1. Photoionized regions in NGC 6822 Liliana Hernández-Martínez lhernand@astroscu.unam.mx Instituto de Astronomía Universidad Nacional Autonóma de México Liliana Hernández-Martínez lhernand@astroscu.unam.mx Instituto de Astronomía Universidad Nacional Autonóma de México IAC-150408

2. Dwarf Irregular Galaxies  Low mass  Low metallicity  Gas rich.  Star Formation  Chemical homogeneity  Low mass  Low metallicity  Gas rich.  Star Formation  Chemical homogeneity IAC-150408

4. NGC 6822 - Optical radius 2.9kpc x 2.9kpc (Mateo, 1998) - HI radius 6kpc x 14kpc (Blok & Walter, 2000) - Optical radius 2.9kpc x 2.9kpc (Mateo, 1998) - HI radius 6kpc x 14kpc (Blok & Walter, 2000) N E NGC 6822. Three colors: H  -green, OIII-red and continuum-blue. MOSAIC2 image (4m Blanco, CTIO). 36.8 x 36.8 arcmin. Hernández-Martínez, L., & Peña, M. Sep-Oct, 2005. NGC 6822. Three colors: H  -green, OIII-red and continuum-blue. MOSAIC2 image (4m Blanco, CTIO). 36.8 x 36.8 arcmin. Hernández-Martínez, L., & Peña, M. Sep-Oct, 2005. Barred dwarf galaxy of type Ir IV-V -L v =9.44x10 7 L sun -M tot =1.6x10 9 M sun -L v =9.44x10 7 L sun -M tot =1.6x10 9 M sun -Distance 490 ± 40 kpc - Vel Hel:-54 Km/s -Distance 490 ± 40 kpc - Vel Hel:-54 Km/s IAC-150408

5. Objects with emission Lines NGC 6822 (previous knowledge)  Killen & Dufour (1982): - 36 emission stellar objects - 31 diffuse and extended objects - 14 compact HII regions - 14 stars with H  emission line.  Hodge et al (1988): 157 HII regions  Ford & Peng (2002): 7 PNe.  Leisy et al (2005): 17 PNe (total).  Killen & Dufour (1982): - 36 emission stellar objects - 31 diffuse and extended objects - 14 compact HII regions - 14 stars with H  emission line.  Hodge et al (1988): 157 HII regions  Ford & Peng (2002): 7 PNe.  Leisy et al (2005): 17 PNe (total). IAC-150408

6. Extragalactic PNe  Baade (1955): 5 PNe in M31  Westerlund (1968): ~100 PNe in LMC and SMC  Jacoby & Lesser (1981) found NPs in 5 galaxies in the LG  Ciardullo et al. (1989): 429 PNe in M31  Magrini et al. (2000): 134 PNe in M33  Merrett et al. (2003): 2611 PNe in M31  The “Local Group Census” (2001-2004): survey in 14 galaxies.  Baade (1955): 5 PNe in M31  Westerlund (1968): ~100 PNe in LMC and SMC  Jacoby & Lesser (1981) found NPs in 5 galaxies in the LG  Ciardullo et al. (1989): 429 PNe in M31  Magrini et al. (2000): 134 PNe in M33  Merrett et al. (2003): 2611 PNe in M31  The “Local Group Census” (2001-2004): survey in 14 galaxies. IAC-150408

7. PNe in the Local Group of galaxies Milky Way

8. Extragalactic PNe  Planetary Nebulae Luminosity Function (PNLF) - distance determination.  PNe emission lines -“easy to measure” stellar cinematic  Chemical tracers of the past component of the ISM  Planetary Nebulae Luminosity Function (PNLF) - distance determination.  PNe emission lines -“easy to measure” stellar cinematic  Chemical tracers of the past component of the ISM IAC-150408

