Physical Sciences and Mathematics Commons^™

11-12 Gyr Old White Dwarfs 30 Pc Away, Mukremin Kilic, John R. Thorstensen, P. M. Kowalski, J. Andrews

Dartmouth Scholarship

We present a detailed model atmosphere analysis of two of the oldest stars known in the solar neighbourhood, the high proper motion white dwarfs SDSS J110217.48+411315.4 (hereafter J1102) and WD 0346+246 (hereafter WD0346). We present trigonometric parallax observations of J1102, which places it at a distance of only 33.7 ± 2.0 pc. Based on the state-of-the-art model atmospheres, optical, near-infrared, mid-infrared photometry and distances, we constrain the temperatures, atmospheric compositions, masses and ages for both stars. J1102 is an 11-Gyr-old (white dwarf plus main-sequence age), 0.62 M_⊙ white dwarf with a pure H atmosphere and T_eff= 3830 …