DUSTY04 – Paris ALMA and ISM / Star Formation Stéphane GUILLOTEAU Observatoire de Bordeaux

26 Octobre 2004S.Guilloteau – ISM & Star Formation What’s new with ALMA ? (compared to current mm arrays) A fast instrument  surveys become possible A sensitive instrument  weak lines, small objects become accessible High angular resolution  details of star formation Wide field imaging with ACA  from large to small scales Wide frequency coverage  wide range of physical conditions can be adressed Polarisation But a large survey, at high angular resolution, in full polarisation, over arcmin scales, in several lines, would take forever  Choices will have to be made

26 Octobre 2004S.Guilloteau – ISM & Star Formation Star Formation Physics Initial mass function from large scale surveys (gas + dust images) Polarization: the role of magnetic fields Complete samples in several types of star-forming regions Velocity field (accretion) in envelopes of Class 0 protostars (non)-Keplerian disks around YSOs: –Star masses from disk kinematics –Evolutionary tracks of proto / PMS stars –Evolutionary status of disks –Planet formation Binarity (70 %): gas + dust distribution, tidal truncation of inner / outer disks

26 Octobre 2004S.Guilloteau – ISM & Star Formation Structure of the ISM Mosaics of a few arcmin squared, at angular resolution of 0.4 to 2”, could reveal the filamentary structure of the ISM (e.g. Pety & Falgarone 2004) High spectral resolution required to reveal non Gaussian line wings which trace turbulence What is the inner scale of the turbulence cascade ? Chemistry in shocked regions or vortices? Several molecular lines required

26 Octobre 2004S.Guilloteau – ISM & Star Formation Initial Conditions of Star Formation The link between condensations and IMF (Motte et al 1998) Can be extended to much lower masses, and/or very different environments (e.g. High mass star forming regions)

26 Octobre 2004S.Guilloteau – ISM & Star Formation Initial Conditions of Star Formation Density and temperature gradients in starless cores Molecular chemistry of cloud cores: depletion and deuteration Searching for infall motions (e.g. Di Francesco et al 2001). Beware of interferometer filtering (Gueth et al 1997)

26 Octobre 2004S.Guilloteau – ISM & Star Formation Massive Stars Formation by collapse or merging ? High angular resolution of massive protostars may help solving this issue Proper motions studies may be needed  very high angular resolution + long term monitoring Will outflow contaminate the picture (Beuther et al 2004)

26 Octobre 2004S.Guilloteau – ISM & Star Formation Fragmentation & Multiplicity Example from Looney et al 1997 Small number of proto-binaries detected so far Comparison of fraction of binaries in proto-stars and PMS stars constrain theories Dependence upon environment (isolated vs cluster) is critical  surveys of different regions required

26 Octobre 2004S.Guilloteau – ISM & Star Formation Tidal Truncation It does exist (e.g. GG Tau, Guilloteau, Dutrey & Simon)

26 Octobre 2004S.Guilloteau – ISM & Star Formation Tidal Truncations But not always: AS 205 ALMA can study significant samples rather than a few objects

26 Octobre 2004S.Guilloteau – ISM & Star Formation Disk around young stars Current arrays have done about 20 sources... (e.g. IRAM PdB Survey) ALMA sensitivity 50 times better... ALMA could do hundreds of sources in continuum, to a much better level, and at much higher angular resolution

26 Octobre 2004S.Guilloteau – ISM & Star Formation Zooming on inner disks Nice, circularly symmetric, Keplerian disks don’t really exists E.g. AB Aur 1.3 mm image at 0.6” resolution: “spiral” density enhancements 100 AU from the star (black: IR from Fukagawa et al 2004, White: mm from Piétu et al 2004) Are such phenomena comon? Long-lived ?

26 Octobre 2004S.Guilloteau – ISM & Star Formation Stellar Masses (and more) From the (Keplerian) rotation curve, measured from CO (Simon et al 2000) Temperature from CO isotopes (Dartois et al 2003) A sample of 40 sources, in CO and its isotopes at 0.2” resolution requires 2600 hours of ALMA !

26 Octobre 2004S.Guilloteau – ISM & Star Formation Transition Disks ? ALMA can image the “débris” disks around (young) stars But also perhaps unveil the transition stage between proto-planetary disks and “débris” disks Small disks just being found: e.g. BP Tau (Dutrey et al 2003) But studies will require long integration time even with ALMA (>> 10 hours / object)

26 Octobre 2004S.Guilloteau – ISM & Star Formation Long term schedule Proper motions can be measured with ALMA Clumps in “debris” disks (  evidence for planets ?) Orbital motions of proto-stellar condensations in massive star forming regions  Plan in advance and for the long term...

26 Octobre 2004S.Guilloteau – ISM & Star Formation Chemistry Chemistry is a major issue in all components of the ISM ALMA will be invaluable in many areas, due to high sensitivity, angular resolution and frequency coverage (especially sub-mm domain) Examples –Diffuse ISM in absorption against quasars (e.g. Lucas & Liszt) –Shock chemistry in outflows –Chemistry in proto-stellar envelopes –Chemistry in proto-stellar disks –Hot core chemistry –PDR regions

26 Octobre 2004S.Guilloteau – ISM & Star Formation Diffuse Clouds e.g. Sulfur chemistry (Lucas & Liszt 2003) ALMA can reach much fainter sources ALMA can reach much weaker lines (isotopes...)

26 Octobre 2004S.Guilloteau – ISM & Star Formation Outflows High angular resolution required to resolve multiple shocks in outflow system (L1157, Bachiller & Perez- Guttierez 1997)

26 Octobre 2004S.Guilloteau – ISM & Star Formation Hot Cores Angular resolution is essential to separate multiple cores E.g. W3(OH) (Wyrowski et al 1997)

26 Octobre 2004S.Guilloteau – ISM & Star Formation Proto-Stellar envelopes Short spacing information is essential (i.e. ACA and total power) E.g. N 2 H + in IRAM (Belloche et al 2002)

26 Octobre 2004S.Guilloteau – ISM & Star Formation Photo Dissociation Regions e.g. Orion Bar (Lis & Schilke 2003) (False color: CO(7-6) Black contours: H 2 v = 1 0 S(1) Red contours: O I 1.32 μm Blue contours: H 13 CN(1-0) White contours: 13 CO(3-2) ) Sub-mm data (for high excitation lines) and short-spacing information essential