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Polarimetry of the protoplanetary nebula AFGL 2688 |
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| Authors: | V. G. Klochkova V. E. Panchuk M. V. Yushkin A. S. Miroshnichenko |
| Affiliation: | (1) Special Astrophysical Observatory, Russian Academy of Sciences, Nizhnii Arkhyz, Karachai-Cherkessian Republic, 357147, Russia;(2) Main Astronomical Observatory, Russian Academy of Sciences, Pulkovskoe sh. 65, St. Petersburg, 196140, Russia;(3) Ritter Observatory, University of Toledo, Toledo, OH 43606-3390, USA |
| Abstract: | Our spectroscopic (with resolution R=75 000) and spectropolarimetric (R=15 000) observations with the 6-m telescope of the Special Astrophysical Observatory have enabled us to distinguish photospheric and circumstellar features in the optical spectrum of the bipolar protoplanetary nebula AFGL 2688 for the first time. The linear polarization of the radiation was measured at 5000–6600 Å. The emission in the lines of the sodium doublet and the Swan bands is formed in the envelope, and the mechanism exciting the transitions is resonance fluorescence. We conclude that the circumstellar envelope has a low density. Features of the structure of the nebula are discussed based on published high-angular-resolution photometric and polarimetric (HST NICMOS) data. |
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