2026/02/28 by Noel D. Richardson, Ryan M. T. White, Anthony J. Fabrega +8 · 1 voice
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Stellar, planetary, and galactic studies
paper · doi:10.3847/1538-4357/ae4d0d
openalex created_date 2026/03/04 · openalex publication_date 2026/04/02 · openalex updated_date 2026/06/11
Abstract When two massive stars orbit each other, their winds create a shock cone. In some cases, an evolved, carbon-rich Wolf–Rayet (WR) star’s wind collides with that of an orbiting OB star, condensing into dust downstream. This dust is then seen as large spiral structures that eventually move into the interstellar medium. Among these colliding-wind binaries, the archetypal system WR 104 has become an enigma. Aperture masking interferometry with Keck revealed an evolving, face-on dust spiral, with multiple rungs of dust visible from years of observations. In contrast to direct imaging, recent spectroscopic results imply that the orbit must have an inclination quite different from a face-on geometry. We examined photometry from the All-Sky Automated Survey (ASAS) and the All-Sky Automated Survey for SuperNovae (ASAS-SN) to place further constraints on the geometry of the orbit. By phase-binning the light curve, we find that the recent g -band light curve is brightest when the OB star lies in front of the WR star along our line of sight, with the lowest flux occurring at the opposite conjunction. We fit the light curve with an illustrative model for scattering eclipses, allowing us to infer a system inclination of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo stretchy="false">(</mml:mo> <mml:mn>41</mml:mn> <mml:mo>.</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>8</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>14.9</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>13.0</mml:mn> </mml:mrow> </mml:msubsup> <mml:mo stretchy="false">)</mml:mo> <mml:mo>°</mml:mo> </mml:math> . This inclination agrees with the recent spectroscopic orbit, and presents challenges to previous interpretations of high-angular-resolution images of the dust plume. We provide a qualitative geometric model for the dust plume that reconciles these results and show how WR 104 can provide a means for studying the properties of WR dust in detail.