Surveys for Planetary Nebulae in the Magellanic Clouds SMC LMC Where we simultaneously study stellar and galaxy evolution ESO Workshop: May 19-21, 2004 Orientation The View from Cerro Tololo SMC MW LMC ESO Workshop: May 19-21, 2004 Relationship to MW HI map from Putnam et al (2003) Magellanic Stream extends >90° across sky, but has few stars Distances: accurate to ±10% 50 kpc to LMC* 62 kpc to SMC *depth within LMC ±3% ESO Workshop: May 19-21, 2004 Extent of LMC: van de Marel 2001 SMP 78 24° 22° RGB and AGB counts indicate the LMC subtends ~130 sq. deg. ESO Workshop: May 19-21, 2004 Common Survey Techniques To identify PN candidates via – Direct imaging through filters (on-band and off-band) – Objective prism imaging (historically photographic) – Spectral “imaging” (PN Spectrograph) Other kinds of surveys – Follow-up High resolution imaging (HST, AO systems) – Follow-up spectroscopy • Candidate verification • Chemical composition • Central star atmospheric properties • Kinematic probe of host galaxy properties: dark matter? • Kinematic probe of nebula itself: expansion properties ESO Workshop: May 19-21, 2004 “Modern” SMC Surveys Survey Team Number Number Depth, Found New mags SMP 1978 28 3 3 Jacoby 1980 27 19 5 Sanduleak & Pesch 1981 6 6 3 Morgan & Good 1985 13 10 3 Meyssonnier & Azzopardi 93 62 18 4 Morgan 1995 62 9 3 Murphy & Bessel 2000 131 108 ? Jacoby & De Marco 2002 59 25 6 Galle, Winkler, & Smith* 69 13 4? Jacoby & De Marco 15 4 7 Magellanic Cloud Emission Line Survey * ESO Workshop: May 19-21, 2004 Technology Helps The Clouds are easy targets with large format CCD mosaic cameras on large telescopes ESO 2.2m CTIO 4m Example: MB 233 – but, probably not a PN CTIO 4m extends ~1 mag beyond ESO 2.2m ESO Workshop: May 19-21, 2004 SMC Completeness Most Recent Surveys 2+1 +1 3 Jacoby & De Marco (2002) • 10 fields of 0.5° each (2.2M) 2 5 6 2 +2 • Depth of ~6 mags 5 12 7 Jacoby & De Marco (in prep) • 6 fields, 3 new PN (CTIO 4m) 4 7 8 • Depth of ~7 mags • Not very productive more depth doesn’t help outer fields have few PN ESO Workshop: May 19-21, 2004 “Modern” LMC Surveys Survey Team Number Number Depth, Found New mags SMP 1978 28 3 3 Jacoby 1980 27 19 5 Sanduleak 1984 25 13 3 Morgan & Good 1992 98 86 5 Morgan 1994 265 54 5 Leisy, Francois, & Fouqué 10 4 9 Jacoby & De Marco 15 10 7 Reid & Parker ~1000* 136 7? *Candidates to be verified ESO Workshop: May 19-21, 2004 “Modern” LMC Surveys The pioneering surveys by Henize (1956), Lindsay (1961), Henize & Westerlund (1963), Lindsay & Mullan (1965), and Westerlund & Smith (1964) defined the extragalactic PN field. Survey Team Number Number Depth, Found New mags SMP 1978 28 3 3 Jacoby 1980 27 19 5 Sanduleak 1984 25 13 3 Morgan & Good 1992 98 86 5 Morgan 1994 265 54 5 Leisy, Francois, & Fouqué 10 4 9 Jacoby & De Marco 15 10 7 Reid & Parker ~1000* 136 7? Candidates to be verified * ESO Workshop: May 19-21, 2004 LMC Completeness Most Recent Surveys Reid & Parker (in prep) • 25 sq.deg.; 1000 candidates • Photographic Hα stacked Leisy et al (in prep) • Many fields & new PN (2.2m) Jacoby & De Marco (in prep) 5+10 • 1 field, 10 new PN (4m) • Depth of ~7 mags ESO Workshop: May 19-21, 2004 The Clouds are a Special Place Nearest (by 10X) large population of EG PN (50-70 kpc) – Distances known: 50 and 62 kpc (common for each sample) – Faintest PN are observable (unbiased statistical sample) – Central stars can be studied directly (photometry, spectra) • Masses for low-metallicity initial-to-final mass relation • Identify binaries via velocity variations – PN are easily resolved: from space or with AO facilities • Morphology • Physical radii allow expansion ages to be measured – High S/N spectroscopy allows studies for • Compositional analysis across full luminosity range • Internal dynamics Large samples: hundreds of PN can be studied Low/Intermediate metallicity sample ESO Workshop: May 19-21, 2004 Challenges for MC PN Surveys Contaminants in surveys – Compact HII regions, especially if low surface brightness – Novae (2 “PN” in SMC, 1 in LMC) – Background emission-line galaxies Faint nebulae are extended detection shifts from point source domain to surface brightness problem Very large area on sky – SMC: ~ 20 sq. deg. – LMC: ~130 sq. deg. ESO Workshop: May 19-21, 2004 Challenges for MC PN Surveys Confirmation and follow-up spectroscopy compromised by – Crowding from stars – Diffuse HII emission Nomenclature (Parker, Cibis) – Surveys began without naming convention – We have near-chaos today Accurate coordinates – objects may be extended 5-10 arcsec ESO Workshop: May 19-21, 2004 Galaxy Cluster Behind SMC Field 11 [OIII] Diff HST image of MA 1682 ESO Workshop: May 19-21, 2004 Spectroscopy is Complicated CTIO 4m spectrum of JD-17: Hα+[NII]+[SII] region Raw Sky subtracted Issues remain: • Incomplete subtraction from diffuse HII emission • Stellar spectra from background • Nebula resolves, so some flux falls off slit • Faintest PN