Thermodynamic structure of Betelgeuse’s temperature-minimum region

Constrain the non-unique temperature structure of Betelgeuse’s semi-empirical thermodynamic radio-continuum model near the temperature minimum by obtaining observations in ALMA Bands 9 and 10.

Background

The semi-empirical model combines non-contemporaneous VLA and ALMA data to infer the radial density and temperature structure of Betelgeuse’s extended atmosphere. The temperature minimum is probed by ALMA Bands 6–8, but these data do not bracket the region with higher-frequency observations that would sample deeper layers closer to the optical photosphere. The resulting temperature profile near the minimum is therefore non-unique and requires additional constraints.

References

The temperature of the SEM is not unique, especially near the temperature minimum region (Bands 7 and 8) because they are not bracketed by constraints from ALMA Bands 9 and 10, which have not yet been observed.

— ALMA high resolution observations of Betelgeuse: Persistent structure spanning the inner atmosphere  (2608.19339 - Dent et al., 19 Aug 2026) in Appendix, Section “Semi-empirical thermodynamic radio continuum model” (label sec:appendix_model)