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arXiv · 2610.21566

An HST survey of photometry and multiplicity of brown dwarfs and planetary-mass objects in the field of Taurus

Pengyu Liu·Beth A. Biller·Clémence Fontanive·Michele Scalco·Loïc Albert·Luigi R. Bedin·Matthew De Furio·Belinda Damian·Jessy Jose·Zhoujian Zhang·Wen-Ping Chen·Sophie Dubber·Bhavana Lalchand·Michael C. Liu
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Abstract

We present a photometric and multiplicity survey of 26 young objects with masses between 6 Mj and 37 Mj and spectral type later than M8 in the Taurus star-forming region with the Hubble Space Telescope. We search for companion candidates using two methods: a dedicated photometric technique based on the combination of colours from multi-band photometry and point spread function fitting. No companion candidates are detected beyond 30 au. With an updated membership and age identification, we determine luminosity, temperature, and mass for the 26 young objects using evolutionary models. We demonstrate that our HST observations are sensitive to companions down to masses of 1 Mj and even lower for some targets by artificial star injection tests. After survey completeness correction, we derive a binary frequency < 6.5% for this sample in the 68% confidence interval for companions with mass ratios between 0.1 and 1 and separations between 30 and 7,000 au. We find no significant difference in binary frequency among planetary-mass objects in Taurus, Upper Scorpius, and the field. These findings support that the binary frequency of planetary-mass objects is settled at young ages, probably younger than 1--10 Myr, suggesting that the formation of wide-orbit planetary-mass binaries is inefficient and the disruption of them likely occurs at a very early stage in a low density environment.

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Pengyu Liu, Beth A. Biller, Clémence Fontanive, Michele Scalco, Loïc Albert, Luigi R. Bedin, Matthew De Furio, Belinda Damian, Jessy Jose, Zhoujian Zhang, Wen-Ping Chen, Sophie Dubber, Bhavana Lalchand, Michael C. Liu. 2026-10-15. An HST survey of photometry and multiplicity of brown dwarfs and planetary-mass objects in the field of Taurus. https://arxiv.org/abs/2610.21566

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