Search Publications
Evolution of isolated G-band bright points: size, intensity and velocity
Feng, Song; Wang, Feng; Deng, Hui +3 more
We study the evolution pattern of isolated G-band bright points (GBPs) in terms of their size, intensity and velocity. Using a high resolution image sequence taken with the Hinode/Solar Optical Telescope (SOT), we detect GBPs in each image by the Laplacian and Morphological Dilation algorithm, and track their evolutions by a 26-adjacent method in …
Observations of counter-propagating Alfvénic and compressive fluctuations in the chromosphere
He, Jian-Sen; Liu, Zi-Xu; Yan, Li-Mei
Recent observations have found that chromospheric spicules behave like Alfvénic fluctuations. Low-frequency Alfvén waves are predicted to partially reflect in the transition region that has a gradient in the Alfvén speed, thereby producing inward Alfvén waves, which may interact nonlinearly with outward Alfvén waves to generate Alfvénic turbulence…
Association of CMEs with solar surface activity during the rise and maximum phases of solar cycles 23 and 24
Li, Ting; Zhang, Jun; Gao, Peng-Xin
The cyclical behaviors of sunspots, flares and coronal mass ejections (CMEs) for 54 months from 2008 November to 2013 April after the onset of Solar Cycle (SC) 24 are compared, for the first time, with those of SC 23 from 1996 November to 2001 April. The results are summarized below. (i) During the maximum phase, the number of sunspots in SC 24 is…
On the line profile changes observed during the X2.2 class flare in the active region NOAA 11158
Raja Bayanna, Ankala; Kumar, Brajesh; Venkatakrishnan, Parameswaran +4 more
The solar active region NOAA 11158 produced a series of flares during its passage through the solar disk. The first major flare (of class X2.2) of the current solar cycle occurred in this active region on 2011 February 15 around 01:50 UT. We have analyzed the Dopplergrams and magnetograms obtained by the Helioseismic and Magnetic Imager (HMI) inst…
Identification of emission sources of umbral flashes using phase congruency
Feng, Song; Ji, Kai-Fan; Yang, Yun-Fei +1 more
The emission sources of umbral flashes (UFs) are believed to be closely related to running umbral and penumbral waves, and are concluded to be associated with umbral dots in the solar photosphere. Accurate identification of emission sources of UFs is crucial for investigating these physical phenomena and their inherent relationships. A relatively …
A study of the relation between intensity oscillations and magnetic field parameters in a sunspot: Hinode observations
Venkatakrishnan, P.; Kumar, Brajesh; Mathew, Shibu K. +2 more
We present properties of intensity oscillations of a sunspot in the photosphere and chromosphere using G band and Ca II H filtergrams from Hinode. Intensity power maps as function of magnetic field strength and frequency reveal reduction of power in the G band with an increase in photospheric magnetic field strength at all frequencies. In Ca II H,…