Abstract

PENA, M.. The low excitation planetary nebulae HUDO 1 and HUBI 1 and their [WC10] central stars. Rev. mex. astron. astrofis [online]. 2005, vol.41, n.2, pp.423-433. ISSN 0185-1101.

Low- and high-resolution spectra of the planetary nebulae HuDo 1 and HuBi 1, around [WC-late] stars, are analyzed. The objects belong to the galactic disk, with heliocentric radial velocities of -12 km s^-1 (HuDo 1) and 57 km s^-1 (HuBi 1). C(H/β) reddening values are of 2.04 for HuDo 1 and 1.22 for HuBi 1. Plasma line ratios are used to estimate physical conditions and abundances. We find log(O/H)+12 = 8.43 and 8.57, and N/O = 0.2 and 0.1 for HuDo 1 and HuBi 1 respectively. HuBi 1 is the only PN excited by a very late [WC] star showing intense nebular He I recombination lines. From the stellar lines we derive a [WC 10] type for both stars, although HuBi 1 central star should be slightly hotter to provide a large amount of He⁰ ionizing photons. Nebular and stellar parameters of HuDo 1 and HuBi 1 are compared with those of other [WC 10] objects, and we conclude that the stars of HuDo 1 and HuBi 1 should be intrinsically fainter. In particular HuBi 1 seems a low-density evolved nebula around a low-mass slowly-evolving star.

Keywords : Planetary Nebulae [Individual (HUDO 1, HUBI 1)]; Stars [Post-AGB]; Stars [Wolf-Rayet].