9. PNe in NGC6822 (CTIO) E N 36.8arcmin Dithered (to cover the gaps) IAC-150408

10. NGC 6822 MOSAIC2 CTIO  Observations: sept 4 th and oct 9 th, 2005. CTIO - Mosaic II CCD imager - 8 CCD’s - 36.8 arcmin. 4 filters: [OIII] 4990Å 50Å (2hrs) D51 (DDO) 5130Å 154Å (1.3hrs) Halpha 6563Å 80Å (1hr) Halpha+8 6650Å 80Å (1hr)  Reduction: mscred (IRAF). Buell T. Jannuzi, Jenna Claver, and Frank Valdes, June 2003. http://www.noao.edu/noao/noaodeep/ReductionOpt/framesv6.html. http://www.noao.edu/noao/noaodeep/ReductionOpt/framesv6.html - cross talk correction, trimsec, overscan, bias, flats, bpm (bad pixel mask), astrometric calibration - wcs (USNO-A2.0 catalogue), crmask, fixpix (bpm y crmask), tangent-plane projected, skysub.  Observations: sept 4 th and oct 9 th, 2005. CTIO - Mosaic II CCD imager - 8 CCD’s - 36.8 arcmin. 4 filters: [OIII] 4990Å 50Å (2hrs) D51 (DDO) 5130Å 154Å (1.3hrs) Halpha 6563Å 80Å (1hr) Halpha+8 6650Å 80Å (1hr)  Reduction: mscred (IRAF). Buell T. Jannuzi, Jenna Claver, and Frank Valdes, June 2003. http://www.noao.edu/noao/noaodeep/ReductionOpt/framesv6.html. http://www.noao.edu/noao/noaodeep/ReductionOpt/framesv6.html - cross talk correction, trimsec, overscan, bias, flats, bpm (bad pixel mask), astrometric calibration - wcs (USNO-A2.0 catalogue), crmask, fixpix (bpm y crmask), tangent-plane projected, skysub. IAC-150408

11. 8 OIII average images 4 D51 average images Continuum subtracted [OIII] - D51 [OIII] - D51 8 OIII average images 4 D51 average images Continuum subtracted [OIII] - D51 [OIII] - D51 Searching for PNe… IAC-150408

12. By blinking on-band, off -band… IAC-150408

13. New PNe in NGC6822.  Selection criteria: - objects in OIII, but not in continuum - objects in H ,  but not in continuum  Pollution agents: -compact Supernova Remnants -compact HII regions (stellar continuum, stars of PNe are 2mag fainter)  apparent magnitudes (punctual objects) measured with digiphot.apphot.phot (IRAF). PSF=6.5pix  comparative photometry (PN7, Leisy et al. 2005)  Selection criteria: - objects in OIII, but not in continuum - objects in H ,  but not in continuum  Pollution agents: -compact Supernova Remnants -compact HII regions (stellar continuum, stars of PNe are 2mag fainter)  apparent magnitudes (punctual objects) measured with digiphot.apphot.phot (IRAF). PSF=6.5pix  comparative photometry (PN7, Leisy et al. 2005) IAC-150408

14. Flux calibration… UCLAN 260308

15. Spatial Distribution N E 26 PNe candidates in NGC 6822. IAC-150408

16. Cumulative Planetary Nebula Luminosity Function. N = normalization constant  = apparent distance modulus m* = apparent peak magnitudes of the luminosity function m*=19.35 Nexp (-0.307  = 6.72x10 -3 IAC-150408

17. …Cumulative PNLF. Hernandez-Martinez, L. et al, in preparation IAC-150408

18. Absolute peak magnitud of the PNLF. We can use the true distance modulus 23.48mag (Van de Bergh 2000) and the extinction A V =0.73 (Gallart et al, 1996) to derive a peak absolute magnitude of the luminosity function of NGC 6822. M* 5007 (0) -4.83 This work M*=-4.47±0.05 Ciardullo et. al (2002) M*=-4.47±0.05 Ciardullo et. al (2002) M*=-4.57, NGC3109 Peña et al, 2007 IAC-150408

