The coexistence of spectral features of dust particles and of ionized gas as found in IRAS data
We present some preliminary data obtained by the Low Resolution Spectrometer onboard IRAS, in the wavelength range 8–22.5 um. Spectra of about 900 point sources brighter than 20 Jy at 12 μm and than 100 Jy at 25 um have been examined. Two thirds of the sample could be classified according to the shape of their spectra. Emission lines are seen in the spectra of 118 sources, of which 98 (83%) show the “unidentified” 11.3 um feature, together with the 7.7 um and 8.6 μm, assumed to be due to dust particles. Among these latter sources, 90% also show the [NeII]12.8 um line, and 50% show in addition the [SIII]18.7 um line.
This suggests that the “unidentified dust features” occur frequently in strong compact infrared sources, and mainly in regions where the dust is associated with ionized gas.
KeywordsEmission Feature Planetary Nebula Objective Prism Reflection Nebula IRAS Data
Unable to display preview. Download preview PDF.
- Aitken, D.K., 1981, in Infrared Astronomy, IAU Symposium No. 96, eds. C.G. WynnWilliams and D.P. Cruikshank, Reidel, Holland, p.207.Google Scholar
- Allamandola, L.J., 1984, in Galactic and Extragalactic Infrared Spectroscopy, XVIth ESLAB Symposium, eds. M.F. Kessler and J.P. Phillips, D. Reidel, ASSL Vol. 108, p.5.Google Scholar
- Allamandola, L.J., Greenberg, J.M., and Norman, C.A., 1979, Astron. Astrophys. 77, 66.Google Scholar
- Bregman, J.D., 1977, P.A.S.P. 89, 335.Google Scholar
- Duley, W.W. and Williams, D.A., 1981, M.N.R.A.S. 196, 269.Google Scholar
- Dwek, E., Sellgren, K., Soifer, B.T., and Werner, M.W., 1980, Astrophys. J. 238, 140.Google Scholar
- Gillett, F.C., Forrest, W.J., and Merrill, K.M., 1973, Astrophys. J. 183, 8.Google Scholar
- Herter, T., Helfer, H.L., Pipher, J.L., Briotta, D.A., Forrest, W.J., Houck, J.R., Rudy, R.J., and Willner, S.P., 1982, Astrophys. J. 262, 153.Google Scholar
- Herter, T., Helfer, H.L., Pipher, J.L., Forrest, W.J., McCarthy, J., Houck, J.R., Willner, S.P., Puetter, R.C., Rudy, R.J., and Soifer, B.T., 1981, Astrophys. J. 250, 186.Google Scholar
- Léger, A., and Puget, J.L., 1984, Astron. Astrophys. 137, L5.Google Scholar
- Russell, R.W., Soifer, B.T., and Willner, S.P., 1977, Astrophys. J. 217, L149.Google Scholar
- Russell, R.W., Soifer, B.T., and Willner, S.P., 1978, Astrophys. J. 220, 568.Google Scholar
- Sellgren, K., 1984, Astrophys. J. 277, 623.Google Scholar
- Tokunaga, A.T., and Young, E.T., 1980, Astrophys. J. 237, L93.Google Scholar
- Wildeman, K.J., Beintema, D.A., and Wesselius, P.R., 1983, J. British. Interplanet. Soc., 36, 21.Google Scholar
- Willner, S.P., 1984, in Galactic and Extragalactic Infrared Spectroscopy, XVIth ESLAB Symposium, eds. M.F. Kessler and J.P. Phillips, D. Reidel, ASSL Vol. 108, p. 37.Google Scholar