AI 中文总结
研究对WISPIT 2主恒星进行光谱分析，利用多种仪器观测，通过建模、分析发射线及径向速度测量等方法，发现其为光谱双星，给出相关参数，检测到低吸积率，该系统成为首个有直接成像原行星的环绕双星系统，为行星形成研究提供基准。
AI 中文摘要
虽然已对数百个原行星盘进行了详细研究，但仍很少能探测到仍处于原生盘中的原行星。WISPIT 2是第二个能直接研究行星形成过程的实例。该系统在多环盘中有两颗巨型原行星。本文旨在通过光谱对WISPIT 2主恒星进行特征分析，以确定其恒星属性、吸积率和内盘诊断，从而更全面了解该系统。利用ESO VLT/X - Shooter和2.2米/FEROS仪器进行了光学和近红外光谱观测。通过对恒星光谱建模确定光谱类型和有效温度，分析发射线估计吸积率，利用径向速度测量寻找紧密恒星伴星证据。观测发现WISPIT 2是光谱双星，周期为$4.8\pm 0.1$天，由一颗约$0.97 M_{\odot}$的K3型主星（$T_{\rm eff} \sim 4700K$）和一颗约$0.33M_\odot$的次星（质量比约0.34）组成，检测到弱H$\alpha$发射，吸积率约为$\sim 2 \times 10^{-11}\,M_{\odot}\,\mathrm{yr}^{-1}$，低于色球层水平。这一发现使WISPIT 2盘成为首个有直接成像原行星的环绕双星系统，为研究双星周围行星形成和盘演化提供了独特基准。
英文摘要
While hundreds of protoplanetary discs have been studied in great detail, the detection of protoplanets still embedded in their native discs remains rare. WISPIT 2 is only the second laboratory allowing for direct study of planet formation while in progress. The recently discovered system hosts two giant protoplanets in a multi-ringed disc. Here, we aim at characterising the WISPIT 2 host star spectroscopically to determine its stellar properties, accretion rate, and inner disc diagnostics, providing a more complete picture of the system. We present optical and near-infrared spectroscopic observations obtained with the ESO VLT/X-Shooter and 2.2 m/FEROS instruments. We model the stellar spectrum to determine the spectral type and effective temperature, analyse the emission lines to estimate the accretion rate, and search for evidence of a close stellar companion using radial velocity measurements. Our observations reveal that WISPIT 2 is a spectroscopic binary. The binary has a period of $4.8\pm 0.1$ days, which corresponds to a semi-major axis of $0.072$ au or $15.54 R_\odot$, assuming co-planarity with the disc and a circular orbit. The binary system consists of a $\sim 0.97 M_{\odot}$ primary of spectral type K3 ($T_{\rm eff} \sim 4700K$), and a $\sim 0.33M_\odot$ secondary (mass ratio $\sim$0.34). We detect weak H$α$ emission, implying an accretion rate of $\sim 2 \times 10^{-11}\,M_{\odot}\,\mathrm{yr}^{-1}$. However, this value is below the chromospheric level, suggesting little to no ongoing accretion onto the young stars. This discovery makes the WISPIT 2 disc the first circumbinary system with directly imaged protoplanets, establishing this system as a unique benchmark for studying planet formation and disc evolution around binary stars.
CommentsAccepted for publication in A&A
