1. Universidad de Concepción
Planetary Nebulae as Resolved Stellar Tracers: kinematics, abundances, and X-ray binaries
Aaron J. Romanowsky
Universidad de Concepción

2. Planetary Nebulae as stellar tracers
Unique probe for regions of
low stellar surface brightness }
Abundances
Spatial distribution
Distances
Kinematics }
~15 Mpc w/
resolved stars
~100 Mpc w/
PNe
(Gerhard et al. 2005)

3. Planetary Nebulae basics
Post-AGB stage for MS stars of M :
cast-off envelope ionized by remnant core;
luminosity up to 6000 L , ~104 yr lifetime
(Marigo et al. 2001)

4. Extragalactic Planetary Nebulae 10% of the energy comes out at 5007 Å
(“nebulium”: Huggins & Miller 1864)
Planetary Nebulae
→ use narrow-band filter for high contrast

5. PNe: slitless spectroscopy
5' x 2' (1 kpc x 0.5 kpc) field in M31 (Merrett et al. 2006)

6. PNe as tracers of intergalactic stars
CWRU Burrell Schmidt image
of Virgo Cluster core
1.5°×1.5° (200×200 kpc)
to μV = 29.6
(Mihos et al. 2005)
PNe also trace
low light levels,
uniquely trace
kinematics
M86
M84
M87
FIGSS survey of Fornax Cluster with Baade+IMACS
(Romanowsky et al.)

7. PN luminosity function as distance indicator
Characteristic PNLF with
bright cutoff M*5007 = -4.48
Weakly sensitive to metallicity (Ciardullo et al. 2002)
PNLF, Cepheid
distances to galaxies in
Virgo Cluster consistent
(PNLF metallicity correction applied)
(Feldmeier et al. 2004)

8. PNe as abundance tracers
Producers of C,N,(He),(O) → stellar evolution
Preservers of Ne,S,Arg,(He),(O) → galactic evolution
NGC 5128
(early-type merger
remnant at 4 Mpc)
(Peng et al. 2006)
Young LMC
N5128
LMC/SMC

9. PNe as abundance tracers
Producers of C,N,(He),(O) → stellar evolution
Preservers of Ne,S,Arg,(He),(O) → galactic evolution
NGC 4697
(L* elliptical at 11 Mpc)
(Méndez et al. 2005)
PN O,Hβ
Stellar Mg,Fe,Hβ
Suprisingly
metal-rich halo

10. PN kinematics in M31 Sb , MB = -21.2 D = 0.8 Mpc WHT+PN.S, WYFFOS:
Oct 2002, 2003
9 nights :
2615 PN
velocities
over 7 deg2
(Halliday et al. 2006;
Merrett et al. 2006)
× : approaching
× : receding

11. Stellar halo substructure in M31
Detected in deep
RGB counts
(Ibata et al. 2001;
Ferguson et al. 2002)
Northern spur
Key part of orbit undetectable against disk crowding
Southern stream

12. Halo stream kinematics
Friends-of-friends outlier algorithm with PN data (Merrett et al. 2003)
Initial data: ambiguous orbit direction
M32
New data:
orbit turning point;
stream not obviously
related to M32
nor to N spur

13. Star Streams in M31 Modeling with stellar velocities suggests
PN stream
is progenitor
of stellar stream
(Fardal et al. 2005)

14. PNe as kinematical tracers in elliptical galaxies
Angular momentum
Substructures
Orbit properties
Halo mass PN
Globular Cluster

15. PNe in NGC 3379 E1 , MB = -19.9 D = 10 Mpc Leo I central WHT+PN.S:
2002,2003
7 hrs :
186 PN velocities
to 8 Reff ,
v = 20 km/s
Douglas et al., ApJ, submitted

16. Extended stellar/PN dispersion profiles
5 “ordinary” (L*)
ellipticals:
p(R) declining with R
(Ciardullo et al. 1993; Méndez et al. 2001; Romanowsky et al. 2003; Teodorescu
et al. 2005;
Douglas et al. 2007)
Population of ordinary ellipticals with low DM content?

17. Natural outcome of merger?
Dekel et al. 2005, Nature, 437, in response to Romanowsky et al. 2003, Science, 301, 1696

18. Natural outcome of merger?
Declining dispersions
produced by:
radial anisotropy
young PNe
flattened systems
D+05 simulations
N3379 data

19. Population issues: PNe trace (which) stars?
1. Color gradient  metallicity gradient
 [O III] gradient  systematic bias in PN detections
(Bright?) PNe from recent star formation
NGCs 4697, 5128 PNe (Méndez et al. 2005; Walsh 2006):
metallicity gradient flattens out in halo
NGC RGB CMD from HST+NICMOS
(Gregg et al. 2004):
mean halo abundance ~ Solar, no change w/ radius
mean age ~ 8-15 Gyr, no evidence for < 5 Gyr pop
1-2% young stars (< 1 Gyr) in ellipticals (Yi et al. 2005)
Test PN-stellar population connections empirically…

20. PNLF dependencies on population
M31
PNLF cutoff M* ~independent of age, metallicity
(except for most
metal-poor systems)
bulge
disk
…dip in PNLF at M*+4 seen in star-forming galaxies
halo
(Ciardullo 2005)

21. PNLF dependencies on population
PNLF normalization (specific frequency) α2.5 depends on galaxy color → but not strongly enough!
5-30% stars in
ellipticals with
AGB progenitor
mass ~2 M !
(age < 1 Gyr)
(Ciardullo 2005)

22. PNLF : theoretical puzzles
Young & old populations should have AGB→PN stage corresponding to very different masses
→ so why are luminosities the same?
(Marigo et al. 2004)

23. PNLF : theoretical problems
Scenarios for PNLF universality:
young stars in ellipticals
extinction conspiracy
symbiotic stars: AGB → WD binary mass transfer (Soker 2006)
blue stragglers (Ciardullo et al. 2005)
→ Bright PNe all binary progenitors?
(Sun will not become PN??)
Works well for PNLF, α2.5
Observational constraints on BS fractions...?

24. PNe - stellar populations links in M31
(Merrett et al. 2006)
Disk kinematics
doesn’t correlate
with luminosity
→ PN kinematics
not contaminated by recent SF
No evidence for
significant
fluctuations
in PNLF, α2.5

25. PNe - stellar populations links in NGC 3379
Steeper profile from hypothetical young stars difficult to discern
Kinematics of stars, PNe consistent
(Douglas et al. 2007)

26. [OIII] emitter - X-ray source connections in M31
X-ray sources should ionize nearby ISM
6 M31 XRS-PN coincidences,
but offset ~5 pc!
Too fast for
SNR ejections
Co-members of
relic clusters?
Williams et al. (2004)

27. [OIII] emitter - X-ray source connections in M31
X-ray sources should ionize nearby ISM
Correlating PN.S
[OIII] catalogue in M31
with 75 Chandra+XMM supersoft sources
Only 2 possible
matches:
→ < 0.1-1% LX
re-emitted as [OIII]
(PNe re-emit as
much as 15% of LWD)
(Romanowsky & Di Stefano)

28. Summary
PNe trace resolved stellar densities, abundances, distances, kinematics
Need to know what makes PNe...