论文标题
UOC。 V.使用Astrosat的旧开放群集NGC 188的紫外线研究
UOCS. V. UV study of the old open cluster NGC 188 using AstroSat
论文作者
论文摘要
我们介绍了使用使用紫外线望远镜（UVIT）在Astrosat卫星上获得的图像获得的旧开放群集NGC188的紫外光度法，该图像得以使用，其中两个远处（FUV）和一个近紫外（NUV）过滤器。紫外线数据与光学光度数据结合使用，以构建光学和紫外线尺度图（CMDS）。在FUV图像中，我们仅检测到热和明亮的蓝色Straggler星（BSS），一个热门少量和一个白矮人（WD）候选者。在NUV图像中，我们发现成员的微弱极限为〜22 mag，其中包括21个BSS，2个黄色Straggler星（YSSS）和一个WD候选者。这项研究介绍了第一个NUV光学CMD，并覆盖了更新的Basti-IAC同句和WD冷却序列，这些冷却序列与观察到的CMD非常吻合。我们使用光谱能分布（SED）拟合来估计紫外线恒星的有效温度，半径和亮度。我们发现该群集具有三颗恒星的HB人群（TEFF = 4750-21000 K）。我们还检测到两个黄色的散颗星，其中一个紫外线与紫外线过量连接到其二进制和X射线发射。
We present the UV photometry of the old open cluster NGC188 obtained using images acquired with Ultraviolet Imaging Telescope (UVIT) on board the ASTROSAT satellite, in two far-UV (FUV) and one near-UV (NUV) filters. UVIT data is utilised in combination with optical photometric data to construct the optical and UV colour-magnitude diagrams (CMDs). In the FUV images, we detect only hot and bright blue straggler stars (BSSs), one hot subdwarf, and one white dwarf (WD) candidate. In the NUV images, we detect members up to a faintness limit of ~22 mag including 21 BSSs, 2 yellow straggler stars (YSSs), and one WD candidate. This study presents the first NUV-optical CMDs, and are overlaid with updated BaSTI-IAC isochrones and WD cooling sequence, which are found to fit well to the observed CMDs. We use spectral energy distribution (SED) fitting to estimate the effective temperatures, radii, and luminosities of the UV-bright stars. We find the cluster to have an HB population with three stars (Teff = 4750 - 21000 K). We also detect two yellow straggler stars, with one of them with UV excess connected to its binarity and X-ray emission.
