Optical and infrared interferometers definitively established that the photometric standard Vega (alpha Lyrae) is a rapidly rotating star viewed nearly pole-on. Recent independent spectroscopic analyses could not reconcile the inferred inclination an
gle with the observed line profiles, preferring a larger inclination. In order to resolve this controversy, we observed Vega using the six-beam Michigan Infrared Combiner on the Center for High Angular Resolution Astronomy Array. With our greater angular resolution and dense (u,v)-coverage, we find Vega is rotating less rapidly and with a smaller gravity darkening coefficient than previous interferometric results. Our models are compatible with low photospheric macroturbulence and also consistent with the possible rotational period of ~0.71 days recently reported based on magnetic field observations. Our updated evolutionary analysis explicitly incorporates rapid rotation, finding Vega to have a mass of 2.15+0.10_-0.15 Msun and an age 700-75+150 Myrs, substantially older than previous estimates with errors dominated by lingering metallicity uncertainties (Z=0.006+0.003-0.002).
The last part of SpS5 dealt with the circumstellar environment. Structures are indeed found around several types of massive stars, such as blue and red supergiants, as well as WRs and LBVs. As shown in the last years, the potential of IR for their st
udy is twofold: first, IR can help discover many previously unknown nebulae, leading to the identification of new massive stars as their progenitors; second, IR can help characterize the nebular features. Current and new IR facilities thus pave the way to a better understanding of the feedback from massive stars.
