Emission line fluxes for 28 planetary nebulae are presented. The nebulae were chosen to cover a wide range of excitation classes, apparent diameters, location in the sky, and types of central stars. All objects were observed in the low dispersion mode of the IUE spectrographs, using the large entrance aperture

Feibelman, W. A.

Mccracken, C. W.

English

NASA Technical Reports Server

AN ATLAS OF EMISSION LINE FLUXES OF PLANETARY
O
NEBULAE IN THE I150-3200A REGION
A. Boggess, W. A. Feibelman and C. W. McCracken
Laboratory for Astronomy and Solar Physics
Goddard Space Flight Center
ABSTRACT
-12 -2 -i
Emission line fluxes in units of i0 erg cm sec for 28
planetary nebulae are presented. The nebulae were chosen to
cover a wide range of excitation classes, apparent diameters, location in the
sky, and types of central stars. All objects were observed in the low-
dispersion mode of the IUE spectrographs, using the large entrance aperture.
INTRODUCTION
Ultraviolet observations have an important role to play in the study and
interpretation of planetary nebulae. The range from 1200 to 3200_ contains
lines of carbon, nitrogen, oxygen and silicon in ionization stages difficult
to observe from the ground. In addition, forbidden lines from ions such as
three and four times ionized neon and argon provide opportunities for
probing the high temperature regions of these objects. The first spectra
obtained of planetaries throughout this range were those of NGC7027 and
NGC7662, by Bohlin and his collaborators using sounding rockets (i, 2).
However, it has only been with the advent of the IUE that such data could be
obtained routinely for a large number of nebulae to m = 12. With this in
mind, a systematic program of observing planetary nebulae has been conducted
during the first two years of IUE operations in order to provide data on
these objects covering a wide range of excitation class, apparent diameter,
and spectral type of the central star. The results presented here are from low
dispersion observations of 28 planetary nebulae. Intensities of the emission
lines in these objects are given in the accompanying tables. Plots of the
actual calibrated spectra will be published elsewhere.
OBSERVATIONS
All the planetary nebulae listed in the accompanying tables have been
observed in the low-dispersion mode, corresponding to a resolution of about
7_, through the 10"x20" large apertures, with the nebulae centered in the
aperture. Thus the resulting data correspond essentially to slitless spectra
of the nebulae and their central stars. The majority of the objects
(about 75%) are small enough so that the measured fluxes represent those of
the entire nebula. Many of the nebulae have been observed more than once to
extend the dynamic range of the data, and in these cases the fluxes tabulated
are from the spectrogram yielding the best signal-to-noise ratio for the
line in question.
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https://ntrs.nasa.gov/search.jsp?R=19810017431 2020-03-21T12:06:04+00:00Z
The fluxes have been generated from the net extracted spectra and corrected,
when necessary, for ITF errors. The data have been converted to absolute
units using the calibration curve of Bohlin, et al. (3). All the spectra
were processed for "extended source extraction" in order to measure the total
emission in the entrance aperture, even when the nebula was known to be small
or semi-stellar. As a test, a few of these small objects were processed in
both "extended source" and "point source" extraction and the results were
identical, as one would expect. For those objects that exceed the entrance
aperture dimension, allowances have to be made to convert the measured fluxes
into actual percentages of the entire flux emitted by the nebula and the
position angle may have to be considered, too.
The tabulated emission line fluxes are believed to have internal