19. Spectroscopy… -VLT Multi-Object Spectrograph observations, carried on August 19th to 22nd, 2006. - We used FORS-2 spectrograph with a field of 6.8’x6.8’ covering the central part of the galaxy. -VLT Multi-Object Spectrograph observations, carried on August 19th to 22nd, 2006. - We used FORS-2 spectrograph with a field of 6.8’x6.8’ covering the central part of the galaxy. IAC-150408

20. N E PN1 PN4 IAC-150408

21. 9 Planetary Nebulae2 HII regions Observations PN1,PN4 PN7, HII8, PN14, PN13, PN19, PN11 and PN9, PN12, H24, quiet faint Spectrophotometric Standards EG274 600B 600 RI LDS749B 600B 600RI BPM16274 600B 600RI IAC-150408

22. VLT spectra: IAC-150408

23. 4363 4471 HH PN1 blue

24. PN1 red [SII] 6678 [NII] HH IAC-150408

25. Data analysis  Reddening correction: c(H  )  F(H  )/F(H  ) red F(H  )/F(H  ) blue F(H  )/F(H  ) blue  Direct Method (4363) Te, Ne, ionic abundances. IRAF: temden, ionic  Total abundances: Ionization Correction Factors (ICFs,Kingsburgh & Barlow, 1994).  Reddening correction: c(H  )  F(H  )/F(H  ) red F(H  )/F(H  ) blue F(H  )/F(H  ) blue  Direct Method (4363) Te, Ne, ionic abundances. IRAF: temden, ionic  Total abundances: Ionization Correction Factors (ICFs,Kingsburgh & Barlow, 1994). IAC-150408

26. Ionic Abundances 7 PNe,VLT 1 HII Region IAC-150408

27. Total Abundances Richer & McCall 2007 Peimbert et al. 2006 Richer & McCall 2007 I I * * IAC-150408

28. PN-VLT HII-VLT PN-M HII-M HII-P IAC-150408

29. Chemical evolution Model (IRA)  Accretion (f).  Chemical abundances of the accreted gas (X accreted i ).  Star Formation Rate (SFR,  ).  Initial Mass Function (IMF,  ). (Kroupa et al, 1993)  Stellar Yields (Y i, R).  Galactic winds (w).  Metallicity dependence IAC-150408

30. Infall IAC-150408 Carigi et al. 2006

31. Initial Mass Function IMF normalized from 0.01 to 60 M_sun IAC-150408

32. Star Formation Rate  Carigi et al, 2006 IAC-150408

33. Yields Karakas & Lattanzio,2007 Geneva’s group & Woosley & Weaver (1995) IAC-150408

34. (very) Preliminary results

35. Conclusions.  We have increased the PNe sample. The distribution of HII regions appear to be confined to the center of the galaxy instead PNe apparently being over the whole galaxy.  We have derived the peak absolute magnitude of the luminosity function of NGC 6822. We get M*>4.48, Metallicity dependent?, problems with calibrations? Galactic extinction?  In this work we obtained the abundances of 7 PNe. Given a total number of 10 PNe abundances for this galaxy.  Two PNe in our sample are Type I (2. 4-8 Msun).  Two are oxygen self-enrichment. This are not useful as observational constraint of Oxygen.  All these results will be taken into account in our chemical model of NGC 6822.  We have increased the PNe sample. The distribution of HII regions appear to be confined to the center of the galaxy instead PNe apparently being over the whole galaxy.  We have derived the peak absolute magnitude of the luminosity function of NGC 6822. We get M*>4.48, Metallicity dependent?, problems with calibrations? Galactic extinction?  In this work we obtained the abundances of 7 PNe. Given a total number of 10 PNe abundances for this galaxy.  Two PNe in our sample are Type I (2. 4-8 Msun).  Two are oxygen self-enrichment. This are not useful as observational constraint of Oxygen.  All these results will be taken into account in our chemical model of NGC 6822. IAC-150408

37. On-band, off-band UCLAN 260308