A Multiwavelength View of $ρ$ Oph II: Disentangling the Variability of the Multi-Star Component C

Sean J. Gunderson; Walter W. Golay; Jackson Codd; David P. Huenemoerder; Felipe Navarete; Christiana Erba; Alexandrea Moreno; John M. Cannon; Richard Ignace; Pragati Pradhan; the MACRO consortium

arXiv · 2609.29809

A Multiwavelength View of $ρ$ Oph II: Disentangling the Variability of the Multi-Star Component C

Sean J. Gunderson·Walter W. Golay·Jackson Codd·David P. Huenemoerder·Felipe Navarete·Christiana Erba·Alexandrea Moreno·John M. Cannon·Richard Ignace·Pragati Pradhan·the MACRO consortium

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Abstract

We present a multiwavelength analysis of the star $ρ$ Oph C, covering X-ray, optical, near-infrared, and radio observations to test for the presence of interferometrically-detected cool star companions. The X-ray observations from Chandra, XMM-Newton, and NuSTAR show flare-like events lasting minutes or days in time and spectral properties consistent with those of cooler stars instead of the primary magnetic B star. The near-infrared data is also consistent with the proposed trinary system properties due to the presence of CO-band heads. After removing the primary B star's rotation, the optical data from TESS shows a residual signal at the level of 0.8 mmags, matching the variations expected from cool stars in orbit around a bright B star. Finally, multi-epoch radio data reveals that $ρ$ Oph C exhibits significant large scale flux variations that are atypical for a magnetic massive star. Taken as a whole, the multi-epoch and -wavelength data presents a consistent picture of $ρ$\,Oph\,C as a rare trinary system composed of a hot star and two cool stars.

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Sean J. Gunderson, Walter W. Golay, Jackson Codd, David P. Huenemoerder, Felipe Navarete, Christiana Erba, Alexandrea Moreno, John M. Cannon, Richard Ignace, Pragati Pradhan, the MACRO consortium. 2026-09-24. A Multiwavelength View of $ρ$ Oph II: Disentangling the Variability of the Multi-Star Component C. https://arxiv.org/abs/2609.29809

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