Physics of Thermal Gaseous Nebulae pp 18-38 | Cite as

# Spectra of Gaseous Nebulae

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## Abstract

In the 19th Century there raged an argument as to whether fuzzy telescopic objects loosely called nebulae were really stellar aggregates or a gas. Although he had resolved some diffuse objects as star clusters, Herschel, who was an astute observer, commented that the light of others appear so “soft” that it might arise from “a luminous fluid.”

## Keywords

Central Star Planetary Nebula Optical Region Magnetic Dipole Transition Balmer Line
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## Some Suggested References

- The primary mechanisms for the excitation of hydrogen and helium lines by photoionization followed by recombination have been discussed by: Zanstra, H. 1927, Ap. J., 65, 50.ADSGoogle Scholar
- The primary mechanisms for the excitation of hydrogen and helium lines by photoionization followed by recombination have been discussed by: Zanstra, H. 1931, Dom. Astrophys. Obs. Publ., 4, 209.ADSGoogle Scholar
- The primary mechanisms for the excitation of hydrogen and helium lines by photoionization followed by recombination have been discussed by: Zanstra, H. 1931, Zeits. f. Astrofis., 2, 1.ADSzbMATHGoogle Scholar
- A discussion of the helium problem with suitable bibliographical references may be found in: Osterbrock, D.E. “Astrophysics of Gaseous Nebulae,” 1974, San Francisco: W.H. Freeman Co., p. 25 (hereafter referred to as A.G.N.).Google Scholar
- A classical early reference to forbidden lines is: Bowen, I.S. 1936, Rev. Mod. Phys., 8, 55.ADSGoogle Scholar
- The basic theory is reviewed in: Condon, E.H., and Shortley, G.H. “Theory of Atomic Spectra,” 1935, Cambridge University Press.Google Scholar
- The importance of permitted lines of ions of elements heavier than H and He was first pointed out by A.B. Wyse, 1942, Ap. J., 95, 356.ADSGoogle Scholar
- A comprehensive discussion of excitation of permitted lines in gaseous nebulae and quasars is given by: Grandi, S.A. 1975, Ap. J., 196, 465.ADSGoogle Scholar
- A comprehensive discussion of excitation of permitted lines in gaseous nebulae and quasars is given by: Grandi, S.A. 1976, Ap. J., 206, 658.ADSGoogle Scholar
- A comprehensive discussion of excitation of permitted lines in gaseous nebulae and quasars is given by: Grandi, S.A. 1980, Ap. J., 238, 10.ADSGoogle Scholar
- Our discussion of absorption and emission processes involving H is taken from D.H. Menzel, 1937, Ap. J., 85, 330. This and other papers of the Harvard series on physical processes in gaseous nebulae are reprinted in: Physical Processes in Ionized Plasmas, ed. D.H. Menzel (New York: Dover Publications, 1962, hereafter referred to as PPIP).ADSzbMATHGoogle Scholar
- Hydrogenic line and continuous absorption coefficients have been discussed by: Menzel, D.H., and Pekeris, C.L. 1935, M.N.R.A.S., 96, 77.ADSzbMATHGoogle Scholar
- Hydrogenic line and continuous absorption coefficients have been discussed by: Karzas, W.V., and Latter, R. 1961, Ap. J. Suppl., 6, 167.ADSGoogle Scholar
- Hydrogenic line and continuous absorption coefficients have been discussed by: Burgess, A. 1964, M.N.R.A.S., 69, 1.Google Scholar
- The basic theoretical references to the ionization of hydrogen and the formation of H II regions with sharp boundaries are: Stromgren, B. 1939, Ap. J., 89, 526ADSGoogle Scholar
- The basic theoretical references to the ionization of hydrogen and the formation of H II regions with sharp boundaries are: Stromgren, B. 1948, Ap. J., 108, 242.ADSGoogle Scholar
