Dynamical Mass Ratios of the Youngest Low-Mass Stars Gregory Mace Mentor: Lisa Prato Northern Arizona University Physics and Astronomy

This Project Goal: To measure mass ratios of very young binary stars. Why: To calibrate the parameters used in models of young star formation. How: High resolution IR spectroscopy of young spectroscopic binaries.

All are pre-main sequence single-lined spectroscopic binaries. Target Objects RX J0529.3+1210 P= 462.54 days e=0.91 SpT= K7-M0 NTTS 160814-1857 P= 144.7 days e=0.26 SpT= K2 NTTS 155808-2219 P=16.93 days e=0.10 SpT=M3 All are pre-main sequence single-lined spectroscopic binaries.

Introduction

Introduction Why infrared? Flux Ratio Closer to Unity Reference: Web http://www.astro.helsinki.fi/~lehtinen/Work/DC303.html

Observations Data from the instrument CSHELL on the 3-meter NASA IRTF Telescope. NASA IRTF CSHELL

Observations Data from the instrument NIRSPEC on the Keck II Telescope. Keck NIRSPEC

Spectral Changes NTTS 160814-1857 CSHELL NIRSPEC

Spectral Changes RX J0529.3+1210 NIRSPEC

Parameter Determination Two-Dimensional Cross Correlation (Dashed line) (Solid line) Spectrum Compared to Templates

Mass Ratio Determination RX J0529.3+1210 Mass ratio: q = - slope Center of Mass Velocity:  = (y-intercept)/(1+q) O. C. Wilson (1941)

Mass ratio and center of mass velocity to be determined. Results RX J0529.3+1210 q= 0.93 ± 0.13 = 16.74 ± 1.69 km/s periastron  0.12 AU apastron  2.56 AU NTTS 160814-1857 Mass ratio and center of mass velocity to be determined. NTTS 155808-2219

Results

Future Research RX J0529.3+1210 Future work: Observe RX J0529.3+1210 Complete mass ratios for NTTS stars

Conclusions The mass ratio of RX J0529.3+1210 is near unity. RX J0529.3+1210 is the most eccentric pre-main-sequence spectroscopic binary know. RX J0529.3+1210 has 24m excess which my be evidence of a circumbinary debris disk. Planet formation in RX J0529.3+1210 is unlikely. Comparison of templates supports likelihood of lower mass ratios for NTTS stars.