The Census of Planetary Nebulae in the Local Group Romano L.M. Corradi Isaac Newton Group of Telescopes, La Palma Laura Magrini Dip. di Astronomia, Universita’ di Firenze

The census of planetary nebulae in the Local Group Romano L.M. Corradi Isaac Newton Group of Telescopes, La Palma Laura Magrini Dip. di Astronomia, Universita’ di Firenze

An overview of the Local Group (LG) galaxy type log LV D (kpc) M 31 Sb 10.43 760 Milky Way Sbc 10.31 - M 33 Sc 9.51 795 LMC Ir 9.35 50 SMC 8.79 60 M 32 E2 8.55 NGC 205 Sph 8.51 IC 10 8.47 660 NGC 6822 dIr 8.35 500 NGC 185 8.19 IC 1613 8.07 725 NGC 147 7.99 WLM 7.71 925 Sagittarius dSph 7.47 24 Fornax 7.19 138 Pegasus 6.87 Leo I* 6.71 250 And I dSph 6.67 810 And II 700 Leo A dIr 6.55 690 DD210* 6.47 1025 SagDIG 6.23 1300 PegasusII 6.19 830 Pisces 6.11 And V 6.03 And III 760 Leo II 5.99 210 Phoenix 5.87 395 Sculptor 87 Cassiopeia 5.75 Tucana 870 Sextans 86 Carina 5.71 100 Draco 5.39 79 Ursa Min 5.35 63 In green galaxies for which data exist to search for PNe or at least one PN is known. In red data from our LG survey, the new results of it (still unpublished) I will present later *data not reduced yet

At the outer fringes of the LG… GR 8 dSph 6.59 2200 NGC 3109 dIr 8.27 1360 Antlia 6.33 1330 Sextans B 7.67 1320 Sextans A 7.63 1450 EGB0427+63* 6.31 possible physical association Beyond the LG, the IC342/Maffei group, the South Polar (Sculptor) group, the M 81 group… Is the LG ultimately going to merge into an elliptical galaxy with approximately the luminosity of the Milky Way? Van den Bergh 2000, “The Galaxies of the Local Group”

Imaging searches for PNe in the LG Baade (1955): 5 PNe in M31 ~100 PNe in LMC and SMC (see Westerlund 1968) In the 70’s, Ford and collaborators detected a large number of PNe in M31 (bulge) and a few ones in its companions Jacoby & Lesser (1981) found PNe in 5 galaxies of the LG Ciardullo et al. (1989): 429 PNe in M31 Magrini et al. (2000): 134 PNe in M33 Jacoby & De Marco (2002): deep survey of SMC Merrett et al. (2003): 2611 PNe in M31 with the P.N.S. the “Local Group Census” (2001-2004): 14 galaxies searched

The Local Group Census (LGC) It is a narrow- and broad-band imaging survey of the galaxies of the LG observable from La Palma (Dec>-30). Collaborators: J. Beckman, M. Bryce, A. Cardwell, R. Corradi, P. Crowther, R. Greimel, A. Herrero, M. Irwin, P. Leisy, D. Lennon, A. Mampaso, L. Magrini, M. Perinotto, R. Peletier, D. Pollacco, S. Prins, I. Skillen, S. Smartt, L. Smith, J. Telting, E. Tolstoy, J. Walsh, N. Walton, A. Zijlstra, A. Zurita Institutions: ING, IAC, Open Univ., Univ. of Amsterdam, ESO, Univ. of Firenze, Univ. de Granada, Institute of Astronomy Cambridge, Jodrell Bank, Univ. of Manchester, Queens Univ. Belfast, Univ. College London, Univ. of Nottingham, Univ. of Oxford, Univ. of Victoria, UMIST It is aimed to find, catalogue and study old and young emission-line populations (e.g. HII regions, planetary nebulae, SN remnants, LBVs, WR stars, symbiotic binaries, etc.) to unprecedented levels. The value of narrowband images is enhanced with complementary broadband data. This enable the linkages between stellar populations (e.g. AGB  PNe) in the range of LG galaxies to be probed.

The LGC observations Instrumentation: Wide Field Camera of the 2.5m Isaac Newton Telescope (mosaic of four 4k2k CCDs, f.o.v. 3434 arcmin2). Filters and exposure times: [OIII] (500.8/8 nm), Ha+[NII] (656.8/10), [SII] (672.5/8), HeII (468.6/10) 60 min (24.5 mag) Stromgren Y 30 min Sloan g, r, i 20 min (25,24.5,24) PNe search methods: visual search of point-like sources in the [OIII] and Ha+[NII] continuum-subtracted images [OIII]-g vs. Ha-r color-color diagrams No constraints on the [OIII]/Ha ratio to (statistically) distinguish from HII regions, because otherwise PNe could be missed and we do not want this, specially in dwarf galaxies where the Pne population size is extremely small

[OIII]-g vs. Ha-r color-color diagrams NGC 205 [OIII]-g Ha-r

Datasets are mostly reduced and public The LGC observations The observations have basically being completed during a total of some 40 clear nights (out of 50 allocated). Details can be found at http://www.ing.iac.es/~rcorradi/LGC Datasets are mostly reduced and public

poster by Zijlstra & Gesicki PNe in the Milky Way subgroup 3 PNe Zijlstra & Walsh 1996 A&A 312 L21 poster by Zijlstra & Gesicki 1 PN Danziger et al. 1978 ApJ 220, 458 talk of G. Jacoby Esposizioni tipiche: 1 ora nei filtri in banda stretta, 20 minuti negli altri

