1. IGRINS for Stellar Abundances & Nucleosynthesis Chris Sneden, Natalie Gosnell, Dan Jaffe, Greg Mace, Richard Seifert (UT Austin) Hwihyun Kim + IGRINS team members (KASI) Melike Afşar (Ege U, Izmir Turkey) Caty Pilachowski (Indiana U)

2. Topics for today  two famous very low metallicity stars  is there anything left to discover?  red horizontal-branch stars  better CNO will help solve their existence puzzle  open cluster stars:  IR data can refine their evolutionay states Abundance Definitions  log ε(X) = log 10 (N X /N H ) + 12 for element “X”  [X/Y] = log 10 (N X /N Y ) ★ – log 10 (N X /N Y ) 

3. Topic I what can we learn about very metal-poor stars with H- and K- band IR spectra?

4. Two famous very bright, very metal-poor stars HD 122563  B = 7.10 V = 6.19 H = 3.76 K = 3.73  575 papers in the literature have something about this star  red giant: T eff = 4500K, log(g) = 0.8, [Fe/H] = –2.9  40+ years after my PhD, I’m still working on this same star HD 140283  B = 7.11 V = 7.21 H = 5.70 K = 5.59  first high-res metal-poor star: Chamerlain & Aller (1952)  warm: T eff = 5650K, log(g) = 3.4, [Fe/H] = –2.7  a legendary “cheat” on metallicity; a moral lesson for us Afşar et al. 2015, ApJ, submitted

5. most of the IGRINS H-band in our stars HIP 54048 is a solar metallicity red horizontal branch star ✔ ✔ stay tuned

6. and most of the IGRINS K Band ✔ ✔ ends of orders with lots of tellurics have been chopped here

7. reductions & analyses in brief  IGRINS pipeline, and IRAF “telluric” package  standard analysis techniques using MOOG code  NIST transition probabilities when available, otherwise Kurucz database  line-to-line scatter is reasonable: σ ≈ 0.1  happiest results: better abundances for “alpha” elements (Mg, Si, S, Ca)  OH, CO molecular lines visible in HD 122563  probably detections of 1 Na line and 2 Al lines, but we are not confident of abundances

8. some lines are obvious, with some unexpected detections simple extrapolations from Arcturus spectrum predict that Mg I will be strong at low metallicity good question for thesis defenses: why is weak, fragile molecule OH visible in HD 122563? Note the 1% deep S I lines; these are real

9. Si I lines are BETTER in the IR analysis issues; watch out! lines are too weak lines are just right for reliable abundances

10. IGRINS alpha abundances are trustworthy No possibility of getting sulfur in the optical much of the line-line scatter must be in the (NIST) basic line data HD 140283 gives similar results, but there are fewer lines in that warmer star optical IGRINS

11. how low in metallicity can we go??? we could have added in more CO lines only a simple mean was done here arbitrary C, O to fit observed line the syntheses differ by 0.3 dex in C abundan ce

12. Topic II Application of H- and K-band IGRINS spectra to the curious case of field red horizontal- branch stars

13. red clump vs red horizontal branch http://spiff.rit.edu/classes/phys373/lect ures/colors/colors.html young, higher-mass metal-rich field stars: the red clump https://en.wikipedia.org/wiki/H orizontal_branch old, low mass, usually metal-poor stars: the blue and red horizontal branch

14. why are there so many bright RHB field stars? Afşar et al. 2012 RC HR diagram of color- selected sample of bright G-type giants Many with Hipparcos parallaxes that confirm their “giant” status filled circles and x symbols have “evolved” carbon isotopic ratios: 12 C/ 13 C < 30

15. they are not very metal-poor; they are often thin disk; they really(?) are chemically evolved this is a“Toomre” diagram for the field RHB stars low 12 C/ 13 C is a telltale sign of CN- cycle H-burning and envelope mixing many are low velocity thin disk stars Afşar et al. 2012

16. But believing carbon isotopes from one very weak transition is very risky Afşar et al. 2012

17. IGRINS to the rescue! one 2%-deep CN optical feature versus a whole IR CO bandheads

18. and for HIP 54048, better light-element abundances in the IR than in the optical note especially P I, S I, K I only in IR; good agreement between Ti I & Ti II Afşar et al.,in prep

19. Topic III Some uses of IGRINS spectra for fundamental evolution of open cluster stars

20. our first effort used optical spectra of NGC 752 http://www.employees.org/~ddavison/Astro/astro.php?image=ngc752-2.jpg&images=NGC Böcek Topcu et al. 2015

21. light elements + HR-diagram = stellar evolution open cluster NGC 752 Böcek Topcu et al. 2015

22. fred http://www.alsonwongastro.com/ngc6940.htm red symbols are stars observed by IGRINS Now attack with IGRINS

23. fred http://cs.astronomy.com/asy/m/starclusters/464451.aspx red symbols are stars observed by IGRINS Now attack with IGRINS

24. CNOLi abundances in open cluster giants ELEMENTOPTICAL LINESIGRINS LINES lithiumLi I 6707Åno features carbonCH 4300Å – saturatedCO all over C 2 5160, 5630Å – weak nitrogenCN mostly >8000ÅCN strong in H oxygen[O I] 6300,6363Å - ??OH all over some other considerations  red giants typically 2-3 mag brighter in K than in V  H and K bands have drastically reduced extinction  mostly can get around gravity worries with CMD

25. a first IGRINS look at an exotic light element in M67

26. mostly an easy victory: 12 C/ 13 C = 25 but what are the things that don’t “fit”? ? ? ? ??

27. where IR spectrum analyses struggle: ions also in the heavy neutron-capture elements

28. IGRINS spectra of cool stars are dazzling – let’s be half as good as our data! from Pierre Magain’s contribution at IAU Symp 132 (1988): It is just a matter of will: do we intend to continue to provide the Galactic evolution theorists with data we cannot reasonably guarantee their reliability, or will we concentrate part of our efforts on checking the validity of our assumptions? the good news is that IGRINS will bring qualitative advances to our knowledge of stellar chemical compositions... and employment for us for many years! Many thanks for this excellent meeting!

29. fred