UVCS/SOHO catalog of coronal mass ejections from 1996 to 2005: Spectroscopic proprieties

Abstract

[1] Ultraviolet spectra of the extended solar corona have been routinely obtained by SOHO/UltraViolet Coronagraph Spectrometer (UVCS) since 1996. Sudden variations of spectral parameters are mainly due to the detection of coronal mass ejections (CMEs) crossing the instrumental slit. We present a catalog of CME ultraviolet spectra based upon a systematic search of events in the Large Angle and Spectrometric Coronagraph (LASCO) CME catalog, and we discuss their statistical properties. Our catalog includes 1059 events through the end of 2005, covering nearly a full solar cycle. It is available online at the URL http://solarweb.oato.inaf.it/UVCS_CME and embedded in the online LASCO CME catalog (http://cdaw.gsfc.nasa.gov/CME_list). The emission lines observed provide diagnostics of CME plasma parameters, such as the light-of-sight velocity, density, and temperature and allow to link the CME onset data to the extended corona white-light images. The catalog indicates whether there are clear signatures of features such as shock waves, current sheets, O VI flares, helical motions, and which part of the CME structures (front, cavity, or prominence material) are detected. The most common detected structure is the cool prominence material (in about 70% of the events). For each event, the catalog also contains movies, images, plots, and information relevant to address detailed scientific investigations. The number of events detected in UV is about one tenth of the LASCO CMEs and about one fourth of the halo events. We find that UVCS tends to detect faster, more massive, and energetic CME than LASCO, and for about 40% of the events, it has been possible to determine the plasma light-of-sight velocity.

Neutral Hydrogen and Its Emission Lines in the Solar Corona

“…Second, as for Lβ, in our streamer model the intensity variation with distance compares relatively well to the results of Labrosse, Li, and Li (2006) in terms of number of photons. According to Giordano et al (2013), the Lβ intensity is 0.03 erg s −1 cm −2 sr −1 at 1.9 R ⊙ where we find 0.09 (note that the Lα values are closer: 8 for our computations and 6.4 for Giordano et al (2013) at 1.9 R ⊙ ). The ratio Lβ/Lα is about 10 −3 as in Labrosse, Li, and Li (2006) at 3 R ⊙ but it is about 10 −1 instead of 10 −2 in Labrosse, Li, and Li (2006) for 1 R ⊙ .…”

Multi-viewpoint Coronal Mass Ejection Catalog Based on STEREO COR2 Observations

“…This discrepancy could be explained if most of the cool material detected at 1au was from ions other than hydrogen. For example, off-limb spectroscopy from the Ultraviolet Coronal Spectrometer (UVCS; Kohl et al 1995) shows that about 38% of the events captured by UVCS had prominence material in Lyα emission (Giordano et al 2013). The resolution and the proper investigation of the thermal evolution and composition of the ejected plasma from the low corona to Earth requires the deployment of off-limb spectroscopic capabilities in addition to white light coronography (e.g., Kohl et al 2006).…”

Three-Dimensional Stereoscopic Analysis of a Coronal Mass Ejection and Comparison With Uv Spectroscopic Data

“…UVCS data are available in the catalog until 2012 December, but starting from early 2006 some dark columns began to appear and to broaden over the UVCS detectors, thus significantly reducing the region available for scientific analysis on the data and in turn the number of detected CMEs. For this reason, the UVCS CME catalog recently released stops at the end of year 2005 (see Giordano et al 2013). On the other hand, the STEREO mission was launched in 2006 October, when the UVCS detector already had some problems, thus making very difficult a contemporary observation of the same CME.…”