2007/11/28 by N. Rowell, Mukremin Kilic, M. Kilic +1 · 1 citation
Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Star Formation Studies #Brown dwarf #Infrared #Opacity #Optics #Parallax #Photometry (optics) #Physics #Sky #Stars #Stellar, planetary, and galactic studies #White dwarf #astro-ph
paper · pdf · doi:10.1111/j.1745-3933.2008.00425.x
Accepted for publication in MNRAS
arxiv created 2007/11/28 · openalex publication_date 2008/02/04 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Abstract We present BJ, R59F and IN photometry, and optical and near-infrared spectroscopy, of a new ultracool white dwarf (UCWD) discovered in the SuperCOSMOS Sky Survey. The spectrum of SSS J1556−0806 shows strong flux suppression due to the presence of collisionally induced absorption by molecular hydrogen, a feature characteristic of the cool, high-density environments found in the atmospheres of UCWDs. SSS J1556−0806 therefore joins a list of less than 10 UCWDs displaying extreme flux suppression. Synthetic model fitting suggests an effective temperature of <3000 K, which if true would make this one of the coolest white dwarf currently known. We also exploit the similarity between the spectral energy distributions of SSS J1556−0806 and the well-studied UCWD LHS 3250 to aid in the determination of the atmospheric parameters in a regime where models consistently fail to reproduce observations. SSS J1556−0806 is relatively bright (R∼ 17.8), making it particularly amenable to follow up observations to obtain trigonometric parallax and infrared photometry.