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AIRS: The Antarctic Infrared Survey

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  1. AIRS: The Antarctic Infrared Survey James M. Jackson Institute for Astrophysical Research Boston University Sydney Zoo

  2. Our Local Universe:Key Astrophysical Questions • Earliest stages of planet formation • Nature and number of brown dwarfs • Earliest stages of star formation Sydney Zoo

  3. 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 Sydney Zoo

  4. RCW 38 Another essential advantage: Infrared penetrates dust clouds (M. Petr 2000) VLT-FORS optical VLT-ISAAC infrared (JHK) Sydney Zoo Lada 2002

  5. 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 Sydney Zoo

  6. 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 Sydney Zoo Phillips et al. 1999

  7. Wide-field infrared surveys are essential to study the local Universe: 2MASS 2MASS 2mm optical Sydney Zoo www.ipac.caltech.edu/2mass

  8. 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 Sydney Zoo

  9. 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 Sydney Zoo

  10. 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 Sydney Zoo

  11. Formation of Planets: Protoplanetary Disks • Dusty disks have temperatures perfectly matched to the thermal infrared. • Their presence can be inferred from excess IR emission. Sydney Zoo

  12. Identifying protoplanetary disks with L band excess L-band SPIREX data redder redder Disks manifest themselves as excess L-band emission (Kenyon & Gomez 2001) Sydney Zoo

  13. 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 Sydney Zoo

  14. IR color vs. stellar type:reddest objects are brown dwarfs Cooler (lower mass) Redder Brown dwarfs Sydney Zoo Burgasser 2002

  15. AIRS can detect much more distant brown dwarfs than 2MASS N ~ R3 Sydney Zoo

  16. 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 Sydney Zoo

  17. 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! Sydney Zoo

  18. 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 Sydney Zoo

  19. 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 Sydney Zoo

  20. AIRCAM Camera Design AIRCAM CONCEPT Sydney Zoo

  21. 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 Sydney Zoo

  22. Expected Optical Performance: Strehl Ratio vs. Field of View Diffraction-limited performance out to edges of 20x20 arcmin AIRCAM field of view Sydney Zoo

  23. Sensitivity: S/N of 5 in 9 minutes Sydney Zoo

  24. Mapping Times: K = 19.4, L = 15.0 Sydney Zoo

  25. 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 Sydney Zoo

  26. 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. Sydney Zoo

  27. 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 Sydney Zoo

  28. Another Advantage of Dome C:Land Transport • Large pieces can be hauled in • Greatly reduces assembly time on ice Sydney Zoo

  29. 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 Sydney Zoo

  30. 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 Sydney Zoo

  31. 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 Sydney Zoo

  32. 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. Sydney Zoo