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 Survey Team Number Number Number Number Depth, Depth, Found Found New New mags 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 • Depth of ~6 mags +2 5 12 7 Jacoby & De Marco (in prep) • 6 fields, 3 new PN (CTIO 4m) • Depth of ~7 mags 4 7 8 • 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, Survey Team Number Number Depth, Found New mags 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 Survey Team Number Number Number Number Depth, Depth, Found Found New New mags 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 H α stacked Leisy et al (in prep) • Many fields & new PN (2.2m) Jacoby & De Marco (in prep) • 1 field, 10 new PN (4m) 5+10 • 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: H α +[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 – M V , 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
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