Comparison of PhotometricAnd Spectroscopic Redshifts

SCUBA beam (850 m)

Atacama beam (350 m)

Atacama FOVAtacama FOV

The AtacamaThe AtacamaTelescope bolometerTelescope bolometercamera’s large FOVcamera’s large FOVand high angularand high angularresolution provide aresolution provide apowerful tool inpowerful tool inmeasuring magneticmeasuring magneticfields, by observingfields, by observingthe polarizationthe polarizationof FIR dust of FIR dust emission.emission.NGC2024

[Image: Mathews et al. 2002]

The FIR emissionOf dust is polarizedAt the level betweenA few and several %(Hildebrand, Dragovan &Novak 1984).

• Most PMS stars of < 3—4 solarm are thought to have circumstellar disks• Disks last a few Myr, until they dissipate• Planets form during that phase• Disks’ sizes are thought to vary widely, between a few 10’s and few 100 AU• Disks’ masses also vary widely, about on average a few % of the stellar mass• Disks’ temperatures are consistent with irradiation by the star, hence they exhibit strong thermal gradients• Inner disk morphology can be studied via scattered radiation in the NIR• Understanding of disks’ physics requires measurements of dust mass, which radiates in the FIR• Outer disk structure is tidally disrupted by the presence of planets

Circumstellar DisksCircumstellar Disks

Flu

x (

Jy

)

Wavelength (m)

Heinrichsen et al.1998SED of Disk around Vega go

SOFIA at 38 m

Atacamaat 200 m

SIRTFat 38 m

LMT at1100 m

VegaVega EriEri

.

Scuba beam at 850 mm Atacama beam at 200 mm

SCUBA5-sigma10,000secPWV 1.5mm

JCMTConfusionLimit

Atacama5-sigma10,000secPWV 0.3mm

AtacamaConfusionLimit

LMT5-sigma10,000secPWV 1.5mm

LMTConfusionLimit

Atacama5-sigma10,000sec

AtacamaConfusion Limit

Atacama5-sigma10,000secPWV 0.3mm

AtacamaConfusionLimit

Surface error budgetSurface error budget(micron) and pointing(micron) and pointingError (arcsec) for the Error (arcsec) for the LMT, ALMA and the LMT, ALMA and the Proposed Atacama Proposed Atacama FIR/submm TelescopeFIR/submm Telescope

Both LMT and ALMA telescopeWill operate without dome/windscreenProtection. Their surface errorBudgets are designed for operationIn up to 10 m/s winds.