GMT2010: High-resolution Spectroscopy of Stars with GMTNIRS
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Transcript of GMT2010: High-resolution Spectroscopy of Stars with GMTNIRS
GMT2010: High-resolution Spectroscopy ofStars with GMTNIRS
GMT2010Seoul, Korea
David L. LambertMcDonald ObservatoryThe University of Texas at Austin
William Herschel (1738-1822)William Herschel (1738-1822)
Discovered the infra-red in 1800Discovered the infra-red in 1800 “ “By placing one thermometer within By placing one thermometer within
the [solar] red rays, separated by a the [solar] red rays, separated by a prism, and another beyond them, prism, and another beyond them, he found the temperature of the he found the temperature of the outside thermometer raised by outside thermometer raised by more than that of the inside.” more than that of the inside.”
Humphrey Davy to Davies GiddyHumphrey Davy to Davies Giddy 3 July 18003 July 1800
IntroductionIntroductionCertain exciting problems in stellar astrophysics Certain exciting problems in stellar astrophysics
demanddemandhigh-resolution IR spectra for their solution.high-resolution IR spectra for their solution.
IR advantages include:IR advantages include: Cool starsCool stars
- bright in IR- bright in IR - IR spectra “simpler” than optical- IR spectra “simpler” than optical - key signatures in IR: molecules for elemental- key signatures in IR: molecules for elemental
and isotopic abundancesand isotopic abundances - H- H- - opacity minimum at 1.6 µmopacity minimum at 1.6 µm
- higher dust transparency- higher dust transparency
Cool gas and dustCool gas and dust - circumstellar envelopes- circumstellar envelopes
- prestellar disks- prestellar disks
GMTNIRS: J, H, K, L, M (1.15-5.0GMTNIRS: J, H, K, L, M (1.15-5.0m) in a single exposurem) in a single exposure
IntroductionIntroductionSpectra must be paired with Spectra must be paired with
model model atmospheres and atmospheres and
atomic/molecularatomic/moleculardatadata Atomic spectroscopy: generally high-Atomic spectroscopy: generally high-
excitation excitation neutral atomic linesneutral atomic lines
- Quantitative lab spectroscopy limited - Quantitative lab spectroscopy limited (gf-values for LTE)(gf-values for LTE) - Expect theoretical gf-values to be fairly - Expect theoretical gf-values to be fairly reliablereliable - Astrophysical data (e.g., gf’s from Sun, - Astrophysical data (e.g., gf’s from Sun, Arcturus, etc.)Arcturus, etc.)
Few resonance and low excitation lines.Few resonance and low excitation lines. Therefore - clean spectrum at low metallicity Therefore - clean spectrum at low metallicity
Molecular spectroscopyMolecular spectroscopy Mix of electronic and vibration-rotation transitionsMix of electronic and vibration-rotation transitions
Molecular data generally good but incomplete, but there are few Molecular data generally good but incomplete, but there are few active centers for lab/theoretical work on astrophysical active centers for lab/theoretical work on astrophysical moleculesmolecules
Incomplete: stellar column densities Incomplete: stellar column densities »» laboratory possibilities laboratory possibilities (beware of extrapolation)(beware of extrapolation)
: dissociation energies?: dissociation energies? : gf-values?: gf-values? : new molecules (ZrS, TiS) : new molecules (ZrS, TiS)
Can usually predict isotopic wavelength shiftsCan usually predict isotopic wavelength shifts
C, N, O and F including isotopes accessible (in principle)C, N, O and F including isotopes accessible (in principle)
chemical evolution of stellar systemschemical evolution of stellar systems
stellar evolution, esp. dredge-upsstellar evolution, esp. dredge-ups
IntroductionIntroduction
GMTNIRS performance:GMTNIRS performance: Single exposure: J, H, K, L and M (1.15-5.0Single exposure: J, H, K, L and M (1.15-5.0m) m)
at R = at R = λλ/∆ /∆ λλ = 50,000 (JHK) or 100,000 (LM) = 50,000 (JHK) or 100,000 (LM)
SlitSlit 0.085 x 1.3 arc sec with pixel scale of 20 mas0.085 x 1.3 arc sec with pixel scale of 20 mas
Limiting magnitudeLimiting magnitude
Special (unique) factors: All in one Special (unique) factors: All in one exposureexposure CNO as tracers of dredge-ups in starsCNO as tracers of dredge-ups in stars
CO CO = 1 in M, = 1 in M, = 2 in K, = 2 in K, = 3 in H = 3 in H
CN Red system in JHKCN Red system in JHK
OH OH = 1 in L, = 1 in L, = 2 in H = 2 in H
NH NH = 1 in L = 1 in L
CC22 Ballik-Ramsay and Phillips in HK Ballik-Ramsay and Phillips in HK
(also HF in K and HCl in L)(also HF in K and HCl in L)
Obtain CNO elemental and isotopic abundancesObtain CNO elemental and isotopic abundances
Probe atmospheric dynamics and structure (MOLSPHERE)Probe atmospheric dynamics and structure (MOLSPHERE)
Special (unique) factors: All in one Special (unique) factors: All in one exposureexposure
HR4049, a very metal-poor 7500K giant HR4049, a very metal-poor 7500K giant
in a binary with a circumbinary disk:in a binary with a circumbinary disk:
[Fe/H] = -4.7, but [C, N, O / H] [Fe/H] = -4.7, but [C, N, O / H] 0.0 0.0
Cold CO in absorption at 2.3µmCold CO in absorption at 2.3µm
Lambert, Hinkle & Luck (1988)
Special (unique) factors: All in one Special (unique) factors: All in one exposureexposure(HR 4049 – continued)(HR 4049 – continued)
Look for CO at 4.6µm to obtain Look for CO at 4.6µm to obtain 1212C/C/1313C and C and 1616O/O/1717O ratiosO ratios
Hinkle, Brittain & Lambert (2007)
C18O18CO
CO
H2O
C17O
Special (unique) features: Angular Special (unique) features: Angular resolutionresolution(aperture, AO, pixel scale)(aperture, AO, pixel scale) Mass loss by red giant (or all) stars is very poorly understood Mass loss by red giant (or all) stars is very poorly understood
theoreticallytheoretically and observationally.and observationally.
