Astron. Astrophys. 355, 713-719 (2000)

5. Summary and conclusions

We have detected 134 PN candidates in the spiral galaxy M33, by comparing [O III], H+[N II], and continuum images taken with a panoramic mosaic detector attached to the 2.54 m INT. In addition, other 63 compact emission-line objects were identified which have a non-negligible continuum. Further spectroscopic studies are in order to determine their nature.

The PNe luminosity function of M33 is found to closely follow the general PNLF derived for other galaxies in the Local Group. From it, we derive a distance of M33 of  kpc, equal to the distance known from the Cepheids. This provides further support to the use of the PNLF as a valuable extragalactic distance indicator.

We plan to perform spectroscopic studies of the individual PNe candidates to fully verify their nature and derive information on their physical properties. This will also help in clarifying the possible misclassification of PNe with other emission-line objects in studies based on [O III], H+[N II] and continuum imagery only, a basic information when discussing the PNLF as an extragalactic distance candle.

© European Southern Observatory (ESO) 2000

Online publication: March 9, 2000
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