Airs the antarctic infrared survey
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AIRS: The Antarctic Infrared Survey. James M. Jackson Institute for Astrophysical Research Boston University. Our Local Universe: Key Astrophysical Questions. Earliest stages of planet formation Nature and number of brown dwarfs Earliest stages of star formation.

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Airs the antarctic infrared survey

AIRS: The Antarctic Infrared Survey

James M. Jackson

Institute for Astrophysical Research

Boston University

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Our local universe key astrophysical questions

Our Local Universe:Key Astrophysical Questions

  • Earliest stages of planet formation

  • Nature and number of brown dwarfs

  • Earliest stages of star formation

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Key science is uniquely addressed by thermal infrared observations

Key Science is Uniquely Addressed by Thermal Infrared Observations

  • Wavelengths of 3 to 30 mm correspond to black-body temperatures of 100 to 1000 K

  • Infrared emission probes cooler objects:

    • Protoplanetary disks

    • Brown dwarfs

    • Star forming regions

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James jackson

RCW 38

Another essential advantage:

Infrared penetrates dust clouds

(M. Petr 2000)

VLT-FORS optical

VLT-ISAAC infrared (JHK)

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Lada 2002


Why antarctica for infrared studies it s cold

Why Antarctica for infrared studies?It’s COLD!

  • Reduced infrared thermal background

  • Telescopes and atmosphere emit in the thermal infrared

  • Antarctic mean temperature ~ –50 C

  • IR backgrounds typically 20 to 100 times smaller than at temperate sites

  • Excellent sensitivity

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Greatly reduced infrared sky brightness

H

J

K

M

L

Kd

Greatly Reduced Infrared Sky Brightness

The sky background is 20 – 100 times smaller at the South Pole compared with Mauna Kea

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Phillips et al. 1999


Wide field infrared surveys are essential to study the local universe 2mass

Wide-field infrared surveys are essential to study the local Universe: 2MASS

2MASS 2mm

optical

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www.ipac.caltech.edu/2mass


Wide field infrared imaging surveying large areas

Wide-Field Infrared Imaging: Surveying Large Areas

  • Discover huge numbers of new objects for follow-up by larger telescopes or interferometers

  • Obtain statistically significant samples

  • BUT 2MASS still suffers from extinction

  • Longer wavelengths penetrate dust better

  • There are no large-scale 3 mm < l < 5 mm surveys

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The antarctic infrared survey

The Antarctic Infrared Survey

  • The next generation Antarctic IR telescope

  • 2 meter aperture

  • 2-5 mm wide-field imaging camera

  • Essential step in eventual development of large (15 m) Antarctic IR telescopes and multi-element interferometers

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The antarctic infrared survey1

The Antarctic Infrared Survey

  • Simultaneous K and L band survey

  • 8,000 square degrees (d < -38o)

  • Same sensitivity at L-band as 2MASS at K-band (5s limiting magnitude of 15.0)

  • Detect all 2MASS objects with flat colors

  • Discover hundreds of thousands of redder objects

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Formation of planets protoplanetary disks

Formation of Planets: Protoplanetary Disks

  • Dusty disks have temperatures perfectly matched to the thermal infrared.

  • Their presence can be inferred from excess IR emission.

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Identifying protoplanetary disks with l band excess

Identifying protoplanetary disks with L band excess

L-band SPIREX data

redder

redder

Disks manifest themselves as excess L-band

emission (Kenyon & Gomez 2001)

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L and t dwarfs

L and T Dwarfs

  • Coolest stars and brown dwarfs are called “L and T dwarfs”

  • Boundary between stars and brown dwarfs is 0.07 solar masses

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Ir color vs stellar type reddest objects are brown dwarfs

IR color vs. stellar type:reddest objects are brown dwarfs

Cooler (lower mass)

Redder

Brown dwarfs

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Burgasser 2002


Airs can detect much more distant brown dwarfs than 2mass

AIRS can detect much more distant brown dwarfs than 2MASS

N ~ R3

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How many l and t dwarfs will the antarctic infrared survey detect

How many L and T dwarfs will the Antarctic Infrared Survey detect?

