Connection between optical/infrared and sub-millimetre hot regions

Determine whether the optical and infrared surface patches on Betelgeuse trace the same hot regions observed at millimetre and sub-millimetre wavelengths.

Background

The ALMA observations identify persistent north-east and south-west hot regions on Betelgeuse’s sub-millimetre photosphere. Their locations appear broadly similar to hotspots reported in earlier near-infrared, optical, and ultraviolet observations, potentially indicating structures that extend from the optical photosphere into the inner atmosphere. However, the paper notes that conflicting surface-spot distributions and the differing diagnostics prevent an established identification of these features across wavelengths.

References

However, optical spectropolarimetry suggested a different distribution of surface spots, and the link between optical/infrared patches and those seen in the sub-millimetre is not yet proven.

— ALMA high resolution observations of Betelgeuse: Persistent structure spanning the inner atmosphere  (2608.19339 - Dent et al., 19 Aug 2026) in Section 4, subsection “Stellar disk structure” (label sec:cont_discuss)