- For a discussion of continuous absorption coefficients for complex atoms see: Burke, P.G. Atomic Processes and Applications, ed. P.G. Burke and B.L. Moiseiwitsch (Amsterdam: North-Holland Publications, 1976).Google Scholar
- Calculations for individual cross sections have been given by many workers. A few examples of this work are: Hidalgo, M.B. 1968, Ap. J., 153, 981. (C, N, O, Ne).ADSGoogle Scholar
- Calculations for individual cross sections have been given by many workers. A few examples of this work are: Henry, R.J.W. 1970, Ap. J., 161, 1153. (G, N, O, Ne).ADSGoogle Scholar
- Calculations for individual cross sections have been given by many workers. A few examples of this work are: Chapman, R.D., and Henry, R.J.W. 1971, Ap. J., 168, 169. (S)ADSGoogle Scholar
- Calculations for individual cross sections have been given by many workers. A few examples of this work are: Chapman, R.D., and Henry, R.J.W. 1972, Ap. J., 173, 243. (Al, Si, Ar)ADSGoogle Scholar
- Calculations for individual cross sections have been given by many workers. A few examples of this work are: Reilman, R.F., and Manson, S.T. 1979, Ap, J. Suppl., 40, 815ADSGoogle Scholar
- Calculations for individual cross sections have been given by many workers. A few examples of this work are: Reilman, R.F., and Manson, S.T. 1981, Ap, J. Suppl., 46, 115.ADSGoogle Scholar
- Calculations for individual cross sections have been given by many workers. A few examples of this work are: Sakhibullih, N., and Willis, A.J. 1976, Astron. Astrophys. Suppl., 31, 11. (C IV)ADSGoogle Scholar
- Calculations for individual cross sections have been given by many workers. A few examples of this work are: Pradhan, A.K. 1980, M.N.R.A.S., 190, 5P. (Ne II, Ne III, Ne IV)ADSGoogle Scholar
- Radiative recombination of complex atoms has been discussed by: Gould, R.J. 1978, Ap. J., 219, 250.ADSGoogle Scholar
- Approximate formulae and coefficients have been given by: Tarter, C.B. 1971, Ap. J., 168, 313ADSGoogle Scholar
- Approximate formulae and coefficients have been given by: Tarter, C.B. 1972, Ap. J., 172, 251.ADSGoogle Scholar
- Approximate formulae and coefficients have been given by: Aldrovandi, S.M.V., and Pequignot, D. 1973, Astron. Astrophys., 25, 137.ADSGoogle Scholar
- The cross sections given by these authors for dielectronic recombination appear to be systematically too small. Dielectronic Recombination. A general review with references to previous work is given by: Seaton, M.J., and Storey, P.G. Atomic Processes and Applications, ed. P.G. Burke and B.L. Moiseiwitsch (Amsterdam: North-Holland Publications, 1976, p. 134).Google Scholar
- Most of the discussions have pertained to high temperatures as in the solar corona and high densities as in quasars where the effects become more complex. See, e.g.: Burgess, A. 1964, Ap. J., 139, 776. (Corona)ADSGoogle Scholar
- Most of the discussions have pertained to high temperatures as in the solar corona and high densities as in quasars where the effects become more complex. See, e.g.: Burgess, A., and Summers, H.P. 1969, Ap. J., 157, 1008.ADSGoogle Scholar
- Most of the discussions have pertained to high temperatures as in the solar corona and high densities as in quasars where the effects become more complex. See, e.g.: Davidson, K. 1975, Ap. J., 195, 285. (Quasars)ADSGoogle Scholar
- Dielectronic recombination rates appropriate to nebular temperatures and densities are discussed, for example, by: Jacobs, V.L., Davis, J., Rogerson, J.E., and Blaha, M. 1979, Ap. J., 230, 627.ADSGoogle Scholar
