Disks, Envelopes and Magne2c Field. Infall, Ou9lows and Magne2c Braking

Transcription

1 Disks, Envelopes and Magne2c Field Infall, Ou9lows and Magne2c Braking

2 Envelopes and Infall Signatures What is the evidence of infall in the envelope? How can ALMA strengthen the evidence? What is the evidence of rota2on in the envelope? Is the angular momentum conserved when gas collapses from large distances to small distances? What is the best evidence of large 100- AU rota2onally- supported disks in Class I objects? What is the connec2on between Class 0 and I disks? (e.g. Jørgensen, C.- F. Lee, Tyler Bourke, Shige Takakuwa)

3 Magne2c Field and Polariza2on What is the observed evidence for magne2c fields on the core scale and disk scale? How does the magne2c field affect the core collapse and disk forma2on? How can ALMA polariza2on observa2on help in this regard?

4 Kinema2c and Chemical Signatures Can we disentangle/differen2ate between rota2on and other possible kinema2c effects on large scales (i.e. turbulent mo2ons, infalling flows, etc.) in 'realis2c' cores? Can we tell observa2onally if angular momentum is being lost via magne2c braking?' What are the physical condi2ons of the ini2al disk - - and how much of the material we see in the solar system might trace itself to that state. How much material (meteorites/comets/planets) trace their chemical composi2on to the ini2al disk and can this be probed?

5 Other Considera2ons Does the evolu2onary status of the cores and the protostellar system ma\er? Yes! How do signatures of kinema2cs change Ou9low stripping late in the game, perhaps that is the reason why disks around Class I sources can grow to be large 3D effects and mul2ple systems do they help with reducing the strengths of magne2c braking?

6 Beware Things could be complicated!

7 RS Disk- making recipes, and their taste Recipe Advantages Disadvantages Observa3on? B/Ω misalignment Numerically proven Needs λ > [a few], and misalignment Ohmic decoupling Works (at large η) May need high ρ such as found at <1AU Envelope deple2on through either ou9lows or infall Expected to allow disks to grow S2ll unproven. May require a small seed disk. Hall torque Works (at large QH) Requires very large QH (dust grains may help). Turbulent reconnec2on diffusion Gravita2onal torques Basic limita2ons of ideal MHD. Simula2ons work. Ar2ficial simula2ons: numerical diffusion, turbulence driving B/envelope rota2on misalignment Look for small RS disks in Class 0: ALMA RS disk growth about the Class 0/1 transi2on. About 50% envelope/disk counter- rota2on: ALMA Specific kind of turbulence Lab experiments may help with theory problems. Spiral arms? MHD instabili2es Universal seems counterproduc2ve? Ambipolar diffusion Solves B flux problem seems to increase braking? Weak field HD and nearly HD models work Needs very large λ Very small field intensi2es Your own imagina2on Unlimited possibili2es Not always works Submit the proposal! Nature itself Makes disks reliably We do not know for sure how that s done SEARCH FOR EARLY CLASS 0 DISKS WITH ALMA

8 Some Reality Check

9 Resolu2on REALLY Ma\ers CARMA B-array, ~0.8 (110 AU) res. CARMA A-array, ~0.4 (55 AU) res. 9

10 Disks in Class 0 Phase l ~18 Class 0 protostars observed with resolu2on to detect disks (<= 80 AU) (e.g. Maury+10, Lee+09, Chiang+12, Murillo+13,...) - L1527, Per- emb14, L1448 IRS2, L1165, HH211, VLA1623A; have evidence of large disks - L1527 confirmed rota2onal support l HH211, L1448 IRS2, VLA1623A, L1165 have rota2on, Keplerian not yet confirmed l Large rota2onally supported disk frac2on could be 6/18 l ~33% Points to a variety of disk proper2es, likely linked to ini2al condi2ons ALMA can check! 4/22/13 ALMA Rocks! 10

11 Core Kinema2cs: Rota2on? AU AU Rest velocity CB230 NH 3 Magenta: Infalling Filament model l If cores are asymmetric, do velocity gradients really trace rotation? l Can we determine if Magentic braking is happening? 4/22/13 ALMA Rocks! 11

12 L1527: A Gradient Reversal 0.1 M sun 0.5 M sun 300 AU 0.1 M sun 0.5 M sun l Disk rotation opposite of large-scale gradient l Evidence that large scale kinematics do not probe rotation alone? 4/22/13 ALMA Rocks! 12

13 Chemical Tracers? Start with CO... Visser et al van Kempen, Kristensen et al Visser et al yellow: passive heated envelope green: bipolar jet red: UV heated cavity walls blue: small scale shocks along cavity walls

14 Chemical Tracers? Water is known to form at higher temperatures in abundance might chemically select hot inner gas - perhaps in a disk High J lines of other species? worry about contamina2on from other hot dense components one (crazy?) idea is X- rays - - when do they X- rays turn on - - they could produce molecular ions that would highlight structure Persson, Jørgensen, and Van Dishoeck