Small Magellanic Cloud Reaching The Outer Edge Noelia

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Small Magellanic Cloud: Reaching The Outer Edge? Noelia E. D. Noël & Gallart 2007,

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

ü Introduction • Data • The SMC Outskirts • Surface Brightness Profile • Discussion

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

Faint Outskirts of Galaxies • Host clues about the galaxy assembly processes. • Sandage

Faint Outskirts of Galaxies • Host clues about the galaxy assembly processes. • Sandage (1962) first discovered faint red stars extended beyond IC 1613’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) with 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 old population at ~5. 5 kpc from the SMC center but only young stars at ~7 kpc Breaking News, IAC, 18 de diciembre 2007

Faint Outskirts of Galaxies (cont. ) Recently, Noël et al. (2007) presented the age

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

But… how is the actual stellar content in the outer parts? . . Two

But… how is the actual stellar content in the outer parts? . . Two differentiated stellar components? i. e. do d. Irr 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

 • Introduction üData • The SMC Outskirts • Surface Brightness Profile • Discussion

• Introduction üData • The SMC Outskirts • Surface Brightness Profile • Discussion Breaking News, IAC, 18 de diciembre 2007

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

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

Fields from Noël et al. (2007) -76º B, R images 2. 2 m at

Fields from Noël et al. (2007) -76º B, R images 2. 2 m at La Silla Mosaic 2048 x 4096 CCDs 34’ x 33’ (0. 64 x 0. 615 kpc) -78º Breaking News, IAC, 18 de diciembre 2007

 • Introduction • Data ü The SMC Outskirts • Surface Brightness Profile •

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

CMDs of the SMC WFI fields 4. 7 kpc Mosaic field: 34’ x 33’

CMDs of the SMC WFI fields 4. 7 kpc Mosaic field: 34’ x 33’ 5. 6 kpc 6. 5 kpc Foreground stars’ contamination was simulated using the TRILEGAL code (Girardi et al. 2005) Breaking News, IAC, 18 de diciembre 2007

CMDs of the SMC WFI fields with Ba. STI isochrones (Pietrinferni et al. 2004)

CMDs of the SMC WFI fields with Ba. STI isochrones (Pietrinferni et al. 2004) 4. 7 kpc 4. 7 Z=0. 002: 1, 2, 3 Gyr Z=0. 001: 6, 7, 10, 13 Gyr 6. 5 kpc 5. 6 kpc • 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

CMDs of the SMC WFI fields 4. 7 kpc Mosaic field: 34’ x 33’

CMDs of the SMC WFI fields 4. 7 kpc Mosaic field: 34’ x 33’ 5. 6 kpc 6. 5 kpc Foreground stars’ contamination was simulated using the TRILEGAL code (Girardi et al. 2005) Breaking News, IAC, 18 de diciembre 2007

 • Introduction • Data • The SMC Outskirts ü Surface Brightness Profile •

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

B (mag/arcsec 2 ) Surface Brightness in the B band • Eastern fields •

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

 • Introduction • Data • The SMC Outskirts • Surface Brightness Profile ü

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

Ø If intermediate-age and old stars were formed at their current position, the SMC

Ø If intermediate-age and old stars were formed at their current position, the SMC is more extended and more massive than previously thought Ø Stars unlikely represent tidal debris torn off through interactions MW-LMC-SMC since the falling surface profile is well fit by exponential disk Ø 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 Ø 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

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

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