- Dielectronic recombination rates appropriate to nebular temperatures and densities are discussed, for example, by: Storey, P.J. 1981, M.N.R.A.S., 195, 27P. See also I.A.TJ. Symposium No. 103.ADSGoogle Scholar
- Dielectronic recombination rates appropriate to nebular temperatures and densities are discussed, for example, by: Nussbaumer, H., and Storey, P.J. 1983, Astron. Astrophys.Google Scholar
- Charge Exchange. A brief summarizing account of the problems of charge exchange, with references to earlier work and timely warnings pertaining to inherent uncertainties in theoretical calculations, is given by: Dalgamo, A. Planetary Nebulae (ed. Y. Terzian, International Astronomical Union Symposium No. 76, Dordrecht, Reidel, 1978, p. 139).Google Scholar
- The astrophysical importance of oxygen-hydrogen charge exchange reactions was noticed by: Chamberlain, J.W. 1956, Ap. J., 124. 390.ADSGoogle Scholar
- Its effect on nebular ionization structure was examined by: Williams, R.E. 1973, M.N.R.A.S., 164, 111.ADSGoogle Scholar
- Some representative calculations of charge exchange coefficients are: Dalgamo, A., Butler, S.E., and Heil, T.G. 1980, Ap. J., 241. 442.ADSGoogle Scholar
- Some representative calculations of charge exchange coefficients are: Dalgamo, A., and Butler, S.E. 1980, Ap. J., 241, 838.ADSGoogle Scholar
- The Zanstra method has been applied to planetary nebulae symbiotic stars, Be stars, and diffuse galactic nebulae. See: Zanstra, H. 1931, Zeits. f. Astrofis., 2, 1, 329, 1239.ADSzbMATHGoogle Scholar
- The Zanstra method has been applied to planetary nebulae symbiotic stars, Be stars, and diffuse galactic nebulae. See: Zanstra, H. 1930, Publ. Dom. Ap. Obs. vTctoria, 4, 209.ADSGoogle Scholar
- A systematic formulation is given by: Harman, R.J., and Seaton, M.J. 1966, M.N.R.A.S., 132. 15.ADSGoogle Scholar
- A summary of the earlier work with descriptions of investigations by: Ambarzumian (1932), Stoy (1933), Wurm (1951), and others are given by: Aller, L.H., and Liller, W. 1968, Stars and Stellar Systems, 7, 546Google Scholar
- A summary of the earlier work with descriptions of investigations by: Ambarzumian (1932), Stoy (1933), Wurm (1951), and others are given by: Aller, L.H., and Liller, W. 1968, Nebulae and Interstellar Matter, ed. by Barbara Middlehurst and L.H. Aller, Chicago, Univ. Chicago Press.Google Scholar
- Modernized versions of the Stoy method are given by: Kaler, J.B. 1976, Ap. J., 210, 843.ADSGoogle Scholar
- Modernized versions of the Stoy method are given by: Preite-Martinez, A., and Pottasch, A.S. 1983, Astron. Astrophys., 126, 31.ADSzbMATHGoogle Scholar
- The pioneering ultraviolet study (with the ANS satellite is): Pottasch, R., Wesselius, P.R., Wu, C.C., Fieten, H., and van Duinen, R.J. 1979, Astron. Astrophys., 62, 95,ADSGoogle Scholar
- see also: Pottasch, R. 1983, Planetary Nebulae, Dordrecht, Reidel Publ. Co.Google Scholar
- Bowen proposed his fluorescent mechanism in: 1935, Ap. J., 81, 1. The earliest theoretical treatments by D.H. Menzel and L.H. Aller, 1941, Ap. J., 94, 436Google Scholar
- W. Unno, 1955, Publ. Astr. Soc. Japan, 7, 81, were hampered by poor atomic and observational data.ADSGoogle Scholar
- The first accurate models were given by R.J. Weymann and R.E. Williams, 1969, Ap. J., 157, 1201ADSGoogle Scholar
- Replace earlier calculations by H. Nussbaumer, 1969, Astrophys. Lett., 4, 183. A. Dalgarno and A. Sternberg, 1982, Ap. J., discuss the role of charge exchange. The BFM may play a role in many astrophysical sources.ADSGoogle Scholar
