小熊座π1
小熊座π1[14]是在拱极星座小熊座北部的共同自行联星[15]。该对的视星等分别为+6.58和+7.31，综合星等为+6.1[2]。它们位于距离太阳约71光年的地方。两星的角距离为31.4弧秒[15]，其对应于实际约680AU[16]，并以大约13,100年的周期互绕着彼此运行[9]。
| 观测数据 历元 J2000.0 分点 J2000.0 (ICRS) | |
|---|---|
| 星座 | 小熊座 |
| 小熊座 π1 A | |
| 赤经 | 15h 29m 11.18599s[1] |
| 赤纬 | +80° 26′ 54.9713″[1] |
| 视星等 (V) | +6.58[2] |
| 小熊座π1 B | |
| 赤经 | 15h 29m 23.59426s[1] |
| 赤纬 | +80° 27′ 00.9675″[1] |
| 视星等 (V) | +7.31[2] |
| 特性 | |
| 光谱分类 | G1.5 V(n)[3] + G9 V[4] |
| U−B 色指数 | +0.13[2] + +0.37[2] |
| B−V 色指数 | +0.67[2] + +0.79[2] |
| 天体测定 | |
| 小熊座π1 A | |
| 径向速度 (Rv) | −16.27±0.09[5] km/s |
| 自行 (μ) | 赤经：−225.109[6] mas/yr 赤纬：+107.575[6] mas/yr |
| 视差 (π) | 45.8577 ± 0.0328[6] mas |
| 距离 | 71.12 ± 0.05 ly (21.81 ± 0.02 pc) |
| 绝对星等 (MV) | 4.94±0.04[7] |
| π1 UMi B | |
| 径向速度 (Rv) | −15.40±0.70[5] km/s |
| 自行 (μ) | 赤经：−217.817[8] mas/yr 赤纬：+105.947[8] mas/yr |
| 视差 (π) | 45.8038 ± 0.0352[8] mas |
| 距离 | 71.21 ± 0.05 ly (21.83 ± 0.02 pc) |
| 详细资料 | |
| 小熊座π1 A | |
| 质量 | 1.02[9] M☉ |
| 半径 | 0.98[6] R☉ |
| 表面重力 (log g) | 4.40[10] |
| 亮度 | 0.929[6] L☉ |
| 温度 | 5,771[10] K |
| 金属量 [Fe/H] | −0.22[11] dex |
| 年龄 | 9.22±3.84[12] Gyr |
| π1 UMi B | |
| 质量 | 0.92[9] M☉ |
| 半径 | 0.84[8] R☉ |
| 表面重力 (log g) | 4.50[10] |
| 亮度 | 0.520[8] L☉ |
| 温度 | 5,408[10] K |
| 其他命名 | |
| 参考数据库 | |
| SIMBAD | π1 UMi AB |
| π1 UMi A | |
| π1 UMi B | |
这两颗恒星都是类太阳恒星，并已被列为天琴-武仙星协的可能成员，该星协是距离太阳最近的移动星群之一[16]，然而现在认为这不太可能[17]。 主星小熊座π1 A，质量比太阳高2%，表面有效温度为5,771 K，半径为太阳的的98%和辐射热光度为太阳的93%。伴星，小熊座π1 B，质量是太阳的92%，温度略低为5,408 K，半径是太阳的 84%，光度略高于太阳的一半。
参考资料
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- ^ 8.0 8.1 8.2 8.3 8.4 Brown, A. G. A.; Vallenari, A.; Prusti, T.; de Bruijne, J. H. J.; et al. Gaia Data Release 2. Summary of the contents and survey properties. Astronomy & Astrophysics. 2018. Bibcode:2018A&A...616A...1G. arXiv:1804.09365 . doi:10.1051/0004-6361/201833051. VizieR中此天体在盖亚望远镜第二批数据发布的记录
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