Spectroscopic and Spectropolarimetric Observations of V838 Monocerotis

The spectroscopic and spectropolarimetric variability of the peculiar variable V838 Monocerotis during the brighter phases of its multiple outbursts in 2002 is presented. Significant line profile variability of Hα and Si II 6347.10 and 6371.36 Å occurred in spectra obtained between 2002 February 5 and March 14, and a unique secondary absorption component was observed near the end of this time period. Our observations also suggest that multiple shifts in ionization states occurred during the outbursts. Spectropolarimetric observations reveal that V838 Mon exhibited both intrinsic and interstellar polarization components during the initial stages of the second outburst, indicating the presence of an asymmetric geometry; however, the intrinsic component had declined significantly by February 14. We determine the interstellar polarization to be P max = 2.746% ± 0.011%, λ max = 5790 ± 37 Å, and P.A. = 153 43 ± 0 12, and we find the integrated intrinsic V -band polarization on February 5 to be P = 0.983% ± 0.012% at a position angle of 127 0 ± 0 5. The implications of these observations for the nature of V838 Monocerotis, its distance, and its ejecta are discussed.