- T. Kallman and R. McCray, 1980, Ap. J., 242, 615, discuss its possible importance in X-ray sources where much of the soft X-ray luminosity absorbed by the nebula appears as Lya (He II) which controls the ionization and temperature structure of the plasma until degraded. The BFM is expected to have a major effect on the fate of these He II photons.ADSGoogle Scholar
- Early investigations of the Balmer decrement by Plaskett (1928), Carroll (1930), and Cillie (1932) culminated in the studies by: Menzel, D.H., and Baker, J.B. 1937, Ap. J., 86, 70ADSzbMATHGoogle Scholar
- Early investigations of the Balmer decrement by Plaskett (1928), Carroll (1930), and Cillie (1932) culminated in the studies by: Menzel, D.H., and Baker, J.B. 1938, Ap. J., 88, 52.ADSzbMATHGoogle Scholar
- Further contributions were made by: Seaton, M.J. 1959, M.N.R.A.S., 119, 90MathSciNetADSGoogle Scholar
- Further contributions were made by: Pengelly, R.M., and Seaton, M.J. 1964, M.N.R.A.S., 127, 145.ADSGoogle Scholar
- The standard theory of Balmer decrement for H and He II is that by: Brocklehurst, M. 1971, M.N.R.A.S., 153, 471.ADSGoogle Scholar
- Whose results are very similar to those derived by W. Clarke (1965), which are described in Stars and Stellar Systems, 7, Nebulae and Interstellar Matter, 504, ed. B. Middlehurst and lT Aller, Chicago, Univ. of Chicago Press. See also: Brocklehurst, M., and Seaton, M.J. 1972, M.N.R.A.S., 157, 179.ADSGoogle Scholar
- Whose results are very similar to those derived by W. Clarke (1965), which are described in Stars and Stellar Systems, 7, Nebulae and Interstellar Matter, 504, ed. B. Middlehurst and lT Aller, Chicago, Univ. of Chicago Press. See also: Gerola, H., and Panagia, N. 1968, Astrophys. Space Sci., 2, 285ADSGoogle Scholar
- Whose results are very similar to those derived by W. Clarke (1965), which are described in Stars and Stellar Systems, 7, Nebulae and Interstellar Matter, 504, ed. B. Middlehurst and lT Aller, Chicago, Univ. of Chicago Press. See also: Gerola, H., and Panagia, N. 1970, Astrophys. Space Sci., 8, 120.ADSGoogle Scholar
- Theoretical calculations for helium are given by: Brocklehurst, M. 1970, M.N.R.A.S., 157, 211.ADSGoogle Scholar
- Theoretical calculations for helium are given by: Robbins, R.R. 1968, Ap. J., 151, 497, 511ADSGoogle Scholar
- Theoretical calculations for helium are given by: Robbins, R.R. 1970, Ap. J., 160, 519.ADSGoogle Scholar
- Theoretical calculations for helium are given by: Robbins, R.R., and Bernat, A.P. 1974, Ap. J., 188, 309.ADSGoogle Scholar
- Balmer decrement measurements have been made by many observers. See, e.g.: Miller, J.S. 1971, Ap. J. Lett., 165. L101.ADSGoogle Scholar
- Balmer decrement measurements have been made by many observers. See, e.g.: Lee, P., et al. 1969, Ap. J., 155, 853.ADSGoogle Scholar
- The theory of continuous thermal radio-frequency radiation from H II regions and gaseous nebulae is given by many workers. Some representative papers are: Terzian, Y. 1974, Vistas in Astronomy, 16, 279.ADSGoogle Scholar
- The theory of continuous thermal radio-frequency radiation from H II regions and gaseous nebulae is given by many workers. Some representative papers are: Mezger, P., and Henderson, A.O. 1967, Ap. J., 147, 471.ADSGoogle Scholar
- The theory of continuous thermal radio-frequency radiation from H II regions and gaseous nebulae is given by many workers. Some representative papers are: Schraml, J., and Mezger, P.G. 1969, Ap. J., 156, 269.ADSGoogle Scholar
