1. Star Formation Research Now & With ALMA Debra Shepherd National Radio Astronomy Observatory ALMA Specifications: Today’s (sub)millimeter interferometers are becoming more powerful – yet ALMA will surpass them all by 2012: Color image of the G34 massive star forming cluster from the Spitzer GLIMPSE survey. G34.26 illustrates the formation of an O star (~20M o ) while the UC HII region and G34.4 MM shows a site forming only early B stars along a dense filament of gas. Current Capabilities Show spectrum below – a sample ALMA Band 6 spectrum taken on the SMT (Ziurys, et al.) These images represent very good VLA data of free-free continuum emission from ionized outflow gas toward forming, early B stars. Multiple VLA configurations allow increased sensitivity to low-level, complex structure. Resolution ~ 0.3” (700 AU at D = 2 kpc) RMS ~ 30 mJy/beam 2-4 hours on-source integration time. No velocity information. ALMA will resolve the disk outflow interface with many resolution elements while still recovering extended emission – the challenge will be to find appropriate chemical species that trace different parts of the disk and perhaps find adequate continuum to develop good continuum image over many GHz. With the Atacama Large Millimeter Array (ALMA) 100 AU = 0.3” at d=300pc ~ Highest ALMA resolution at 300 GHz = 1 mm (0.015”) ~ Highest ALMA resolution at 850 GHz = 350  m Jet escaping from UC HII region in G192.16 (young B2 star, 10 5 years old) McMaster University Ionized flow with wide opening angle, UC HII region not detected Large-scale outflow axis 1800 AU Ionized outflow Jet from companion protostar 2000 AU Ionized flow from early B protostar (pre-MS, 10 4 years old) – no UC HII region created yet. Observations & model of 7mm continuum Dynamics of ionized gas can be recovered with RRL observations but only for strongest sources, will likely need > 8 hrs on-source integration time Millimeter lines and continuum emission cannot be obtained with similar resolution and sensitivity. 1.4 pc Inset shows red- and blue-shifted CO(1- 0) emission made with the Owens Valley Millimeter Array. Each of the two mosaiced fields has roughly 9 hours on source integration time takin in multiple array configurations. RMS ~ 60 mJy/beam in channels with 1.3 km/s resolution. Spatial resolution ~ 3.5” (~13,600 AU at D = 3.9 kpc). Extended emission resolved out so relationship between the outflows and gas in extended filaments cannot be obtained at similar resolutions. Only the most massive flows and cores can be detected at this distance of 3.9 kpc ALMA will be able to image entire structures, and recover all size scales – relate outflows and embedded sources to larger scale structure and kinematics observed at the same resolution. Matched resolution with EVLA. Not easy at first! Obtain full census of star formation & cloud properties in dense filaments, not just small area. Study triggered star formation along SNR shocks as well as the shock dynamics in RRLs and molecular lines. Dynamics of ionized gas in RRLs, protostars (O star(s) & forming cluster) in mm continuum, shocks & gas in molecular lines. ELVA to map free- free continuum & RRLs at cm l’s O star UC HII region G34.26 Massive stars forming along SNR shock ALMA pre-production band 6 (1mm) spectrum taken at the SMT (Ziurys et al.) shows incredibly complex spectra toward SgrB2 (N). Must develop complex imaging & analysis tools to deal with information density! Continuum?Frequency 30 to 950 GHz (initially only 84-720 GHz) Bandwidth 8 GHz, fully tunable Spectral resolution 31.5 kHz (0.01 km/s) at 100 GHz Angular resolution 1.4 to 0.015” at 300 GHz Dynamic range 10000:1 (spectral); 50000:1 (imaging) Flux sensitivity 0.2 mJy in 1 min at 345 GHz (median conditions) Antenna complement 50 (64) 12m antennas, 12-7m antennas, 4-12m SD antennas Polarization All cross products simultaneously Parts of this research made possible by the Origins Institute