The molecular environment of the Yellow Hypergiant HD 269953

CIDALE, L. S.; ARIAS, M. L.; KOURNIOTIS, M.; KRAUS, M.; TORRES, A. F.

Córdoba (Virtual)

Congreso; 63ra Reunión Anual de la Asociación Argentina de Astronomía; 2021

Asociación Argentina de Astronomía

Yellow hypergiants (YHGs) are massive (initial masses in the range 20?40 solar masses) stars in their late evolution. Stars in this category are supposed to have undergone heavy mass-loss in the red-most evolutionary state and are now returning to the blue, hot side of the Hertzsprung-Russell diagram. When the star?s surface temperature reaches a value of about 6 000 K, its envelope becomes dynamically unstable and the star start to shed its outer layers in a series of outbursts. The object HD 269953 resides in the Large Magellanic Cloud and is considered a possible YHG candidate. Previous studies revealed emission of CO from that object. We used the IGRINS spectrograph attached to GEMINI-South to obtain high-resolution (R∼45 000) H and K-band spectra of HD 269953 to unveil the dynamics within its molecular environment and to search for further emission features from the close-by environment of that star. The spectra are rich in emission features. In particular, we detect emission from the 12CO and 13CO molecular bands. The latter is strongly enriched, in agreement with an evolvedstate of the star. Moreover, we identified emission of hot water vapor, which is the first detection of water in the close vicinity of an evolved massive star. In addition, we will present first results from our analysis of the kinematics of the molecular gas.