Multiplicity Of Young Isolated Planetary Mass Objects In Taurus And Upper Scorpius
Free-floating planetary mass objects-worlds that roam interstellar space untethered to a parent star-challenge conventional notions of planetary formation and migration, but also of star and brown dwarf formation.
We focus on the multiplicity among free-floating planets. By virtue of their low binding energy (compared to other objects formed in these environments), these low-mass substellar binaries represent a most sensitive probe of the mechanisms at play during the star formation process.
We use the Hubble Space Telescope and its Wide Field Camera 3 and the Very Large Telescope and its ERIS adaptive optics facility to search for visual companions among a sample of 77 objects members of the Upper Scorpius and Taurus young nearby associations with estimated masses in the range between approximately 5-33 MJup.
We report the discovery of one companion candidate around a Taurus member with a separation of 111.9±0.4 mas, or ∼18 au assuming a distance of 160pc, with an estimated primary mass in the range between 3-6 MJup and a secondary mass between 2.6-5.2 MJup, depending on the assumed age. This corresponds to an overall binary fraction of 1.8+2.6−1.3% among free-floating planetary mass objects over the separation range ≥7 au.
Despite the limitations of small-number statistics and variations in spatial resolution and sensitivity, our results, combined with previous high-spatial-resolution surveys, suggest a notable difference in the multiplicity properties of objects below ∼25 MJup between Upper Sco and Taurus.
In Taurus, five companions were identified among 78 observed objects (4.9+2.8−2.0%), whereas none were found among 97 objects in Upper Sco (≤1.2%).}
Positions of the USco targets on a color photograph showing the clouds and nebulae. HST targets are represented with red dots and VLT targets with orange squares. Background photograph credit: Mario Cogo. — astro-ph.SR
Positions of the Taurus targets on a color photograph showing the main Taurus molecular clouds. HST targets are represented with red dots and the new binary candidate is indicated with a white cross. Background photograph credit: Chris McGrew — astro-ph.SR
H. Bouy, G. Duchêne, G. Strampelli, J. Aguilar, J. Olivares, D. Barrado, S. N. Raymond, N. Huélamo, M. Tamura, E. Bertin, W. Brandner, J.-C. Cuillandre, P. A. B. Galli, N. Miret-Roig
Comments: Submitted to A&A on 2025-04-04 ; awaiting the initial review
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2506.14380 [astro-ph.SR] (or arXiv:2506.14380v1 [astro-ph.SR] for this version)
https://doi.org/10.48550/arXiv.2506.14380
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From: Herve Bouy
[v1] Tue, 17 Jun 2025 10:24:36 UTC (4,956 KB)
https://arxiv.org/abs/2506.14380
Astrobiology,
