论文标题
分解长期彗星C/2019 Y4（ATLAS）的观察结果 - C/1844 Y1的兄弟姐妹（Great Comet）
Observations of Disintegrating Long-Period Comet C/2019 Y4 (ATLAS) -- A Sibling of C/1844 Y1 (Great Comet)
论文作者
论文摘要
我们使用Sloan $ gri $观察结果从1月中旬到2020年4月初进行了C/2019 Y4（ATLA）的研究。在此时间段期间，彗星在有效的横截面$ \ left（2.0 \ pm 0.1 \ right）的有效横截面增长下增长，\ times \ times \ times 10^{2} $ m $^$^$^$^$^$^$^$^$^$^$^$^$ s $^$ s $^$ s $ s $^$ s $^$ s $ s $ 1 2020年3月下旬的预伊利昂，随后亮度褪色，彗星逐渐失去了中央冷凝。同时，当亮度达到峰值时，彗星变得越来越蓝，甚至比太阳（$ g -r \约0.2 $）更蓝，这可能是由于激活地下新鲜挥发物暴露于阳光的情况。通过尾随偏置校正的天文统计，我们发现了一个巨大的径向非驱动参数，$ a_ {1} = \ left（+2.25 \ pm 0.13 \ right）\ times 10^{ - 7} $ au d $ d $^{ - 2} $在comet的地球化运动中。考虑到所有这些发现，我们得出结论，彗星自2020年3月中旬以来已经分解。绝不是彗星的新手，正如我们量化的那样，我们量化了该彗星在上一个围节$ \ sim $ 5 kyr左右发生了另一个分裂事件$ \ gtrsim $ 1 m s $^{ - 1} $。我们限制了瓦解前C/2019 Y4的核为$ \ gtrsim $ 60 m的半径，并且一直在长期弹出$ \ sim $ 10-40 $ $ m $ m $ m $ m $ m $ $ m $ $ m $ $ m $ $ $ $ $ $ \ cm $ $ $ $ $ $ $^{ - 3} $ axpodeption $ 3020 $ 3020 $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s s $ s $ s $ s $ s S $^ - $ \ sim $ 80 m s $^{ - 1} $在月底$ \ sim $ 10 $μ$ m。
We present a study of C/2019 Y4 (ATLAS) using Sloan $gri$ observations from mid-January to early April 2020. During this timespan, the comet brightened with a growth in the effective cross-section of $\left(2.0 \pm 0.1 \right) \times 10^{2}$ m$^{2}$ s$^{-1}$ from the beginning to $\sim$70 d preperihelion in late March 2020, followed by a brightness fade and the comet gradually losing the central condensation. Meanwhile, the comet became progressively bluer, and was even bluer than the Sun ($g - r \approx 0.2$) when the brightness peaked, likely due to activation of subterranean fresh volatiles exposed to sunlight. With the tailward-bias corrected astrometry we found an enormous radial nongravitational parameter, $A_{1} = \left(+2.25 \pm 0.13\right) \times 10^{-7}$ au d$^{-2}$ in the heliocentric motion of the comet. Taking all of these finds into consideration, we conclude that the comet has disintegrated since mid-March 2020. By no means was the split new to the comet, as we quantified that the comet had undergone another split event around last perihelion $\sim$5 kyr ago, during which its sibling C/1844 Y1 (Great Comet) was produced, with the in-plane component of the separation velocity $\gtrsim$1 m s$^{-1}$. We constrained that the nucleus of C/2019 Y4 before disintegration was $\gtrsim$60 m in radius, and has been protractedly ejecting dust grains of $\sim$10-40 $μ$m (assuming dust bulk density 0.5 g cm$^{-3}$) with ejection speed $\sim$30 m s$^{-1}$ in early March 2020 and increased to $\sim$80 m s$^{-1}$ towards the end of the month for grains of $\sim$10 $μ$m.
