Evidence of Increasing Acoustic Emissivity at High Frequency with Solar Cycle 23 in Sun-as-a-star Observations

We used long high‐quality unresolved (Sun‐as‐a‐star observations) data collected by GOLF and VIRGO instruments on board the ESA/NASA SOHO satellite to investigate the amplitude variation with solar cycle 23 in the high‐frequency band (5.7<ν<6.3 mHz). We found an enhancement of acoustic emissivity over the ascending phase of about 18±3 in velocity observations and a slight enhancement of 3±2 in intensity. Mode conversion from fast acoustic to fast magneto‐acoustic waves could explain the enhancement in velocity observations. These findings open up the possibility to apply the same technique to stellar intensity data, in order to investigate stellar‐magnetic activity.