Z CMa NW emission lines

We derive an accretion rate of 10^-4^M_{sun}_/yr in outburst. The FeI and weak FeII lines arise from an irradiated, flared disk at ~0.5-3(M*/16M_{sun}_) au with asymmetric upper layers, revealing that the energy from the accretion burst is deposited at scales below 0.5au. Some line profiles have redshifted asymmetries, but the system is unlikely sustained by magnetospheric accretion, especially in outburst.

The accretion-related structures extend over several stellar radii and, like the wind, are likely non-axisymmetric. The stellar mass may be ~6-8M_{sun}_, lower than previously thought (~16M_{sun}_). Emission line analysis is found to be a powerful tool to study the innermost regions and accretion in stars within a very large range of effective temperatures.

The density ranges in the disk and accretion structures are higher than in late-type stars, but the overall behavior, including the innermost disk emission and variable wind, is very similar independently of the spectral type. Our work suggests a common outburst behavior for stars with spectral types ranging from M-type to intermediate-mass stars.