Properties of a Decaying Sunspot

TL;DR

This study investigates the magnetic and flow properties of a decaying sunspot using multi-instrument observations, revealing persistent moat flows, chromospheric downflows, and complex magnetic field height dependence.

Contribution

It provides new insights into the magnetic field structure and flow dynamics of decaying sunspots through multi-height spectropolarimetric analysis.

Findings

Moat flow persists around the decaying sunspot.

Chromospheric downflows exceed 10 km/s near the spot.

Height dependence of magnetic field strength shows reduced discrepancies.

Abstract

A small decaying sunspot was observed with the Vacuum Tower Telescope (VTT) on Tenerife and the Japanese Hinode satellite. We obtained full Stokes scans in several wavelengths covering different heights in the solar atmosphere. Imaging time series from Hinode and the Solar Dynamics Observatory (SDO) complete our data sets. The spot is surrounded by a moat flow, which persists also on that side of the spot where the penumbra already had disappeared. Close to the spot, we find a chromospheric location with downflows of more than 10 km/s without photospheric counterpart. The height dependence of the vertical component of the magnetic field strength is determined in two different ways that yielded different results in previous investigations. Such a difference still exists in our present data, but it is not as pronounced as in the past.