  • AIRS will reach Llim=15.0, Klim =19.4 mag (tint = 9 minutes)

  • Survey 8,000 square degrees

  • L dwarfs

    • K-band detections ~350,000

    • L-band detections ~3,000 to 6,000

    • Increase known sample by factor of ~30

  • T dwarfs

    • K and L band detections ~16 to 32

    • Increase known sample by factor of ~2

Kirkpatrick et al. 1999

Burgasser 2001

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Star forming regions 30 doradus

Star-forming Regions: 30 Doradus

SPIREX/Abu data

Blue: J, Green: K, Red: L

Deeply embedded stars show as red.

L-band detects deeply embedded YSOs undetected at K-band.

This is the world’s most sensitive ground-based L-band image (19 mag) taken with only a

60 cm telescope!

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Airs scientific goal

AIRS Scientific Goal

  • To survey the sky in the thermal infrared in order to significantly increase the known samples of protoplanetary disks, brown dwarfs, and young stellar objects

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Telescope design

Telescope Design

  • Cassegrain

  • 2 meter primary

  • f/1.6

  • 0.6 m secondary

  • 9.6% blockage

  • 42 arcmin field of view

  • Plate scale 58.18 mm/arcsec

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Aircam camera design

AIRCAM Camera Design

AIRCAM

CONCEPT

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Camera

Camera

  • Simultaneous L and K band imaging

    • Registration

    • Cross-calibration with 2MASS

  • 2048 x 2048 InSb array for L and M bands

  • 1024 x 1024 HgCdTe array for K band

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Expected optical performance strehl ratio vs field of view

Expected Optical Performance: Strehl Ratio vs. Field of View

Diffraction-limited performance out to edges of 20x20 arcmin AIRCAM field of view

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Sensitivity s n of 5 in 9 minutes

Sensitivity: S/N of 5 in 9 minutes

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Mapping times k 19 4 l 15 0

Mapping Times: K = 19.4, L = 15.0

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Prototype spirex abu

Prototype: SPIREX/Abu

  • Every aspect of AIRS has been successfully demonstrated by SPIREX/Abu:

    • Telescope

    • Camera

    • Community Access

    • Data pipeline

  • AIRS requires no new technology

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The south pole site

The South Pole Site

  • Excellent, low sky backgrounds

  • Good, stable weather

  • Adequate, steady seeing

  • The South Pole site is extremely well characterized!

  • Excellent infrastructure and support

  • AIRS can achieve its technical requirements at Pole.

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Dome c a better site

Dome C: A better site?

Compared with the South Pole, Dome C is

  • Higher

  • Less windy

  • May well have better sensitivity and seeing

  • Not at 90o S

    • More sky coverage

    • Better access to communications satellites

      BUT….

      Site testing just beginning

      Infrastructure not yet comparable

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    Another advantage of dome c land transport

    Another Advantage of Dome C:Land Transport

    • Large pieces can be hauled in

    • Greatly reduces assembly time on ice

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    Schedule

    Schedule

    • Years 1 and 2 (Boston U.):

      • Detailed design

      • IR surveys with MIMIR at Lowell 72-inch

    • Years 3 and 4 (Boston U. + Lowell)

      • Procurement + construction

      • Prepare test site at Anderson Mesa, Arizona

    • Year 5 (Lowell):

      • Systems integration

      • Automation and remote operations

      • Comprehensive tests

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    James jackson

    Plan

    • Complete conceptual design work 2003

    • Submit new proposal to US NSF Office of Polar Programs June 2004

    • Evaluate Dome C site-testing

    • Explore collaborations with French, Italians, Australians, and other partners

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    James jackson

    AIRS

    • An L-band survey is critical to bridge the gap between near- and mid-IR surveys.

    • Will revolutionize our understanding of protoplanetary disks, brown dwarfs, and star forming regions.

    • A 2-meter class telescope is the next step for Antarctic IR astronomy.

    • Essential step for larger telescopes and interferometers

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    Summary

    Summary

    • Key science well-suited to Antarctica

    • SPIREX/Abu demonstration

    • Optical design well-developed

    • Solid plan with low risk

    • Will work well at South Pole

    • May work even better at Dome C

      AIRS concept is sound and ready to go.

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