The CHARA Science Meeting 2021

The First Dynamical Mass Determination of a Nitrogen-rich Wolf– Rayet Using a Combined Visual and Spectroscopic Noel Richardson, Laura Lee, et al. Embry-Riddle Aeronautical University

1 The CHARA Science Meeting 2021 What is a Wolf-Rayet star?

• Classical WR are H-free, evolved massive stars. They have extremely high effective temperatures and strong stellar winds.

WR124, HST

Sana et al. (2012)

2 The CHARA Science Meeting 2021 Previous Interferometry of WR stars

• Due to the rarity of these objects, only a few have been observed. • Large distances – not much to resolve for most WR stars • Binaries are main focus with current instrumentation

3 The CHARA Science Meeting 2021 Gamma2 Vel • WC8 + O7.5III • P = 78.53 d • e = 0.33 • Lamberts et al. 2017 + Richardson et al. 2017 • M_O = 28.4 Msun • M_WR = 9 Msun

4 The CHARA Science Meeting 2021 WR140 – Monnier et al. (2011); Thomas, Richardson et al. (submitted)

• WC7pd + O5.5fc • P = 7.93 • e = 0.8993 • M_O = 29.3 Msun • M_WR = 10.3 Msun

5 The CHARA Science Meeting 2021 WR137, WR138 – resolved with CHARA (Richardson et al. 2016)

• WR 137 • WC7 + O • P = 13 yr • Dust formation at periastron

• WR 138 • WN + O • P – unknown, possibly ~4 yr?

• CLIMB observations resolved the binaries – began a long-term NOAO NOIR Lab program for . • Upgraded MIRC-X made the program finally take off!

6 The CHARA Science Meeting 2021 WR 133 - background

• WN5o + O9I • Known SB2 orbit with P=133 d, but relatively understudied. • member of NGC 6871 • Inclination at least 115deg from polarimetric analysis

7 The CHARA Science Meeting 2021 CHARA observations and the new paper

8 The CHARA Science Meeting 2021 Archive of DAO Spectra

1.2 1.1 2452838.8 1.0

0.9 2449145.8 0.8 NORMALIZED FLUX 0.7 5200 5400 5600 5800 6000 WAVELENGTH (ANGSTROMS) 1.2 He II O III He I

1.0

0.8 NORMALIZED FLUX

0.6 -2000 -1000 0 1000 -400 -200 0 200 400 -400 -200 0 200 400 RADIAL VELOCITY (km s-1)

9 The CHARA Science Meeting 2021 CHARA

10 The CHARA Science Meeting 2021 Orbital Elements/Masses

• P = 112.78 d • e = 0.36 • d = 1.73 kpc • a = 0.79 mas = 292 Rsun • M_O = 18.1 Msun • M_WR = 8.2 Msun

11 The CHARA Science Meeting 2021 Comparisons with Theoretical models Best models indicate a spectroscopic mass of 14 Msun, ~2-3 sigma from measured mass!

12 The CHARA Science Meeting 2021 If you need supporting spectroscopy for CHARA observations…

We have a small telescope and an eshel (R~10,000) spectrograph that covers the ~4500-6800A range. We have up to 300 clear nights per , and my students and I will gladly help with coverage.

Early results show that we can accurately measure an SB2 with a half hour exposure and a stellar contrast of

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