accuracies of ±10%, except for those values shown in brackets where the
accuracy may be on the order of ±20%. This lower accuracy is usually due to
weaker lines with low S/N ratio or because of high-radiation backgrounds
during the time of observation. To these errors, one must add the uncertainty
of the IUE absolute calibration, which is estimated to be about 10%. No
corrections for interstellar extinction have been applied. The presence of
geocoronal^Ly-_ on all spectra prevents any measurements of nebular features
within~15X of Ly-_ .
Although determinations of intensity ratios of doublets for establishing
electron densities or electron temperatures, llne profiles, expansion
velocities and line splitting will require high-dispersion spectrograms of
the objects studied so far, there are nevertheless some preliminary con-
clusions that can be drawn from the low-resolutlon spectra. The sampling
of 28 objects is sufficiently large to make some general statements:
i) There are remarkable differences among the UV spectra even between objects
of similar excitation class and extinction. 2) All nebulae show CIII] k1907-
09 and this feature can be used as an indicator in surveys for nebular emission
objects. 3) Objects that are classified as low/excitatlon nebulae in the
visible generally show the emission lines of CII_, _II]and MgII. 4) HeII
may be present in both low- and hlgh-excltatlon nebulae, and a few planetarles
show mixtures of both very high- and low-excitatlon lines. 5) Those classified
as high-excitation objects show NV,[NelVI and[MgV]lines.
RESULTS
In the accompanying tables the nebulae have been grouped roughly according
to excitation class. The tables give excitation classes and nebular
diameters from Lang (4) and spectral types of central stars from A_½er (5).,2
All__ntries give the measured emission line fluxes in units of I0 erg cm
sec . Fluxes of lower accuracy are shown in brackets. Letter entries in
the tables are defined as follows:
a = absorption line
b = blended lines
p = emission component of P-Cygni feature
s = a few pixels saturated
WR = broad emission feature of Wolf-Rayet type
z = line is probably present.
664
REFERENCES
I. Bohlin, R. C., Marionni, P. A., Stecher, T. P.: Ap. J. 202, p. 415,
1975.
2. Bohlin, R. C., Harrington. J. P., and Stecher, T. P.: Ap. J. 219 p. 57_
1978.
3. Bohlin, R. C., Holm, A. V., Savage, B. D., Snijders, M. A. J., and
Sparks, W. M.: A. & A. (in press) 1980.
4. Lang, K. R.: "Astrophysical Formulae", Springer, New York, 1974.
5. Aller, L. H.: Mem. Soc. Roy. Sci., Liege7 IX, p. 271, 1976.
Table 1
Emission Line Fluxes for Low Excitation Planetary Nebulae
I BD 3003639 I IC418 IC2149 I IC3568
Diameter (arcsec) 3.0 12.4 8.6 18
Excitation Class 1 3 4 5
Central Star WC9 07fp 07.5fp 05f
1239/41 NV 7.71 - - -
1309 SiII 9.60 - - .
1335 c_ 6.64 (21.85) - -
1403/09 olv] 4 57 - - -
1487 NI_ 5.14 - 3.93 -
1548/50 CIV a 16.64p 3.05p 3.42p
1640 HeII 5.23 - - -
1661/66 OII_ 2.91 - - -
1674 ? 3..80 - - -
1747 NIII 5.78 - - -
1892 SiIII 4.23 - - -
1907/09 CII_ 44.63 29.92 4.94 7.11
2297 c_ 28.59 -
2325129 c_ ,[0_ 20.37 82.52 208
2470 [0_ - 27.50 119
2798 MgII - 29.75s - -
2830 HeI 12.78 - - -
3047 OIII - 1.23 - -
3095 ? - 6.64 - -
3133 OIII - 6.64 - -
3188 HeI, OIII - - z (0.27)
665
Table 2
Emission Line Fluxes From Moderately High Excitation
Planetary Nebulae
I J320 I IC4846 NGC6891 Hu 2 - 1 I NGC7026
Diameter 6.4 2.0 12.6 - 11.2
(arcsec)
Excitation 5 5 5 - 6
Class
Central - - 07f - OVI
Star
1309 SiII - - - (0.15) (0.04)
1371 OV .... 0.30
1487 NIVJ (0.55) - (1.67) - 0.12
1548 CIV 5.41 - 3.86p a 0.83
1640 HeII 1.88 - - - 0.67
1661/66 OII_ .....
1718 NIV,SiI_ - - (0.41) - -
1747 NIII - - - (0.19) -
1892 SiIII 0.20 ....
1907/09 czi_ 7.76 047 3.12 1.77 0.49
2325/29 cz_],_ 1.07 (0.43) - 1.94 -
2423/26 _eIVJ 0.52 ....
2470 _I_ - (0.70) - (0.98) -
2734 HeII (0.30) (0.90) - - -
2946 HeI (0.22) ....
