（90482）Orcus-Vanth的积分场光谱
Integral-field spectroscopy of (90482) Orcus-Vanth
摘要：
目标。我们试图限制海王星外天体（90482）Orcus及其小卫星Vanth的表面组成，以及它们的质量和密度。方法.我们使用安装在欧洲南方天文台甚大望远镜Yepun/UT 4上的自适应光学馈电积分场摄谱仪SINFONI获得了（90482）Orcus及其伴星Vanth的近红外光谱（1.4-2.4 μm）。我们利用奥库斯和UCAC 2 29643541恒星（R = 11.6）之间非常有利的appulse（仅4”），使用SINFONI的自适应光学模式，允许空间分辨两个分量，并从奥库斯独立提取Vanth颜色。结果我们获得的Orcus光谱具有迄今为止最高的信噪比，我们确认了晶体形式的H2O冰的存在，以及在2.2 μm处的吸收带的存在。我们设定甲烷存在的上限约为2%，乙烷为5%。由于甲烷不能单独解释2.2 μm波段，因此氨的存在被认为是百分之几。发现凡斯的颜色比奥库斯的颜色略红，但测量的不确定性很大，使我们无法对这对双星的起源（捕获或共形成）得出结论。最后，我们重置了Vanth在Orcus周围的轨道相位，并证实了Brown等人（2010，AJ 139）推导的轨道参数。
英文摘要：
Aims. We seek to constrain the surface composition of the Trans-Neptunian Object (90482) Orcus and its small satellite Vanth, as well as their mass and density. Methods. We acquired near-infrared spectra (1.4-2.4 μm) of (90482) Orcus and its companion Vanth using the adaptive-optics-fed integral-field spectrograph SINFONI mounted on Yepun/UT4 at the European Southern Observatory Very Large Telescope. We took advantage of a very favorable appulse (separation of only 4") between Orcus and the UCAC2 29643541 star (R = 11.6) to use the adaptive optics mode of SINFONI, allowing both components to be spatially resolved and Vanth colors to be extracted independently from Orcus. Results. The spectrum of Orcus we obtain has the highest signal-to-noise ratio to date, and we confirm the presence of H2O ice in crystalline form, together with the presence of an absorption band at 2.2 μm. We set an upper limit of about 2% for the presence of methane, and 5% for ethane. Because the methane alone cannot account for the 2.2 μm band, the presence of ammonia is suggested to the level of a couple of percent. The colors of Vanth are found slightly redder than those of Orcus, but the large measurement uncertainties forbid us from drawing conclusions on the origin of the pair (capture or co-formation). Finally, we reset the orbital phase of Vanth around Orcus, and confirm the orbital parameters derived by Brown et al. (2010, AJ 139).
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。
