Spectroscopic orbits for three SB2s and one hierarchical triple using SALT data

Abstract

We confirmed four spectroscopic binary candidates using new observations obtained with SALT. Three SB2 systems (HD 20784, HD 43519A, HD 62153A) exhibit circular orbits with periods shorter than 10 days, whereas one hierarchical triple system (HD 56024) contains a close binary with an inner eccentric orbit with a period of approximately 14 days, composed of nearly identical stellar components, and a rapidly rotating star on an outer eccentric orbit with a period of approximately 400 days. For two additional SB2 candidates (HD 198174 and HD 208433), our new observations do not allow us to derive reliable orbital solutions.

Figures (6)

• Figure S1: Circular orbit fit for HD 20784. Blue circles are RV measurements from FEROS spectra hd20784.
• Figure S2: Circular orbit fit for HD 43519A. Black asterisk shows RV measurement from APOGEE for HD 43519B
• Figure S3: HD 56024: (a) Example for fitting with three spectral components in selected spectral intervals. The hot fast rotator is shown as a dark green line, while two cool components are shown as blue and orange lines respectively. Fit residuals are shown as a green line around zero. To improve visibility and readability of the Figure, we remove the gaps and plot the observed spectrum and best fit model twice: without offset (gray and red lines) and with offset -1.05 (gray and black lines) (b) Orbit fit with hierarchical triple configuration. (c) Spectral disentangling results by FD3 using SB3 orbit. Here we removed sine-like modulations and shifted derived components with arbitrary offsets, to make it similar to panel (a)
• Figure S4: Circular orbit fit for HD 62153A.
• Figure S5: Gaia DR3 SB1 orbit and RV from binary and single-star model for HD 198174. Dotted line shows systemic velocity.