Optimal Masks for Low-Degree Solar Acoustic Modes

Area of Science:

• Solar physics
• Helioseismology
• Astronomy

Background:

• Accurate measurements of solar acoustic (p) mode oscillation frequencies are crucial for understanding the Sun's internal structure and rotation.
• Mode leakage in observational helioseismology, caused by projecting Doppler images onto spherical harmonic masks, contaminates power spectra and hinders precise frequency determination.

Purpose of the Study:

• To develop and present a novel method for constructing optimal masks to minimize mode leakage in solar acoustic oscillation power spectra.
• To improve the accuracy of helioseismology measurements, particularly for low-degree solar acoustic modes.

Main Methods:

• The study proposes a method to calculate optimal masks tailored for specific target modes.
• This involves minimizing the signal contribution from other solar acoustic modes in the vicinity of the target mode.
• The method was applied to 2-year time series data from the Michelson Doppler Imager on the Solar and Heliospheric Observatory.

Main Results:

• The developed optimal mask construction method effectively reduces the leakage of unwanted solar acoustic p-modes.
• Demonstrated significant reduction in mode leakage, leading to cleaner oscillation power spectra.
• The application to real observational data confirmed the efficiency of the proposed technique.

Conclusions:

• The optimal mask method provides a significant advancement in observational helioseismology.
• This technique enhances the reliability of solar core structure and rotation studies by improving the accuracy of low-degree mode frequency measurements.
• The findings contribute to a more precise understanding of solar dynamics.