[en] stars: massive ; stars: fundamental parameters ; stars: emission-line ; stars: winds ; outflows ; stars: binaries: general
[en] Stars of spectral type O play a key role in many processes in our Galaxy and beyond. However, there are still a number of open issues about these massive and luminous objects that need to be ad-dressed. Several of these questions require (long-term) spectroscopic monitoring that is difficult to achieve with the highly-demanded equipment on most modern professional instruments. However, these kinds of studies offer an opportunity for collaborations between amateur spectroscopists and professional astrophysicists.