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arXiv 2107.07481astro-ph.EP
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来自NEOWISE再激活任务第六年和第七年的小行星直径和反照率

Asteroid Diameters and Albedos from NEOWISE Reactivation Mission Years Six and Seven

Joseph R. Masiero, A. K. Mainzer, J. M. Bauer, R. M. Cutri, T. Grav, E. Kramer, J. Pittichová, E. L. Wright

摘要:

我们目前的直径和计算的近地天体宽视场红外巡天探测器(NEOWISE)航天器在第六和第七年的重新激活任务的近地和主带小行星。这些直径和半径是根据NEOWISE对$199$近地天体和$5851$ MBA的观测以及对第七年以来探测到的$175$近地天体和$5861$ MBA的观测拟合热模型计算出来的。将从“再激活”数据得出的近地天体直径与从WISE低温飞行任务数据得出的近地天体直径进行比较,显示出$\sim30\%$的相对不确定性。与来自低温飞行任务的数据相比,这种较大的不确定性是由于需要假设一个波束参数,以适应重新激活飞行任务所限于的较短波长数据。我们还对NEOWISE在重新激活期间发现的主带小行星的轨道参数进行了分析,发现这些物体往往位于导致其近日点远离黄道的轨道上,因此被其他调查错过。迄今为止,NEOWISE重新激活调查提供了$1415$独特近地天体的热拟合。将航天器休眠前的飞行任务阶段包括在内,增加了从WISE发射至今被定性为$1845$的独特近地天体的数量。

英文摘要:

We present diameters and albedos computed for the near-Earth and Main Belt asteroids observed by the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) spacecraft during the sixth and seventh years of its Reactivation mission. These diameters and albedos are calculated from fitting thermal models to NEOWISE observations of $199$ NEOs and $5851$ MBAs detected during the sixth year of the survey, and $175$ NEOs and $5861$ MBAs from the seventh year. Comparisons of the near-Earth object diameters derived from Reactivation data with those derived from the WISE cryogenic mission data show a $\sim30\%$ relative uncertainty. This larger uncertainty compared to data from the cryogenic mission is due to the need to assume a beaming parameter for the fits to the shorter wavelength data that the Reactivation mission is limited to. We also present an analysis of the orbital parameters of the Main Belt asteroids that have been discovered by NEOWISE during Reactivation, finding that these objects tend to be on orbits that result in their perihelia being far from the ecliptic, and thus missed by other surveys. To date, the NEOWISE Reactivation survey has provided thermal fits of $1415$ unique NEOs. Including the mission phases before spacecraft hibernation increases the count of unique NEOs characterized to $1845$ from WISE's launch to the present.

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