1. Interstellar extinction law and its dust model in the infrared 姜碧沩 北京师范大学天文系 bjiang@bnu.edu.cn Group members: 高健 王舒 李爱根 etc.

2. 2015-07-14 星际 / 星周尘埃暑期班 2

3. IMPORTANCE OF INTERSTELLAR EXTINCTION 2015-07-14 星际 / 星周尘埃暑期班 3

4. Influence of Extinction Herschel's map of the Milky Way On the Construction of the Heavens. By William Herschel, Esq. F. R. S. Philosophical Transactions of the Royal Society of London, Vol. 75. (1785), pp. 213-266. 2015-07-14 星际 / 星周尘埃暑期班 4

5. Distortion of colors and SED – Distance – Structure Revealing the dust properties 2015-07-14 星际 / 星周尘埃暑期班 5

6. 6 红外消光的强度 红外测光的精度 消光改正的难度 红外的深度 Galactic Center Gao, Li, Jiang, 2013 EPS, 65,1127 2015-07-14 星际 / 星周尘埃暑期班

7. INFRA-RED INTERSTELLAR EXTINCTION 2015-07-14 星际 / 星周尘埃暑期班 7

8. 8 Draine 1989 NIR: power law almost constant index MIR: silicate features 2015-07-14 星际 / 星周尘埃暑期班

9. NEAR INFRA-RED INTERSTELLAR EXTINCTION 2015-07-14 星际 / 星周尘埃暑期班 9

10. 10 Wang et al. 2013 Fritz et al. (2011) 2015-07-14

11. Universality of NIR extinction law located in the Galactic plane | b |≤ 5 ◦ classified as 'K' type in APOGEE 3500K ≤ T eff ≤ 4800K log g ≤ 3.0 metallicity ＞ -1 photometric quality – J_err ≤ 0.05 – H_err ≤ 0.05 – Ks_err ≤ 0.05 snr ≥ 100 Sample: 6074 giants 2015-07-14 星际 / 星周尘埃暑期班 11 K & G type 3500K-5200K Wang & Jiang 2014 ApJL 788, L12

12. The intrinsic NIR color indexes for K-type giants 2015-07-14 星际 / 星周尘埃暑期班 12

13. the lines are forced to pass through (0,0) three ratios are independently calculated very good internal consistency 2015-07-14 星际 / 星周尘埃暑期班 13

14. Dependence of E(J− H)/E(J− K S ) on E(J- K S ) E(J− K S ) vs. E(J− H)/E(J− K S ) diagram for K-type stars stars around the red line → no clear systematic tendency correlation analysis of E(J− H)/E(J− K S ) on E(J- K S ) – a Pearson correlation coefficient of 0.03 → no relation 0 ≤ E(J − K S ) ≤ 1 large dispersions – take into account the error 2015-07-14 星际 / 星周尘埃暑期班 14 Red lines: color excess ratio derived from fitting, E(J− H)/E(J− K S ) = 0.641

15. Error Analysis Error of the E(J− H)/E(J− K S ) originate from photometry and T eff JHK S bands photometry uncertainties ≤ 0.05 mag – average photometric error ∼ 0.02 – observed color index error is ∼ 0.04 (< 1% of stars have observed color error ∼ 0.1) The average error of APOGEE stellar parameter T eff ∼ 100K – T eff → NIR intrinsic color – the errors of (J−H) 0, (H− K S ) 0, (J− K S ) 0 are 0.05, 0.02, 0.07 the uncertainties of color excess – E(J − H)err ∼ 0.09, – E(H − K S )err ∼ 0.06 – E(J − K S )err ∼ 0.11. 2015-07-14 星际 / 星周尘埃暑期班 15

16.  The error of the color excess ratio [E(J − H)/E(J − K S )]err dependence on both E(J − H) and E(J − K S )  calculate under the error propagation theory 16  E(J − H)/E(J − K S )=0.641  If a star have E(J − K S )=0.3 [E(J − H)/E(J − K S )]err = 0.38  If a star have E(J − K S )=3 [E(J − H)/E(J − K S )]err = 0.038  At E(J − K S )=0.1 the error reaches 1.14  the dispersion can be fully explained by the error 2015-07-14 星际 / 星周尘埃暑期班

