The Local Group Census: planetary nebulae in IC 10, Leo A and Sextans A
Magrini L., Corradi R.L.M., Greimer R., Leisy P., Lennon D.J.,
Mampaso A., Perinotto M., Pollacco D.L., Walsh J.R., Walton N.A.,
Zijlstra A.A., 2003, A&A, 407, 51
Abstract
In the framework of our narrow-band survey of the Local Group
galaxies, we present the results of the search for planetary nebulae
(PNe) in the dwarf irregular galaxies IC 10, Leo A and Sextans
A. Using the standard on-band/off-band technique, sixteen new
candidate PNe have been discovered in the closest starburst galaxy, IC
10. The optical size of this galaxy is estimated to be much larger
than previously thought, considering the location of the new PNe in an
area of 3.6 kpc x 2.7 kpc. We also confirm the results of previous
studies for the other two dwarf irregular galaxies, with the detection
of one candidate PN in Leo A and another one in Sextans A. We review
the number of planetary nebulae discovered in the Local Group to date
and their behaviour with metallicity. We suggest a possible fall in
the observed number of PNe when [Fe/H] << -1.0, which might indicate
that below this point the formation rate of PNe is much lower than for
stellar populations of near Solar abundances. We also find
non-negligible metallicity effects on the [O III] luminosity of the
brightest PN of a galaxy.
Based on observations obtained at the 2.5 m INT telescope
operated on the island of La Palma by the Isaac Newton Group in the
Spanish Observatorio del Roque de Los Muchachos of the Instituto de
Astrofisica de Canarias.
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