arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2109.09852astro-ph.EP
收藏

C/2014 UN271（Bernardinelli-Bernstein）：彗星中的近球形母牛

C/2014 UN271 (Bernardinelli-Bernstein): the nearly spherical cow of comets

Pedro H. Bernardinelli, Gary M. Bernstein, Benjamin T. Montet, Robert Weryk, Richard Wainscoat, M. Aguena, S. Allam, F. Andrade-Oliveira, J. Annis, S. Avila, E.… 展开作者

Pedro H. Bernardinelli, Gary M. Bernstein, Benjamin T. Montet, Robert Weryk, Richard Wainscoat, M. Aguena, S. Allam, F. Andrade-Oliveira, J. Annis, S. Avila, E. Bertin, D. Brooks, D. L. Burke, A. Carnero Rosell, M. Carrasco Kind, J. Carretero, R. Cawthon, C. Conselice, M. Costanzi, L. N. da Costa, M. E. S. Pereira, J. De Vicente, H. T. Diehl, S. Everett, I. Ferrero, B. Flaugher, J. Frieman, J. García-Bellido, E. Gaztanaga, D. W. Gerdes, D. Gruen, R. A. Gruendl, J. Gschwend, G. Gutierrez, S. R. Hinton, D. L. Hollowood, K. Honscheid, D. J. James, K. Kuehn, N. Kuropatkin, O. Lahav, M. A. G. Maia, J. L. Marshall, F. Menanteau, R. Miquel, R. Morgan, R. L. C. Ogando, F. Paz-Chinchón, A. Pieres, A. A. Plazas Malagón, M. Rodriguez-Monroy, A. K. Romer, A. Roodman, E. Sanchez, M. Schubnell, S. Serrano, I. Sevilla-Noarbe, M. Smith, M. Soares-Santos, E. Suchyta, M. E. C. Swanson, G. Tarle, C. To, M. A. Troxel, T. N. Varga, A. R. Walker, Y. Zhang

备注：
19 pages, submitted to ApJ Letters
阅读 PDF
arXiv 页面 ↗HTML 原文 ↗

摘要：

C/2014 UN 271（Bernardinelli-Bernstein）是一颗从奥尔特云进入的彗星，它拥有所有测量过的彗星中最明亮（也可能是最大）的彗星核，并且被发现的日心距离$r_h\approx29$ au比奥尔特云的任何成员都远。我们描述了可以从2021年6月第一次活动报告之前记录的图像中推断出的属性。该轨道有$i=95^\circ,$，近日点为10.97 AU，将于2031年到达，之前的远日点为$40,400\pm260$ AU。在标准的银河潮汐模型和已知的恒星碰撞下，对轨道的后向积分表明这是一颗原始的新彗星，在350万年前的最近点上，近日点为$q\approx18$ au。测光数据显示，一个未解决的核心与绝对星等$H_r=8.0,$的颜色是典型的彗星核或达摩克类星体，并没有长期的趋势，因为它穿越范围34- 23 au。对于$r$ -带几何轨道$p_r,$，这意味着直径为$150 (p_r/0.04)^{-0.5}$ km.有强有力的证据表明$\pm0.2$等的亮度波动，但没有旋转周期可以辨别。当彗星从28到20 au接近时，一个与"静止“$1/ρ$表面亮度分布一致的彗发在散射截面中以指数速率从$A f ρ\approx1$ m增长到$\approx150$ m。活动是一致的一个简单的模型升华的表面物种与太阳的辐射平衡。推断的升华焓与$CO_2$和$NH_3$的升华焓相匹配。更易挥发的物质-- $N_2,$、$CH_4,$和$CO$ --在升华表面上的含量肯定要少得多。

英文摘要：

C/2014 UN271 (Bernardinelli-Bernstein) is a comet incoming from the Oort cloud which is remarkable in having the brightest (and presumably largest) nucleus of any well-measured comet, and having been discovered at heliocentric distance $r_h\approx29$ au farther than any Oort-cloud member. We describe the properties that can be inferred from images recorded until the first reports of activity in June 2021. The orbit has $i=95^\circ,$ with perihelion of 10.97 au to be reached in 2031, and previous aphelion at $40,400\pm260$ au. Backwards integration of the orbit under a standard Galactic tidal model and known stellar encounters suggests this is a pristine new comet, with a perihelion of $q\approx18$ au on its previous perihelion passage 3.5 Myr ago. The photometric data show an unresolved nucleus with absolute magnitude $H_r=8.0,$ colors that are typical of comet nuclei or Damocloids, and no secular trend as it traversed the range 34--23 au. For $r$-band geometric albedo $p_r,$ this implies a diameter of $150 (p_r/0.04)^{-0.5}$ km. There is strong evidence of brightness fluctuations at $\pm0.2$ mag level, but no rotation period can be discerned. A coma consistent with a ``stationary' $1/ρ$ surface-brightness distribution grew in scattering cross-section at an exponential rate from $A f ρ\approx1$ m to $\approx150$ m as the comet approached from 28 to 20 au. The activity is consistent with a simple model of sublimation of a surface species in radiative equilibrium with the Sun. The inferred enthalpy of sublimation matches those of $CO_2$ and $NH_3$. More-volatile species -- $N_2,$ $CH_4,$ and $CO$ -- must be far less abundant on the sublimating surfaces.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

↑