Surveys for Planetary Nebulae in the Magellanic Clouds SMC LMC - - PowerPoint PPT Presentation

ESO Workshop: May 19-21, 2004

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

SMC LMC MW

The View from Cerro Tololo

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 24° 22°

RGB and AGB counts indicate the LMC subtends ~130 sq. deg.

SMP 78

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

4? 13 69 Galle, Winkler, & Smith* 7 4 15 Jacoby & De Marco Depth, Depth, mags mags Number Number New New Number Number Found Found Survey Team Survey Team 6 25 59 Jacoby & De Marco 2002 ? 108 131 Murphy & Bessel 2000 3 9 62 Morgan 1995 4 18 62 Meyssonnier & Azzopardi 93 3 10 13 Morgan & Good 1985 3 6 6 Sanduleak & Pesch 1981 5 19 27 Jacoby 1980 3 3 28 SMP 1978

*Magellanic Cloud Emission Line Survey

ESO Workshop: May 19-21, 2004

Technology Helps

Example: MB 233 – but, probably not a PN CTIO 4m extends ~1 mag beyond ESO 2.2m

The Clouds are easy targets with large format CCD mosaic cameras on large telescopes

ESO 2.2m CTIO 4m

ESO Workshop: May 19-21, 2004

SMC Completeness

Most Recent Surveys

Jacoby & De Marco (2002)

• 10 fields of 0.5° each (2.2M)
• Depth of ~6 mags

Jacoby & De Marco (in prep)

• 6 fields, 3 new PN (CTIO 4m)
• Depth of ~7 mags
• Not very productive

more depth doesn’t help

• uter fields have few PN

3 6 5 5 4 12 7 2 7 8 +2 2 2+1 +1

ESO Workshop: May 19-21, 2004

“Modern” LMC Surveys

7 10 15 Jacoby & De Marco 7? 136 ~1000* Reid & Parker Depth, Depth, mags mags Number Number New New Number Number Found Found Survey Team Survey Team 9 4 10 Leisy, Francois, & Fouqué 5 54 265 Morgan 1994 5 86 98 Morgan & Good 1992 3 13 25 Sanduleak 1984 5 19 27 Jacoby 1980 3 3 28 SMP 1978

*Candidates to be verified

ESO Workshop: May 19-21, 2004

“Modern” LMC Surveys

7 10 15 Jacoby & De Marco 7? 136 ~1000* Reid & Parker Depth, Depth, mags mags Number Number New New Number Number Found Found Survey Team Survey Team 9 4 10 Leisy, Francois, & Fouqué 5 54 265 Morgan 1994 5 86 98 Morgan & Good 1992 3 13 25 Sanduleak 1984 5 19 27 Jacoby 1980 3 3 28 SMP 1978

The pioneering surveys by Henize (1956), Lindsay (1961), Henize & Westerlund (1963), Lindsay & Mullan (1965), and Westerlund & Smith (1964) defined the extragalactic PN field.

*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)

• 1 field, 10 new PN (4m)
• Depth of ~7 mags

5+10

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

HST image of MA 1682 Diff [OIII]

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 (<1 and 8-10 Gyr) – Binary stars in old pops (common envelope evolution)

Hints from M33 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 1.5X 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

• f 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

1 1 1 1 2 3 4 5 6 7 8 9

ESO Workshop: May 19-21, 2004

[NII]/Hα Ratios: JD 10 – 18

10 11 12 13 14 15 16 17 18

ESO Workshop: May 19-21, 2004

[NII]/Hα Ratios: PN 19 – 25

19 20 21 22 23 24 25 Nova