Wolf-Rayet Stars

Manuel Wolff ; Johannes Zabl ; Jürgen Leschhorn
Leonard Storz
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Group 142

Exercises

We would propose a three step exercise to amateur astronomers:

1. Watching WR stars just with naked eyes, binoculars or telescope

 If you assume 6m as a limit for naked eye observation, you only find three stars that are within this range. ( Gamma2 Velorum [1,74m]; HD 152408[5,29m]; Theta Mus [5,88m]). The main problem is that all three of them are not observable from our latitude (+48°). The use of binoculars under good conditions opens some objects to our view, but a wider range of objects is only pos s ible with larger telescopes. We tried our luck by observing WR 133 (HD 190918), a 6.7 m WN-5 star with a O9I companion. ( RA : 20:05:57, Dec : + 35° 47‘ 18“). Our group (Johannes, Manuel, Jürgen) during the observation.
2. Taking pictures of the nebulas around WR-Stars

If you have good amateur equipment and good atmospherical
ly conditions you can even photograph the nebulous shells around the WR stars. One good result we found you can see in section examples. The third picture of the " Crescent Nebula " was made by an amateur.

3. Photograph ing their characteristic spectr a

With pictures taken by a good spectrograph you can clearly identify the emission lines.

 Spectra by an amateur WR 136 (WN 6; 7,65 mag) WR 135 (WC 8; 8,36 mag)

For both the last points we didn‘t have the opportunities.

And finally an exercise for bad weather conditions:

 Exercise Question 1: How long does it take for the light to travel this 160 AU? Question 2: What diameter of mirror would be at least necessary to seperate these details, if you had a classical telescope without further instruments? www2.keck.hawaii.edu/news/wr104.html