KX Andromedae (often abbreviated to KX And) is a spectroscopic binary star in the constellation Andromeda. Its apparent visual magnitude varies between 6.88 and 7.28. It is at a distance of .
The primary component of the KX Andromedae system is a Be star with a spectral classification B3pe as of 2017, although in historical records it has varied from B1 to B7.
The secondary star is difficult to detect in the spectrum, but has been given a K1III spectral type. It is likely to be an asymptotic giant branch star that fills its Roche lobe, transferring mass to the primary star.
The system is only about 25 million years old. The pair complete a circular orbit every 38.919 days at an inclination of .
KX Andromedae is surrounded by bipolar jets of ejected material, that extend out from it in each direction (angular size ). These faint jets were discovered in hydrogen-alpha emission in 2024 by astronomer Stefan Ziegenbalg. Subsequent studies in other emission lines revealed a more complex structure (see image): the jets were detected only in singly ionized sulfur and hydrogen, while an outer shell is also visible in doubly ionized oxygen. This suggests the presence of different ionization mechanisms. The shell may be visible as a result of shock ionization of the surrounding interstellar medium, whereas the gas within the jets may be ionized by the B3pe component of KX Andromedae, which likely does not emit sufficient energy to doubly ionize oxygen.
References KX And, database entry, Combined General Catalog of Variable Stars (GCVS5.1, 2017 Ed.), N. N. Samus, O. V. Durlevich, et al., CDS ID II/250 Accessed on line 2018-10-17.
Database entry, Catalogue of Stellar Photometry in Johnson's 11-color system (2002 Ed.), J. R. Ducati, CDS ID II/237 Accessed on line 2018-11-10.
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