Surveys for Planetary Nebulae in the Magellanic Clouds

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 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 SMP 1978 Jacoby 1980 Sanduleak & Pesch 1981 Morgan & Good 1985 Meyssonnier & Azzopardi 93 Morgan 1995 Murphy & Bessel 2000 Jacoby & De Marco 2002 Galle, Winkler, & Smith* Jacoby & De Marco Number Found Number New Depth, mags 28 27 6 13 62 62 131 59 69 15 3 19 6 10 18 9 108 25 13 4 3 5 3 3 4 3 ? 6 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. 2 m CTIO 4 m Example: MB 233 – but, probably not a PN CTIO 4 m extends ~1 mag beyond ESO 2. 2 m ESO Workshop: May 19 -21, 2004

SMC Completeness 2+1 2 Most Recent Surveys +1 3 5 6 2 +2 5 12 7 4 7 8 Jacoby & De Marco (2002) • 10 fields of 0. 5° each (2. 2 M) • Depth of ~6 mags Jacoby & De Marco (in prep) • 6 fields, 3 new PN (CTIO 4 m) • Depth of ~7 mags • Not very productive Ø more depth doesn’t help Ø outer fields have few PN ESO Workshop: May 19 -21, 2004

“Modern” LMC Surveys Survey Team Number Found Number New Depth, mags SMP 1978 Jacoby 1980 Sanduleak 1984 28 27 25 3 19 13 3 5 3 Morgan & Good 1992 Morgan 1994 Leisy, Francois, & Fouqué 98 265 10 86 54 4 5 5 9 Jacoby & De Marco 15 10 7 ~1000* 136 7? Reid & Parker *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 Found Number New Depth, mags SMP 1978 Jacoby 1980 Sanduleak 1984 28 27 25 3 19 13 3 5 3 Morgan & Good 1992 Morgan 1994 Leisy, Francois, & Fouqué 98 265 10 86 54 4 5 5 9 Jacoby & De Marco 15 10 7 ~1000* 136 7? Reid & Parker *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 H stacked Leisy et al (in prep) • Many fields & new PN (2. 2 m) 5+10 Jacoby & De Marco (in prep) • 1 field, 10 new PN (4 m) • Depth of ~7 mags ESO Workshop: May 19 -21, 2004

The Clouds are a Special Place ¤ Nearest (by 10 X) 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 4 m spectrum of JD-17: H +[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 (<1 and 8 -10 Gyr) – Binary stars in old pops (common envelope evolution) ¤ Hints from M 33 ¤ Age? , metallicity? , IMF? 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. 5 X more ¤ LMC surveys are largely complete to 5 mags 3 X more Currently known, entire SMC With deeper survey (8 mags) 84 120 -170 Currently known, entire LMC With deeper survey (8 mags) 350* 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 N 66 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]/H > 1 ¤ 7 (28% of 25) new Jacoby & De Marco PN have strong [NII] ¤ Fraction of PN with [NII]/H > 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