Spectroscopy of PNe in Sextans A, Sextans B, NGC 3109 and Fornax A.Y. Kniazev (MPIA), E.K. Grebel (Basel), A.G. Pramskij, S.A. Pustilnik (SAO RAS) 20 May 2004 PNe ESO Workshop

Introduction PNe with their prominent emission lines can be used to measure metallicity in nearby galaxies Together with HII regions PNe provide a probe of the chemical enrichment and star formation history of a galaxy In spite of the importance of the topic for PNe in extermal galaxies, only few spectroscopic data have been obtained 20 May 2004 ESO Workshop

Observations Some PNe and HII in 3 dIrr galaxies which form a small group just beyond the Local Group (D ~ 1.3 Mpc) and PN in the Local Group Fornax dwarf spheroidal galaxy (D ~ 140 kpc) NTT, 2003-2004 as a backup block for the main program “Toward Establishing a Complete Sample of Low Surface Brightness Galaxies” Red EMMI channel, Grisms #5 (3900-6800 Å, 1.6 Å/pix), #6 (5700-8500 Å, 1.4 Å/pix) Seeing was in the range 0.4" – 0.6" and slit = 2" 20 May 2004 ESO Workshop

Reduction MIDAS + IRAF Method of emission line measurements and calculation of abundances was described in detail in Kniazev et al. (2004, astro-ph/0404133) [Strong Emission Line HII Galaxies in the Sloan Digital Sky Survey] 20 May 2004 ESO Workshop

PN in Fornax Spectroscopy was published by Danziger et al. (1978) and by Walsh et al. (1997) (without [OIII] λ4363 Å line).

PN in Fornax Conclusion: The new abundance determinations Maran et al. (1984) Our He 11.08 10.98 ± 0.03 N <7.5 7.06 ± 0.03 O 8.4 ± 0.12? 8.28 ± 0.03 Ne 7.6 7.45 ± 0.05 Ar 5.9 6.08 ± 0.03 S <6.7 6.45 ± 0.05 Electron number density = 750 cm -3 Conclusion: The new abundance determinations with much better accuraces are well consistent with old ones.

PN Candidates in NGC 3109 PN candidates in NGC 3109 were taken from Richer & McCall (1992) 20 May 2004 ESO Workshop

PN Candidates in NGC 3109 Preliminary Conclusions: PN1: 12 + log(O/H) = 7.50 ± 0.04 PN2: 12 + log(O/H) = 7.58 ± 0.04 HII: 12 + log(O/H) = 7.65 ± 0.06 PN4: 12 + log(O/H) = 7.78 ± 0.09 PN5: 12 + log(O/H) = 7.71 ± 0.04 HII: 12 + log(O/H) = 7.72 ± 0.08 Preliminary Conclusions: 1. Oxygen abundances of PNe and HII regions are all in the small range near 12+log(O/H) ~ 7.65 ± 0.1 2. Oxygen abundances for HII is well consistent with previous from Lee et al. (2003) 20 May 2004 ESO Workshop

PN Candidate in Sextans A Sextans A was taken from Jacoby & Lesser (1981) and from Magrini et al. (2003) 20 May 2004 ESO Workshop

PN Candidate in Sextans A HII(a): 12 + log(O/H) = 7.54 ± 0.09 HII(b): 12 + log(O/H) = 7.54 ± 0.09 (see Kaufer et al. 2004) HII(c): 12 + log(O/H) = 7.56 ± 0.09 PN: 12 + log(O/H) = 7.84 ± 0.06 Preliminary Conclusions: 1. The oxygen abundances of HII regions and the PN are different at high confidence level 2. Factor of ~2 higher metallicity of the PN likely implies unusual evolutionary scenario for the PN progenitor. 20 May 2004 ESO Workshop

PN Candidate in Sextans B PN candidates in Sextans B were taken from Magrini et al. (2002) 20 May 2004 ESO Workshop

PN Candidate in Sextans B Preliminary conclusions: 1. We spectroscopically confirmed that PN3 candidate in SextansB is PN. 2.At the confidence level of 67% the oxygen abundance of PN3 in SextansB is 12+log(O/H) > 7.3. This is consistent with measured 12+log(O/H) in the two nearby HII regions. 20 May 2004 ESO Workshop

Heliocentric Velocities Fornax PN Vel = 129 ± 14 km/s (measured) Fornax Vel = 58 ± 9 km/s (from NED) 20 May 2004 ESO Workshop

Diagnostic Diagrams Diagnostic diagrams can separate confidently some of PNe, but significant part of them can be hidden in the region which is more typical for HII regions. 20 May 2004 ESO Workshop

Summary We observed the Fornax PN and 6 PN candidates in the Local Group galaxies Sextans A, Sextans B and NGG3109 With high quality spectroscopy we confirmed PN nature of all 6 observed candidates We derived oxygen abundances for the PN and all but one observed PN candidates by direct measurement of Te 20 May 2004 ESO Workshop