# Solar Filament Longitudinal Oscillations along a Magnetic Field Tube with Two Dips

## TL;DR

This study investigates how two magnetically connected filament threads influence the longitudinal oscillations in solar filaments, revealing that thread interaction mainly affects damping timescales, which is crucial for filament seismology.

## Contribution

It extends previous models by considering two magnetic dips and their interaction, showing the impact on oscillation damping timescales.

## Key findings

- Oscillation period is weakly affected, changing by at most 20%.
- Thread-thread interaction significantly influences damping timescales.
- Implications for filament seismology when multiple threads are involved.

## Abstract

The large-amplitude longitudinal oscillations of solar filaments have been observed and explored for more than ten years. Previous studies are mainly based on the one-dimensional rigid flux tube model with a single magnetic dip. However, it is noticed that there might be two magnetic dips, and hence two threads, along one magnetic field line. Following the previous work, we intend to investigate the kinematics of the filament longitudinal oscillations when two threads are magnetically connected, which is done by solving one-dimensional radiative hydrodynamic equations with the numerical code MPI-AMRVAC. Two different types of perturbations are considered, and the difference from previous works resulting from the filament thread-thread interaction is investigated. We find that even with the inclusion of the thread-thread interaction, the oscillation period is modified weakly, by at most 20% compared to the traditional pendulum model with one thread. However, the damping timescale is significantly affected by the thread-thread interaction. Hence, we should take it into account when applying the consistent seismology to the filaments where two threads are magnetically connected.