Paola Caselli School of Physics and Astronomy FACULTY OF MATHEMATICS & PHYSICAL SCIENCES Protoplanetary disks INITIAL CONDITIONS Boley 2009 Quiescent molecular clouds High-mass star forming regions Pre-stellar cores 13CO(1-0)-FCRAO Narayanan et al. 2008 Nearby cluster forming regions 1.3 mm - IRAM 30m Ward-Thompson et al. 1999 Composite Spitzer Gutermuth et al. 2008 Herschel/PACS-70µm Henning et al. 2010
Protoplanetary disks Quiescent molecular clouds High-mass star forming regions Pre-stellar cores 13CO(1-0)-FCRAO Narayanan et al. 2008 Boley 2009 1.3 mm - IRAM 30m Ward-Thompson et al. 1999 Nearby cluster forming regions Composite Spitzer Gutermuth et al. 2008 Herschel/PACS-70µm Henning et al. 2010
Outline The starting point: pre-stellar cores - Herschel first detection of (cold) water vapor The dawn of protoplanetary disks Pre-stellar cores in high-mass star-forming regions - ALMA Cycle 0 data
Freeze-out & deuterium fractionation Color: dust emission Color: N 2 H + (1-0) N 2 D + (2-1) peaks at dust peak Caselli et al. 1999, 2002: D-fraction increases toward the core center, as predicted by theory (Dalgarno & Lepp 1984). N 2 D + /N 2 H + ~0.2 (~10,000 times the cosmic D/H) N 2 H + (1-0) peaks away from dust peak
ortho-h 2 D + in pre-stellar cores The o-h 2 D + line is strong and its emission is extended ~5000 AU Only models including all multiply deuterated forms of H 3 + can reproduce these data (Roberts et al. 2003; Walmsley et al. 2004; Aikawa et al. 2005) Caselli et al. 2003, 2008 Vastel et al. 2006 (see also Parise et al. 2010) o-h 2 D + CSO N 2 H + (1-0) IRAM N 2 D + (2-1) IRAM
Deuterated species are good probes of pre-stellar core central regions! N(NH 3 ) @ VLA USING INTERFEROMETERS D-fractionation increases to ~0.4 in the central 3000 AU. The gas temperature drops to ~6 K in the central 1000 AU At 1000 AU (~ 10 6 cm -3 ): no significant NH 3 freeze-out N(NH 2 D) @ PdBI L1544 Loss of specific angular momentum toward small scales (factor of ~15 from 10000 to 2000 AU). Crapsi, Caselli, Walmsley & Tafalla 2007
The physical structure of pre-stellar cores Static and contracting Bonnor- Ebert sphere Simple CO chemistry (freeze-out + photodissociation) Radiative energy balance (+photoelectric heating) Radiative transfer ζ~ 1x10-17 s -1, fluffy grains, n c ~2 10 7 cm -3 within 500 AU v inf ~ 0.1 km s -1 at 1000 AU CO desorption rate: ~30 standard value. N 2 H + (1-0) (Keto & Caselli 2008, 2010)
The pre-stellar core physical/chemical structure??? (Caselli 2011, IAU 280)
2010 Data Caselli et al. 2010
B68 The two classes of starless cores L1544 Keto & Caselli 2008
FIRST DETECTION OF WATER VAPOR IN A PRE-STELLAR CORE Caselli, Keto, Bergin, Tafalla, Aikawa, Douglas, Pagani, Yildiz, van der Tak, Walmsley, Codella, Nisini, Kristensen, van Dishoeck 2012, ApJL
KEY PHENOMENA: / 10 4 c.r.-uv: yes c.r.-uv: no x(h 2 O) 10-9 - maintained by FUV photons produced by c.r. (total mass of water vapor: ~0.5 Earth masses; total mass of water ice: ~2.6 Jupiter masses). n H 10 6 cm -3, to explain H 2 O emission. Contraction motions.
15 N-fractionation? (Bizzocchi et al. 2010, 2013) 14 N/ 15 N = 1050±220 14 N/ 15 N in PSC lower than protosolar value! disagreement with model predictions (see also Wirström et al. 2012; Hily-Blant et al. 2013) Gerin et al. 2009 14 N/ 15 N = 1110±240 14 N/ 15 N
The dawn of protoplanetary disks Boley 2009 Ilee, Boley, Caselli et al. 2011
Douglas, Caselli, Ilee, Boley et al. 2013, submitted: ALMA SIMULATIONS CASA simulation of ALMA observations of dust continuum emission at 300 GHz of a 0.39 M self-gravitating protoplanetary disks around 1M star (hydrodynamical simulation of Boley et al. 2009) + spectral line simulations (not shown) using 3D radiative transfer.
Deuteration in massive star forming regions (Fontani, Palau, Caselli et al. 2011) Massive starless cores embedded in quiescent Infrared Dark Clouds See also Chen et al. (2010), Vasyunina et al.(2010), Pillai et al. (2011)
Pre-stellar cores in massive star forming regions ALMA Cycle 0 N 2 D + (3-2) data have allowed us to locate and study massive pre-stellar cores embedded in infrared dark clouds, precursors of high-mass stars and stellar clusters. Tan et al. 2013 Constraints on star formation theories (Turbulent Core Accretion Model favored important role played by magnetic fields).
ortho-to-para H 2 ratio Combining ALMA and CARMA data: large D-fractions (N 2 D + /N 2 H + ~1). N 2 D + /N 2 H + Needed large freezeout (> 100) and a few million years (~ t amb ) to reproduce observations. Kong, Caselli, Tan & Wakelam, in prep. Kong, Tan & Caselli, in prep.
SUMMARY The initial conditions of star formation - low-mass (i) T c ~6K f D (CO) > 10 D frac > 0.2 subsonic contraction grain growth (ii) (cold) water vapor: importance of FUV photons produced by cosmic rays. Young protoplanetary disks (i) Spiral structure can be detected with ALMA Band 7 at a wide range of inclination angles. (ii) OCS, H 2 CO, C 17 O and HCO + allow to probe the whole disk. Star formation & environment - massive/clustered (i) Beginning to see similarities with low-mass: CO depletion, deuteration, virialization; (ii) Chemical ages similar to ambipolar diffusion time.