Derivation of Instrument Requirements for Polarimetry Using Mg, Fe, and Mn Lines between 250 and 290 nm

• Published in: The Astrophysical journal Vol. 952; no. 2; pp. 138 - 146
• Main Authors: de Wijn, A. G., Judge, P. G., Ezzeddine, R., Sainz Dalda, A.
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 01-08-2023; IOP Publishing
• Subjects: Astrophysics; Chromosphere; Iron; Magnesium; Magnetic fields; Magnetism; Manganese; Noise measurement; Polarimeters; Polarimetry; Signal to noise ratio; Solar atmosphere; Solar chromosphere; Solar instruments; Solar spectrum; Spectropolarimetry; Zeeman effect
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ace041

Judge et al. recently argued that a region of the solar spectrum in the near-UV between about 250 and 290 nm is optimal for studying magnetism in the solar chromosphere, due to an abundance of Mg
ii
, Fe
ii
, and Fe
i
lines that sample various heights in the solar atmosphere. In this paper, we derive requirements for spectropolarimetric instruments to observe these lines. We derive a relationship between the desired sensitivity to magnetic field and the signal-to-noise ratio of the measurement from the weak-field approximation of the Zeeman effect. We find that many lines will exhibit observable polarization signals for both longitudinal and transverse magnetic field with reasonable amplitudes.