148 research outputs found
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]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
Polarization in the Lagoon nebula
A V-band polarimetric survey of stars associated with the Lagoon nebula was conducted. The data were combined with existing photometric and spectroscopic observations in order to investigate the alignment of magnetic field lines with identifiable symmetry axes and to evaluate the nature of dust in the immediate vicinity. Although stars are not in general highly polarized, electric vectors align with the minor axis of the Lagoon nebula, perpendicular to the major axis of the spatial distribution of massive stars. The observations indicate that the collapse of the molecular cloud progenitor was inhibited along directions perpendicular to magnetic field lines. Considering the low polarization efficiency and the high ratio of total to selective extinction, smaller grains of intranebular dust appear to have been destroyed
- …