AI 中文总结
本研究利用AstroSat搭载的UVIT观测数据，结合多波段数据构建色-星等图，探测NGC 3201中的紫外亮源，明确了不同恒星的物理参数，为该星团的恒星演化与动力学研究提供了新见解。
AI 中文摘要
我们利用AstroSat卫星搭载的紫外成像望远镜（UVIT），对球状星团NGC 3201中的紫外（UV）亮恒星群开展了一项综合研究。通过将UVIT的F148W和F169M滤光片的远紫外测光数据，与盖亚（Gaia）及地面望远镜的光学数据相结合，我们构建了紫外-光学色-星等图（CMDs），以识别紫外亮恒星的演化阶段。我们通过将恒星大气模型拟合到观测到的多波段光谱能量分布（SEDs），推导了所有探测到的源的物理参数。水平分支蓝星（BHBs）的有效温度范围为7250至11250开尔文。我们识别出两颗极端水平分支星（EHBs），其有效温度分别约为25000开尔文和17000开尔文；其中一颗位于星团核心半径（r_c=1.3角分）以内，另一颗则位于核心半径之外。我们还探测到两颗处于水平分支星与白矮星过渡阶段的候选“间隙”天体，它们可能代表热蓝钩（BHk）星。对于蓝 straggler 星（BSSs），我们通过SED拟合确定了其有效温度、半径和光度，并使用PARSEC等时线估算了它们的质量和等时线等效年龄。最后，我们研究了观测到的BHB星、BSS星、主序星（MS星）、红巨星分支星（RGB星）以及变星的归一化累积径向分布，以及BSS星在星团中的特定频率。这些结果为NGC 3201的晚期恒星演化和动力学过程提供了新的见解。
英文摘要
We present a comprehensive study of the ultraviolet (UV)-bright stellar population in the globular cluster NGC 3201 using the Ultraviolet Imaging Telescope (UVIT) onboard AstroSat. By combining far-UV photometry of the UVIT F148W and F169M filters with Gaia and ground-based telescope optical data, we construct UV$-$optical color-magnitude diagrams (CMDs) to identify UV-bright stellar evolutionary phases. Physical parameters of all detected sources are derived by fitting stellar atmosphere models to the observed multi-wavelength spectral energy distributions (SEDs). The effective temperatures of blue horizontal branch stars (BHBs) span the range 7250$-$11250 K. We identify two extreme horizontal-branch stars (EHBs) with effective temperatures of approximately 25,000 K and 17,000 K; one lies within the cluster core radius ($r_\mathrm{c}$=1.3$'$), while the other is located outside. We also detect two candidate ``gap'' objects in the transitional phase between HB stars and white dwarfs, which may represent hot blue hook (BHk) stars. For the blue straggler stars (BSSs), we determine effective temperatures, radii, and luminosities through SED fittings, and estimate their masses and isochrone-equivalent ages using PARSEC isochrones. Finally, we studied the normalized cumulative radial distribution of the observed BHB stars, BSSs, MS stars, RGB stars, and variable stars along with the specific frequency of BSSs across the cluster. These results provide new insights into the late-stage stellar evolution and dynamical processes in NGC 3201.
CommentsAppected for publication in Journal of Astrophysics and Astronomy (JAA)
