1. Small Magellanic Cloud: Reaching The Outer Edge? Noelia E. D. Noël Noël & Gallart 2007, ApJL, 665, 23 Breaking News, IAC, 18 de diciembre 2007

2. Introduction Data The SMC Outskirts Surface Brightness Profile Discussion Breaking News, IAC, 18 de diciembre 2007

3. Host clues about the galaxy assembly processes. Sandage (1962) first discovered faint red stars extended beyond IC1613’s center. Controversy: some authors affirm the outer faint stellar envelopes evidence old stellar halos, others suggest they are tidal debris, while others find a range of ages. SMC studies of outer parts began with Gardiner & Hatzidimitriou (1992) withGardiner & Hatzidimitriou CMDs reaching R~20 up to ~6 kpc in the LMC direction Carbon stars were detected in outer regions of the SMC (e.g. Kunkel 2000) Recent bursts of star formation were found in the Wing area (Demers & Battinelli 1998) Harris (2007) analyzed the MCs Bridge region and found intermediate-age and oldHarris (2007) population at ~5.5 kpc from the SMC center but only young stars at ~7 kpc Faint Outskirts of Galaxies

4. SMC CMD Gardiner & Hatzidimitriou (1992) Breaking News, IAC, 18 de diciembre 2007

5. C-R R-I C-R R-I Breaking News, IAC, 18 de diciembre 2007 R,I 5.5 kpc 7 kpc Harris (2007)

6. Faint Outskirts of Galaxies (cont.) Recently, Noël et al. (2007) presented the age distribution of 12 SMC fields through unprecedented deep CMDs: Breaking News, IAC, 18 de diciembre 2007

7. But… how is the actual stellar content in the outer parts?.... Two differentiated stellar components? i.e. do dIrr have stellar halos? (MW-like ones: old, metal poor, devoid of gas, kinematically hot) Smooth gradient of stellar ages? e.g. star formation shrinking with time? Breaking News, IAC, 18 de diciembre 2007

8. Introduction Data The SMC Outskirts Surface Brightness Profile Discussion Breaking News, IAC, 18 de diciembre 2007

9. Small Magellanic Cloud Location smc lmc Milky Way Breaking News, IAC, 18 de diciembre 2007

10. B, R images 2.2m at La Silla Mosaic 2048x4096 CCDs 34’ x 33’ (0.64 x 0.615 kpc) -78º -76º Breaking News, IAC, 18 de diciembre 2007 Fields from Noël et al. (2007)(2007)

11. Introduction Data The SMC Outskirts Surface Brightness Profile Discussion Breaking News, IAC, 18 de diciembre 2007

12. CMDs of the SMC WFI fields 4.7 kpc 5.6 kpc 6.5 kpc Mosaic field: 34’ x 33’ Breaking News, IAC, 18 de diciembre 2007 Foreground stars’ contamination was simulated using the TRILEGAL code (Girardi et al. 2005)

13. CMDs of the SMC WFI fields with BaSTI isochrones (Pietrinferni et al. 2004) 4.7 kpc 5.6 kpc 6.5 kpc 4.7 kpc Z=0.002: 1, 2, 3 Gyr Z=0.001: 6, 7, 10, 13 Gyr Presence stars as young as ~3 Gyr old at 5.6 kpc There is still galaxy at 6.5 kpc from the SMC center Lack of blue extended Horizontal Branch Breaking News, IAC, 18 de diciembre 2007

14. CMDs of the SMC WFI fields 4.7 kpc 5.6 kpc 6.5 kpc Mosaic field: 34’ x 33’ Breaking News, IAC, 18 de diciembre 2007 Foreground stars’ contamination was simulated using the TRILEGAL code (Girardi et al. 2005)

15. Introduction Data The SMC Outskirts Surface Brightness Profile Discussion Breaking News, IAC, 18 de diciembre 2007

16. r (arcmin) B (mag/arcsec 2 ) Surface Brightness in the B band Simulation of foreground stars Eastern fields Western fields Southern fields WFI fields analyzed here Dot-dashed boxes: portion of CMD devoided of SMC stars Solid lines: area where SMC stars are expected Breaking News, IAC, 18 de diciembre 2007

17. Introduction Data The SMC Outskirts Surface Brightness Profile Discussion Breaking News, IAC, 18 de diciembre 2007

18.  If intermediate-age and old stars were formed at their current position, the SMC is more extended and more massive than previously thought  Stars unlikely represent tidal debris torn off through interactions MW-LMC-SMC since the falling surface profile is well fit by exponential disk  SMC disk is dominating over a possible old MW-like halo (if it does exist!) in agreement with the results for the LMC (Gallart et al. 2004), pointing out the importance of reaching the old MS turnoffs  More studies farther away from the SMC center and with larger spatial coverage are needed to confirm the actual extent of the SMC Breaking News, IAC, 18 de diciembre 2007

19. FIN… GRACIAS!!!! Breaking News, IAC, 18 de diciembre 2007