Planetary nebulae in M32 and the bulge of M31: Line intensities and oxygen abundances

We present spectroscopy of planetary nebulae in M32 and in the bulge of M31 that we obtained with the MOS spectrograph at the Canada-France-Hawaii Telescope. Our sample includes 30 planetary nebulae in M31 and 9 planetary nebulae in M32. We also observed one H II region in the disk of M31. We detected [O III]$\lambda$4363 in 18 of the planetary nebulae, 4 in M32 and 14 in the bulge of M31. We use our line intensities to derive electron temperatures and oxygen abundances for the planetary nebulae.Comment: 17 pages, 12 figures, accepted by Astronomy & Astrophysics Supplement Serie

The Evidence for a Binary origin of the Young Planetary Nebula HB 12

The young planetary nebulae play an important role in stellar evolution when intermediate- to low-mass stars (0.8 $\sim$ 8 M$_\odot$) evolve from the proto-planetary nebulae phase to the planetary nebulae phase. Many young planetary nebulae display distinct bipolar structures as they evolve away from the proto-planetary nebulae phase. One possible cause of their bipolarity could be due to a binary origin of its energy source. Here we report our detailed investigation of the young planetary nebula, Hubble 12, which is well-known for its extended hourglass-like envelope. We present evidence with time-series photometric observations the existence of an eclipsing binary at the center of Hubble 12. Low-resolution spectra of the central source show, on the other hand, absorption features such as CN, G-band & Mg b{\arcsec}, which can be suggestive of a low-mass nature of the secondary component.Comment: 9 pages, 11 figures, Accepted for publication in A

New groups of planetary nebulae with peculiar dust chemistry towards the Galactic bulge

We investigate Galactic bulge planetary nebulae without emission-line central stars for which peculiar infrared spectra have been obtained with the Spitzer Space Telescope, including the simultaneous signs of oxygen and carbon based dust. Three separate sub-groups can be defined characterized by the different chemical composition of the dust and the presence of crystalline and amorphous silicates. We find that the classification based on the dust properties is reflected in the more general properties of these planetary nebulae. However, some observed properties are difficult to relate to the common view of planetary nebulae. In particular, it is challenging to interpret the peculiar gas chemical composition of many analyzed objects in the standard picture of the evolution of planetary nebulae progenitors. We confirm that the dual-dust chemistry phenomenon is not limited to planetary nebulae with emission-line central stars.Comment: 17 pages, 13 figure

Searching for Binary Stars in Planetary Nebulae Using the ISIS Image Subtraction Software

We explored the theory that binary central stars of planetary nebulae may be contributing factor in the formation of planetary nebulae. We searched for this photometric variability in central stars of planetary nebulae because consistent periodic variability is indicative of a close binary system. The variability of our targets was assessed with the image subtraction software, ISIS. We found that the central stars of the planetary nebulae Hen 2-84, NGC 6326, and K 1-22 showed clear variability. A preliminary light curve for Hen 2-84 showed periodic behavior, suggesting a binary system. Of the remaining targets observed, with sufficient data, five did not appear to have substantial variability detected through ISIS and for 2 targets we were unable to determine true variability