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Abundance analysis on Late G giants — 59 stars of Xinglong Planet search sample Yujuan Liu( 劉玉娟 ) NAOC/NAOJ Ando H., G. Zhao, Sato Bun’ei, Takeda Y.,
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Contents Introduction of purpose of this work Sample observation and reduction Stellar parameters and kinematic parameters Surface chemical compositions analysis
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Host Stars’ Metallicity--dwarf More planets around more metal-rich stars No planets around metal-poor (-2<[Fe/H]<-0.8) stars so far Fisher et al. 2005
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Host Stars’ Metallicity--giants About 20 candidates around giants, more than half of them are under solar metallicity Pasquini et al. 2007 blue line- 14 giants red dashed line--dwarfs The giants show a distribution shifted to lower metallicity by about 0.2-0.3 dex with respect to the dwarf.
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Takeda et al. 2008 Since the small number of detected planets around giants, this statistics results remain unclear.
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Lack of giants with [Fe/H] > 0.2 Soubiran et al. 2008 (891 sample) Takeda et al. 2008 (322 sample) Metallicity distribution of thin disk clump giants of the local (filled) and distant sample (red line)
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Red giants Branch CNO cycle: C decrease N increase O decrease or unchanged NaNe cycle: Na increase When the star moves towards RGB, the nucleosynthesis products penetrate into the atmosphere due to first dredge-up phase, changing the surface abundance of Li, C, N, O and Na. The effect depends both on the stellar mass and metallicity.
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Mishenina et al. (2006)- 177 RCG Na C deplete 0.28 dex N overabundance 0.21 dex O no change Na overabundance 0.1dex
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Luck et al. 2007 -298 giants C depleted O unaffected
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Purpose of this work Establish stellar parameters and kinematic parameters Determine surface chemical compositions, focusing on C, O, Na Find super metal-rich stars ([Fe/H]>0.2)
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Observational Data Sample selection B-V: 0.6-1.0 M v : -3 -- 2.5 V: 6 δ: >-20° Data Observation HIDES attached to OAO R=67000 wavelength coverage: 44 stars 5000-6200 15 stars 4000-7500 S/N: 100-250
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Data reduction IRAF: bias subtraction, flat-fielding, scattered-light subtraction, spectrum extraction, wavelength calibration, continuum normalization EW: fitting by a Gaussion function--SPSHOW program developed by Takeda et al. 2005
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Stellar Parameters-T eff Effective temperature – (B-V) color index and [Fe/H] from empirical calibration of Alonso et al. (1999) E(B-V)s --Schlegel et al. (1998) For nearby stars
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Stellar Parameters-Teff E(B-V) can be acceptable
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Stellar Parameters-logg Surface gravity log(g/g ⊙ ) = log(M/M ⊙ ) + 4 log(Teff/Teff ⊙ ) + 0.4(Mbol - Mbol ⊙ ) where : M bol = V + BC - 5 logπ + 5-Av A v = 3.1E(B-V) Mass– evolution track of Yonsei-Yale (Yi et al. 2003) within 0.3 M ⊙ difference with those from Giradi (2000)---Liu et al. 2007
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Stellar Parameters-V t Microturbulent velocities were calibrated by forcing different Fe I lines with 10< EW <120 mÅ give a uniform iron abundance value. Finally, the whole procedure of determination of T eff, logg and metallicity was repeated until the final metallcity from the equivalent width calculation was full consistency with input [Fe/H] within 0.01 dex.
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Ionization equilibrium test
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◊ Brown et al. 1989 (7 stars) ○ Mishenina et al. 2006 (4 stars) ∆ Luck et al. 2007 (4 stars) stellar parameter consistency check with literatures
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[Fe/H] 0.05 dex higher than literature
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Stellar parameters with Takeda 2008
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Error analysis( HD47366, Teff=4834,logg=2.76,vt=1.3,[Fe/H]=-0.01 ) Δ T eff (+100K) Δ Logg (0.1) Δ[Fe/H] (0.1) Δv t (0.3kms-1) tot Δ[Fe/H]0.080.010.02-0.080.12 Δ[Fe/H] II -0.060.050.04-0.080.12 Δ[C/Fe II ]-0.01 -0.040.070.09 Δ[O/Fe]-0.090.030.020.080.13 Δ[Na/Fe]0.02-0.02-0.010.020.04 Δ[Si/Fe]-0.070.010.000.050.09 Δ[Ca/Fe]0.04-0.03-0.01-0.040.07 Δ[Ti/Fe]0.07-0.010.000.010.07 Δ[Cr/Fe]0.03-0.02 0.010.04 Δ[Ni/Fe]-0.030.00 -0.010.03 Δ[Y/Fe] II 0.08-0.010.000.050.09
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Kinematic parameters Most stars belong to thin disk. Thick disk stars—higher eccentricity
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Thick disk stars—higher space velocity —low mass (old stars)
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● O 6363 Δ O 5557 Abundance Analysis [O/Fe] 6300 = -0.02±0.04 dex + [O/Fe] 6363
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Abundance Analysis O5577-- O6300 [O/Fe] 6300 = 0.08±0.05 dex + [O/Fe] 5577
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Carbon Oxygen C depleted O remain unaffected
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Sodium Na overabundance 0.1 dex
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C,O,Na with Mass
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Si,Ca
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Ti, Cr
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Ni, Mn
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Ce,Y
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Sc
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Remind problems Abundance from O 5057 maybe not correct
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Conclusion Stellar parameter lie in the main group of Takeda et al. 2008, lack of stars [Fe/H]>0.2 Most sample belong to thin disk stars C depleted 0.13 dex(-0.1<[Fe/H]<0.1) O remain unaffected Na overabundance 0.1 dex The effect dependt on [Fe/H] and Mass. Other elements remain unaffected, consisting with results of Takeda et al. (2008) Consist with theoretical results
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