Dynamic Ly alpha jets

TL;DR

This study investigates whether dynamic Ly alpha jets in the solar atmosphere are similar to H alpha fibrils, finding that many jets exhibit supersonic motion and bifurcating acceleration patterns, indicating a common shock-driven origin.

Contribution

The paper provides the first observational evidence linking dynamic Ly alpha jets to magnetoacoustic shocks, expanding understanding of solar chromospheric dynamics.

Findings

Most Ly alpha jet tops move supersonically.

Jets show bifurcating acceleration and deceleration patterns.

Ly alpha jets are similar to H alpha fibrils in behavior.

Abstract

The solar chromosphere and transition region are highly structured and complex regimes. A recent breakthrough has been the identification of dynamic fibrils observed in H alpha as caused by field-aligned magnetoacoustic shocks. We seek to find whether such dynamic fibrils are also observed in Ly alpha. We used a brief sequence of four high-resolution Ly alpha images of the solar limb taken by the Very high Angular resolution ULtraviolet Telescope (VAULT), which displays many extending and retracting Ly alpha jets. We measured their top trajectories and fitted parabolas to the 30 best-defined ones. Most jet tops move supersonically. Half of them decelerate, sometimes superballistically, the others accelerate. This bifurcation may arise from incomplete sampling of recurrent jets. The similarities between dynamic Ly alpha jets and H alpha fibrils suggest that the magnetoacoustic shocks causing dynamic H alpha fibrils also affect dynamic Ly alpha jets.