3047 OIII 0.49 (0.39) - z -
3133 OIII 2.32 - (0.84) - 1.17
3188 HeI,OIII - (0.17) (0.88) 2.21 -
666
Table 3
Emission Line Fluxes for Moderately High
Excitation Planetary Nebulae
INGC6572 I IC4997 I NGC6565 NGC6644 1 NGC3132
Diameter 16.4 i. 6 9.0 2.6 (56)
(arcsec)
Excitation 5 5 6 6 6p
Class
Central Of+WR OftWR - - A+sdO
Star
1239/41 NV (2.33) 0.56 0.29 - -
1309 SiII 0.82 (0.93) - - -
1335 CII z 0.29 - 0.31 -
1371 OV 1.91 - (0.81) - -
1403/09 OIV_ (1.03) 0.09 - - -
1487 NI_J z 0.15 - - -
1548/50 CIV 2.66p 3.51 0.78 9.50 -
1575 [NeVJ - - 0.44 - -
1640 HeII 1.57 0.34 2.04 2.39 6.62
1661/66 OII_ .. 0.95 5.11 - 0.89 0.74
1718 NIV, SiI_ 2.03 - - - z
1747 Nizz 1.32 2.16 0.48 - 0.75
1817 [NeII_ ,SiII - 0.23 - - -
1892 SiIII (0.72) 0.33 - - -
1907/09 CII_ 50.52s 17.67 2.55 12.31s 4.21
2252 HeII - 0.26 - -- -
2325/29 CII 3, _III 3 10.47 2.35 0.98 1.71 -
2423/26 _eIVJ - - (0.37) 0.71
2470 5.62 1.59 (0.49) 0.60 -
2511 HeII - z - - -
2734 HelI - z - - (0.58)
2798/03 MgII - 1.90 - 1.66s -
2830 HeI 1.84s 0.33 - 0.24 (0.33)
2852 MgI - z - - -
2946 HeI (0.70) 0.38 - - -
3047 OIII - (0.18) (0.33) - -
3133 OIII - - 1.12 2.65 2.27
3188 HeI,OIII 2.33 - - (0.98) -
3204 HeII - (1.96) - - -
, , , ,,
667
Table 4
Emission Line Fluxes for High Excitation Planetary Nebulae
I NGC1535 J900 NGC324211 IC1297 I HM Sge* I NGC7009
Diameter 18.4 9.4 (40) - - 26.8
(arcsec)
Excitation 7 7 7 - - 7p
Class cont.
Central 07 em? cont? - -
Star
1239/41 NV 29.71 (0.23) 5.63 - 0.87 21.91
1286 ? (2.98) .... '
1309 SiII (3.46) .....
1335 CII (0.24) - - (0.09) -
1371 OV 7.82 - (1.06) 2.41 0.35 4.98p
1391 S_IV .... 0.25 -
1403/09 OIVJ (3.43) (0.18) - 0.68 0.31 -
1487 NIVJ - 0.51 (3.85) z i. 15 z
1548/50 CIV i0.74 5.23 -- 7.62 5.02 i0.86
1575 [Ne_ z - - 0.42 (0.12) 4.36
1640 HeII 14.30 1.68 118.30 14.98 3.44b,WR 43.00
1661/66 OII_ _ z (0.24) - 1.38 2.66b 3.68
1718 NIV,SiI_ .... 2.07b,WR -
1747 NIII 7.84 - - 1.30 5.15b 1.29
1817 _eII_ ,SiII .... 0.57 -
- - -
2101 CIIi - - (0.93) - - -
2252 HeII - - 0.87 - - -
2297 c_ - - 519 - - 260
2328/29 r__z3,[o_J - 1.o7 2.01 0.90 1.67 1.93
2423/26 LNeIV_ - 0.52 9.15 0.70 0.36 1.93
2470 D__ .... 0.22 -
2511 Hell - - 0.85 z - (0.64)
2734 HeII - 0.30 2.45 0.52 0.20 1.73
2784 _gv3 - - - (0.71)- -
2798/03 Mg_ .... 7.16
2830 Hel 1.18 - 3.33 0.77 1.75 3.68
2946 Hel ..... 1.17
3024 OIII - - 2.65b - - (0.97)b
3047 OIII - 0.50 6.04b 0.47 0.19 3.99b
3133 OIII 3.81 2.30 36.188 4.41 0.43 24.81
3188 HeI,OIII - - - (1.18) - 3.21b
3204 HeII - z 6.41 - z 3.56b
*The fluxes of HM Sge are for the first set of observations, 6 June 1978.
Considerable changes have occurred duringthe past two years and will be
described elsewhere.
668
Table 5
Emission Line Fluxes for Very High Excitation Planetary Nebulae
I IC2165 NGC3211 INGC6818 I NGC7027 Hu 1 - 2
Diameter 8.0 13.8 18.4 14.2 5
(arcsec)
Excitation 9 8 9 lOp i0
Class
Central cont? ? cont. - -
Star
1239/41 NV 0.44 0.46 0.47 (0.71) 0.71
1309 SiII - - - 1.21 -
1335 CII - 0.17 - z -
1391 si_v - - (1.54) - -
o_vJ 0.82 1.74 - - 0.541403/09
1487 NIVJ 1.02 1.72 2.22 0.65 1.85
1548/50 _IV 21.95 4.42 7.05 17.06 5.49
1575 eVJ - - z - -
1640 HeII 6.71 14.90 21.888 3.47 5.55
1661/66 OIII_ 0.62 1.12 1.78 z -
1747 NIII 063 107 151 153
1817 _eIIIJ,SiII 0.18 ....
1892 SiIII z b z b 0.67 z b -
CIII_ 21.84bs 28.83b 35.92 9.64b 3.951907/09
2252 HeII 1.00 - - 1.03 -
2297 CIII - - 0.21 - -
2325/29 CII], _IIIJ 1.36 1.21 2.11 1.90 0.43
2423/26 _eIV_ 2.70s 5.44s 8.37 1.02 2.26
2470 _IIJ - - - 0.53 -
2511 HeII 0.28 0.29 0.57 - 0.22
2734 HelI 1.31 0.96 1.23 0.49 0.36
_gv3 0.37 0.27 0.50 2.29b -2784
2830 HeI 0.86 0.34 0.72 0.40b -
2929 MgII - - 0.ii 0.27 -
3024 OIII 0.36 - 0.54 0.67 -
3047 OIII 1.80 0.80 1.20b 1.17 0.37
3133 OIII 9.83s 4.23 8.33 11.03 0.87
3204 HerI 2.40 (2.12) 3.30 1.61 (i. 00)
669


An atlas of emission line fluxes of planetary nebulae in the 1150-3200 A region

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