An automated system in detecting solar radio bursts type II and IV associated to multiple Coronal Mass Ejections

Nurain Mohamad Ansor, Zety Sharizat Hamidi, Nur Nafhatun Md Shariff
2019 Journal of Physics, Conference Series  
This paper presents an automated system named as CALLISTO which is implemented to record solar radio bursts emissions associated to solar activity. CALLISTO is a spectrometer used in solar activity observations in order to monitor the Sun's activity and behaviour and also as an indicator of upcoming solar events. Solar radio bursts type II is known as slow drift going from high to low frequency at a range of 20 MHz-150 MHz. It is found to be associated to Earth-directed Coronal Mass Ejections
more » ... al Mass Ejections (CMEs) travelling at a very high speed. On 4th November 2015, type II and IV bursts were detected by Almaty and Bir station respectively along with multiple formation of CMEs throughout the day. Due to the shock wave from CMEs, a minor G1 storm was triggered on 7th November 2015 leaving an aurora scenery over the skies of several states in USA. However, no damages on power systems were reported. Comprehensive discussions on this event are discussed in this paper. 2 corona and occurs ahead of the eruptions. During reconnection, a process of break and re-join between magnetic field lines and low-energy configuration converts magnetic energy into kinetic energy [4] . This paper is aimed to analyse the production of type II and IV bursts which happened on the same day and associated to formation of multiple CMEs. Next section will be an introduction part of solar radio burst, followed by methodology, results and discussion and conclusion. Solar radio bursts Studies on solar radio burst have been actively carried out since more than a decade ago. The first radio observation was commenced in 1944 by J. S Hey when he dis-covered radio wave emissions coming from the Sun [5]. Basically, solar radio burst is a radio emission of solar flares which focuses on its brief energetic and explosive characteristic [6] . Radio emissions are prompted when there is an acceleration of electrons to energies well above their thermal energy in the quiet corona [7] . Lowfrequency solar radio bursts are initiated in the same layers where solar flares and CMEs are launched [8] . At low frequencies, plasma emission is dominant which includes a resonant process of generating Langmuir waves by a beam of high-speed electrons. The waves are then converted to electromagnetic waves that propagate transversely. Generally, solar radio bursts can be categorized into 5 main types; type I, II, III, IV and V based on their pattern of spectrograph and frequency drift. Type I bursts are brief and narrowband emissions associated with an active region [9] and usually occur at frequency range of 80 MHz until 200 MHz [10]. These bursts are not related to flare phenomena and appear whether in continuum or burst component. When they are in continuum component, they are also classified as noise storm due to energetic electrons trapped on closed coronal magnetic field lines [8] . Type II bursts are seen to be slow drift going from high to low frequency at a range of 20 MHz-150 MHz. There are believed to be excited by magnetohydrodynamic shockwaves associated with CMEs [11] . Apart from being the hint of earth-directed CMEs, numerous studies in recent years have shown a strong correlation between type II bursts and the presence of CMEs which strengthen the suggestion that shocks producing type II bursts are coming from CMEs [12] [13] . Next, type III bursts rapidly drift from high to low frequency and are usually present along with high-class flares. The emissions are due to energetic particles rush away from open magnetic field lines in the corona. The general idea on this burst mechanism is on Langmuir waves, where they are converted to electromagnetic waves as seen as radio waves [14] . Type III bursts can also imply the beginning of magnetic reconnection [15] . Mean-while, type IV burst are broad continuum emission with rapidly varying fine structures [16] and are present with energetic CMEs. They are also related to the development of sunspot groups [17] . The emission is due to electrons trapped in closed field lines in the subsequent arcades after flares erupt [8] . Type IV bursts last for from hours to a few days in between 20 MHz till 2 GHz [16] and may be the source of geomagnetic disturbance. Lastly, type V bursts are in long-duration low-frequency component that seems to be emerging with the decay phase of the type III [8] with gradually decrease in frequency. The lifespan of a burst can be studied from its frequency drift rate. The drift rate shows the burst's changes in frequency over time. Equation (1) is used in order to calculate the drift rate: (1) where is the final frequency, is the initial frequency, is the final time and is the starting time. Methodology This study was conducted by utilizing data from e-CALLISTO website which was detected by Almaty station in Kazakhstan. Some of data were also obtained from SOHO, and NASA. In order to observe solar activity in radio region, a ground instrument is needed to detect the emissions produced by the Sun. CALLISTO is an acronym which stands for Compact Astronomical Low-Cost Frequency Instrument for Spectroscopy and Transportable Observatory. The named was inspired from
doi:10.1088/1742-6596/1411/1/012015 fatcat:ad6lr7qvpbfwnkw7pm22mfebci