Search Publications
Polarization Accuracy Verification of the Chromospheric LAyer SpectroPolarimeter
Hara, Hirohisa; De Pontieu, Bart; Carlsson, Mats +25 more
We have developed an advanced UV spectropolarimeter called Chromospheric LAyer SpectroPolarimeter (CLASP2), aimed at achieving very high accuracy measurements (<0.1% at 3 σ ) of the linear (Q /I and U /I ) and circular (V /I ) polarizations of the Mg II h and k lines (280 nm). CLASP2 was launched on board a NASA sounding rocket on April 11, 201…
Observation of a Flare and Filament Eruption in Lyman-α on 8 September 2011 by the PRoject for OnBoard Autonomy/Large Yield Radiometer (PROBA2/LYRA)
Kretzschmar, M.; Dammasch, I. E.; Dominique, M. +3 more
The Large Yield Radiometer (LYRA) instrument onboard the PRoject for OnBoard Autonomy (PROBA2) observes the solar irradiance in four channels in the UV-EUV. One of these channels is centered around the hydrogen line at 121.6 nm. The solar Lyman-α emission line is an optically thick line mostly formed in the chromosphere. Although it is one of the …
Relationships Between the Spectra of Near-Earth Proton Enhancements, Hard X-Ray Bursts, and CME Speeds
Grechnev, V. V.; Kiselev, V. I.; Meshalkina, N. S.
Some studies propose the transfer of flare-accelerated protons in an erupting flux rope until its reconnection with an open structure releases the trapped protons. Coulomb collisions in the dense flux-rope body deplete the low-energy part of the proton spectrum. On the other hand, shock acceleration progressively replenishes this part of the spect…
Exploring the Origin of Stealth Coronal Mass Ejections with Magnetofrictional Simulations
Yeates, A. R.; Bhowmik, P.; Rice, O. E. K.
Coronal mass ejections (CMEs) - among the most energetic events originating from the Sun - can cause significant and sudden disruption to the magnetic and particulate environment of the heliosphere. Thus, in the current era of space-based technologies, early warning that a CME has left the Sun is crucial. Some CMEs exhibit signatures at the solar …
Multi-Spacecraft Observations of an Interplanetary Coronal Mass Ejection Interacting with Two Solar-Wind Regimes Observed by the Ulysses and Twin-STEREO Spacecraft
Foullon, Claire; Barnes, David; Davies, Jackie +2 more
We present a combined study of a coronal mass ejection (CME), revealed in a unique orbital configuration that permits the analysis of remote-sensing observations on 27 June 2007 from the twin Solar Terrestrial Relations Observatory (STEREO)-A and -B spacecraft and of its subsequent in situ counterpart outside the ecliptic plane, the interplanetary…
Complex Catalogue of High Speed Streams Associated with Geomagnetic Storms During Solar Cycle 24
Besliu-Ionescu, Diana; Maris Muntean, Georgeta; Dobrica, Venera
A complex catalogue of high speed streams produced by coronal holes and their effects in the terrestrial magnetosphere - the so-called geomagnetic storms - for Solar Cycle 24 (2009 to 2019) is presented here. This catalogue is structured in three parts describing the high-speed stream characteristics, the interplanetary magnetic field state, and t…
Arrival Time Estimates of Earth-Directed CME-Driven Shocks
Shanmugaraju, A.; Gopalswamy, N.; Suresh, K.
We report on the travel times of 19 interplanetary (IP) shocks driven by Earth-directed coronal mass ejections (CMEs) that occurred from 2010 to 2017. We track the shocks ahead of CMEs using the graduated cylindrical shell (GCS) model constructed from multiple-view observations from the Solar TErrestrial RElations Observatory (STEREO) and Solar an…
Precursory Signals of Forbush Decreases Not Connected with Shock Waves
Mavromichalaki, H.; Belov, A.; Eroshenko, E. +4 more
Forbush decreases (FDs) are sharp reductions of the cosmic-ray (CR) intensity, following intense solar activity such as coronal mass ejections (CMEs) and their corresponding interplanetary shocks. In some cases, shocks create sudden storm commencements (SSCs) at the Earth's magnetosphere with significant interest for space-weather studies. Preincr…
Amplitudes of Solar Gravity Modes: A Review
Buldgen, G.; Belkacem, K.; Pinçon, C.
Solar gravity modes are considered the Rosetta Stone for probing and subsequently deciphering the physical properties of the solar inner-most layers. Recent claims of positive detection therefore shed some new light on the long-standing issue of estimating solar gravity mode amplitudes. In this article, our objective is to review the theoretical e…
Spectral Lines in FUV and EUV for Diagnosing Coronal Magnetic Field
Nagaraju, K.; Khan, Raveena
The diagnostic capabilities of spectral lines in the far-ultraviolet (FUV) and extreme-ultraviolet (EUV) wavelength ranges are explored in terms of their Hanle and Zeeman sensitivity to probe the vector magnetic fields in the solar corona. The temperature range covered is log10(T)=5.5 - 6.3. The circular-polarization signal due to longi…