Map circumstellar structure in CO 4.6µm linesMap circumstellar structure in CO 4.6µm lines
Smith et al. (2009)
Special (unique) features: Angular Special (unique) features: Angular resolutionresolution(aperture, AO, pixel scale)(aperture, AO, pixel scale)
HST/WFPC 2 Phoenix slit positions
Smith et al. (2009, AJ, 137, 3558)
Special (unique) features: Angular Special (unique) features: Angular resolutionresolution(aperture, AO, pixel scale)(aperture, AO, pixel scale)
Smith et al. (2009)
Special (unique) features: Angular Special (unique) features: Angular resolutionresolution(aperture, AO, pixel scale)(aperture, AO, pixel scale) Velocity-position mapsBetelgeuse VY CMaKI 7699 Å CO 1 – 0 R2 4.64μm
Slit 4'' from star x: 1 pixel = 1.3 km/s y: 1 pixel = 0''.27
Slit 33'' from star Plez & Lambert (2002)
Smith et al. (2009)
Special (unique) features: Angular Special (unique) features: Angular resolutionresolution(aperture, AO, pixel scale)(aperture, AO, pixel scale) Betelgeuse and VY CMa are SN II progenitorsBetelgeuse and VY CMa are SN II progenitors
Maps of circumstellar envelopesMaps of circumstellar envelopes clues to mass loss understandingclues to mass loss understanding
environment in which SN II explodesenvironment in which SN II explodes
CO has advantages over KI or NaICO has advantages over KI or NaI
GMTNIRS with JHKLM coverage will reveal completeGMTNIRS with JHKLM coverage will reveal complete circumstellar coverage (despite short slit)circumstellar coverage (despite short slit)
- will provide look at innermost regions- will provide look at innermost regions
- larger number of giants in its grasp- larger number of giants in its grasp
Special (unique) features: Limiting Special (unique) features: Limiting magnitudemagnitude LMC, SMC, and just a little furtherLMC, SMC, and just a little further
Dredge-up in red giantsDredge-up in red giants
Special (unique) features: Limiting Special (unique) features: Limiting magnitudemagnitude
Origins of Origins of FluorineFluorine FCNO and internal FCNO and internal
mixingmixing
Smith et al. (2005) Smith et al. (2002)
Special (unique) features: Limiting Special (unique) features: Limiting magnitudemagnitude
K
- 12.5
- 15.5
- 15.5
Smith et al. (2002)
Special (unique) features: Limiting Special (unique) features: Limiting magnitudemagnitude Dwarf galaxies beyond the LMC at distance modulus of Dwarf galaxies beyond the LMC at distance modulus of
18.518.5 Sculptor 19.5Sculptor 19.5 Sextans 19.7Sextans 19.7 Carina 20.0Carina 20.0 Fornax 20.7Fornax 20.7
Large surveys of “nearby” systems and starsLarge surveys of “nearby” systems and stars - Our globular clusters- Our globular clusters
- Field stars after GAIA- Field stars after GAIA
CNOF chemical evolution and internal mixingCNOF chemical evolution and internal mixing
DO NOT FORGET!DO NOT FORGET! Glorious puzzles remain in stellar astrophysics in this age of Glorious puzzles remain in stellar astrophysics in this age of
cosmologycosmology
The GMT and GMTNIRS will help solve many puzzlesThe GMT and GMTNIRS will help solve many puzzles
“ “Nature shows us of the lion Nature shows us of the lion only the tail. But there is no only the tail. But there is no doubt in my mind that the doubt in my mind that the lion belongs with it, even if he lion belongs with it, even if he cannot reveal himself to the cannot reveal himself to the eye all at once because of his eye all at once because of his huge dimensions.”huge dimensions.”
A. EinsteinA. Einstein
Even Einstein observed!Even Einstein observed!
The GMT will reveal the lions!