Photoionized regions in NGC 6822 Liliana Hernández-Martínez Instituto de Astronomía Universidad Nacional Autonóma de México Liliana Hernández-Martínez Instituto de Astronomía Universidad Nacional Autonóma de México IAC

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

NGC 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 Three colors: H  -green, OIII-red and continuum-blue. MOSAIC2 image (4m Blanco, CTIO) x 36.8 arcmin. Hernández-Martínez, L., & Peña, M. Sep-Oct, NGC Three colors: H  -green, OIII-red and continuum-blue. MOSAIC2 image (4m Blanco, CTIO) x 36.8 arcmin. Hernández-Martínez, L., & Peña, M. Sep-Oct, 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

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

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” ( ): 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” ( ): survey in 14 galaxies. IAC

PNe in the Local Group of galaxies Milky Way

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

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

NGC 6822 MOSAIC2 CTIO  Observations: sept 4 th and oct 9 th, CTIO - Mosaic II CCD imager - 8 CCD’s arcmin. 4 filters: [OIII] 4990Å 50Å (2hrs) D51 (DDO) 5130Å 154Å (1.3hrs) Halpha 6563Å 80Å (1hr) Halpha Å 80Å (1hr)  Reduction: mscred (IRAF). Buell T. Jannuzi, Jenna Claver, and Frank Valdes, June 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, CTIO - Mosaic II CCD imager - 8 CCD’s arcmin. 4 filters: [OIII] 4990Å 50Å (2hrs) D51 (DDO) 5130Å 154Å (1.3hrs) Halpha 6563Å 80Å (1hr) Halpha Å 80Å (1hr)  Reduction: mscred (IRAF). Buell T. Jannuzi, Jenna Claver, and Frank Valdes, June 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

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

By blinking on-band, off -band… IAC

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

Flux calibration… UCLAN

Spatial Distribution N E 26 PNe candidates in NGC IAC

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

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

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 M* 5007 (0) 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

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

N E PN1 PN4 IAC

9 Planetary Nebulae2 HII regions Observations PN1,PN4 PN7, HII8, PN14, PN13, PN19, PN11 and PN9, PN12, H24, quiet faint Spectrophotometric Standards EG B 600 RI LDS749B 600B 600RI BPM B 600RI IAC

VLT spectra: IAC

HH PN1 blue

PN1 red [SII] 6678 [NII] HH IAC

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

Ionic Abundances 7 PNe,VLT 1 HII Region IAC

Total Abundances Richer & McCall 2007 Peimbert et al Richer & McCall 2007 I I * * IAC

PN-VLT HII-VLT PN-M HII-M HII-P IAC

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

Infall IAC Carigi et al. 2006

Initial Mass Function IMF normalized from 0.01 to 60 M_sun IAC

Star Formation Rate  Carigi et al, 2006 IAC

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

(very) Preliminary results

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 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 ( 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  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 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 ( 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 IAC

On-band, off-band UCLAN