Carbon stars from LAMOST DR4

Transcription

1 National Astronomical Observatories (NAOC) Center for Oeration and Develoment of Guo Shoujing Telescoe (LAMOST) Carbon stars from LAMOST DR4 Yin-bi Li, A-li Luo, Chang-de Du, et al

2 2 Outline Background How to find carbon stars? Sectra MK Classification Carbon stars from LAMOST DR4 Comared with revious work Multile-wavelength Data 2

3 Background Definition of carbon star C/O > 1 Otical sectra: CH, C2 or CN band Infrared sectra: SiC band Origins of carbon Giants: from the third dredge-u of TP- AGB hase Dwarfs: from their comanion Why is carbon star rare? The short time scale of TP-AGB hase (a few hundred years) Only third dredge-u can convect carbon to surface Only strong dredge-u can roduce carbon stars Why do we study carbon stars? Play an imortant role in the nuclear synthesis rocess Synthesize about half of elements heavier than iron by the s-rocess Synthesize carbon by the trile-alha rocess Hel us to understand the evolution of galaxies As robes to investigate the dark matter halo, Galactic otential, dwarf galaxies or stellar streams. 3

4 Background Detection History Alksnis, A. et al. 2001, 10, carbon stars Christlieb, N. et al. 2001, 375, FHLCs --- HES sectra SDSS Margon, B., et al. 2002, 124, FHLCs Downes, R., A., et al. 2004, 127, FHLCs Green, P. 2013, 765, FHLCs Si, J.M., et al. 2014, 57, carbon stars LAMOST Si, J.M., et al. 2015, 15, carbon stars Ji, W., et al. 2016, 226, carbon stars DFBS Gigoyan, K.S., et al. 2012, 544, A FHLCs Gigoyan, K.S., et al FHLCs Gigoyan, K.S., et al FHLCs 4

5 How to find carbon stars? The rocess of finding carbon stars Construction and Classification of ositive samle set Sectra rerocessing Research of Retrieval algorithms Artificial identification 5

6 How to find carbon stars? Comleteness: at least 95% 6

7 How to find carbon stars? Bagging ToPush Algorithm + over one billion sectra 2651 carbon stars from LAMOST DR of them are new findings 17 carbon-enhanced metal-oor main sequence turn off stars Examles of Sectral Binaries 7

8 How to find carbon stars? Examle of G-tye carbon stars 8

9 How to find carbon stars? Examles of emission line carbon stars 9

10 How to find carbon stars? Examles of carbon-enhanced metal-oor main sequence turn off stars 10

11 Sectral MK Classification Sectral MK Classification Classification Criteria CJ stars --- AJ, 2009, 705, 1298 First successful try to classify CJ stars from sectra features D6168 / D6192 & EW6260 / EW6206 à J index >= 4 First classify CJ stars into three tyes: CJ(N), CJ(H) & CJ(R) CH, CR, CN, and Ba stars --- artificial identification Classification Results C-H: 864 C-R: 226 C-J: 400 CJ(N) : 353 CJ(H): 41 CJ(R): 6 C-N: 266 Ba: 719 Unknown: 164 Binary: 12 (No sectra tye) 11

12 Sectral MK Classification Two C-J(N) stars 12

13 Sectral MK Classification C-J(H) and C-J(R) stars 13

14 Sectral MK Classification C-J(binary) and C-J(EM) stars 14

15 Sectral MK Classification 15

16 Carbon stars from LAMOST DR4 Parameter Catalog for carbon stars of LAMOST DR4 Designation Equatorial Coordinates Signal to Noise ratio PPMXL roer motion UCAC4 roer motion GALEX hotometry Pan-STARRS hotometry 2MASS hotometry Wise hotometry Flag_new: new finding or not Flag_tye: a sectral binary, a G-tye star, a emission line star, or not Sectra_tye: CH, CR, CJ, CN, and Ba 16

17 Carbon stars from LAMOST DR4 17

18 Carbon stars from LAMOST DR4 18

19 Carbon stars from LAMOST DR4 19

20 Carbon stars from LAMOST DR4 20

21 Comared with Previous Work RAA, 2015, 15, 1671 (183 carbon stars from LAMOST Pilot Survey) 4 stars with low quality sectra are not in our catalog AJS, 2016, 226, 1 (894 carbon stars from LAMOST DR2) Their 5 stars with low quality sectra are not in our catalog Our catalog include all their 894 carbon stars 21

22 Multile-wavelength Data GALEX Ultraviolet Detections 1099 detections 25 FUV-detections --- likely have white dwarf star comanions 1098 NUV-detections 22

