The Chemical Inventory of the Planet-hosting Disk PDS 70

被引:49
|
作者
Facchini, Stefano [1 ]
Teague, Richard [2 ]
Bae, Jaehan [3 ]
Benisty, Myriam [4 ,5 ]
Keppler, Miriam [6 ]
Isella, Andrea [7 ]
机构
[1] European Southern Observ, Karl Schwarzschild Str 2, D-85748 Garching, Germany
[2] Ctr Astrophys Harvard & Smithsonian, 60 Garden St, Cambridge, MA 02138 USA
[3] Carnegie Inst Sci, Earth & Planets Lab, 5241 Broad Branch Rd NW, Washington, DC 20015 USA
[4] Univ Chile, UMI 3386 Dept Astron, Unidad Mixta Int Franco Chilena Astron, Camino El Observ 1515, Santiago, Chile
[5] Univ Grenoble Alpes, IPAG, CNRS, F-38000 Grenoble, France
[6] Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany
[7] Rice Univ, Dept Phys & Astron, 6100 Main St,MS-108, Houston, MS 77005 USA
来源
ASTRONOMICAL JOURNAL | 2021年 / 162卷 / 03期
基金
欧盟地平线“2020”;
关键词
SOLAR-SYSTEM; ATMOSPHERIC CHARACTERIZATION; PROTOPLANETARY; ABUNDANCE; FRACTIONATION; ARCHITECTURE; MOLECULES; CHEMISTRY; EMISSION; RADIUS;
D O I
10.3847/1538-3881/abf0a4
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
As host to two accreting planets, PDS 70 provides a unique opportunity to probe the chemical complexity of atmosphere-forming material. We present ALMA Band 6 observations of the PDS 70 disk and report the first chemical inventory of the system. With a spatial resolution of 0.'' 4-0.'' 5 (similar to 50 au), 12 species are detected, including CO isotopologs and formaldehyde, small hydrocarbons, HCN and HCO+ isotopologs, and S-bearing molecules. SO and CH3OH are not detected. All lines show a large cavity at the center of the disk, indicative of the deep gap carved by the massive planets. The radial profiles of the line emission are compared to the (sub)millimeter continuum and infrared scattered light intensity profiles. Different molecular transitions peak at different radii, revealing the complex interplay between density, temperature, and chemistry in setting molecular abundances. Column densities and optical depth profiles are derived for all detected molecules, and upper limits obtained for the nondetections. Excitation temperature is obtained for H2CO. Deuteration and nitrogen fractionation profiles from the hydrocyanide lines show radially increasing fractionation levels. Comparison of the disk chemical inventory to grids of chemical models from the literature strongly suggests a disk molecular layer hosting a carbon-to-oxygen ratio C/O > 1, thus providing for the first time compelling evidence of planets actively accreting high C/O ratio gas at present time.
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页数:20
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