标题： 利用iSHELL观测测量年轻恒星的磁场：BP Tau和V347 Aur 显示英文标题

标题： Measuring the magnetic field of young stars using iSHELL observations: BP Tau and V347 Aur

摘要： 尽管有人提出年轻恒星的磁场特性和内部结构之间存在联系，但在最早期阶段还没有足够的磁场测量数据来明确建立这种相关性。 在此，我们通过展示BP Tau和V347 Aur（这两颗恒星均使用近红外光谱仪iSHELL观测）的恒星参数和磁场强度测量值，为这一研究做出了贡献。 首先，我们通过将合成恒星光谱拟合到一组九个主序星和后主序星样本上，测试了我们方法的准确性。我们报告温度的不确定性为$\sigma_{\rm Teff}$ = 91 K，重力的不确定性为$\sigma_{\rm log(g)}$ = 0.14。 然后，我们将建模技术应用于BP Tau，并测量出表面磁场强度为$\langle \rm B \rangle $ = 2.5$^{+0.15}_{-0.16}$千高斯，证实了文献中的结果。 然而，对于这颗恒星，我们得到的温度值比之前光学研究的结果（$\Delta \rm T \sim 400$K）低得多，并将这一显著的温度差异解释为由于在近红外波段恒星黑子的影响相对较大，而在光学波段影响较小。 我们进一步将该技术应用于一类原恒星源 V347 Aur，并首次测量其磁场强度$\langle \rm B \rangle = $1.36$^{+0.06}_{-0.05}$千高斯以及其表面重力 log(g) = 3.25$^{+0.14}_{-0.14}$。 最后，我们将测量结果与前主序恒星演化模型相结合，展示了恒星黑子对年轻恒星获取的质量和年龄所产生的影响。 显示英文摘要

摘要： While it has been suggested that there is a connection between the magnetic properties and the internal structure of young stars, there have not been enough magnetic measurements to firmly establish such a correlation at the earliest ages. Here, we contribute to this endeavor by presenting stellar parameters and magnetic field strength measurements of BP Tau and V347 Aur, both stars observed with the near-infrared spectrograph iSHELL. We first test the accuracy of our method by fitting synthetic stellar spectra to a sample of nine main and post-main-sequence stars. We report uncertainties of $\sigma_{\rm Teff}$ = 91 K in temperature and $\sigma_{\rm log(g)}$ = 0.14 in gravity. We then apply the modeling technique to BP Tau and measure a surface magnetic field strength of $\langle \rm B \rangle $ = 2.5$^{+0.15}_{-0.16}$ kG, confirming literature results. For this star, however, we obtain a much lower temperature value than previous optical studies ($\Delta \rm T \sim 400$ K) and interpret this significant temperature difference as due to the relatively higher impact of starspots at near-infrared wavelengths than at optical wavelengths. We further apply this technique to the class I protostellar source V347 Aur and measure for the first time its magnetic field strength $\langle \rm B \rangle = $ 1.36$^{+0.06}_{-0.05}$ kG and its surface gravity log(g) = 3.25$^{+0.14}_{-0.14}$. Lastly, we combine our measurements with pre-main-sequence stellar evolutionary models and illustrate the effects produced by starspots on the retrieved masses and ages of young stars.