B-type Binaries Characterisation (BBC) Programme

Overview

Early B-type stars are common, bright, and often live in pairs. By tracking periodic shifts in their spectral lines across many nights, we can measure orbits, map how frequent binaries are, and catch systems mid-interaction.

BBC I. Orbital solutions for a large, homogeneous sample of early B-type binaries in 30 Doradus (LMC) — establishing period statistics and highlighting systems that may hide compact companions.

BBC II. A deep dive on VFTS 291, revealing a recently stripped, bloated star orbiting an early-B companion: direct evidence of the short-lived stage just after mass transfer.

BBC III. Mass-transferring and post-interaction systems: OGLE photometry and light-curve modelling of eclipsing binaries (in prep).

My contributions

• BBC I: led the orbital fitting and period-distribution analysis; led the search for compact-companion candidates.
• BBC II: led the analysis and modelling of VFTS 291 — one of the first post-mass-transfer, stripped-star systems identified in the LMC.
• Ongoing: supervising MSc student Henry Willems (graduation 03/2025) and integrating thesis results into the third BBC paper.

Key results (so far)

• Orbit catalogue: multi-epoch survey of 88 candidates; 64 binaries confirmed (50 SB1, 14 SB2), plus 20 with tentative periods; 84 orbits delivered — the largest homogeneous set for early B-type binaries in the LMC to date.
• Period statistics: broadly similar to O-type binaries, suggesting a common formation channel.
• Compact-companion candidates: 16 systems fall in the high-probability region for hidden black-hole companions (flagged for high-resolution follow-up).
• Post-MT system (BBC II): VFTS 291 with P ≈ 108 d, K₁ ≈ 94 km s⁻¹; a ~1.5–2.5 M☉ stripped star with an early-B ~13.2 ± 1.5 M☉ companion — consistent with recent Case-B mass transfer.

Publications