• DOI:10.1051/0004-6361/202243516
• Corpus ID: 249836684

Physical properties and trigonometric distance of the peculiar dwarf WISE J181005.5-101002.3

@article{Lodieu2022PhysicalPA,
  title={Physical properties and trigonometric distance of the peculiar dwarf WISE J181005.5-101002.3},
  author={Nicholas Lodieu and Mar{\'i}a Rosa Zapatero Osorio and E. L. Mart{\'i}n and R. R. Lopez and Bartosz Gauza},
  journal={Astronomy \& Astrophysics},
  year={2022}
}

• N. Lodieu, M. Osorio, +2 authors B. Gauza
• Published 20 June 2022
• Physics
• Astronomy & Astrophysics

Aims. Our goal is to characterise the physical properties of the metal-poor brown dwarf population. In particular, we focus on the recently discovered peculiar dwarf WISE 1810055 − 1010023. Methods. We collected optical iz and near-infrared J -band imaging on multiple occasions over 1.5years to derive accurate trigono- metric parallax and proper motion of the metal-depleted ultra-cool dwarf candidate WISEJ1810055 − 1010023. We also acquired low-resolution optical spectroscopy (0.6 − 1.0 µ m) and new infrared (0.9 − 1.3 µ m) spectra of WISEJ1810055 − 1010023 that were combined with our photometry, other existing data from the literature and our trigonometric distance to determine the object’s luminosity from the integration of the observed spectral energy distribution covering from 0.6 through 16 µ m. We compared the full optical and infrared spectrum with state-of-the-art atmosphere models to further constrain its e ff ective temperature, surface gravity and metallicity. Results. WISEJ1810055 − 1010023 is detected in the iz bands with AB magnitudes of i = 23 . 871 ± 0 . 104 and z = 20 . 147 ± 0 . 083mag in the Panoramic Survey Telescope and Rapid Response System (PanSTARRS) system. It does not show any obvious photo- metric variability beyond 0.1 − 0.2mag in any of the z - and J -band filters. The very red z − J ≈ 2 . 9mag colour is compatible with an ultra-cool dwarf nature. Fitting for parallax and proper motion, we measure a trigonometric parallax of 112.5 + 8 . 1 − 8 . 0 mas for WISEJ1810055 − 1010023, placing the object at only 8.9 + 0 . 7 − 0 . 6 pc, about three times closer than previously thought. We em- ployed Monte Carlo methods to estimate the error on the parallax and proper motion. The object’s luminosity was determined at log L / L (cid:12) = − 5 . 78 ± 0 . 11dex. From the comparison to atmospheric models, we infer a likely metallicity of [Fe / H] ≈ − 1 . 5 and an e ff ective temperature cooler than 1000K. The estimated luminosity and temperature of this object are below the known substellar limit. low metallicity, we derive space are more typical of the old disc than the halo of the Milky Way. among field T-type distance has strong implications on the density of metal-poor brown dwarfs in the solar vicinity, which may be higher than that of metal-poor stars.