Comment on “Detection of Emerging Sunspot Regions in the Solar Interior”

with emerging sunspot regions before their appearance on the solar surface. An independent analysis using helioseismic holography does not confirm these travel-time anomalies for the four regions illustrated by Ilonidis et al. This negative finding is consistent with expectations based on current emerging flux models. Ilonidis et al. (1) claim the detection of acoustictravel-time decreases of 12 to 16 s, between1 and 2 days before the maximum surface flux emergence rate, using a time-distance anal-ysis of acoustic waves penetrating between 42 and 75Mm below the solar surface. This result is contrary to recent numerical simulations of emerg-ingmagnetic flux tubes (2) that predict travel-time shifts due to flows of about 1 s and shifts on the order of 10−1 to 10−2 s due to magnetic field or temperature fluctuations. Ilonidis et al. (1) note this discrepancy and acknowledge that the phys-ical origin of the observed travel-time shifts is un