More about the MONS Campaign (WR targets)

So you may have read about this double star system, WR140, with a Wolf-Rayet star(WR) and an O Giant orbiting each other.. These guys will stage a spectrographic fireworks display soon, as they zoom past each other near periastron. Stellar winds will collide, and the spectacle is imaginable as the high excentricity of the orbit will make this happen fast and during a short time (a few weeks).
The spectra of this double system a few weeks around the periastron passage will show abundant line-emission from the colliding winds.
However, this campaign will not focus only on WR140. A few other WR stars will be observed. Ones that show a period in rotation.
Normally, determining the period of rotation of the star is rather simple: stars have this atmosphere that absobs certain radiation, so just measuring the width of absorption lines in the spectrum tells about its rate of rotation. The thing is WR stars don't have this atmosphere absorbing radiation visible, due to all the wind and star material that is being thrown out. However, some WR stars show large-scale structures in their winds, and if you can assume that is related to the rotation of the surface of the star, you can determine that period.
This may have implications in what we know about Gamma-Ray Bursts (RGBs), as the models that say they can be created from WR stars also say the core of these stars needs to rotate very fast. The observable structure in winds will not tell us the rotation rate of the star's core, but knowing the surface rotation rate is likely to be the next best thing.

Apart from WR stars, this mission will also be observing other targets, but I will talk about them on later posts ;)