Volume 547, November 2012
|Number of page(s)||8|
|Published online||31 October 2012|
1 Instituto de Astronomía, Universidad Nacional Autónoma de México, Apdo. Postal 70264, Méx. D. F., 04510 México, México
e-mail: firstname.lastname@example.org; email@example.com; firstname.lastname@example.org; email@example.com
2 Instituto Nacional de Astrofísica, Optica y Electrónica, Tonantzinta, Pue., México
Received: 26 April 2012
Accepted: 27 August 2012
Aims. [O iii] 5007 Å on-band and off-band images, obtained with the Very Large Telescope (VLT) and FORS 2 spectrograph in two zones (center and outskirts) of the spiral galaxy NGC 300, are analyzed searching for emission line objects. In particular we search for planetary nebula (PN) candidates to analyze their distribution and luminosity properties, to perform follow-up spectroscopy, and to study the planetary nebula luminosity function, PNLF.
Methods. In the continuum-subtracted images, a large number of emission line objects were detected. From this sample we selected those objects with stellar appearance and no detectable central star as PN candidates. [O iii] 5007 Å instrumental magnitudes were measured and calibrated by using spectrophotometric data from the follow-up spectroscopy.
Results. We have identified more than a hundred PN candidates and many compact HII regions. The PN sample is the largest one reported for this galaxy so far. For all the objects we present coordinates, instrumental [O iii] 5007 magnitudes, and apparent nebular [O iii] 5007 fluxes and magnitudes. The [O iii] 5007 observed luminosity function for PNe (PNLF) was calculated for the whole sample and for the central and outskirts samples. The three PNLF are similar within uncertainties. We fit the empirical PNLF to the observed PNLF for all the samples. From our best fit for the whole sample, we derived a maximum value for the apparent magnitudes of m✩5007 = 22.019 ± 0.022 and obtained a tentative estimate of the distance modulus m5007–M5007= 26.29+0.12-0.22 mag, which agrees well with the recent value derived from Cepheid stars.
Key words: galaxies: individual: NGC 300 / planetary nebulae: general / HII regions / galaxies: distances and redshifts
Based on observations collected at the European Southern Observatory, VLT, Paranal, Chile, program ID 077.B-0430.
Table 2 is also available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (188.8.131.52) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/547/A78
© ESO, 2012
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