics limited by the trapping conditions. We derive an equivalent Schrödinger equation for the trapped mode and solve it in cylindrical symmetry, obtaining the eigenfrequencies. Trapping occurs for sufficiently large density modulations. The expected frequency spacing is as narrow as observed. The trapped upper hybrid modes may mode convert into radio emission in order to radiate away; such mode conversion occurs in several other space physics radio emissions, such as terrestrial continuum radiation and auroral electron cyclotron harmonic waves (``auroral roar''). This model of the ZEBRA emissions implies that they can be used to remotely sense the fluctuating density structure in the solar corona under type IV conditions.
Karlicky Marian
LaBelle James
Treumann Rudolf A.
Yoon Peter H.
No associations
LandOfFree
A Mechanism for ZEBRA Burst Radio Emission in the Solar Corona does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with A Mechanism for ZEBRA Burst Radio Emission in the Solar Corona, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A Mechanism for ZEBRA Burst Radio Emission in the Solar Corona will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1723210