Search Publications
Properties of High-Frequency Type II Radio Bursts and Their Relation to the Associated Coronal Mass Ejections
Gopalswamy, N.; Yashiro, S.; Mäkelä, P. +3 more
Solar radio bursts are often early indicators of space weather events such as coronal mass ejections (CMEs). In this study, we determined the properties of a sample of 40 high-starting-frequency (≥ 150 MHz) type II radio bursts and the characteristics of the associated CMEs such as width, location and speed during 2010-2016. The high starting freq…
DH Type II Radio Bursts During Solar Cycles 23 and 24: Frequency-Dependent Classification and Their Flare-CME Associations
Joshi, Bhuwan; Cho, Kyung-Suk; Patel, Binal D. +1 more
We present the characteristics of DH type II bursts for the Solar Cycles 23 and 24. The bursts are classified according to their end frequencies into three categories: Low-Frequency Group (LFG; 20 kHz ≤ f ≤ 200 kHz), Medium-Frequency Group (MFG; 200 kHz <f ≤1 MHz), and High-Frequency Group (HFG; 1 MHz <f ≤16 MHz). We find that the sources fo…
Irradiance Variations of the Sun and Sun-Like Stars - Overview of Topical Collection
Kopp, Greg; Shapiro, Alexander
This topical collection summarizes recent advances in observing and modeling irradiance variations of the Sun and Sun-like stars, emphasizing the links between surface magnetic fields and the resulting solar and stellar variability. In particular, the articles composing this collection summarize recent progress in i) solar-irradiance measurements;…
Two Classes of Eruptive Events During Solar Minimum
Yeates, A. R.; Bhowmik, P.
During solar minimum, the Sun is relatively inactive with few sunspots observed on the solar surface. Consequently, we observe a smaller number of highly energetic events such as solar flares or coronal mass ejections (CMEs), which are often associated with active regions on the photosphere. Nonetheless, our magnetofrictional simulations during th…
The Balloon-Borne Investigation of Temperature and Speed of Electrons in the Corona (BITSE): Mission Description and Preliminary Results
Cho, K. -S.; Kim, Y. -H.; Gopalswamy, N. +16 more
We report on the Balloon-borne Investigation of Temperature and Speed of Electrons in the corona (BITSE) mission launched recently to observe the solar corona from ≈3 Rs to 15 Rs at four wavelengths (393.5, 405.0, 398.7, and 423.4 nm). The BITSE instrument is an externally occulted single stage coronagraph developed at NASA's Goddard Space Flight …
Imaging and Spectral Observations of a Type-II Radio Burst Revealing the Section of the CME-Driven Shock That Accelerates Electrons
Gopalswamy, Nat; Kumari, Anshu; Patel, Ritesh +4 more
We report on a multi-wavelength analysis of the 26 January 2014 solar eruption involving a coronal mass ejection (CME) and a Type-II radio burst, performed by combining data from various space and ground-based instruments. An increasing standoff distance with height shows the presence of a strong shock, which further manifests itself in the contin…
VLA Measurements of Faraday Rotation Through a Coronal Mass Ejection Using Multiple Lines of Sight
Ascione, Madison L.; Kooi, Jason E.; Ashas, Mohammad +2 more
Coronal mass ejections (CMEs) are large eruptions of magnetized plasma from the Sun that play an important role in space weather. The key to understanding the fundamental physics of a CME is measurement of the plasma properties within heliocentric distances of <20 R⊙. Faraday rotation, a radioastronomical propagation measurement, is …
Automated Detection of Accelerating Solar Eruptions Using Parabolic Hough Transform
West, Matthew J.; Mierla, Marilena; Pant, Vaibhav +3 more
Solar eruptions such as coronal mass ejections (CMEs) observed in the inner solar corona (up to 4 R⊙) show acceleration profiles that appear as parabolic ridges in height-time plots. Inspired by the white-light automated detection algorithms Computer Aided CME Tracking System (CACTus) and Solar Eruptive Events Detection System (SEEDS), …
LASCO-C3 Observations of the K- and F-Coronae over 24 Years (1996 - 2019): Photopolarimetry and Electron Density Distribution
Lamy, Philippe; Quémerais, Eric; Gilardy, Hugo +2 more
We present the polarimetric analysis of the white-light images of the corona obtained with the Large-Angle Spectrometric COronagraph LASCO-C3 onboard the Solar and Heliospheric Observatory (SOHO) from 1996 to 2019, leading to the separation of the K- and F-components and the derivation of the electron-density distribution. The analysis makes use o…
Polarization of the Corona Observed During the 2017 and 2019 Total Solar Eclipses
Hanaoka, Yoichiro; Sakai, Yoshiaki; Takahashi, Koichi
We carried out polarimetric observations of the white-light corona during the total solar eclipses that occurred on August 21, 2017, and July 2, 2019, and successfully obtained data at two different sites for both eclipses. After eliminating the sky background, we derived the brightness, polarization brightness, and degree of polarization of the K…