Spectroscopic Observations of Planetary Nebulae in the Northern Spur of M31

Abstract

We present spectroscopy of three planetary nebulae (PNe) in the Northern Spur of the Andromeda Galaxy (M31) obtained with the Double Spectrograph on the 5.1 m Hale Telescope at the Palomar Observatory. The samples are selected from the observations of Merrett et al. Our purpose is to investigate formation of the substructures of M31 using PNe as a tracer of chemical abundances. The [O III] 4363 auroral line is detected in the spectra of two objects, enabling temperature determinations. Ionic abundances are derived from the observed collisionally excited lines, and elemental abundances of nitrogen, oxygen, and neon as well as sulphur and argon are estimated. Correlations between oxygen and the alpha-element abundance ratios are studied, using our sample and the M31 disk and bulge PNe from the literature. In one of the three PNe, we observed relatively higher oxygen abundance compared to the disk sample in M31 at similar galactocentric distances. The results of at least one of the three Northern Spur PNe might be in line with the proposed possible origin of the Northern Spur substructure of M31, i.e. the Northern Spur is connected to the Southern Stream and both substructures comprise the tidal debris of the satellite galaxies of M31.

5 tables, 17 figures; accepted for publication in ApJ

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• Reconstructing the Subsurface Three-Dimensional Magnetic Structure of A Solar Active Region Using SDO/HMI Observations
• Keck HIRES Spectroscopy of Extragalactic HII Regions: C and O Abundances from Recombination Lines
• A deep kinematic survey of planetary nebulae in the Andromeda Galaxy using the Planetary Nebula Spectrograph

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• Metal-Rich PNe in the Outer Reaches of M31
• The survey of planetary nebulae in Andromeda (M31). IV. Radial oxygen and argon abundance gradients of the thin and thicker disc
• Chemical Abundances of Planetary Nebulae in the Substructures of M31
• Chemical Abundances of Planetary Nebulae in the Substructures of M31 -- II. The Extended Sample and A Comparison Study with the Outer-disk Group
• Metallicity gradients in M31, M33, NGC 300 and the Milky Way using abundances of different elements
• Planetary Nebulae in the Circumnuclear Region of M31: A Spectroscopic Sample
• Spectroscopic Studies of an Ultraluminous Supersoft X-Ray Source in M81