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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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Presentation on theme: "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.,"— Presentation transcript:

1 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.,

2 Contents Introduction of purpose of this work Sample observation and reduction Stellar parameters and kinematic parameters Surface chemical compositions analysis

3 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

4 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.

5 Takeda et al. 2008 Since the small number of detected planets around giants, this statistics results remain unclear.

6 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)

7 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.

8 Mishenina et al. (2006)- 177 RCG Na C deplete 0.28 dex N overabundance 0.21 dex O no change Na overabundance 0.1dex

9 Luck et al. 2007 -298 giants C depleted O unaffected

10 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)

11 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

12 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

13 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

14 Stellar Parameters-Teff E(B-V) can be acceptable

15 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

16 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.

17 Ionization equilibrium test

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19 ◊ Brown et al. 1989 (7 stars) ○ Mishenina et al. 2006 (4 stars) ∆ Luck et al. 2007 (4 stars) stellar parameter consistency check with literatures

20 [Fe/H] 0.05 dex higher than literature

21 Stellar parameters with Takeda 2008

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24 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

25 Kinematic parameters Most stars belong to thin disk. Thick disk stars—higher eccentricity

26 Thick disk stars—higher space velocity —low mass (old stars)

27 ● O 6363 Δ O 5557 Abundance Analysis [O/Fe] 6300 = -0.02±0.04 dex + [O/Fe] 6363

28 Abundance Analysis O5577-- O6300 [O/Fe] 6300 = 0.08±0.05 dex + [O/Fe] 5577

29 Carbon Oxygen C depleted O remain unaffected

30 Sodium Na overabundance 0.1 dex

31 C,O,Na with Mass

32 Si,Ca

33 Ti, Cr

34 Ni, Mn

35 Ce,Y

36 Sc

37 Remind problems  Abundance from O 5057 maybe not correct

38 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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