X射线和吸积变异性对年轻盘双星系统DQ Tau中红外谱线的影响
The Effect of X-Ray and Accretion Variability on Mid-Infrared Lines in the Young Disk-Bearing Binary DQ Tau
浏览论文内容
中文总结 AI 辅助
本研究结合多历元X射线/紫外观测、JWST中红外光谱和热化学模型，发现常规吸积变异性使DQ Tau盘雪线外移17%，而X射线耀发显著增强H I、Ar II和Ne II发射，解释了非爆发系统的谱线变异性。
中文摘要 AI 辅助
恒星辐射场是行星形成盘的主要能量来源。从X射线到光学的恒星光子在内原行星盘中被再处理，使得中红外诊断能够揭示盘的物理条件。大多数前主序恒星以中等速率吸积并高效发射X射线。这种活动预计会驱动恒星光谱的随机变异性。目前尚不清楚这种变异性在多大程度上影响原行星盘的热化学结构。我们旨在研究常规吸积变异性和X射线耀发对原行星盘热化学结构和中红外谱线发射光谱的影响。我们将DQ Tau双星系统的多历元、同时期的X射线和近紫外/光学观测与其环双星盘的JWST/MIRI光谱相结合。我们使用一个代表该系统的热化学模型来解释数据并评估变化恒星光谱对盘的影响。由于吸积光度增强，CO、CO2、HCN和H2O的合成通量在近星点处系统性高于远星点处。各历元间积分通量的变化在两倍以内，与DQ Tau的JWST/MIRI光谱一致。常规恒星变异性仅引起盘结构的适度变化，但仍可使雪线相对于其远星点位置向外移动17%。由于JWST观测未与X射线耀发同时发生，我们的耀发结果依赖于模拟：中等强度耀发使大多数中红外分子发射保持不变；相反，X射线耀发强烈增强了盘表面H I、Ar II和Ne II的丰度及中红外光度。我们的结果表明，在非爆发系统中观测到的Spitzer/JWST谱线变异性与由吸积和磁层活动驱动的中等变化恒星光谱一致。
英文摘要
A star's radiation field is the main energy source of a planet-forming disk. Stellar photons---from X-rays to optical---are reprocessed in the inner protoplanetary disk enabling mid-IR diagnostics of the disk's physical conditions. Most pre-main-sequence stars accrete at moderate rates and emit X-rays efficiently. Such activity is expected to drive stochastic variability in the stellar spectrum. It is not clear to what extent such variability affects the thermochemical structure of protoplanetary disks. We aim to examine the effect of routine accretion variability and X-ray flares on the thermochemical structure and mid-IR line emission spectra of protoplanetary disks. We combine multiepoch, contemporaneous X-ray and NUV/optical observations of the DQ Tau binary with JWST/MIRI spectra of its circumbinary disk. We interpret the data and assess the effect of a varying stellar spectrum on the disk using a thermochemical model illustrative of the system. Synthetic fluxes of CO, CO2, HCN, and H2O are systematically stronger at periastron than at apastron due to an enhanced accretion luminosity. Variations in the integrated fluxes lie within a factor of two between epochs, in agreement with the JWST/MIRI spectra of DQ Tau. Routine stellar variability induces only modest changes in the disk's structure, yet it can still shift the snowline outwards by 17 percent relative to its apastron position. Because the JWST observations did not coincide with X-ray flares, our flare results rely on simulations: moderate-intensity flares leave most mid-IR molecular emission unchanged; in contrast, X-ray flares strongly enhance the abundances and mid-IR luminosities of H I, Ar II, and Ne II in the disk surface. Our results imply that the Spitzer/JWST line variability observed in non-outbursting systems is consistent with moderately variable stellar spectra driven by accretion and magnetospheric activity.
发表机构
- The Pennsylvania State University（宾夕法尼亚州立大学）
- Center for Exoplanets and Habitable Worlds, Penn State University（系外行星与宜居世界中心，宾夕法尼亚州立大学）
- Konkoly Observatory, HUN-REN Research Centre for Astronomy and Earth Sciences（孔科利天文台，匈牙利研究网络天文学与地球科学研究中心）
- Zentrum für Astronomie der Universität Heidelberg（海德堡大学天文学中心）
- Max-Planck-Institut für Astronomie（马克斯·普朗克天文学研究所）
- Institute of Astronomy, Russian Academy of Sciences（俄罗斯科学院天文学研究所）
- Institute of Physics and Astronomy, ELTE Eötvös Loránd University（罗兰大学物理与天文学研究所）
- Centre for Astrophysics Research, University of Hertfordshire（赫特福德大学天体物理学研究中心）
机构由 AI 辅助整理，请以论文原文为准。
