Sunday, 5 February 2012

WR Stars in Eta Carina Nebula

Wolf-Rayet  stars are rare - but we have two quite close to the enigmatic hyper-star Eta Carina. Both belong to the WR subtype WN. WR stars have exhausted their hydrogen fuel, and are, it is said, fusing helium. What causes the nitrogen abundance in WN stars? Is it  the C-N-O cycle? These two stars are fairly faint and no real detail was seen in their spectra in the C8. Perhaps a larger 'scope will show emission bands?

The two WR stars are tagged - the dotted lines and star 'X' aid in locating them in this very starry region. The Fig is a 1990's VR1000 photo with the C8 - a fifty minute hand-guided exposure. It captures the complexity of the huge rich field - and I have tagged some major features. Eta Car is at the top (see spectrum below), with cluster Trumpler 14 rhs - where hyperstar HD93129A lurks. A dark trunk, I dub the "python" (arrowed), enters the field at left and seems to terminate at the famous "keyhole" dark nebula. or does it? An extension, bright in OIII, may continue across the central nebula. (Yes, I know its not a great photo - but it's still useful)

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