We present the analysis of 42 spectra of the Classical T Tauri star TW Hya observed with the FEROS echelle spectrograph over 2 yr. We determined the rotational and radial velocities of TW Hya, obtaining v sin i = 5 ± 2 km s-1 and vrad = 12.5 ± 0.5 km s-1. The star exhibits strong emission lines that show substantial variety and variability in their profile shapes. Emission lines such as Hα, Hβ, and He I show both outflow and infall signatures, which change on different timescales. The system displays periodic variations in line and veiling intensities, but the stellar rotation period remains uncertain. We see evidence of a variation in the mass accretion rate over a 1 yr period from the Na D line profiles that are well fitted by magnetospheric accretion models with moderate mass accretion rates (10-9 up to 10-8 M☉ yr-1). The lower values inferred from the models are close to the average mass accretion rate obtained from the veiling estimates (~2 × 10-9 M☉ yr-1), but the veiling results are consistent with a constant mass accretion rate within the errors of the calculations. The Hα, He I, Na D, and Hβ emission-line equivalent widths corrected from veiling correlate well with each other and are correlated with the veiling, indicating the same mechanism should be powering them and suggesting an origin related to the accretion process. The wings of the main emission lines are generally correlated, except when the Balmer lines exhibit properties suggesting a strong contribution from a wind. The blueward absorption components of the Balmer lines, most likely from a wind, are not correlated with veiling. The spectroscopic analysis allows us to infer the inclination of the stellar rotation axis (i = 18° ± 10°) that matches the current estimations of the disk orientation (0° i 15°). A magnetospheric dipole axis that is misaligned with the stellar/disk rotation axis could produce the observed photometric variability, and we tend to favor a low inclination but not a totally face-on geometry for the system. TW Hya exhibits typical spectral characteristics of many classical T Tauri stars in Taurus despite its older age, indicating that active accretion disks can readily survive up to 10 Myr.
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机译：我们提出了用费罗斯埃切尔光谱仪观测超过2年的经典T陶里星TW Hya的42个光谱的分析。我们确定了TW Hya的旋转速度和径向速度，得出v sin i = 5±2 km s-1和vrad = 12.5±0.5 km s-1。这颗恒星显示出强烈的发射线，这些发射线的轮廓形状表现出极大的多样性和可变性。发射线（例如Hα，Hβ和He I）同时显示流出和流入签名，它们在不同的时间范围内变化。该系统显示线和面纱强度的周期性变化，但恒星旋转周期仍然不确定。我们从Na D线剖面中看到了在1年内质量增加率发生变化的证据，这些曲线很适合具有中等质量增加率（10-9到10-8M☉yr-1）的磁层吸积模型。从模型中推断出的较低值接近从遮罩估计值获得的平均质量增加率（〜2×10-9M☉yr-1），但遮罩结果与恒定的质量增加率一致，且误差范围为计算。从遮罩校正后的Hα，He I，Na D和Hβ发射谱线等效宽度相互关联良好，并且与遮罩相关联，这表明应使用相同的机制为其提供动力，并暗示与积聚过程有关的起源。除巴尔默线表现出暗示风强力作用的特性外，主要发射线的翅膀通常相互关联。 Balmer线的蓝色吸收分量很可能来自风，与遮盖无关。光谱分析使我们可以推断出恒星旋转轴的倾斜度（i = 18°±10°），该倾斜度与当前磁盘取向估计值相匹配（0°展开▼
