Detection of vortex tubes in solar granulation from observations with Sunrise

TL;DR

This study identifies and characterizes vortex tubes in solar granulation using high-resolution observations and simulations, revealing their optical signatures and suggesting they are part of a hierarchy of vortex structures near the solar surface.

Contribution

The paper provides the first observational evidence of vortex tubes in solar granulation and links these features to numerical simulations, enhancing understanding of solar surface convection.

Findings

Granules often contain lanes with bright leading rims and dark trailing edges.

Simulated intensity maps show similar vortex-related structures.

Vortex tubes are likely part of a hierarchy of vortex phenomena near the solar surface.

Abstract

We have investigated a time series of continuum intensity maps and corresponding Dopplergrams of granulation in a very quiet solar region at the disk center, recorded with the Imaging Magnetograph eXperiment (IMaX) on board the balloon-borne solar observatory Sunrise. We find that granules frequently show substructure in the form of lanes composed of a leading bright rim and a trailing dark edge, which move together from the boundary of a granule into the granule itself. We find strikingly similar events in synthesized intensity maps from an ab initio numerical simulation of solar surface convection. From cross sections through the computational domain of the simulation, we conclude that these `granular lanes' are the visible signature of (horizontally oriented) vortex tubes. The characteristic optical appearance of vortex tubes at the solar surface is explained. We propose that the observed vortex tubes may represent only the large-scale end of a hierarchy of vortex tubes existing near the solar surface.