Astronomy and Astrophysics – Astrophysics
Scientific paper
2004-02-20
Astrophys.J. 605 (2004) 854-863
Astronomy and Astrophysics
Astrophysics
18 pages, 5 figures, 2 tables. Accepted by ApJ, April 20 2004
Scientific paper
10.1086/382671
We present optical spectra of the ionized `Outer Ejecta' of Eta Carinae that reveal differences in chemical composition at various positions. In particular, young condensations just outside the dusty Homunculus Nebula show strong nitrogen lines and little or no oxygen -- but farther away, nitrogen lines weaken and oxygen lines become stronger. The observed variations in the apparent N/O ratio may signify either that the various blobs were ejected with different abundances, or more likely, that the more distant condensations are interacting with normal-composition material. The second hypothesis is supported by various other clues involving kinematics and X-ray emission, and would suggest that Eta Car is enveloped in a ``cocoon'' deposited by previous stellar-wind mass loss. In particular, all emission features where we detect strong oxygen lines are coincident with or outside the soft X-ray shell. In either case, the observed abundance variations suggest that Eta Car's ejection of nitrogen-rich material is a recent phenomenon -- taking place in just the last few thousand years. Thus, Eta Carinae may be at a critical stage of evolution when ashes of the CNO cycle have just appeared at its surface. Finally, these spectra reveal some extremely fast nitrogen-rich material, with Doppler velocities up to 3200 km/s, and actual space velocities that may be much higher. This is the fastest material yet seen in Eta Car's nebula, but with unknown projection angles its age is uncertain.
Morse Jon A.
Smith Nathan
No associations
LandOfFree
Nitrogen and Oxygen Abundance Variations in the Outer Ejecta of Eta Carinae: Evidence for Recent Chemical Enrichment does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Nitrogen and Oxygen Abundance Variations in the Outer Ejecta of Eta Carinae: Evidence for Recent Chemical Enrichment, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Nitrogen and Oxygen Abundance Variations in the Outer Ejecta of Eta Carinae: Evidence for Recent Chemical Enrichment will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-709030