23 Multile-wavelength Data Try to classify carbon stars with uv, otical and infrared colors Estimate intrinsic colors Cut samles with large magnitude errors nuv_err <= 0.3, e_w3<=0.1, e_g/r/i/z/y/j/h/ks/w1/w2 <= 0.05 Correct extinctions C0_(H W2) = 0.08 for F, G, K, and M tye stars --- Jian, M.J., Gao, S., Zhao, H, et al. AJ, 2017, 153, 5 2MASS and WISE bands --- relative extinction from Xue, M.Y., Jiang, B.W, Gao, J., et al. 2016, 224, 23 Ultra-violet and otical bands --- extinction coefficients from Yuan, H.B., Liu, X.W., Xiang, M.S , 430, 2188 Calculate intrinsic colors in above 11 colors Extinction of y band --- Mathis, J.S.., 1990, 28, 37 / A(lambda) is ower law 23

24 Multile-wavelength Data C-J: 37 C-N: 11 24

25 Multile-wavelength Data 25

26 Multile-wavelength Data 26

27 Multile-wavelength Data 27

28 Multile-wavelength Data 28

29 Multile-wavelength Data Total number of cool stars: 566 (with intrinsic colors) b >= 30 degree: 33 cool carbon stars H W2 [0.3, 0.5] : 31stars are C-J or C-N cool carbon stars >= 0.5: 16 stars are C-J or C-N cool carbon stars >= 1: 12 stars are C-J or C-N cool carbon stars These carbon stars robably have infrared excess 29

30 Multile-wavelength Data A fraction of carbon stars have infrared excess It is imossible to classify carbon stars into five sectral sub-tyes with colors 30

31 Thank you for your attention! 31

32 Carbon stars from LAMOST DR4 Parameter Catalog for 17 CEMP MSTO stars of LAMOST DR4 Designation Equatorial Coordinates Signal to Noise ratio Atmosheric Parameters Radial Velocities PPMXL roer motion UCAC4 roer motion GALEX hotometry Pan-STARRS hotometry 2MASS hotometry Wise hotometry 32

33 Multile-wavelength Data G-tye stars: 0.3 <= (g - r) <= 0.8 and 3 <= (nuv - r) <= 7.5 Ba stars: 0.3 <= (g - r) <= 1.2 and 7.5 <= (g - r) <= 11 33

34 Multile-wavelength Data G-tye stars: 0.3 <= (g - r) <= 0.8 and 2.5 <= (nuv - g) <= 7 Ba stars: 0.3 <= (g - r) <= 1.2 and 7 <= (g - r) <=

35 Multile-wavelength Data Hot carbon stars: 0 <= (g - r) <= 1 and 0.2 <= (r - i) <= 1.7 Cool CJ and CN stars: Most of them: (r - i) > 1.7 A small fraction of them: (g - r) > 1.0 and (r i) <=

36 Multile-wavelength Data Hot carbon stars: <= (r - i) <= 0.65 and 0.05 <= (i - z) <= 0.9 Cool CJ and CN stars: Most of them: (i - z) > 0.9 A small fraction of them: (r - i) > 0.65 and (i - z) <=

37 Multile-wavelength Data Hot carbon stars: <= (z - y) <= 0.7 and -0.1 <= (i - z) <= 0.4 Cool CJ and CN stars: Most of them: (z - y) > 0.7 A small fraction of them: (i - z) > 0.4 and (i - z) <=

38 Multile-wavelength Data Hot carbon stars are distinguished from cool CJ and CN stars: (z y) 0.8 (y J)+1.45 Roughly criterion: (y J)

39 Multile-wavelength Data Hot carbon stars are distinguished from cool CJ and CN stars: (y J) 3 (J H)+4.3 Roughly criterion: (J H)

40 Multile-wavelength Data Hot carbon stars are distinguished from cool CJ and CN stars: (J H) 3 (H K) Roughly criterion: (H K) 0.35 and (J H)

41 Multile-wavelength Data Hot carbon stars are distinguished from cool CJ and CN stars: (H K) 0.6 (K W1)

42 Multile-wavelength Data Hot carbon stars are distinguished from cool CJ and CN stars: (K W1) 0.9 (W1 W2)

43 Multile-wavelength Data Hot carbon stars are distinguished from cool CJ and CN stars: (W1 W2) 0.05 (W2 W3)

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54 How to find carbon stars? Construction and Classification of Positive Samle Set SDSS + LAMOST (1682) Four stes Positive Samle Set(1050) K-mean Clustering (50 grous) Similarity Measurement 54

55 How to find carbon stars? Research of Retrieval algorithms Six Machine Learning Algorithm Comarison Time Consuming of Key stes of Bagging ToPush Algorithm 55

56 Our Motivations Increase the number of carbon star samles Construct a comlete carbon star catalog as much as ossible for LAMOST Construct new carbon star temlates to imrove the erformance of 1D ieline to classify carbon stars (about 63%) --- correct 978 (about 37%) --- wrong Wrongly classified as A9, F, G, K, M4 and unknown. Carbon star temlate sectra of LAMOST 1D ieline 56