Investigating the Near-Infrared Properties of Planetary Nebula II. Medium Resolution Spectra

We present medium-resolution (R~700) near-infrared (lambda = 1 - 2.5 micron) spectra of a sample of planetary nebulae (PNe). A narrow slit was used which sampled discrete locations within the nebulae; observations were obtained at one or more positions in the 41 objects included in the survey. The PN spectra fall into one of four general categories: H I emission line-dominated PNe, H I and H_2 emission line PNe, H_2-dominated PNe, and continuum-dominated PNe. These categories correlate with morphological type, with the elliptical PNe falling into the first group, and the bipolar PNe primarily in the H_2 and continuum emission groups. Other spectral features were observed in all categories, such as continuum emission from the central star, C_2, CN, and CO emission, and warm dust continuum emission. Molecular hydrogen was detected for the first time in four PNe. An excitation analysis was performed using the H_2 line ratios for all of the PN spectra in the survey where a sufficient number of lines were observed. One unexpected result from this analysis is that the H_2 is excited by absorption of ultraviolet photons in most of the PNe surveyed, although for several PNe in our survey collisional excitation in moderate velocity shocks plays an important role. The correlation between bipolar morphology and H_2 emission has been strengthened with the new detections of H_2 in this survey.Comment: 13 pages, 8 tables, 33 figure

Galactic clusters with associated Cepheid variables. VII. Berkeley 58 and CG Cassiopeiae

Photoelectric, photographic, and CCD UBV photometry, spectroscopic observations, and star counts are presented for the open cluster Berkeley 58 to examine a possible association with the 4.37d Cepheid CG Cas. The cluster is difficult to separate from the early-type stars belonging to the Perseus spiral arm, in which it is located, but has reasonably well-defined parameters: an evolutionary age of ~10^8 years, a mean reddening of E(B-V)_(B0)=0.70+-0.03 s.e., and a distance of 3.03+-0.17 kpc (V_0-M_V=12.40+-0.12 s.d.). CG Cas is a likely cluster coronal member on the basis of radial velocity, and its period increase of +0.170+-0.014 s yr^(-1) and large light amplitude describe a Cepheid in the third crossing of the instability strip lying slightly blueward of strip centre. Its inferred reddening and luminosity are E(B-V)=0.64+-0.02 s.e. and =-3.06+-0.12. A possible K supergiant may also be a cluster member.Comment: Accepted for Publication (MNRAS

Abundances of Planetary Nebula NGC 5315

The ISO and IUE spectra of the elliptical nebula NGC 5315 is presented. These spectra axe combined with the spectra in the visual wavelength region to obtain a complete, extinction corrected, spectrum. The chemical composition of the nebulae is then calculated and compared to previous determinations. The HST Nicmos observations of the nebula in 3 emission lines are also presented. These observations are used to determine the helium abundance as a function of position in the nebula. A discussion is given of possible evolutionary effects