Abstract
The rapid damping of slow magnetoacoustic waves in the solar corona has been extensively studied in previous years. Most studies suggest that thermal conduction is a dominant contributor to this damping, albeit with a few exceptions. Employing extreme-ultraviolet (EUV) imaging data from SDO/AIA, we measure the damping lengths of propagating slow magnetoacoustic waves observed in several fan-like loop structures using two independent methods. \textbf{The dependence of the damping length on temperature has been studied for the first time. The results do not indicate any apparent decrease} in damping length with temperature, which is in contrast to the existing viewpoint. Comparing with the corresponding theoretical values calculated from damping due to thermal conduction, it is inferred that thermal conduction is suppressed in hotter loops. An alternative interpretation that suggests thermal conduction is not the dominant damping mechanism, even for short period waves in warm active region loops, is also presented.
Highlights
Propagating waves along fan-like active region loops have been a common observational feature since their initial discovery in the solar corona (Ofman et al, 1997; Deforest and Gurman, 1998; Berghmans and Clette, 1999; De Moortel et al, 2000)
Slanted ridges of alternating brightness, visible in this map, reveal the propagating waves along the selected loop. Previous studies of such oscillations, especially those propagating along similar fanlike loop structures that are usually rooted in sunspots, confirm their nature as propagating slow magnetoacoustic waves (e.g., Kiddie et al, 2012; Krishna Prasad et al, 2012b)
The spatial damping characteristics of propagating slow magnetoacoustic waves, observed in 35 fan-like loop structures selected from 30 different active regions, have been studied
Summary
Propagating waves along fan-like active region loops have been a common observational feature since their initial discovery in the solar corona (Ofman et al, 1997; Deforest and Gurman, 1998; Berghmans and Clette, 1999; De Moortel et al, 2000). It is believed that these waves are a manifestation of propagating slow magnetoacoustic oscillations that are generated via mode conversion (Spruit, 1991; Cally et al, 1994) in the lower atmospheric layers Their physical properties found in a variety of coronal structures have been extensively studied both from theoretical and observational vantage points (De Moortel, 2009; Wang, 2011; Krishna Prasad et al, 2012b; Banerjee and Krishna Prasad, 2016). Krishna Prasad et al (2018) investigated propagating slow magnetoacoustic waves in a number of active region fan-like loops and found a temperature dependency of the polytropic indices, whereby hotter loops corresponded to larger polytropic index values. Details on the observational data used, the analysis methods employed, and the results obtained are presented in the subsequent sections, followed by a discussion of the obtained results and their implications for future studies of the solar corona
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
