论文标题
DQ TAU二进制系统中的积聚过程
The accretion process in the DQ Tau binary system
论文作者
论文摘要
从星际磁盘上的质量积聚到原恒星是恒星形成期间的一个基本过程。对于属于二进制系统的恒星而言，测量质量积聚率尤其具有挑战性，因为通常很难区分哪个组件正在积聚。 dq〜tau是一个几乎相等的质谱二进制系统，其中组件每15.8〜天相互绕。已知该系统显示脉冲吸积，即，由偏心轨道上的组件对积聚的周期性调节。我们提出了DQ〜TAU的多poch ESO/VLT X-Shooter观测值，目的是确定该系统的哪个组成部分是主要积累源。我们使用光谱中的吸收线来确定这两个组分的径向速度，并测量连续性蔬菜作为波长和时间的函数。我们使用非式模板拟合观察到的光谱，以校正光球和色球贡献。在校正的光谱中，我们详细研究了发射线的曲线，并计算系统的质量吸积率，这是轨道相的函数。根据先前的发现，我们检测到接近Periastron的积聚升高。我们衡量积聚率在$ 10^{ - 8.5} $和$ 10^{ - 7.3} $ msun/yr之间变化。发射线曲线表明，这两个恒星都在积极积聚，并且主要的增生器并不总是相同的成分，在少数轨道上有所不同。
Mass accretion from the circumstellar disk onto the protostar is a fundamental process during star formation. Measuring the mass accretion rate is particularly challenging for stars belonging to binary systems, because it is often difficult to discriminate which component is accreting. DQ~Tau is an almost equal-mass spectroscopic binary system where the components orbit each other every 15.8~days. The system is known to display pulsed accretion, i.e., the periodic modulation of the accretion by the components on eccentric orbit. We present multiepoch ESO/VLT X-Shooter observations of DQ~Tau, with the aim to determine which component of this system is the main accreting source. We use the absorption lines in the spectra to determine the radial velocity of the two components, and measure the continuum veiling as a function of wavelength and time. We fit the observed spectra with non-accreting templates to correct for the photospheric and chromospheric contribution. In the corrected spectra we study in details the profiles of the emission lines and calculate mass accretion rates for the system as a function of orbital phase. In accordance with previous findings, we detect elevated accretion close to periastron. We measure that the accretion rate varies between $10^{-8.5}$ and $10^{-7.3}$ Msun/yr. The emission line profiles suggest that both stars are actively accreting and the dominant accretor is not always the same component, varying in few orbits.
