Diapositiva 1

1
The Chamaeleon II dark cloud
Scuola Nazionale di Astrofisica Il sistema
solare esterno e la missione Cassini - Formazione
stellare October, 10-15, 2005 Volterra (PI)
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Scientific case the IMF
Salpeter 1955 (ApJ 121, 161) IMF of the Solar
Neighborhood (dlog M, 0.4-10 M? )

• M1 M?
• -1.6
• Scalo 1998 ?? 0.5
• (In The Stellar Initial Mass Function, p.201)

• M
• Rising (Orion, Hillenbrand Carpenter 2000
  Pleiades, Bouvier et al. 1 998, etc)
• Deficit (T association Taurus, Luhman 2000
  Briceno et. al. 2002 IC348, Preibisch et al.
  2003 Muench et al. 2003)

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Cha II The survey
Age1-5 My (Hughes Hartigan 1992)
D17818 pc (Whittet et al. 1998)

• H? emission line objects (Schwartz 1991
  Hartigan 1993)
• class-I and class-II Infra-Red sources (Whittet
  et al. 1991 Prusti et al. 1992 Larson et al.
  1998)
• X-rays sources (WTT, Alcalà et al. 2000).

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Strategy
1. Color Magnitude Diagrams and theoretical
isochrones 2. Near-Infrared Colour-Colour
Diagrams 3. Effective Temperature
(2000(WFI2MASSSpitzer) ?L Teff (STURDUSTY
Spectra, Hallard Hauschildt 2000) 6. HR
diagram and Evolutionary tracks ? Mass Age
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Some results..

• Complet characterization of Cha II know
  population (Alcalà et al 2000)
• 2. First clue on Cha II IMF ? ??0.6,1, 0.1?M?1
  M?
• 3. Comparison with other regions ? Universal IMF
• 4. SFE2 , M(12CO) Mizuno et al. 2000
• 5. The first bona fide BD with a disk in the
  cloud
• 6. 24 new PMS star candidates
• 7. 7 BD candidates
• 8. To be continued.?
• substellar IMF?

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WFI Isochrones NextGen spectra by Allard
Hauschildt (1995) stellar radii byBaraffe et
al. 1998
Av by Cambresy 1999
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JHK from 2MASS (Two Micron All Sky Survey )
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STARDUSTY models Teff2000 K? Teff6000 K?
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• Teff2500200 K
• L0.010.20 L?
• R0.400.05 R?
• Mass0.02 M?
• Age 1.5-4 My

• Tdisk(BB)1400 K
• Rdisk? 3R

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• Cha II confirmed members

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• Cha II population would almost double
• SFE3
• ??0.4-0.8