论文标题
最大检测到的Oort-Cloud物体的大小和反照率：C/2014 UN 271（Bernardinelli-Bernstein）
Size and albedo of the largest detected Oort-cloud object: comet C/2014 UN 271 (Bernardinelli-Bernstein)
论文作者
论文摘要
最近宣布的Oort-Cloud Comet C/2014 UN271（Bernardinelli-Bernstein）至少在三个方面非常出色：（i）从太阳中发现了〜29 au的入站（带有prediscovery Images的图像，最高为〜34 au）； （ii）它显示了近24个AU的彗星活动； （iii）其核幅度（HR〜8.0）表示一个异常大的物体。随着彗星在2031年朝着〜11 au毛刺前往〜11 au圆锥体。我们在延长的配置（决议〜0.064英寸）方面进行了检测。测量了1287 um（233 GHz）连续的彗星的连续性。在8月8日，在2021年的距离上，在20.0 au的距离上进行了距离，该量很高的距离是在20.0 au sugn的范围内。尘埃贡献。我们在〜10的sigma中检测到对物体的热发射，基于观察性约束的0.128 +/- 0.012 MJY。 KM和红色几何反照率为5.3 +/- 1.2％。为“通用”核心核心核心的核心核心和独特的尺寸添加信条，是遥远的彗星的重要原型，其活性是由perihelion hyperihelion therperihion驱动的。
The recently announced Oort-cloud comet C/2014 UN271 (Bernardinelli-Bernstein) is remarkable in at least three respects: (i) it was discovered inbound as far as ~29 au from the Sun (with prediscovery images up to ~34 au); (ii) it showed cometary activity already at almost 24 au; and (iii) its nuclear magnitude (Hr ~ 8.0) indicates an exceptionally large object. Detection of gases is expected in the upcoming years as the comet is heading towards a ~11 au perihelion in 2031. We used ALMA in extended configuration (resolution ~0.064") to measure the 1287 um (233 GHz) continuum flux of the comet. Observations were performed on August 8, 2021 at a 20.0 au distance from the Sun. The high spatial resolution was chosen in order to filter out any dust contribution. We detected the thermal emission of the object at ~10 sigma, with a flux of 0.128+/-0.012 mJy. Based on observational constraints and our theoretical estimates of the dust contribution, the entirety of the measured flux can be attributed to the nucleus. From NEATM modelling combined with the Hr magnitude, we determine a surface-equivalent diameter of 137+/-17 km and a red geometric albedo of 5.3+/-1.2 %. This confirms that 2014 UN271 is by far the largest Oort-cloud object ever found (almost twice as large as comet C/1995 O1 Hale-Bopp), and except for the Centaur 95P/Chiron which shows outburst-like activity, the largest known comet in the Solar System. On the other hand, the object albedo is typical of comets, adding credence for a "universal" comet nucleus albedo. With its distant perihelion and uniquely large size, 2014 UN271 is the prominent archetype of distant comets, whose activity is driven by hypervolatiles. Post-perihelion thermal measurements will permit to study possible albedo changes, such as a surface brightening compared to pre-perihelion, as was observed for Hale-Bopp.
