Dust emission from Haebes: Disks and Envelopes

1. Dust emission from Haebes: Disks and Envelopes A. Miroshnichenko (Pulkovo/Toledo) Z. Ivezic (Princeton) D. Vinkovic (UK) M. Elitzur (UK) • ApJ 475, L41 (1997; MIE) • ApJ 520, L115 (1999; MIVE) • in progress (VMIE)

2. CLOUD COMPRESSION  COLLAPSE  FRAGMENTATION  PROTOSTRAS M < Mc  PMS STARS  MS STARS M > Mc  MS STARS

3. Envelope evolves on free-fall time scale: • tff = 2x105 (104 cm-3/n)1/2 years • Hydrostatic PMS low-mass (M  3M) core evolution: • tpms ~ 3x107(M/M)3 years M  2 M T-Tauri 2 M M  10 M Herbig Ae/Be M  10–15 M no PMS

4. Protostellar Accretion Disks • R ~ 10 — 100 AU • M ~ .01 — .1 M Evidence in pre-main-sequence:  T Tau stars (M  2 M) ? Herbig Ae/Be stars (2 M M  10 – 15 M) IR ?

5. Required properties: • Emission from constant-T dust: I = B(T)[1 - exp(-)] • Optically thick: I = B(T) • Optically thin: I = B(T) 

6. Protostellar Accretion Disks Geometrically thin, optically thick: I = B(T), need temperature distribution

7. Illuminated Disk r  • Heating: • Cooling: Fem = T4 • Balance: T  r -3/4 (accretion too!) yields: F-4/3

8. Hillenbrand et al ‘92 • Group 1 (30): F -4/3, disks • Group 2 (11): flat or rising SED, star/disk with additional shell • Group 3 (6): small IR excess

9. Problems: • Hartman et al ’93: accretion rates are excessive • Di Francesco et al ’94: group 1 IR emission is extended!

10. Spherical, optically thin shell: T  r -1/2 with  r -p, - get F -(p - 1)( + 4)/2 Since  ~ 1–2, p ~ 3/2 gives F-4/3

11. Steady-state accretion to point source: Free fall: i.e. v  r-½ so

12. Depends mostly on type of dust grains overall optical depth density profile DOES NOT depend on dimensions density scale luminosity SCALINGIvezic & Elitzur ’95,’97 The emission from radiatively heated dust DUSTY: http://www.pa.uky.edu/~moshe/dusty/

13. MIE ’97:   r -3/2

14. Mannings & Saregnt ’97: 2.6 mm incompatible with MIE: V ~ 102–103 — nonsense! In particular MWC480 MWC683 MS V > 103 600 MIE V = 0.4 0.3 Conclusion: DISKS!

15. indeed:

16. However… Extrapolate from 2.6 mm with F1/3 — too little 2.2 m! • IR best explained with optically thin shells, inconsistent with mm • mm emission best explained with optically thick disks, inconsistent with IR Also, MWC 137 imaging: (50 m) = 66” 2” (100 m) = 58” 2” How can that be?

17. Disk Imbedded in Envelope:

18. envelope disk Disk Imbedded in Envelope: envelope ( -1.5): T  r –0.36 “standard” disk: T  r –0.75 • At the same radius, disk is cooler than envelope • Smaller disk still contains cooler material

19. MIVE ‘99 f = f,disk + (1 - )f,env

20. Implications: • Disk + Envelope resolves all discrepancies • 2 distributions: • Disk: compact mm emission • Envelope: • IR emission • Disk heating • ~ 10-8 Myr –1, Lacc ~ 0.1 L • v ~ 0.1— no molecules • SED + multi- imaging — essential for finding disks

21. ??? Uniqueness ??? Chiang & Goldreich ’97: • Disk surface layer may mimic shell • Equivalent envelope: V R*/Rsub • However: V ~ 0.1, R*/Rsub ~ 0.01

22. AB Aur:

23. Images: NICMOS Grady et al ‘97 Mannings & Sargent ‘97

24. VMIE, in progress Marsh et al ‘95

25. 3’ Herbig, 1960: 15 min exposure: SU Aur AB Aur 60 min exposure: