2004MNRAS.351..935Z

Query : 2004MNRAS.351..935Z

2004MNRAS.351..935Z - Mon. Not. R. Astron. Soc., 351, 935-955 (2004/July-1)

Electron temperatures and densities of planetary nebulae determined from the nebular hydrogen recombination spectrum and temperature and density variations.

ZHANG Y., LIU X.-W., WESSON R., STOREY P.J., LIU Y. and DANZIGER I.J.

Abstract (from CDS):

A method is presented to derive electron temperatures and densities of planetary nebulae (PNe) simultaneously, using the observed hydrogen recombination spectrum, which includes continuum and line emission. By matching theoretical spectra to observed spectra around the Balmer jump at about 3646 Å, we determine electron temperatures and densities for 48 Galactic PNe. The electron temperatures based on this method - hereafter Te(Bal) - are found to be systematically lower than those derived from [Oiii] λ4959/λ4363 and [Oiii] (88 µm + 52 µm)/λ4959 ratios - hereafter Te([Oiii]na) and Te([Oiii]fn). The electron densities based on this method are found to be systematically higher than those derived from [Oii] λ3729/λ3726, [Sii] λ6731/λ6716, [Cliii] λ5537/λ5517, [Ariv] λ4740/λ4711 and [Oiii] 88 µm/52 µm ratios. These results suggest that temperature and density fluctuations are generally present within nebulae. The comparison of Te([Oiii]na) and Te(Bal) suggests that the fractional mean-square temperature variation (t2) has a representative value of 0.031. A majority of temperatures derived from the Te([Oiii]fn) ratio are found to be higher than those of Te([Oiii]na), which is attributed to the existence of dense clumps in nebulae - those [Oiii] infrared fine-structure lines are suppressed by collisional de-excitation in the clumps. By comparing Te([Oiii]fn), Te([Oiii]na) and Te(Bal) and assuming a simple two-density-component model, we find that the filling factor of dense clumps has a representative value of 7x10–5. The discrepancies between Te([Oiii]na) and Te(Bal) are found to be anticorrelated with electron densities derived from various density indicators; high-density nebulae have the smallest temperature discrepancies. This suggests that temperature discrepancy is related to nebular evolution. In addition, He/H abundances of PNe are found to be positively correlated with the difference between Te([Oiii]na) and Te(Bal), suggesting that He/H abundances might have been overestimated generally because of the possible existence of H-deficient knots. Electron temperatures and densities deduced from spectra around the Paschen jump regions at 8250 Åare also obtained for four PNe: NGC 7027, NGC 6153, M 1-42 and NGC 7009. Electron densities derived from spectra around the Paschen jump regions are in good agreement with the corresponding values derived from spectra around the Balmer jump, whereas temperatures deduced from the spectra around the Paschen jump are found to be lower than the corresponding values derived from spectra around the Balmer jump for all the four cases. The reason remains unclear.

Abstract Copyright: 2004 RAS

Journal keyword(s): atomic processes - ISM: abundances - planetary nebulae: general