- The fundamental theory for formation of radio-frequency lines taking non-LTE effects into account was due to: Goldberg, L. 1966, Ap. J., 144, 1225ADSGoogle Scholar
- See also general review by: Brown, R.L., Lockman, F.J., and Knapp, G.R. 1978, Ann. Rev. Astron. Astrophys., 16, 445.ADSGoogle Scholar
- Atomic physics processes relavant to the radio frequency region: Oster, L.F. 1961, Rev. Mod. Phys., 33, 525 (free-free processes).MathSciNetADSzbMATHGoogle Scholar
- Atomic physics processes relavant to the radio frequency region: Menzel, D.H. 1969, Ap. J. Suppl., 18, 221 (f-values for H).ADSGoogle Scholar
- Atomic physics processes relavant to the radio frequency region: Seaton, M.J. 1972, Comments on Atomic and Molecular Physics, 3, 107 (density broadening of r.f. lines).ADSGoogle Scholar
- Atomic physics processes relavant to the radio frequency region: Brocklehurst, M., and Leeman, S. 1971, Astrophys. Lett., 9, 35.ADSGoogle Scholar
- Some illustrative applications to determinations of T
_{e}in Orion are given by: Mills, B.Y., and Shaver, P. 1967, Australian Jl. Phys., 21, 95.ADSGoogle Scholar - Some illustrative applications to determinations of T
_{e}in Orion are given by: Chaisson, E.J., and Dopita, M.A. 1977, Astron. Astrophys., 56, 385.ADSGoogle Scholar - Some illustrative applications to determinations of T
_{e}in Orion are given by: Pauls, T., and Wilson, T.L. 1977, Astron. Astrophys., 60, L31.ADSGoogle Scholar - Some illustrative applications to determinations of T
_{e}in Orion are given by: Lockman, F.J., and Brown, R.L. 1976, Ap. J., 207, 336ADSGoogle Scholar - Some illustrative applications to determinations of T
_{e}in Orion are given by: Lockman, F.J., and Brown, R.L. 1975, Ap. J., 201, 134.ADSGoogle Scholar - The optical continuum of gaseous nebulae was investigated by a number of workers; the importance of the two-photon emission was first pointed out by: Spitzer, L., and Greenstein, J.L. 1951, Ap. J., 114, 407.ADSGoogle Scholar
- The basic reference on nebular optical continua is: Brown, R.L., and Mathews, W.G. 1970, Ap. J., 160, 939.ADSGoogle Scholar
- An observational check on lines and continuum in NGC 7027 is given by: Miller, J.S., and Mathews, W.G. 1972, Ap. J., 172, 593.ADSGoogle Scholar
- The theory of the emission line spectrum of an optically thick nebula at moderate-to-high densities is discussed, e.g., by: Capriotti, E.R. 1965, Ap. J., 142, 1101.MathSciNetADSGoogle Scholar
- The theory of the emission line spectrum of an optically thick nebula at moderate-to-high densities is discussed, e.g., by: Panagia, N., and Ranieri, M. 1973, Astron. Astrophys., 24, 219.ADSGoogle Scholar
- The theory of the emission line spectrum of an optically thick nebula at moderate-to-high densities is discussed, e.g., by: Ferland, G., and Netzer, H. 1979, Ap. J., 229, 274.ADSGoogle Scholar
- The theory of the emission line spectrum of an optically thick nebula at moderate-to-high densities is discussed, e.g., by: Mathews, W.G., Blumenthal, G.R., and Grandi, S.A. 1980, Ap. J., 235, 971.ADSGoogle Scholar
- The theory of the emission line spectrum of an optically thick nebula at moderate-to-high densities is discussed, e.g., by: Drake, S.A., and Ulrich, R.K. 1980, Ap. J. Suppl., 42, 351.ADSGoogle Scholar
- 1.Collisional Excitation and Ionization Rates for H are given, e.g., by: Johnson, L.G. 1972, Ap. J., 174, 227ADSGoogle Scholar
- 1a.see also: Drake, S., and Ulrich, R.K. 1980, Ap. J. Suppl., 42, 351, and references therein cited.ADSGoogle Scholar
