Search Publications
Radio, Hard X-Ray, and Gamma-Ray Emissions Associated with a Far-Side Solar Event
Zimovets, I. V.; Grechnev, V. V.; Mitrofanov, I. G. +9 more
The far-side solar eruptive event SOL2014-09-01 produced hard electromagnetic and radio emissions that were observed with detectors at near-Earth vantage points. Especially challenging was a long-duration > 100 MeV γ -ray burst that was probably produced by accelerated protons exceeding 300 MeV. This observation raised the question how high-ene…
Fragile Detection of Solar g -Modes by Fossat et al.
Gizon, Laurent; Gaulme, Patrick; Schou, Jesper +1 more
The internal gravity modes of the Sun are notoriously difficult to detect, and the claimed detection of gravity modes presented by Fossat et al. (Astron. Astrophys.604, A40, 2017) is thus very exciting. Given the importance of these modes for understanding solar structure and dynamics, the results must be robust. While Fossat et al. described thei…
A Solar Stationary Type IV Radio Burst and Its Radiation Mechanism
Koval, Artem; Chen, Yao; Feng, Shiwei +6 more
A stationary Type IV (IVs) radio burst was observed on September 24, 2011. Observations from the Nançay RadioHeliograph (NRH) show that the brightness temperature (TB) of this burst is extremely high, over 1011 K at 150 MHz and over 108 K in general. The degree of circular polarization (q ) is between −60 % ∼−100 %…
Interplanetary and Geomagnetic Consequences of Interacting CMEs of 13 - 14 June 2012
Srivastava, Nandita; Mishra, Wageesh; Chakrabarty, D.
We report on the kinematics of two interacting CMEs observed on 13 and 14 June 2012. The two CMEs originated from the same active region NOAA 11504. After their launches which were separated by several hours, they were observed to interact at a distance of 100 R⊙ from the Sun. The interaction led to a moderate geomagnetic storm at the E…
High-Speed Solar Wind Streams and Geomagnetic Storms During Solar Cycle 24
Mavromichalaki, H.; Gerontidou, M.; Daglis, T.
An updated catalog is created of 303 well-defined high-speed solar wind streams that occurred in the time period 2009 - 2016. These streams are identified from solar and interplanetary measurements obtained from the OMNIWeb database as well as from the Solar and Heliospheric Observatory (SOHO) database. This time interval covers the deep minimum o…
Evolution of CME Mass in the Corona
Vourlidas, Angelos; Howard, Russell A.
The idea that coronal mass ejections (CMEs) pile up mass in their transport through the corona and heliosphere is widely accepted. However, it has not been shown that this is the case. We perform an initial study of the volume electron density of the fronts of 13 three-part CMEs with well-defined frontal boundaries observed with the Solar and Heli…
Statistical Analysis of Solar Events Associated with Storm Sudden Commencements over One Year of Solar Maximum During Cycle 23: Propagation from the Sun to the Earth and Effects
Pick, M.; Pitout, F.; Bocchialini, K. +9 more
Taking the 32 storm sudden commencements (SSCs) listed by the International Service of Geomagnetic Indices (ISGI) of the Observatory de l'Ebre during 2002 (solar activity maximum in Cycle 23) as a starting point, we performed a multi-criterion analysis based on observations (propagation time, velocity comparisons, sense of the magnetic field rotat…
Single ICMEs and Complex Transient Structures in the Solar Wind in 2010 - 2011
Zhukov, A. N.; Slemzin, V.; Goryaev, F. +3 more
We analyze the statistics, solar sources, and properties of interplanetary coronal mass ejections (ICMEs) in the solar wind. The total number of coronal mass ejections (CMEs) registered in the Coordinated Data Analysis Workshops catalog (CDAW) during the first eight years of Cycle 24 was 61% larger than in the same period of Cycle 23, but the numb…
An Anisotropic Cosmic-Ray Enhancement Event on 07-June-2015: A Possible Origin
Usoskin, Ilya G.; Gil, Agnieszka; Mishev, Alexander +3 more
A usual event, called anisotropic cosmic-ray enhancement (ACRE), was observed as a small increase (≤5 % ) in the count rates of polar neutron monitors during 12 - 19 UT on 07 June 2015. The enhancement was highly anisotropic, as detected only by neutron monitors with asymptotic directions in the southwest quadrant in geocentric solar ecliptic (GSE…
Physical Processes Involved in the EUV "Surge" Event of 9 May 2012
Démoulin, Pascal; Mandrini, Cristina H.; López Fuentes, Marcelo +4 more
We study an extreme ultraviolet (EUV) confined ejection observed on 9 May 2012 in Active Region (AR) NOAA 11476. For the analysis we use observations in multiple wavelengths (EUV, X-rays, Hα , and magnetograms) from a variety of ground- and space-based instruments. The magnetic configuration showed two rotating bipoles within the following polarit…