Hostname: page-component-586b7cd67f-r5fsc Total loading time: 0 Render date: 2024-11-27T14:51:37.101Z Has data issue: false hasContentIssue false
  • English
  • Français

The Internal Extinction Curve of NGC 6302 and its Extraordinary Spectrum

Published online by Cambridge University Press:  05 March 2013

Brent Groves ,
Michael A. Dopita ,
Robert E. Williams  and
Chon-Trung Hua
Brent Groves
Affiliation:
Research School of Astronomy and Astrophysics, Australian National University, Cotter Rd, Weston, ACT 2611, Australia; [email protected]
Michael A. Dopita
Affiliation:
Research School of Astronomy and Astrophysics, Australian National University, Cotter Rd, Weston, ACT 2611, Australia; [email protected]
Robert E. Williams
Affiliation:
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD, 21218, USA; [email protected]
Chon-Trung Hua
Affiliation:
Laboratorie d'Astronomie Spatiale, Marseille, France; [email protected]
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

In this paper we present a new method for obtaining the optical wavelength-dependent reddening function of planetary nebulae (PN), using the nebular and stellar continuum. The data used was a spectrum of NGC 6302 obtained using the Double Beam Spectrograph on the 2.3 m telescope at Siding Springs Observatory over three nights. This resulted in a spectrum covering a wavelength range 3300–8600 Å with a large dynamical range and a mean signal to noise of >102 Å−1 in the nebular continuum. With such a high S/N the continuum can be accurately compared with a theoretical model of nebular plus stellar continuum. The nebular electron temperature and density used in the model are determined using ratios of prominent emission lines. The reddening function can then be obtained from the ratio of the theoretical and the observed continuum. In the case of NGC 6302, it is known that much of the reddening arises from dust within or around the nebula, so that any differences between the measured reddening law and the 'standard' interstellar reddening law will reflect differences in the nebular grain size distribution or composition. We find that for NGC 6302, the visible to IR extinction law is indistinguishable from 'standard' interstellar reddening, but that the UV extinction curve is much steeper than normal, suggesting that more small dust grains had been ejected into the nebula by the PN central star. We have detected the continuum from the central star and determined its Zanstra temperature to be of order 150,000 K. Finally, using the extinction law that we have determined, we present a complete dereddened line list of nearly 600 emission lines, and report on the detection of the He(2–10) and He(2–8) Raman features at λ4331 Å and λ4852 Å, and the detection of Raman scattered O VI features at λ6830 Å and λ7087 Å. We believe this to be the first detection of this process in a PN.

Keywords

planetary nebulae: individual (NGC 6302)dust, extinction
Type
Research Article
Information
Publications of the Astronomical Society of Australia , Volume 19 , Issue 4 , 2002 , pp. 425 - 442
Copyright
Copyright © Astronomical Society of Australia 2002

References

Aller, L. H., Ross, J. E., O'Mara, B. J., & Keyes, C. D. 1981, MNRAS, 197, 95 Google Scholar
Ashley, M. C. B. 1988, PhD Thesis, The Australian National University Google Scholar
Ashley, M. C. B. 1990, PASA, 8, 360 Google Scholar
Ashley, M. C. B., & Hyland, A.R. 1988, ApJ, 331, 532 CrossRefGoogle Scholar
Bessell, M. S. 1999, PASP, 111, 1426 Google Scholar
Brown, R. L., & Mathews, W. G. 1970, ApJ, 160, 939 Google Scholar
Dopita, M. A., & Hua, C. T. 1997, ApJS, 108, 515 Google Scholar
Dopita, M. A., & Sutherland, R. S. 2002, Astrophysics of the Diffuse Universe (Berlin: Springer-Verlag), in pressGoogle Scholar
Habing, H. J., Tignon, J., & Tielens, A. G. G. M. 1994, A&A, 286, 523 Google Scholar
Hua, C. T., Dopita, M. A., & Martinis, J. 1997, A&AS, 133, 361 Google Scholar
Kaler, J. B. 1976, ApJS, 31, 517 Google Scholar
Kemper, F., Jäger, C., Waters, L. B. F. M, Henning, Th., Molster, F. J., Barlow, M. J., Lim, T., & de Koter, A. 2002, Nature, 415, 295 CrossRefGoogle Scholar
Kozasa, T., & Sogawa, H. 1997, Ap&SS, 251, 165 Google Scholar
Lester, D. F., & Dinerstein, H. L. 1984, ApJ, 281, L67 CrossRefGoogle Scholar
Liu, X., & Danziger, J. 1993, MNRAS, 263, 256 CrossRefGoogle Scholar
Liu, X.-W., Luo, S. G., Barlow, M. J., Danziger, I. J., & Storey, P. J. 2001, MNRAS, 327, 141 Google Scholar
Liu, X.-W., Storey, P. J., Barlow, M. J., Danziger, I. J., Cohen, M., & Bryce, M. 2000, MNRAS, 312, 583 Google Scholar
Loup, C., Foreville, T., Omont, A., & Paul, J. F. 1993, A&AS, 99, 291 Google Scholar
Milne, D. K., & Aller, L. H. 1975, A&A, 38, 183 Google Scholar
Osterbrock, D. E. 1989, Astrophysics of Gaseous Nebulae and Active Galactic Nuclei (Mill Valley, CA: University Science Books)CrossRefGoogle Scholar
Péquignot, D., Baluteau, J.-P., Morisset, C., & Boisson, C. 1997, A&A, 323, 217 Google Scholar
Perek, L. 1971, BAICz, 22, 103 Google Scholar
Pottasch, S. R. 1984, Planetary Nebulae – A Study of Late Stages of Stellar Evolution (Dordecht: Reidel)Google Scholar
Rodgers, A., Conroy, P., & Bloxham, G. 1988, PASP, 100, 626 CrossRefGoogle Scholar
Rodriguez, L. F., et al. 1985, MNRAS, 215, 353 Google Scholar
Schmid, H. M. 1989, A&A, 211, 31 Google Scholar
Sutherland, R. S., & Dopita, M. A. 1993, ApJS, 88, 253 Google Scholar
Waters, L. B. F. M., et al. 1996, ApJ, 315, L361 Google Scholar
Whitford, A. E. 1958, AJ, 63, 201 Google Scholar