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Quantifying the Relationship between Moreton-Ramsey Waves and "EIT Waves" Using Observations of Four Homologous Wave Events

Long, DM; Jenkins, J; Valori, G; (2019) Quantifying the Relationship between Moreton-Ramsey Waves and "EIT Waves" Using Observations of Four Homologous Wave Events. Astrophysical Journal , 882 (2) 10.3847/1538-4357/ab338d. Green open access

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Abstract

Freely propagating global waves in the solar atmosphere are commonly observed using extreme ultraviolet passbands (EUV or "EIT waves"), and less regularly in H-alpha (Moreton–Ramsey waves). Despite decades of research, joint observations of EUV and Moreton–Ramsey waves remain rare, complicating efforts to quantify the connection between these phenomena. We present observations of four homologous global waves originating from the same active region between 2014 March 28 and 30 and observed using both EUV and H-alpha data. Each global EUV wave was observed by the Solar Dynamics Observatory, with the associated Moreton–Ramsey waves identified using the Global Oscillations Network Group network. All of the global waves exhibit high initial velocity (e.g., 842–1388 km s−1 in the 193 Å passband) and strong deceleration (e.g., −1437 to −782 m s−2 in the 193 Å passband) in each of the EUV passbands studied, with the EUV wave kinematics exceeding those of the Moreton–Ramsey wave. The density compression ratio of each global wave was estimated using both differential emission measure and intensity variation techniques, with both indicating that the observed waves were weakly shocked with a fast magnetosonic Mach number slightly greater than one. This suggests that, according to current models, the global coronal waves were not strong enough to produce Moreton–Ramsey waves, indicating an alternative explanation for these observations. Instead, we conclude that the evolution of the global waves was restricted by the surrounding coronal magnetic field, in each case producing a downward-angled wavefront propagating toward the north solar pole, which perturbed the chromosphere and was observed as a Moreton–Ramsey wave.

Type: Article
Title: Quantifying the Relationship between Moreton-Ramsey Waves and "EIT Waves" Using Observations of Four Homologous Wave Events
Open access status: An open access version is available from UCL Discovery
DOI: 10.3847/1538-4357/ab338d
Publisher version: https://doi.org/10.3847/1538-4357/ab338d
Language: English
Additional information: This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Sun: activity; Sun: chromosphere; Sun: corona
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics
URI: https://discovery.ucl.ac.uk/id/eprint/10081573
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