1. Near-Infrared Spectroscopic Study of AA Tau Logan R. Brown Erika L. Gibb Nathan X. Roth University of Missouri – St. Louis

2. © Bill Saxton, NRAO / AUI / NSF

3. Observations High-resolution (λ/Δλ ∼ 25,000), near-infrared spectroscopic data obtained 2010 Feb 23 using NIRSPEC at Keck II (McLean et al. 1998) Observations range from 2860 cm -1 to 3477 cm -1, chosen to cover many transitions of OH and Water Reduced using a standard method: dark subtracted, flat fielded, cleaned of hot and dead pixels, spectrally and spatially straightened (Bonev 2005, DiSanti et al. 2001) Telluric model fit to and subtracted from reduced spectra

4. AA Tau Fairly typical Classical T Tauri Star: K7 spectral type Well-know, shows strong H - alpha emission and IR excesses indicating the presence of a gaseous and dusty accretion disc Undergoes periodic eclipses caused by a warped inner disk structure CO absorption studied in the 2 micron region Water and prebiotic molecules observed in emission in the Mid-IR

5. Comparison of the observed spectrum of AA Tauri to the combined model spectrum. All the unlabeled features are rotational transitions of H 2 O. (Carr & Najita 2008)

6. AA Tau Inclination Warped inner disc structure producing periodic eclipses Period of eclipses used to calculate equatorial rotation velocity (8.22 ± 0.03 d) Coupled with measured v sin i (11.3 ± 0.7 km s -1 ) Calculated inclination of 70 o ± 10 o (Donati et al. 2010)

7. Red = 75 o (traces top of dark lane), orange = 72 o, yellow = 70 o, blue = 68 o inclination (traces bottom of dark lane. Derived i = 71 o ± 1 o. (Cox et al. 2013)

8. Henning & Semenov 2013 Near-IR Mid-IR (Sub)millimeter

9. Portion of the observed spectra Error envelope plotted in grey, telluric model in pink

10. Schematic representation of the line-of-sight geometry for the inner region of T Tauri star disk. (McJunkin et al. 2013)

11. Portion of the observed spectra Error envelope plotted in grey, telluric model in pink

12. 001-000 blue, 011-010 purple, 020-000 brown, 100-000 red, 110-010 green, OH tick marks Single temperature, LTE model

13. 001-000 blue, 011-010 purple, 020-000 brown, 100-000 red, 110-010 green, OH tick marks Single temperature, LTE model

14. CO spectrum from HL Tau. The broad emission features result from hot CO gas near the star. The narrow absorption features that are superposed on these emission features have a lower rotational temperature indicating colder gas along the line of sight. (Brittain et al. 2005)

15. Fractional abundance of H 2 O as a function of disk radius and height up to a radius of 10 AU (Walsh et al. 2010)

17. See Brown et al. 2013 for discussion of modeling

19. Going Forward Apply the developed emission line model with disk appropriate line profile Simultaneously modeling emission and absorption Finalize temperature and column density Search for and identify other species such as HCN

20. Acknowledgments NASA Missouri Space Grant Consortium NSF’s Stellar Astronomy program The American Recovery and Reinvestment Act of 2009 NASA Exobiology and Evolutionary Biology program W.M. Keck Observatory The cultural role and reverence that the summit of Mauna Kea has with the indigenous Hawaiian community