17. Result the color excess ratio E(J−H)/E(J− K S ), represented the NIR extinction law, show no apparent variation. – E(J − H)/E(J − K S )=0.64 – E(H − K S )/E(J − K S )=0.36 – E(J−H)/E(H− K S )=1.78 The corresponding power law index α = 1.95 and A J /A KS =2.88 consistent with the MRN dust size distribution 2015-07-14 星际 / 星周尘埃暑期班 17

18. MIDDLE INFRA-RED INTERSTELLAR EXTINCTION 2015-07-14 星际 / 星周尘埃暑期班 18

19. 2015-07-14 星际 / 星周尘埃暑期班 19 1.Flat in the 3-8um range 2.Lack the dip around 7um predicted by the classical dust model 3.Dispersion between works Wang, Li & Jiang 2014

20. 2015-07-14 星际 / 星周尘埃暑期班 20 Source selection Color indexes based on photometry Red clump Red giant Gao, Jiang & Li 2009

21. 2015-07-14 星际 / 星周尘埃暑期班 21 Method Linear fitting of observed color respective to J-Ks Convert to relative extinction

22. 4.5 μ m diffuse dense Dependence on the Environment Wang, Jiang, Gao et al. 2013 2015-07-14 星际 / 星周尘埃暑期班 22

23. MODELING THE EXTINCTION LAW 2015-07-14 星际 / 星周尘埃暑期班 23

24. 2015-07-14 星际 / 星周尘埃暑期班 24

25. Background Establishment of flat extinction law in MIR in various environments Present models – Draine (2003) Rv=5.5, only applicable to dense region – Dwek (2004) Metallic needles (l/a ~ 600) – Gao et al (2013) GC, cannot fit simultaneously to both NIR and MIR 2015-07-14 星际 / 星周尘埃暑期班 25

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27. Our dust model Wang et al. 2014 2015-07-14 星际 / 星周尘埃暑期班 27

28. 2015-07-14 星际 / 星周尘埃暑期班 28

29. Idea Add large grains – Dust scatters and absorbs starlight most effectively at the wavelengths comparable to its size, i.e. 2  a/  1 Steps – Fit the UV/V and NIR part first – Large grains have little effect on the UV/V and NIR wavelengths 2015-07-14 星际 / 星周尘埃暑期班 29

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31. Results The flat MIR extinction is best explained in terms of  m-sized AC which consumes C/H ~ 60ppm – Existence of  m-sized dust Dust impact detectors Radar detection of a=30  m particles Shortcoming – Requires a solid-phase C abundance of C/H~352 ppm, considerably exceeding the available in ISM (<200 ppm) 2015-07-14 星际 / 星周尘埃暑期班 31

32. 2015-07-14 星际 / 星周尘埃暑期班 32 Wang, Li & Jiang, 2015, MN, submitted

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34. On the universality of NIR extinction law Wang & Jiang (2014) 2015-07-14 星际 / 星周尘埃暑期班 34

35. DUST IN SNR 2015-07-14 星际 / 星周尘埃暑期班 35

36. 2015-07-14 星际 / 星周尘埃暑期班 36 Dunne et al. 2003, Nature

37. The amount of dust: cold dust or not? No – Cas A, an upper limit of M dust ~0.2 M Sun (Krause et al. 2004, Nature) Foreground contribution to sub-mm radiation – Kepler and Tycho, Type Ia, 10 -3 M Sun (Gomez et al. 2012) The Herschel observation, foreground and background Yes – Kepler’s SNR, M dust ~1.0 M sun, 1000 times greater than previous estimation (Morgan et al. 2003) – Cas A M dust ~2-4 M Sun (Dunne et al. 2003, Nature ) M dust ~0.2-0.5M Sun, polarimetry (Dunne et al. 2009) 2015-07-14 星际 / 星周尘埃暑期班 37

38. Problems in estimating the dust mass from radiation Morgan et al. 2003 2015-07-14 星际 / 星周尘埃暑期班 38 Foreground & background

39. summary Universality in NIR – Based on spectrum survey Flat in MIR – Micron-meter sized particles 2015-07-14 星际 / 星周尘埃暑期班 39

40. THANKS 2015-07-14 星际 / 星周尘埃暑期班 40