Amanda Truitt & Patrick A. Young Arizona State University, School of Earth and Space Exploration Using TYCHO [13] we have modeled the evolutionary tracks for a total of 1232 stars, each with a different combination of mass, scaled metallicity, and speciLic elemental composition. TYCHO is a 1D stellar evolution code with a hydrodynamic formulation of the stellar evolution equations. It uses OPAL opacities [14, 15, 16], and a combined OPAL and Timmes equation of state [17]. TYCHO outputs data on stellar surface quantities for each time-step of the evolution, which we use to produce a predicted radius for the inner and outer edges of the HZ as a function of the star’s age. To calculate the HZ for an individual star at each point in its evolution, we use equations from [6], combined with TYCHO outputs. Our program CHAD (Calculating HAbitable Distances) then determines the inner and outer HZ boundaries, discussed in [7]. The original grid of 376 models [18] includes “solar-type” stars, with masses ranging from 0.5–1.2 M¤. Models are also calculated for scaled metallicity values of 0.1–1.5 Z¤, and four models for oxygen abundance values (0.44, 0.67, 1.28, and 2.28 O/Fe¤) calculated at Z¤. The end-member oxygen models are also calculated at each scaled Z value. The grid is complete for the MS until hydrogen is exhausted in the core. Since it has been determined observationally that carbon and magnesium make the most difference (after oxygen) to the stellar evolution [19, 20, 21], we have simulated tracks to represent variations in these elements as well. The spread in values we use reLlects the diversity in abundances that have been directly measured in nearby stars [12, 22, 23, 24, 25]. This more recent grid includes a total of 480 models: 240 models each for variations in carbon and magnesium (ranging from 0.58–1.72 C/Fe¤ and 0.54–1.84 Mg/Fe¤) [paper in prep]. 1. Catanzarite, J. & Shao, M. 2011, ApJ, 738, 151 2. Petigura, E.A., Howard, A.W., & Marcy, G.W. 2013, PNAS, 110, 19273 3. Gaidos, E. 2013, ApJ, 770, 90 4. Batalha, N.M., Rowe, J.F., Bryson, S.T., et al. 2013, ApJS, 204, 24 5. Borucki, W.J., Koch, D., Basri, G., et al. 2011, ApJ, 736, 1 6. Kopparapu, R.K., Ramírez, R.M., Kasting, J.F., et al. 2013, ApJ, 765, 131 7. Kopparapu, R.K., Ramírez, R.M., SchottelKotte, J., et al. 2014, ApJL, 787, L29 8. Kasting, J.F., Whitmire, D.P., & Reynolds, R.T. 1993, Icarus, 101, 108 9. Selsis, F., Kasting, J.F., Levrard, B., et al. 2007, A&A, 476, 1373 10. Anbar, A.D., Duan, Y., Lyons, T.W., et al. 2007, Science, 317, 1903 11. Young, P.A., Liebst, K., & Pagano, M. 2012, ApJ, 755, 31 12. Hinkel, N.R., Young, P.A., Timmes, F.X., et al. 2014, ApJ, 148, 54 13. Young, P.A. & Arnett, D. 2005, ApJ, 618, 908 14. Iglesias, C.A. & Rogers, F.J. 1996, ApJ, 464, 943 15. Alexander, D.R. & Ferguson, J.W. 1994, ApJ, 437, 879 16. Rogers, F.J. & Nayfonov, A. 2002, ApJ, 576, 1064 17. Timmes, F.X. & Arnett, D. 1999, ApJS, 125, 277 18. Truitt, A., Young, P.A., Spacek, A., et al. 2015, ApJ, 804, 145 19. Neves, V., Santos, N.C., Sousa, S.G., et al. 2009, A&A, 497, 563 20. Mishenina, T.V., Soubiran, C., Bienaymè, O., et al. 2008, A&A, 489, 923 21. Takeda, Y. 2007, PASJ, 59, 335 22. Bond, J.C., Tinney, C.G., Butler, R.P., et al. 2006, MNRAS, 370, 163 23. Bond, J.C., Lauretta, D.S., Tinney, C.G., et al. 2008, ApJ, 682, 1234 24. Ramírez, I., Allende Prieto, C., & Lambert, D.L. 2007, A&A, 465, 271 25. González Hernández, J.I., Israelian, G., Santos, N.C., et al. 2010, ApJ, 720, 1592 26. Pagano, M.D., Truitt, A., Young, P.A., Shim, D. 2015, ApJ, 803, 90 27. http://bahamut.sese.asu.edu/~payoung/AST_522/ Evolutionary_Tracks_Database.html 28. Blackman, E.G. & Owen, J.E., 2016, MNRAS, 458, 2 We are working to understand how stars of different mass and composition evolve, and how stellar evolution directly inOluences the location of the habitable zone (HZ) around a star. It is now estimated that more than 20% of all Sun-like stars and 50% of M-dwarfs may host a planet in the H