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GMT2010: High-resolution Spectroscopy of Stars with GMTNIRS

GMT2010: High-resolution Spectroscopy of Stars with GMTNIRS. David L. Lambert McDonald Observatory The University of Texas at Austin. GMT2010 Seoul, Korea. William Herschel (1738-1822). Discovered the infra-red in 1800

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GMT2010: High-resolution Spectroscopy of Stars with GMTNIRS

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  1. GMT2010: High-resolution Spectroscopy of Stars with GMTNIRS David L. Lambert McDonald Observatory The University of Texas at Austin GMT2010 Seoul, Korea

  2. William Herschel (1738-1822) • Discovered the infra-red in 1800 “By placing one thermometer within the [solar] red rays, separated by a prism, and another beyond them, he found the temperature of the outside thermometer raised by more than that of the inside.” Humphrey Davy to Davies Giddy 3 July 1800

  3. Introduction Certain exciting problems in stellar astrophysics demand high-resolution IR spectra for their solution. IR advantages include: • Cool stars - bright in IR - IR spectra “simpler” than optical - key signatures in IR: molecules for elemental and isotopic abundances - H- opacity minimum at 1.6 µm - higher dust transparency • Cool gas and dust - circumstellar envelopes - prestellar disks GMTNIRS: J, H, K, L, M (1.15-5.0m) in a single exposure

  4. Introduction Spectra must be paired with model atmospheres and atomic/molecular data • Atomic spectroscopy: generally high-excitation neutral atomic lines - Quantitative lab spectroscopy limited (gf-values for LTE) - Expect theoretical gf-values to be fairly reliable - Astrophysical data (e.g., gf’s from Sun, Arcturus, etc.) • Few resonance and low excitation lines. Therefore - clean spectrum at low metallicity

  5. Introduction Molecular spectroscopy • Mix of electronic and vibration-rotation transitions • Molecular data generally good but incomplete, but there are few active centers for lab/theoretical work on astrophysical molecules • Incomplete: stellar column densities » laboratory possibilities (beware of extrapolation) : dissociation energies? : gf-values? : new molecules (ZrS, TiS) • Can usually predict isotopic wavelength shifts • C, N, O and F including isotopes accessible (in principle) chemical evolution of stellar systems stellar evolution, esp. dredge-ups

  6. GMTNIRS performance: • Single exposure: J, H, K, L and M (1.15-5.0m) at R = λ/∆ λ = 50,000 (JHK) or 100,000 (LM) • Slit 0.085 x 1.3 arc sec with pixel scale of 20 mas • Limiting magnitude

  7. Special (unique) factors: All in one exposure • CNO as tracers of dredge-ups in stars CO  = 1 in M,  = 2 in K,  = 3 in H CN Red system in JHK OH  = 1 in L,  = 2 in H NH  = 1 in L C2 Ballik-Ramsay and Phillips in HK (also HF in K and HCl in L) • Obtain CNO elemental and isotopic abundances • Probe atmospheric dynamics and structure (MOLSPHERE)

  8. Special (unique) factors: All in one exposure • HR4049, a very metal-poor 7500K giant in a binary with a circumbinary disk: [Fe/H] = -4.7, but [C, N, O / H]  0.0 • Cold CO in absorption at 2.3µm Lambert, Hinkle & Luck (1988)

  9. Special (unique) factors: All in one exposure(HR 4049 – continued) • Look for CO at 4.6µm to obtain 12C/13C and 16O/17O ratios C18O 18CO CO C17O H2O Hinkle, Brittain & Lambert (2007)

  10. Special (unique) features: Angular resolution(aperture, AO, pixel scale) • Mass loss by red giant (or all) stars is very poorly understood theoretically and observationally. • Map circumstellar structure in CO 4.6µm lines Smith et al. (2009)

  11. Special (unique) features: Angular resolution(aperture, AO, pixel scale) HST/WFPC 2 Phoenix slit positions Smith et al. (2009, AJ, 137, 3558)

  12. Special (unique) features: Angular resolution(aperture, AO, pixel scale) Smith et al. (2009)

  13. Special (unique) features: Angular resolution(aperture, AO, pixel scale) Velocity-position maps BetelgeuseVY CMa KI 7699 ÅCO 1 – 0 R2 4.64μm Smith et al. (2009) Slit 33'' from star Slit 4'' from star x: 1 pixel = 1.3 km/s y: 1 pixel = 0''.27 Plez & Lambert (2002)

  14. Special (unique) features: Angular resolution(aperture, AO, pixel scale) • Betelgeuse and VY CMa are SN II progenitors • Maps of circumstellar envelopes clues to mass loss understanding environment in which SN II explodes • CO has advantages over KI or NaI • GMTNIRS with JHKLM coverage will reveal complete circumstellar coverage (despite short slit) - will provide look at innermost regions - larger number of giants in its grasp

  15. Special (unique) features: Limiting magnitude • LMC, SMC, and just a little further • Dredge-up in red giants

  16. Special (unique) features: Limiting magnitude Origins of Fluorine FCNO and internal mixing Smith et al. (2002) Smith et al. (2005)

  17. Special (unique) features: Limiting magnitude K - 12.5 - 15.5 - 15.5 Smith et al. (2002)

  18. Special (unique) features: Limiting magnitude • Dwarf galaxies beyond the LMC at distance modulus of 18.5 Sculptor 19.5 Sextans 19.7 Carina 20.0 Fornax 20.7 • Large surveys of “nearby” systems and stars - Our globular clusters - Field stars after GAIA • CNOF chemical evolution and internal mixing

  19. DO NOT FORGET! • Glorious puzzles remain in stellar astrophysics in this age of cosmology • The GMT and GMTNIRS will help solve many puzzles “Nature shows us of the lion only the tail. But there is no doubt in my mind that the lion belongs with it, even if he cannot reveal himself to the eye all at once because of his huge dimensions.” A. Einstein

  20. Even Einstein observed!

  21. The GMT will reveal the lions!

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