天弁二
观测资料 历元 J2000 | |
---|---|
星座 | 盾牌座 |
星官 | |
赤经 | 18h 42m 16.422137s[1] |
赤纬 | −09° 03′ 09.19206″[1] |
视星等(V) | 4.60 - 4.79[2] |
特性 | |
光谱分类 | F2 IIIp[3] |
U−B 色指数 | +0.16[4][2] |
B−V 色指数 | +0.35[4] |
变星类型 | 盾牌座δ |
天体测定 | |
径向速度 (Rv) | −44.8[5] km/s |
自行 (μ) | 赤经:9.21[1] mas/yr 赤纬:0.82[1] mas/yr |
视差 (π) | 16.11 ± 0.31[1] mas |
距离 | 202 ± 4 ly (62 ± 1 pc) |
绝对星等 (MV) | ±0.04 0.72[6] |
详细资料 | |
质量 | +0.06 −0.05 2.23[7] M☉ |
表面重力 (log g) | 3.5[8] |
温度 | 7000[8] K |
金属量 [Fe/H] | 0.41[6] dex |
自转速度 (v sin i) | 25.5[8] km/s |
年龄 | ±0.1 0.7[6] Gyr |
其他命名 | |
参考资料库 | |
SIMBAD | 资料 |
天弁二(盾牌座δ)是在南天盾牌座的一颗巨星,视星等4.72等[4],是在这个小且没有特征星座的第五亮星。分析依巴谷卫星任务期间测量的视差,这颗恒星与地球的距离大约是202光年(62秒差距)[1]。天弁二是盾牌座δ变星的原型,这种变星来自体积胀缩造成光度的高振幅大约都在0.15星等左右。这颗恒星特有的化学丰度与Am星相似[8]。
在1900年,天文学家威廉·华莱士·坎贝尔(William Wallace Campbell)和威廉·哈蒙德·赖特使用利克天文台的米尔斯光谱仪确定该恒星的径向速度会变化[10]。在1935年,测量出光度以77日(4.65小时)的周期有著0.2等(在+4.60至+4.79之间变化)的振幅,并证实这种变化是内在的,而不是 0.193光谱联星造成的结果[11]。在1938年,发现了次要的周期,并提出脉动理论来模拟这种变异[12]。之后对天弁二的观测表明,它是在多重离散的径向和非径向模式下脉动。模式最强的频率是59.731μHz,其次是61.936μHz,依此类推,现在共建模了八种不同的频率模式[13]。
这颗恒星在银道坐标系的空间速度是[U, V, W] = [–42, –17, –1] km·s−1。它以离心率0.11的轨道绕行银河系,最接近银河中心的距离是22.31 kly(6.84 kpc),最远的距离是27.59 kly(8.46 kpc)[6]。如果天弁二维持现在的运动和光度,它将以10光年的距离内经过太阳系附近[14],并且在西元150000至 1330000 CE成为天空中最亮的恒星,视星等为-1.84,比 1天狼星现在的-1.46还要明亮[15]。
天弁二有二颗光学伴星。第一颗距离15.2角秒,视星等+12.2。第二颗距离53角秒,视星等+9.2[16]。
佛兰斯蒂德没有将天弁二标示在盾牌座,而是将它与其它几颗星纳入天鹰座,并在星表中标记为天鹰座2。拜耳名称的盾牌座δ是由古德命名的[17]。
参考资料
- ^ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F., Validation of the new Hipparcos reduction, Astronomy and Astrophysics, November 2007, 474 (2): 653–664, Bibcode:2007A&A...474..653V, arXiv:0708.1752
, doi:10.1051/0004-6361:20078357
- ^ 2.0 2.1 Samus, N. N.; Durlevich, O. V.; et al. VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013). VizieR On-line Data Catalog: B/gcvs. Originally published in: 2009yCat....102025S. 2009, 1. Bibcode:2009yCat....102025S.
- ^ Cowley, Anne; Fraquelli, Dorothy, MK Spectral Types for Some Bright F Stars, Publications of the Astronomical Society of the Pacific, February 1974, 86 (509): 7, Bibcode:1974PASP...86...70C, doi:10.1086/129562
- ^ 4.0 4.1 4.2 Johnson, H. L.; et al. UBVRIJKL photometry of the bright stars. Communications of the Lunar and Planetary Laboratory. 1966, 4 (99): 99. Bibcode:1966CoLPL...4...99J.
- ^ Evans, D. S. The Revision of the General Catalogue of Radial Velocities. Batten, Alan Henry; Heard, John Frederick (编). Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30. University of Toronto: International Astronomical Union. June 20–24, 1966. Bibcode:1967IAUS...30...57E.
- ^ 6.0 6.1 6.2 6.3 Holmberg, J.; Nordström, B.; Andersen, J., The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics, Astronomy and Astrophysics, July 2009, 501 (3): 941–947, Bibcode:2009A&A...501..941H, arXiv:0811.3982
, doi:10.1051/0004-6361/200811191
- ^ Nordström, B.; et al, The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ˜14 000 F and G dwarfs, Astronomy and Astrophysics, May 2004, 418: 989–1019, Bibcode:2004A&A...418..989N, arXiv:astro-ph/0405198
, doi:10.1051/0004-6361:20035959
- ^ 8.0 8.1 8.2 8.3 Yushchenko, A.; et al. The chemical composition of δ Scuti. Monthly Notices of the Royal Astronomical Society. May 2005, 359 (55): 865–873. Bibcode:2005MNRAS.359..865Y. doi:10.1111/j.1365-2966.2005.08921.x.
- ^ del Sct – Variable star of delta Sct type. SIMBAD Astronomical Object Database. Centre de Données astronomiques de Strasbourg. [2009-10-23]. (原始内容存档于2020-11-05).
- ^ Campbell, W. W.; Wright, W. H. A list of nine stars whose velocities in the line of sight are variable. Astrophysical Journal. 1900, 12: 254–257. Bibcode:1900ApJ....12..254C. doi:10.1086/140765. Listed as 2 Scuti on p. 256.
- ^ Colacevich, A. On the variable radial velocity of δ Scuti. Publications of the Astronomical Society of the Pacific. August 1935, 47 (278): 231–232. Bibcode:1935PASP...47..231C. doi:10.1086/124599.
- ^ Sterne, T. E. The Secondary Variation of δ Scuti. Astrophysical Journal. March 1938, 87: 133–150. Bibcode:1938ApJ....87..133S. doi:10.1086/143913.
- ^ Templeton, Matthew R.; et al. A New Pulsation Spectrum and Asteroseismology of delta Scuti. The Astronomical Journal. October 1997, 114: 1592–1601. Bibcode:1997AJ....114.1592T. doi:10.1086/118590.
- ^ García-Sánchez, J.; et al, Stellar encounters with the solar system, Astronomy and Astrophysics, 2001, 379 (2): 634–659, Bibcode:2001A&A...379..634G, doi:10.1051/0004-6361:20011330
- ^ Sky and Telescope, April 1998 (p60), based on computations from Hipparcos mission data.
- ^ Burnham, Robert. Burnham's celestial handbook: an observer's guide to the universe beyond the solar system 3. Courier Dover Publications. 1978: 1746. ISBN 0-486-23673-0.
- ^ Wagman, M. Flamsteed's Missing Stars. Journal for the History of Astronomy, Vol.18, NO. 3/AUG, P.209, 1987. August 1987, 18: 212. Bibcode:1987JHA....18..209W. doi:10.1177/002182868701800305.
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