FS Canis Majoris variable

An FS Canis Majoris variable is a type of eruptive variable star. They are somewhat poorly understood, most likely binary star systems in which mass exchange is ongoing or has recently happened, and most likely consist of at least one B-type main-sequence stars in a dust envelope. They undergo irregular light variations over long periods of time, with magnitude variation of approximately 2 magnitudes. The hydrogen emission lines from these stars are much stronger than in normal Be stars, and certain forbidden lines are present in the spectrum as well.^[1]

References

Variable stars
Pulsating	Cepheids and cepheid-like Classical Type II (BL Herculis, W Virginis) RR Lyrae Delta Scuti Rapidly oscillating Ap SX Phoenicis Blue-white with early spectra Alpha Cygni Beta Cephei Slowly pulsating B PV Telescopii Long-period and semiregular Mira Semiregular Slow irregular Other Gamma Doradus RV Tauri Solar-like oscillations White dwarf
Eruptive	Protostar FU Orionis Herbig Ae/Be Orion Giants and supergiants Luminous blue variable R Coronae Borealis (DY Persei) Yellow hypergiant Eruptive binary Double periodic FS Canis Majoris RS Canum Venaticorum Other Flare Gamma Cassiopeiae Lambda Eridani Wolf–Rayet
Cataclysmic	AM Canum Venaticorum Dwarf nova Nova Supernova Symbiotic Z Andromedae
Rotating	Non-spherical Rotating ellipsoidal Stellar spots BY Draconis FK Comae Berenices Magnetic fields Alpha² Canum Venaticorum Pulsar SX Arietis
Eclipsing	Algol Beta Lyrae Planetary transit W Ursae Majoris
Star portal