- 2.A-Values and Collision Strengths See I.A.U. Symposia No. 76 (1978) and No. 103 (1983), also see references in Appendix. A review article summarizing developments up to 1967: Czyzak, S.J. 1968, Stars and Stellar Systems, 7, 403Google Scholar
- See I.A.U. Symposia No. 76 (1978) and No. 103 (1983), also see references in Appendix. A review article summarizing developments up to 1967: Czyzak, S.J. 1968, Nebulae and Interstellar Matter, ed. B. Middlehurst and L.H. Aller, Chicago, Univ. Chicago Press.Google Scholar
- The literature is so extensive that we quote here only a few recent illustrative papers. Thus, for A-values: Mendoza, C, and Zeippen, C.J. 1982, M.N.R.A.S., 198. 127ADSGoogle Scholar
- The literature is so extensive that we quote here only a few recent illustrative papers. Thus, for A-values: Mendoza, C, and Zeippen, C.J. 1982, M.N.R.A.S., 199. 1025.ADSGoogle Scholar
- The literature is so extensive that we quote here only a few recent illustrative papers. Thus, for A-values: Nussbaumer, H., and Rusca, C. 1979, Astron. Astrophys., 72. 129.ADSGoogle Scholar
- The literature is so extensive that we quote here only a few recent illustrative papers. Thus, for A-values: Eissner, W., and Zeippen, C.J. 1981, J. Phys. B., At. Mol. Phys., 14, 2125.ADSGoogle Scholar
- 3.Applications to Nebular Diagnostics Early determinations of T
_{ε}employing [O III] lines (p^{2}configuration) were made by Menzel, Aller and Hebb (1941) using Ω-values computed by Hebb and Menzel (1940), A-values from Pasternack (1940), and from Shortley et al. (1941), Although the absolute values of these Ω’s, which were obtained from an inadequate theory, were substantially in error, the ratios were much less inaccurate, such that electron temperatures found by this method were of the order of 10% lower than the best modern values. They sufficed to show that electron temperatures of gaseous nebulae were in the neighborhood of 10,000°K.Google Scholar - Since forbidden line intensity ratios depend on both electron density and temperature, if we suppose that lines of two ionic species, e.g., O
^{++}and N^{+}, arise in the same strata, we can use the two sets of ratios to obtain N_{e}and T_{e}(Aller and White 1949, A.J., 54, 181). This is the principle applied in diagnostic diagrams (Fig. 13). The method requires accurate Q-values, which were not available in 1949. Seaton’s breakthrough (see e.g., Proc. Roy. Soc. London, A218, 400, 1953; A231, 37, 1955; Phys. Soc. Proc, 68, 457, 1955), in cross section theory which enables reliable collision strengths to be computed, made it possible to determine trustworthy temperatures and densities from nebular line ratios.Google Scholar - That forbidden line doublet ratios could depend on electron density was established by Aller, Ufford, and Van Vleck (1949) who measured the [0 II] 1(3727)/I(3726) ratio in a number of planetary nebulae and compared results with theoretical predictions. The observed intensity ratio was opposite to that predicted by the first-order theory. Improvements in the theory required taking into account the second-order spin-orbit interaction and magnetic interaction between the spin of one electron and the orbit of another! Even with these refinements all discordance was not removed. It was noted that the denser the nebula, the closer was the observed ratio to the predicted value. This variation was interpreted as a result of radiative and collisional processes that competed at different rates to populate and depopulate the
