IRAS 04158+2805 has long been thought to be a very low mass T-Tauri star (VLMS) surrounded by a nearly edge-on, extremely large disc. Recent observations revealed that this source hosts a binary surrounded by an extended circumbinary disc with a central dust cavity. In this paper, we combine ALMA multiwavelength observations of continuum and 12CO line emission, with H α imaging and Keck astrometric measures of the binary to develop a coherent dynamical model of this system. The system features an azimuthal asymmetry detected at the western edge of the cavity in Band 7 observations and a wiggling outflow. Dust emission in ALMA Band 4 from the proximity of the individual stars suggests the presence of marginally resolved circumstellar discs. We estimate the binary orbital parameters from the measured arc of the orbit from Keck and ALMA astrometry. We further constrain these estimates using considerations from binary–disc interaction theory. We finally perform three SPH gas+dust simulations based on the theoretical constraints; we post-process the hydrodynamic output using radiative transfer Monte Carlo methods and directly compare the models with observations. Our results suggest that a highly eccentric e ∼ 0.5–0.7 equal mass binary, with a semimajor axis of ∼55 au, and small/moderate orbital plane versus circumbinary disc inclination θ ≲ 30° provides a good match with observations. A dust mass of ${\sim}1.5\times 10^{-4} \, {\rm M_\odot }$ best reproduces the flux in Band 7 continuum observations. Synthetic CO line emission maps qualitatively capture both the emission from the central region and the non-Keplerian nature of the gas motion in the binary proximity.

中文翻译：

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偏心双星 IRAS 04158+2805 周围的绕星盘和环星盘——双星盘相互作用的试验台

长期以来，IRAS 04158+2805 一直被认为是一颗质量非常低的金牛 T 星 (VLMS)，周围环绕着一个近乎边缘的、极大的圆盘。最近的观察表明，这个源包含一个双星，周围环绕着一个带有中央尘埃空腔的扩展环双星盘。在本文中，我们将 ALMA 对连续谱和 12CO 线发射的多波长观测与双星的 H α 成像和 Keck 天体测量相结合，建立了该系统的相干动力学模型。该系统的特点是在波段 7 观测中在空腔的西部边缘检测到方位角不对称和摆动流出。来自单个恒星附近的 ALMA 波段 4 中的尘埃发射表明存在边缘分辨的星环盘。我们根据 Keck 和 ALMA 天文学测量的轨道弧来估计二元轨道参数。我们使用二元盘相互作用理论的考虑进一步限制这些估计。我们最终基于理论约束进行了 3 次 SPH 气体+粉尘模拟；我们使用辐射传递蒙特卡罗方法对水动力输出进行后处理，并直接将模型与观测结果进行比较。我们的结果表明，一个高度偏心的 e ∼ 0.5-0.7 等质量双星，半长轴为 ∼55 au，小/中等轨道平面与外圆盘倾角 θ ≲ 30° 提供了与观测的良好匹配。${\sim}1.5\times 10^{-4} \, {\rm M_\odot }$ 的尘埃质量最好地再现了带 7 连续观测中的通量。合成的 CO 线排放图定性地捕获了来自中心区域的排放和二元邻近区域中气体运动的非开普勒性质。