Envelope masses and distances to planetary nebulae: IC 5117 and NGC 7293
|1Melekh, BY, 1Demchyna, AV, 1Holovatyi, VV |
1Ivan Franko National University of Lviv, Lviv, Ukraine
|Kinemat. fiz. nebesnyh tel (Online) 2015, 31(2):34-46|
|Start Page: Structure and Dynamics of the Galaxy|
Self-consistent method to determine the masses Mi of the ionized gas in envelopes of planetary nebulae (PNe) and the distances D to those ones is developed. The method is based on the calculation of optimized photoionization model (OPhM) of a planetary nebula envelope. Models of the «young» nebula IC5117 and «old» one NGC7293 are calculated. Correspondingly, the values of Mi and D for IC5117 (Mi = 0.0056M☉, D = 1287 pc) and NGC7293 (Mi= 0.681M☉, D = 201 pc) are determined. The radial gas density distribution in a PN envelope was defined using approximation expression that is close to the normal one and derived by us on the basis of an analysis of isophotoe maps of 12 PNe [Astron. Zhurn.—1992.—69.—P. 1166—1178]. The mass of the ionized gas was determined during OPhM calculation through the integration of the gas radial distribution over nebula volume. The distance to the PN was determined through the OPhM calculation as one of OPhM free parameters from the comparison of the modelling radiation flux in H β line at the distance to the Earth which is assumed by optimizer with the observed one. The values D determined by this means are compared with corresponding results of other investigators.
|Keywords: IC 5117, NGC 7293, Planetary Nebula|
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