^{2}d levels. Thus, the 3729/3726 ratio could provide a clue to the density. It was not until after Seaton had developed an adequate theory of collisional excitation that Seaton and Osterbrock (1967, Ap. J., 125, 66) were able to give a satisfactory treatment of the problem. Applications of np^{3}nebular line ratios of [S II], [a III], [Ar IV], and [K V] have been made by a number of workersGoogle Scholar - With modern computers, we can easily solve equations of statistical equilibrium for five to typically fifteen levels using the best available atomic parameters (see, e.g., the compilation by Mendoza in I.A.U. Symposium No. 103).Google Scholar
- A useful compilation for forbidden lines of np
^{q}configurations of atoms and ions of C, N, O, Ne, Mg, Si, S, and Fe in the temperatore range between 5000 and 2,000,000 degrees has been given by M. Kafatos and J.P. Lynch (1980, Ap. J. Suppl., 42, 611).ADSGoogle Scholar - 4.Evaluations of the accuracy of nebular line intensity predictions are difficult. Illustrative examples are given by Czyzak et al., 1980, Ap. J., 241, 719, for [Ar IV], and in Highlights of Astronomy, 1983, 4, 791, ed. R.M. West, Reidel Publ. Co. Much more work needs to be done on this problem.ADSGoogle Scholar
- 5.Observational Data Pertinent to Nebular Plasma Diagnostics Optical Region. A compilation of spectroscopic data on gaseous nebula up to 1975 is given by: Kaler, J.B. 1976, Ap. J. Suppl., 31, 517.ADSGoogle Scholar
- More recent data obtained by photoelectric photometry, image tube scanners, etc., include: Torres-Peimbert, S., and Peimbert, M. 1977, Rev. Mex. Astron. Astrofis., 2, 181.ADSGoogle Scholar
- Aller, L.H., and Czyzak, S.J. 1982, Ap. J. Suppl., 51, 211, and references cited therein.ADSGoogle Scholar
- Ultraviolet Data for individual nebulae appear in many papers in contemporary periodicals. For a good starter see I.A.U. Symposium No. 103 and references therein, also: Universe at Ultraviolet Google Scholar
- Wavelengths, 1981, ed. R.D. Chapman, NASA Conference Publication No. 2171.Google Scholar
- Infrared. For summaries and references for work on planetaries, see IAU Symposia No. 76, 1978; No. 103, 1983. See also: Aitken, D.K., Roche, P.F., Spenser, P.M., Jones, B. 1979, Ap. J., 233. 925.ADSGoogle Scholar
- Infrared. For summaries and references for work on planetaries, see IAU Symposia No. 76, 1978; No. 103, 1983. See also: Aitken, D.K., and Roche, P.F. 1982, M.N.R.A.S., 200, 217.ADSGoogle Scholar
- Infrared. For summaries and references for work on planetaries, see IAU Symposia No. 76, 1978; No. 103, 1983. See also: Dinerstein, H. 1983, I.A.U. Symposium No. 103, 79.Google Scholar
- Infrared. For summaries and references for work on planetaries, see IAU Symposia No. 76, 1978; No. 103, 1983. See also: Zeilik, M. 1977, Ap. J., 218, 118 (H II regions)ADSGoogle Scholar
- Infrared. For summaries and references for work on planetaries, see IAU Symposia No. 76, 1978; No. 103, 1983. See also: Grasdalen, G. 1979, Ap. J., 229, 587.ADSGoogle Scholar
- Infrared. For summaries and references for work on planetaries, see IAU Symposia No. 76, 1978; No. 103, 1983. See also: Beck, S.C., Lacy, J.H., Townes, C.H., Aller, L.H., Geballe, T.R., and Baas, F. 1981, Ap. J., 249, 592.ADSGoogle Scholar
- Infrared. For summaries and references for work on planetaries, see IAU Symposia No. 76, 1978; No. 103, 1983. See also: Pottasch, S., et al. 1984, Ap. J. Letters (IRAS results).Google Scholar

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© D. Reidel Publishing Company, Dordrecht, Holland 1984