论文标题
调查三个具有球体的小天狼星样系统
Investigating three Sirius-like systems with SPHERE
论文作者
论文摘要
小天狼星样系统是由白矮人(WD)组成的宽二进制系统,比M0早的光谱类型组成。 WD祖细胞孤立地演变,但其在AGB期间的风污染了伴随表面并传递了一些角动量。在使用VLT的Shine调查中,我们获得了HD2133,HD114174和CD-567708的图像,并将这些数据与原始,TESS和文献数据的高分辨率光谱相结合。我们对MS进行了准确的丰度分析。我们发现HD114174B的J和K幅度要比以前获得的明亮,并将光度法降低到0.95微米。我们的新数据表明,该WD的温度更高,然后更短的冷却年龄(5.57 +/- 0.02 Gyr)和更大的质量(0.75 +/- 0.03 mo)。这解决了先前发现MS Star年龄的差异。另外两个WD的质量较小,对于HD2133B和CD-56 7708B,祖细胞分别为〜1.3 mo和1.5-1.8 mo。我们能够对HD114174和CD-56 7708的轨道产生限制。MSStars的组成与WDS的AGB祖细胞对污染的期望相当吻合:HD2133A:HD2133A的污染物具有少量的n贴剂元素,这是对AGB Star污染的预期,这是对Mass agb Star的污染。 CD-56 7708A是先前未识别的轻度BA-Star,这是由于AGB恒星的污染,其质量在1.5-3.0 mo范围内; HD114174具有非常适度的N捕捉元素,这与对大型AGB恒星的质量> 3.0 mo的期望一致。另一方面,这些恒星都没有显示出与N接机元素一起进行的C量的过剩。这可能与以下事实有关:这些恒星处于质量范围的边缘,我们期望与热脉冲相关的核合成。
Sirius-like systems are wide binaries composed of a white dwarf (WD) and a companion of a spectral type earlier than M0. The WD progenitor evolves in isolation, but its wind during the AGB phase pollutes the companion surface and transfers some angular momentum. Within SHINE survey that uses SPHERE at the VLT, we acquired images of HD2133, HD114174, and CD-567708 and combined this data with high resolution spectra of the primaries, TESS, and literature data. We performed accurate abundance analyses for the MS. We found brighter J and K magnitudes for HD114174B than obtained previously and extended the photometry down to 0.95 micron. Our new data indicate a higher temperature and then shorter cooling age (5.57+/-0.02 Gyr) and larger mass (0.75+/-0.03 Mo) for this WD than previously assumed. This solved the discrepancy previously found with the age of the MS star. The two other WDs are less massive, indicating progenitors of ~1.3 Mo and 1.5-1.8 Mo for HD2133B and CD-56 7708B, respectively. We were able to derive constraints on the orbit for HD114174 and CD-56 7708. The composition of the MS stars agrees fairly well with expectations from pollution by the AGB progenitors of the WDs: HD2133A has a small enrichment of n-capture elements, which is as expected for pollution by an AGB star with a mass <1.5 Mo; CD-56 7708A is a previously unrecognized mild Ba-star, which is expected due to pollution by an AGB star with a mass in the range of 1.5-3.0 Mo; and HD114174 has a very moderate excess of n-capture elements, which is in agreement with the expectation for a massive AGB star to have a mass >3.0 Mo. On the other hand, none of these stars show the excesses of C that are expected to go along with those of n-capture elements. This might be related to the fact that these stars are at the edges of the mass range where we expect nucleosynthesis related to thermal pulses.