Abundance Ratios of Oxygen, Neon, and Magnesium in Solar Active Regions and Flares: The FIP Effect
Abstract
Relative abundances of oxygen, neon, and magnesium have been derived for a sample of nine solar active regions, flares, and an erupting prominance by combining plots of the ion differential emission measures. The observations were photographed in the 300-600 A range by the Naval Research Laboratory (NRL) spectroheliograph on Skylab. Methods for deriving the Mg/Ne abundance ratio-which measures the separation between the low- first ionization potential (FIP) and high-FIP abundnace plateaus-have been described in previous papers. In this paper we describe the spectroscopic methods for deriving the O/Ne abundance ratio, which gives the ratio between two high-FIP elements. The plot of the O/Ne ratio versus the Mg/Ne ratio in the sample of nine Skylab events is shown. The variation in the Mg/Ne ratio by a factor of 6 is associated with a much smaller range in the O/Ne ratio. This is broadly consistent with the presence of the standard FIP pattern of abundances in the outer atmosphere of the Sun. However, a real change in the relative abundances of oxygen and neon by a factor of 1.5 cannot be excluded.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 1995
- DOI:
- 10.1086/175452
- Bibcode:
- 1995ApJ...442..446W
- Keywords:
-
- Abundance;
- Line Spectra;
- Magnesium;
- Neon;
- Oxygen;
- Solar Flares;
- Solar Prominences;
- Ion Emission;
- Ratios;
- Spectrum Analysis;
- Temperature Dependence;
- Solar Physics;
- SUN: ABUNDANCES;
- SUN: ACTIVITY;
- SUN: FLARES;
- SUN: PROMINENCES;
- SUN: UV RADIATION