MWC 560 : jets or optically thick expanding envelope ?

Variations in star brightness in the object MWC 560 are discussed based on results of UBV photometric observations and high- and low-resolution spectral data. Specific attention is given to the pronounced violet-shifted Balmer absorption component which contrasts the weak Balmer emission lines. Significant changes are noted in the U-B color, and P Cygni profiles are noted in Fe II, Ti II, and the first members of the Balmer series with violet shifts in the absorption component. The results are used to calculate a distance of about 1 kpc to the object, and two types of jet ejections are assumed to emanate from the source. MWC 560 is theorized to be a M4.5 giant/white dwarf binary with high-velocity discrete jet ejections and low-velocity quasi-stationary jet ejections. The two types of jet ejections are shown to explain the dramatic change in reddening and the P Cygni profiles in the later observations.