Roberta M. Humphreys

Variable C – “a typical” LBV in M 33?

One of the original Hubble-Sandage variables, Variable C in M33 is thought to be a very typical Luminous Blue Variable (LBV). An observational signature of LBVs is a variable brightness which is coupled to a change in spectral type. We compiled a 110 year long light curve of Var C and a set of spectra covering several decades. Analyzing both data sets, various astonishing changes of Var C, some very recent, emerged. Is Var C a typical or an atypical LBV?

Variability in η Car’s circumstellar nebula

We discuss recent HST imaging of η Carinae obtained in near-UV and optical light with WFPC2 and in the near-infrared with NICMOS. Comparison with images obtained at earlier epochs reveals non-uniform photometric variations in the light from the many gas and dust condensations, as well as morphological changes in the inner regions of the nebula. During this same time period, the central object has brightened considerably at all wavelengths, and we discuss the relationship between the brightening of the central star and the variations in the surrounding nebula.