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Astron. Astrophys. 355, 69-78 (2000)

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Appendix A: Notes on individual PNe

Here, we provide detailed information on the physical properties of the PNe of our sample. Unless otherwise noted, B and V magnitudes are from the Acker et al. (1992) catalogue. Fluxes, extinction constants, and diameters are from Cahn et al. (1992, hereafter CKS).

NGC 7027 : The Zanstra analysis yields [FORMULA] and [FORMULA]. We have used the expansion distance from the radio image of Masson (1989). The derived mass of the central star is [FORMULA] [FORMULA].

NGC 2346 : The distance, [FORMULA] kpc, is derived from the average extinction distance (Pottasch 1996). We obtain [FORMULA] and [FORMULA]. The mass of the central star results [FORMULA] [FORMULA].

NGC 7293 : Many distance measurements are available for this nebula. Pottasch (1996) quotes a very uncertain (error up to 100%) parallax distance of [FORMULA] kpc. A more reliable value of [FORMULA] kpc comes from averaging several individual distances (Pottasch 1996). We obtain [FORMULA] and [FORMULA] or [FORMULA], using the parallax and average distances, respectively. The corresponding central star masses are [FORMULA] and 0.60 [FORMULA]. The progenitor masses are 2.6 and 2.0 [FORMULA]. Given the large error on the parallax, we prefer the latter value for the initial mass of NGC 7293.

NGC 6781 : We obtain [FORMULA]. By using the statistical (CKS) and the average of individual (Acker et al. 1992) distances, we obtain respectively [FORMULA] and [FORMULA]. In both cases, the mass of the central star coincides with the evolutionary track for [FORMULA] [FORMULA].

M 1-16 : By using [FORMULA] kpc (CKS method with a newly measured diameter), we find [FORMULA] and [FORMULA]. The inferred mass of the central star is [FORMULA] [FORMULA].

M 1-17 : With a distance of [FORMULA] kpc (from CKS method), we obtain [FORMULA] and [FORMULA]. The location on the HR diagram is just below the 0.55 [FORMULA].

M 2-9 : We calculate the distance with the method of CKS, but we evaluate the effective diameter from the [FORMULA] image ([FORMULA] arcsec). The new distance to this nebula is [FORMULA] kpc. No HeII flux has been detected. Thus, the Zanstra analysis gives lower limits to the temperature and luminosity. We obtain [FORMULA] and [FORMULA] from the hydrogen recombination lines. To date, nothing has been published on this nebula to set better constraints on the mass of the central star.

M 2-51 : The Zanstra analysis gives [FORMULA] and [FORMULA]. The luminosity is estimated using a distance [FORMULA] kpc, derived with the CKS method and a new estimate of the diameter. The resulting final mass is [FORMULA] [FORMULA].

M 4-9 : The distance evaluated with the newly measured angular size based on the H[FORMULA] image by Schwarz et al. (1992) is [FORMULA] kpc. For the central star, only a photographic magnitude exists. Thus, the resulting Zanstra analysis is quite uncertain. The [FORMULA] flux is from Acker et al. . The HeII flux has never been measured. We obtain [FORMULA] and [FORMULA]. A value of the mass of the central star cannot be derived.

CRL 2688 : Catalogued as a "possible planetary nebula", the famous Egg nebula is actually a proto-PN. The standard analysis via Zanstra method is not feasible, as the nebula is still very thick to optical radiation. There are two mass estimates in the literature, [FORMULA] or 2.7 [FORMULA] respectively, which depend on the assumed mass loss rate (Sahai et al. 1998).

CRL 618 : The HeII flux is not available. Therefore, we cannot derive a Zanstra temperature. Hydrogen recombination lines give [FORMULA] and a luminosity of [FORMULA], if [FORMULA] kpc is used. This distance has been derived with the CKS method and diameter measured by Manchado et al. (1996). No mass determination is possible.

OH 09+1.3 : Another proto-PN, with no published mass to date.

IC 5117 : The distance is the average of the extinction distances quoted in Acker et al. (1992). We calculate [FORMULA] and [FORMULA]. The derived mass of the central star is [FORMULA] [FORMULA].

M 1-59 : Since no stellar magnitudes are available for this object, we calculate the effective temperature with the "crossover" method (Kaler 1983). We use the statistical distance [FORMULA] kpc from CKS, based on a new diameter measured by Manchado et al. (1996) and obtain [FORMULA] and [FORMULA]. The mass of the central star mass is [FORMULA] [FORMULA].

NGC 6853 : The parallax distance quoted in Pottasch (1996) is of the best quality, so we can confidently use this value to evaluate the luminosity. From the Zanstra analysis we derive [FORMULA] and [FORMULA], and a central mass [FORMULA] [FORMULA]

BD+30o3639 : The HeII flux is not detected. Thus, we obtain lower limits to the luminosity and temperature: [FORMULA] and [FORMULA], using the hydrogen recombination lines and the average of extinction distances from Acker et al. (1992). No mass determination is possible.

NGC 7008 : We calculate [FORMULA] and [FORMULA]. The distance used is the average of the extinction distances quoted in Acker et al. (1992). The derived central mass is [FORMULA] [FORMULA].

M 1-7 : The Zanstra analysis gives [FORMULA] and [FORMULA] when using [FORMULA] kpc, as derived from the diameter of Manchado et al. (1996) and the method of CKS. The mass of the central star is [FORMULA] [FORMULA].

M 1-13 : Since no stellar magnitudes are available for this object, we calculate the effective temperature with the "crossover" method (Kaler 1983). We use the statistical distance [FORMULA] kpc from CKS to obtain [FORMULA] and [FORMULA]. The central star mass is [FORMULA] [FORMULA].

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© European Southern Observatory (ESO) 2000

Online publication: March 17, 2000
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