The JWST Early-release Science Program for Direct Observations of Exoplanetary Systems II: A 1 to 20 μm Spectrum of the Planetary-mass Companion VHS 1256-1257 b
The JWST Early-release Science Program for Direct Observations of Exoplanetary Systems II: A 1 to 20 μm Spectrum of the Planetary-mass Companion VHS 1256-1257 b
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DOI：
10.3847/2041-8213/acb04a
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发表时间：
2023-03-01
影响因子：
7.9
通讯作者：
Zhang, Zhoujian
中科院分区：
文献类型：
--
作者：
Miles, Brittany E.;Biller, Beth A.;Zhang, Zhoujian
我们提出了迄今为止最高保真度的光谱的行星质量的对象。VHS 1256 B是一颗距离很远的M（Jup）伴星（类似于8“，a = 150 Au），年轻，行星质量，与直接成像的系外行星HR 8799 c，d和e共享光度颜色和光谱特征。作为一个L到T转变天体，VHS 1256 B沿着色星等图中星下大气从多云转变为晴朗的区域存在。我们观察了VHS 1256 B与JWST的NIRSpec IFU和MIRI MRS模式，覆盖范围从1到20 μ m，分辨率类似于1000-3700。水、甲烷、一氧化碳、二氧化碳、钠和钾在JWST光谱的几个部分中被观察到，这是基于与模板褐矮星光谱、分子不透明度和大气模型的比较。VHS 1256 B的光谱形状受到不平衡化学和云的影响。我们直接探测到硅酸盐云，这是第一次发现行星质量的伴星。
We present the highest fidelity spectrum to date of a planetary-mass object. VHS 1256 b is a M (Jup) widely separated (similar to 8 '', a = 150 au), young, planetary-mass companion that shares photometric colors and spectroscopic features with the directly imaged exoplanets HR 8799c, d, and e. As an L-to-T transition object, VHS 1256 b exists along the region of the color-magnitude diagram where substellar atmospheres transition from cloudy to clear. We observed VHS 1256 b with JWST's NIRSpec IFU and MIRI MRS modes for coverage from 1 to 20 mu m at resolutions of similar to 1000-3700. Water, methane, carbon monoxide, carbon dioxide, sodium, and potassium are observed in several portions of the JWST spectrum based on comparisons from template brown dwarf spectra, molecular opacities, and atmospheric models. The spectral shape of VHS 1256 b is influenced by disequilibrium chemistry and clouds. We directly detect silicate clouds, the first such detection reported for a planetary-mass companion.