Simbad objects: 52

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Number of rows : 52
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 NGC 40 PN 00 13 01.0170097248 +72 31 19.033338720   11.63 11.46     [WC8] 632 2
2 PN Vy 1-1 PN 00 18 42.1732297536 +53 52 19.778622996           [WC] 135 0
3 IC 2003 PN 03 56 21.9884187048 +33 52 30.759977028   13.11 11.87 13.44   [WC3?] 261 0
4 PN A66 30 PN 08 46 53.4639874872 +17 52 46.369394580   14.23 14.30 13.47   [WC5] 431 0
5 IC 3568 PN 12 33 06.8549162136 +82 33 50.202643608   11.809 10.730 12.651   ~ 407 0
6 WRAY 16-165 PN 15 06 13.7137862736 -42 59 56.499680904   13.2 13.20     ~ 78 0
7 NGC 5873 PN 15 12 50.8605628680 -38 07 31.585496844   11.6 9.7     [WC] 146 0
8 NGC 5882 PN 15 16 49.9562553264 -45 38 58.616280132   11.9 10.9     ~ 281 1
9 PN Mz 3 PN 16 17 13.3915382496 -51 59 10.711893480   10.8 14.00     O9.5 359 0
10 NGC 6153 PN 16 31 30.5708444544 -40 15 12.646208700   10.7 15.55     ~ 320 0
11 PN DdDm 1 PN 16 40 18.1517248296 +38 42 20.033859348   14.0 13.90     sd+G/K 153 0
12 NGC 6210 PN 16 44 29.5191019368 +23 47 59.421958296   12.3 11.7     Of/[WR] 597 0
13 IC 4634 PN 17 01 33.5816774904 -21 49 33.015515916   12.3 11.3     O3If 286 0
14 NGC 6302 PN 17 13 44.5 -37 06 11           O-rich 821 2
15 PN M 1-20 PN 17 28 57.6165015264 -19 15 54.033719256           ~ 136 0
16 PN H 1-35 PN 17 49 13.9398459192 -34 22 52.812575256     12.90     wels? 118 0
17 PN Cn 2-1 PN 17 54 33.010 -34 22 21.15     12.70 14.47 13.70 ~ 136 0
18 NGC 6543 PN 17 58 33.4039587288 +66 37 58.750734000   11.09 11.28     [WC] 1197 2
19 PN M 2-24 PN 18 02 02.8945854456 -34 27 47.275175592   15.62 14.60 15.29   ~ 100 0
20 PN M 3-21 PN 18 02 32.33 -36 39 11.3     12.20     ~ 109 1
21 PN H 1-50 PN 18 03 53.5082954976 -32 41 42.015068628   10 12.80     ~ 87 0
22 PN M 1-42 PN 18 11 04.99 -28 58 59.1   13.1 14.00     ~ 221 0
23 NGC 6572 PN 18 12 06.3181909152 +06 51 13.027935240   9.3 10.8     [WC] 761 0
24 NGC 6567 PN 18 13 45.1636643352 -19 04 34.071637152     10.9     [WC5/6] 277 0
25 PN M 2-36 PN 18 17 41.43 -29 08 19.9         17.012 ~ 140 0
26 NGC 6620 PN 18 22 54.182 -26 49 17.19   12.8 13.30 14.34 14.55 ~ 145 0
27 PN Hf 2-2 PN 18 32 30.9015918072 -28 43 20.276106312     15.90     ~ 110 0
28 PN M 3-32 PN 18 44 43.03 -25 21 34.8           ~ 79 0
29 IC 4776 PN 18 45 50.705 -33 20 34.12   11.98 10.62     [WC]pec 204 1
30 PN Hu 2-1 PN 18 49 47.5610183328 +20 50 39.396894756   12.369 11.126 12.30   ~ 286 0
31 M 57 PN 18 53 35.0967659112 +33 01 44.883287544   15.405 15.769 15.901 16.062 DA(O?) 868 2
32 NGC 6741 PN 19 02 37.10 -00 26 56.7     9.6     ~ 353 0
33 IC 1297 PN 19 17 23.4475188000 -39 36 46.253665872     10.89     [WC3/4] 170 0
34 NGC 6778 PN 19 18 24.9542333399 -01 35 47.155403881   13.747 12.721     ~ 272 0
35 NGC 6790 PN 19 22 56.972976 +01 30 46.40112   12.247 10.504 12.684   wels 329 0
36 NGC 6803 PN 19 31 16.4826019750 +10 03 21.620200381   13.034 11.616 13.242   ~ 254 0
37 NGC 6807 PN 19 34 33.53 +05 41 02.5     12     ~ 144 0
38 NGC 6818 PN 19 43 57.770472 -14 09 13.36932     9.3     ~ 357 1
39 NGC 6826 PN 19 44 48.1500225888 +50 31 30.249034932   9.779 9.359 10.775   O3f(H) 736 0
40 NGC 6833 PN 19 49 46.5667474512 +48 57 40.113276876           ~ 181 0
41 NGC 6884 PN 20 10 23.6424784416 +46 27 39.631794408   11.9 10.9     ~ 322 1
42 NGC 6879 PN 20 10 26.6930056361 +16 55 21.272110541   13.661 12.540 14.075   O3f(He) 157 0
43 NGC 6891 PN 20 15 08.8435405584 +12 42 15.584146740   12.11 12.51     O3Ib(f*) 405 0
44 IC 4997 PN 20 20 08.7557973960 +16 43 53.698933380   11.94 11.15     [WC7/8] 555 0
45 NGC 7009 PN 21 04 10.8155187648 -11 21 48.580157556   12.48 12.07     ~ 1020 1
46 NGC 7027 PN 21 07 01.571952 +42 14 10.47120   10.358 8.831 10.157   ~ 2541 1
47 PN Hu 1-2 PN 21 33 08.3106242400 +39 38 09.554428752     12.0     ~ 295 1
48 PN A66 78 PN 21 35 29.3816259120 +31 41 45.449196108   13.04 13.25     [WC5] 336 0
49 IC 5217 PN 22 23 55.7180137224 +50 58 00.464340252     15.5     [WC7] 314 0
50 NGC 7293 PN 22 29 38.5454047152 -20 50 13.747242408 11.894 13.158 13.524 13.689 13.898 DAO.5 983 1
51 PN Me 2-2 PN 22 31 43.6753782000 +47 48 03.836846628   9.3       ~ 160 0
52 NGC 7662 PN 23 25 53.8318792825 +42 32 05.835828380       11.427   ~ 940 1

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