Corradi et al. 2004 A&A in prep PNe in the M31/M33 subgroup Jacoby & Lesser 1981 AJ 86 185 Corradi et al. 2004 A&A in prep Ciardullo et al. 1989 ApJ 339 53 Magrini et al. 2000 A&A 355 713

M 31 1284 PNe (717 new) in 3.6 deg2 ~2700 PNe talk of H. Merrett Halliday et al. 2003 IAU Symp 219 p.629 1284 PNe (717 new) in 3.6 deg2 ~2700 PNe talk of H. Merrett

IC 10 16 PNe Magrini et al. 2003 A&A 407 51

huge HI envelope 12 x 15 kpc (Huchtmeier 1979 A&A 75 170) Magrini et al. 2003 A&A 407 51 1.3 x 1.1 kpc 2.5 kpc Similar result for NGC 6822 (see Leisy talk) huge HI envelope 12 x 15 kpc (Huchtmeier 1979 A&A 75 170)

PNe in “free-floating” galaxies of the LG NGC 6822 20 PNe talk of P. Leisy WLM 1 PN Magrini et al. 2004 MNRAS in prep IC 1613 3 PNe ” “ “ Leo A 1 PN Jacoby & Lesser 1981 AJ 86 185 Magrini et al. 2003 A&A 407 51

NGC 6822

WLM

IC 1613

Leo A The galaxy with the lowest luminosity and metallicity where a PN has been found

PNe at the outer fringes of the LG Sextans B 5 PNe Magrini et al. 2002 A&A 386 869 talk of L. Magrini Sextans A 1 PN Magrini et al. 2003 A&A 407 51 talk of L. Magrini NGC 3109 18 PNe Prada et al. 2004 in preparation GR 8 0 PN Magrini et al. 2004 MNRAS in prep

Summary: n. of PNe in the Local Group galaxies Galaxy log LV n.PNe magc O/H M 31 10.43 ~2700 9.0 Milky Way 10.31 ~2000 8.7 M 33 9.51 134 2.6 8.4 LMC 9.35 277 8.35 SMC 8.79 105 6 8.03 M 32 8.55 30 2.4 8.29 NGC 205 8.51 35 3.5 8.6 IC 10 8.47 16 2.0 8.2 NGC 6822 20 8.25 NGC 185 8.19 5 2.7 7.9 IC 1613 8.07 3 7.71 NGC 147 7.99 9 <4.4 WLM 1 7.78 Sagittarius 7.47 Fornax 7.19 7.98 Pegasus 6.87 7.93 Leo A 6.55 3.0 7.36 Galaxy log LV n.PNe magc O/H NGC 3109 8.27 18 7.63 Sextans B 7.67 5 3.0 8.12 Sextans A 1 1.9 7.55 Wide range of luminosities (masses) and metallicities. Excellent resource to study properties of PNe in widely different environments. Completeness limit has been computed correcting for extinction and metallicity the cutoff magnitude

Observed population size vs. galaxian luminosity Milky Way M 33 LMC SMC Leo A Sagittarius Pegasus Fornax SexA SexB N147 I1613 N185 N3109 N6822 I10 N205 M32

PNe as tracers of intermediate-age populations log (mass of intermediate-age stars)N(PNe) Relative SFR 2-8 Gyrs  0.2 Relative SFR 2-8 Gyrs < 0.2 Mateo 1998 ARAA 36, 435 Magrini et al. in prep. log (total mass)  van den Bergh 2000

Age effects? Same luminosity, morphology, and metallicity NGC 185 gas-rich and <1Gyr star-formation in its centre NGC 147 gas-free, no SF in the last 3 Gyrs NGC185 NGC147 Mendez & Soffner 1997 A&A 321, 898 (mild age effect on M*) Marigo et al. 2004 A&A in press (strong effect for recent star formation) see talk of P. Marigo

significant SF <1 Gyr NGC 185 Martinez-Delgado et al. 1999 AJ 118 2229 significant SF <1 Gyr some SF 1-3 Gyr very little SF 1-3 Gyr

significant SF <1 Gyr NGC 185 Corradi et al. 2004 A&A in prep. significant SF <1 Gyr SF burst <0.15 Gyr

Metallicity effects: the brightest PN metallicity correction Dopita et al 1992 AJ 389 27 But mixed with population size effects!

Summary PNe have been searched (found) in all LG galaxies with logLV>6.7 Their population size correlates well with the V luminosity of the galaxy, and in particular traces differences in the relative contribution of intermediate-age populations (2-8 Gyr). Deeper searches are needed to strenghten this result LG PNe are valuable indicators of: metallicity (see talks/posters Richer, Magrini, Leisy, Stasinska, Perinotto, Kniazev, Maciel) kinematics (see talk of Merrett for M31, Durrell et al. 2002 AAS 201 1311 for M33) intergalactic light (IC 10, NGC 6822) The effect of star formation in the last 1-2 Gyr on the absolute magnitude of the bright cutoff of the PN luminosity function remains controversial. Possible positive evidence (e.g. NGC 185 vs. NGC 147) is weakened by the small PN population size in most LG galaxies