Dynamical Mass Ratios of the Youngest Low-Mass Stars

Gregory Mace Mentor: Lisa Prato

Northern Arizona UniversityPhysics 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.

Target Objects

• RX J0529.3+1210P= 462.54 days e=0.91 SpT= K7-M0

• NTTS 160814-1857P= 144.7 days e=0.26 SpT= K2

• NTTS 155808-2219P=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.

CSHELL

NASA IRTF

Observations

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

NIRSPEC

Keck

Spectral Changes

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NTTS 160814-1857

NIRSPECCSHELL

Spectral Changes

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RX J0529.3+1210

NIRSPEC

Parameter Determination• Two-Dimensional Cross Correlation

Spectrum Compared to Templates

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(Dashed line)

(Solid line)

Mass Ratio Determination

• Mass ratio: q = - slope

• Center of Mass Velocity: = (y-intercept)/(1+q)

O. C. Wilson (1941)

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RX J0529.3+1210

Results

• RX J0529.3+1210q= 0.93 ± 0.13 = 16.74 ± 1.69

km/s

periastron 0.12 AUapastron 2.56 AU

• NTTS 160814-1857Mass ratio and center of mass velocity to be determined.

• NTTS 155808-2219Mass ratio and center of mass velocity to be determined.

Results

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Future ResearchRX 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 24m 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.