P61-102: Structure and evolution of the ejecta around evolved massive stars

This is a project to detect large-scale nebulae around massive stars. Massive stars evolve through several short-term transition phases, in which their outer envelopes are ejected via eruptive events of unknown origin. The ejected material accumulates in shells, bipolar lobes, and filaments visible on Halpha and infrared images. To shed light on the nebula formation history, detailed studies of their structure and time evolution are indispensable. We propose to use ALFOSC at the NOT to obtain deep images with the narrow-band Halpha filter to resolve the structure of the large-scale nebulae around 13 northern Galactic evolved massive stars. Of these, eight have reported infrared shells. For those, our images will present the first optical detections. The other five have been previously reported to have extended optical nebulae. Their images will be inspected for previously undetected faint filaments and possible high-velocity jet-like features. Moreover, they will be compared to images taken in 2001 to retrieve the proper motions of the nebulae. This information is crucial to improve our comprehension of the mass-loss behavior of these enigmatic objects, and to unveil the formation history of their nebula

For every target, there is a short exposure followed by multiple longer (300-600s) exposures with small dithers.
One target/Group takes about 37 minutes. If for any reason the OB has to be stopped, the acquired frames are probably still useful.

We have chosen certain dates for our observations but in general, any date during the visibility period in grey/dark time, is suitable.
The 1.3’’ seeing is chosen, but up to 1.5’’ would do as well.

Thank you for your co-operation!

If any questions, do not hesitate to contact me:
tiina@obs.ee
+372 56 913161
Tiina Liimets

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