# Signatures of red-shifted footpoints in the quiescent coronal loop system

## TL;DR

This study investigates the footpoint flows of quiescent coronal loops using multi-wavelength solar observations, revealing small or negligible flows in lower atmospheric layers and significant red-shifts in transition region lines, supporting impulsive heating models.

## Contribution

It provides new observational evidence of red-shifted footpoints in quiescent coronal loops, linking spectral Doppler shifts to impulsive heating mechanisms.

## Key findings

- Negligible flows in photospheric and chromospheric lines.
- Significant downflows (1-7 km/s) in transition region Si IV line.
- Red-shifts support impulsive heating in coronal loops.

## Abstract

We observed quiescent coronal loops using multi-wavelength observations from the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) on 2016 April 13. The flows at the footpoints of such loop systems are studied using spectral data from Interface Region Imaging Spectrograph (IRIS). The Doppler velocity distributions at the footpoints lying in the moss region show the negligible or small flows at Ni I, Mg II k3 and C II line corresponding to upper photospheric and chromospheric emissions. Significant red-shifts (downflows) ranging from (1 to 7) km/s are observed at Si IV (1393.78 A; log(T/K) = 4.8) which is found to be consistent with the existing results regarding dynamical loop systems and moss regions. Such downflows agree well with the impulsive heating mechanism reported earlier.