4 What is ALMA? ALMA will be the worlds largest interferometer for millimetre and sub-millimetre wavelengths It is in full construction in the Atacama desert Collaboration between ESO, NRAO, and NAOJ Three sites in Chile
7 ALMA specifications 54 12-m antennas,12 7-m antennas, at 5000 m site 192 antenna stations Array configurations between 150 m and ~15-18 km Angular resolution ~40 mas at 100 GHz (5 mas at 900 GHz) 10 bands in range 31 to 950 GHz (350-7000 µm) Dual polarization ALMA vs Herschel (3.5 m) Wavelengths: 350 – 7000 µm vs 70 – 550 µm Angular resol: 1 – 0.01 vs 6– 35 Lifetime : 30 years vs 3.5 years
9 Status February 2011 8 antennas on site 5000m site and working as interfer. Fringes observed in 4 bands Phase closure achieved ~30 antennas delivered to site in total
ARC meeting - March 2011 10 Main science goals Detect and map CO and [C II] in a Milky Way galaxy at z=3 in less than 24 hours of observation Map dust emission and gas kinematics in proto- planetary disks Massive stars (wind acceleration, photosphere,…) Provide high fidelity imaging in the (sub)millimeter at 0.01 arcsec resolution
ARC meeting - March 2011 13 Early science When? Call in early April, deadline 8 weeks after Observations: Fall 2011 What? 16 antennas, 2 compact configurations Bands 3, 6, 7 and 9 (3mm, 1mm, 0.85mm, 0.45mm) Baselines up to 250m (maybe 500m) At most 30% of the available time for the first call Only service mode Typical project for ES should be few hrs (4-10) and deliver result!
ARC meeting - March 2011 16 Circumstellar disks Imaging protoplanetary disks Accretion, rotation and outflow Molecular gas content, chemistry and removal mechanisms How gaps are created by planets Imaging debris disks Dust evolution, radial dependence of grain properties Following planets with dust rings Probe the growth of dust in disks and constrain planet formation theories
ARC meeting - March 2011 17 Circumstellar disks 1 AU
ARC meeting - March 2011 18 Young Stellar Objects
ARC meeting - March 2011 19 Imaging proto-planets
ARC meeting - March 2011 20 Imaging proto-planets DAngelo et al. 2002
21 Debris disks Optically thin dust in thermal equilibrium with the star : traces mass of debris or infer mass of comets shows scale of planetary system ARC meeting - March 2011 Early ScienceHerschel
21 Debris disks Optically thin dust in thermal equilibrium with the star : traces mass of debris or infer mass of comets shows scale of planetary system ARC meeting - March 2011 Early ScienceHerschel Connection?
ARC meeting - March 2011 22 Debris disks Dust trapped in resonances by migrating planets in disk
ARC meeting - March 2011 23 Debris disks Content of residual gas in debris disks Deep spectroscopy Comet collisions should evaporate H 2 O, CO Method to study exo-comet composition
ARC meeting - March 2011 7 Early science Limitations to be kept in mind: Limited number of antennas (Resolution not better than existing interferometers) Limited sensitivity as compared to full ALMA (Sensitivity ~10x better than existing interferometers) Imaging requires Earth rotation synthesis Limited angular resolution No multi resolution available Limited time available for science observations ALMA ES capabilities and constraints are best suited for limited scope Projects (as opposed to large scale surveys) Typical project for ES should be few hrs (4-10) and deliver result!
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