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The binary η Carinae is the closest example of a very massive star, which may have formed through a merger during its Great Eruption in the mid-19th century. We aimed to confirm and improve the kinematics using a spectroscopic data set taken with the Cerro Tololo Inter-American Observatory 1.5-m telescope over the time period of 2008–2020, covering three periastron passages of the highly eccentric orbit. We measure line variability of H α and H β, where the radial velocity and orbital kinematics of the primary star were measured from the H β emission line using a bisector method. At phases away from periastron, we observed the He ii 4686 emission moving opposite the primary star, consistent with a possible Wolf–Rayet companion, although with a seemingly narrow emission line. This could represent the first detection of emission from the companion.

 

ABSTRACT We present updated orbital elements for the Wolf–Rayet (WR) binary WR 140 (HD 193793; WC7pd  + O5.5fc). The new orbital elements were derived using previously published measurements along with 160 new radial velocity measurements across the 2016 periastron passage of WR 140. Additionally, four new measurements of the orbital astrometry were collected with the CHARA Array. With these measurements, we derive stellar masses of $M_{\rm WR} = 10.31\pm 0.45 \, \mathrm{M}_\odot$ and $M_{\rm O} = 29.27\pm 1.14 \, \mathrm{M}_{\odot }$. We also include a discussion of the evolutionary history of this system from the Binary Population and Spectral Synthesis model grid to show that this WR star likely formed primarily through mass-loss in the stellar winds, with only a moderate amount of mass lost or transferred through binary interactions. 

ABSTRACT The bright and understudied classical Be star HD 6226 has exhibited multiple outbursts in the last several years during which the star grew a viscous decretion disc. We analyse 659 optical spectra of the system collected from 2017 to 2020, along with a ultraviolet spectrum from the Hubble Space Telescope and high cadence photometry from both Transiting Exoplanet Survey Satellite (TESS) and the Kilodegree Extremely Little Telescope (KELT) survey. We find that the star has a spectral type of B2.5IIIe, with a rotation rate of 74 per cent of critical. The star is nearly pole-on with an inclination of 13${_{.}^{\circ}}$4. We confirm the spectroscopic pulsational properties previously reported, and report on three photometric oscillations from KELT photometry. The outbursting behaviour is studied with equivalent width measurements of H α and H β, and the variations in both of these can be quantitatively explained with two frequencies through a Fourier analysis. One of the frequencies for the emission outbursts is equal to the difference between two photometric oscillations, linking these pulsation modes to the mass ejection mechanism for some outbursts. During the TESS observation time period of 2019 October 7 to 2019 November 2, the star was building a disc. With a large data set of H α and H β spectroscopy, we are able to determine the time-scales of dissipation in both of these lines, similar to past work on Be stars that has been done with optical photometry. HD 6226 is an ideal target with which to study the Be disc-evolution given its apparent periodic nature, allowing for targeted observations with other facilities in the future.