will be lost in the stellar continuua • But, see Roth for instrumental solution ESO Workshop: May 19-21, 2004 SMC Luminosity Function Survey extends 8 mags down PNLF Dip seen in PNLF for first time Absent in models, generally Possibilities (Marigo/Girardi models) – Progenitors from multiple ages Hints from M33 (<1 and 8-10 Gyr) Age?, metallicity?, IMF? – Binary stars in old pops (common envelope evolution) ESO Workshop: May 19-21, 2004 How Many PN are There? Technically feasible to survey the SMC and LMC to the faintest PN and find them all, rather than extrapolate A “Complete” survey is “defined” to go 8 mags down LF SMC surveys are largely complete to ~7 mags 1.5X more LMC surveys are largely complete to 5 mags 3X more Currently known, entire SMC 84 With deeper survey (8 mags) 120-170 Currently known, entire LMC 350* With deeper survey (8 mags) 800-900 *sample is neither homogeneous in depth nor spatially complete; Reid and Parker survey will improve statistics significantly. ESO Workshop: May 19-21, 2004 Questions That MC PN Can Answer How many PN are in the Clouds, how do the counts compare to galaxy evolution models, & what are inferences for other galaxies? – Tests stellar and galaxy evolution theory, population mixes – Need to complete the surveys – Need follow-up spectra to confirm candidates What fraction of PN have binary CS? Maybe all of them ??? – De Marco et al (2004) – 11/12 Galactic PN are velocity variables – Need synoptic spectroscopy of PN CS at moderate resolution Velocities of Cloud PN can be accurate to 1 km/s – with forthcoming large samples, can we map the dark matter? – Need spectroscopy of nebulae at moderate resolution – Need kinematic models of the SMC and LMC (with GCs, HII, stellar velocities) ESO Workshop: May 19-21, 2004 Questions That MC PN Can Answer What is the distribution of central star masses, and what is the initial-to-final mass relation as a function of metallicity? – Need medium resolution spectroscopy of central star and nebula Do the brightest PN have the characteristics (CS mass, T*, L*, nebular age/size) predicted by PNLF models (e.g., Marigo et al) – Need specific model predictions – Need statistically complete HST (or ground AO) measurements of nebula (plus above bullet) ESO Workshop: May 19-21, 2004 Astrophysics from Cloud PN at this conference Stanghellini – HST observations of ~half the Cloud PN allow morphology of many PN to be studied in absolute terms (radius, age, shape, kinematics) to link to their progenitor stars Villaver, Arrieta – MV, T*, L*, mass, composition now can be measured directly for many central stars (from spectra) IFMR Shaw – 100 LMC & 30 SMC PN with HST imaging allow correlations of physical properties to explore formation and evolutionary processes of PN that are not possible elsewhere Reid – complete surveys are possible to faintest PN for accurate counts, PN birth rates, tests of stellar evolution models Maciel – Composition correlations in SMC, LMC, and MW Peña – Detailed study of N66 in LMC Tsammis – Recombination and forbidden line analysis in SMC ESO Workshop: May 19-21, 2004 Conclusions Easy to find many PN in Clouds with current methods – this is the only large sample where all PN can be found! – SMC surveys are approaching completeness – LMC surveys could be complete soon (Reid & Parker, Leisy et al) Deficit at 2-4 mags in PNLF is a clue to stellar population content – need models that interpret this feature! Compare in LMC. Almost any kind of PN study can be done better in the Clouds (distances known, spatially resolved, relatively bright) ☺ Confrontation of observations and theory (Ciardullo/Girardi talks) may be solved, in part, with observations of Cloud PN – Models predict properties of bright PN and CS – test them! – Cloud PN derive from a range of metallicities and progenitor ages, the principal parameters driving the model PNLF cut-off ESO Workshop: May 19-21, 2004 END I have never in my life learned anything from anyone who agreed with me. Dudley Field Malone ESO Workshop: May 19-21, 2004 Stellar Abundances in the SMC Stars in SMC are diverse (Larson, Clausen, Storm 2000) From Stromgren photometry of fields stars in SMC ESO Workshop: May 19-21, 2004 Are Faint PN Different From Bright PN? Consider SMC … 1 (5.5% of 18) of SMP PN have [NII]/Hα > 1 7 (28% of 25) new Jacoby & De Marco PN have strong [NII] Fraction of PN with [NII]/Hα > 1, in bright (<2 mags) and intermediate (<6 mags) luminosity groups – LMC ratio = 1.9 (16% vs 31%) – SMC ratio = 4.3 (6% vs 26%) Type I PN in SMC are preferentially faint • They generate more dust (Ciardullo & Jacoby 1999) • Their central stars are massive and fade fast ESO Workshop: May 19-21, 2004 [NII]/Hα Ratios: PN 1 – 9 11 4 7 11 2 5 8 3 6 9 ESO Workshop: May 19-21, 2004 [NII]/Hα Ratios: JD 10 – 18 10 13 16 11 14 17 12 15 18 ESO Workshop: May 19-21, 2004 [NII]/Hα Ratios: PN 19 – 25 19 22 25 20 23 Nova 21 24 ESO Workshop: May 19-21, 2004.