近日，美国SETI研究所的Ariel Graykowski及其研究团队对DART撞击Dimorphos后抛射物的光曲线和颜色进行了研究。研究成果已于2023年3月1日在国际权威学术期刊《自然》上发表。

该研究团队利用全球公民科学望远镜网络对Dimorphos进行了撞击前、撞击期间和撞击后的光学观测，并发现撞击时的最大亮度增加了2.29±0.14星等。Didymos在23.7±0.7天的时间内逐渐恢复到撞击前的亮度。研究人员根据尘埃的大小，估计了抛射物的质量下限，它占Dimorphos质量的0.3 - 0.5%。研究人员还观察到了撞击时抛射物变红。

据悉，双小行星重定向测试(DART)航天器于2022年9月26日撞击了小行星65803 Didymos的卫星Dimorphos。由于这是一个双星系统，可以确定卫星轨道的变化量，作为测试偏转可能威胁地球的小行星所需的参数。在正常情况下，撞击前轨道周期缩短的预测范围约为8.8 - 17.2分钟。

附：英文原文

Title: Light Curves and Colors of the Ejecta from Dimorphos after the DART Impact

Author: Graykowski, Ariel, Lambert, Ryan A., Marchis, Franck, Cazeneuve, Dorian, Dalba, Paul A., Esposito, Thomas M., Peluso, Daniel OConner, Sgro, Lauren A., Blaclard, Guillaume, Borot, Antonin, Malvache, Arnaud, Marfisi, Laurent, Powell, Tyler M., Huet, Patrice, Limagne, Matthieu, Payet, Bruno, Clarke, Colin, Murabana, Susan, Owen, Daniel Chu, Wasilwa, Ronald, Fukui, Keiichi, Goto, Tateki, Guillet, Bruno, Huth, Patrick, Ishiyama, Satoshi, Kukita, Ryuichi, Mitchell, Mike, Primm, Michael, Randolph, Justus, Rivett, Darren A., Ryno, Matthew, Shimizu, Masao, Toullec, Jean-Pierre, Will, Stefan, Yue, Wai-Chun, Camilleri, Michael, Graykowski, Kathy, Janetzke, Ron, Janke, Des, Kardel, Scott, Loose, Margaret, Pickering, John W., Smith, Barton A., Transom, Ian M.

Issue&Volume: 2023-03-01

Abstract: On 26 September 2022 the Double Asteroid Redirection Test (DART) spacecraft impacted Dimorphos, a satellite of the asteroid 65803 Didymos. Because it is a binary system, it is possible to determine how much the orbit of the satellite changed, as part of a test of what is necessary to deflect an asteroid that might threaten Earth with an impact. In nominal cases, pre-impact predictions of the orbital period reduction ranged from ~ 8.8 – 17.2 minutes. Here we report optical observations of Dimorphos before, during and after the impact, from a network of citizen science telescopes across the world. We find a maximum brightening of 2.29 ± 0.14 mag upon impact. Didymos fades back to its pre-impact brightness over the course of 23.7 ± 0.7 days. We estimate lower limits on the mass contained in the ejecta, which was 0.3 – 0.5 % Dimorphos’ mass depending on the dust size. We also observe a reddening of the ejecta upon impact.

DOI: 10.1038/s41586-023-05852-9

Source: https://www.nature.com/articles/s41586-023-05852-9