重力年轻恒星对象调查IV。 CO在Sub-Au量表的51 OPH中的CO叠加发射

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重力年轻恒星对象调查IV。 CO在Sub-Au量表的51 OPH中的CO叠加发射

The GRAVITY Young Stellar Object survey IV. The CO overtone emission in 51 Oph at sub-au scales

论文作者

GRAVITY Collaboration, Koutoulaki, M., Lopez, R. Garcia, Natta, A., Fedriani, R., oGaratti, A. Caratti, Ray, T. P., Coffey, D., Brandner, W., Dougados, C., Garcia, P. J. V, Klarmann, L., Labadie, L., Perraut, K., Sanchez-Bermudez, J., Lin, C. -C., Amorim, A., Bauböck, M., Benisty, M., Berger, J. P., Buron, A., Caselli, P., Clénet, Y., Foresto, V. Coudé du, de Zeeuw, P. T., Duvert, G., de Wit, W., Eckart, A., Eisenhauer, F., Filho, M., Gao, F., Gendron, E., Genzel, R., Gillessen, S., Grellmann, R., Habibi, M., Haubois, X., Haussmann, F., Henning, T., Hippler, S., Hubert, Z., Horrobin, M., Rosales, A. Jimenez, Jocou, L., Kervella, P., Kolb, J., Lacour, S., Bouquin, J. -B. Le, Léna, P., Linz, H., Ott, T., Paumard, T., Perrin, G., Pfuhl, O., Ramírez-Tannus, M. C., Rau, C., Rousset, G., Scheithauer, S., Shangguan, J., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., van Dishoeck, E., Vincent, F., von Fellenberg, S., Widmann, F., Wieprecht, E., Wiest, M., Wiezorrek, E., Yazici, S., Zins, G.

论文摘要

51 OPH是Herbig ae/Be恒星，在2.3微米处表现出强烈的近红外CO RO振动发射，最有可能起源于折光盘的最内向区域。我们旨在通过空间解决内气盘的偶尔环境来获得系统的物理和几何特性。我们使用第二代vlti/重力来空间解析连续体和CO泛音发射。我们通过辅助望远镜获得了12个基线的数据，并获得了可见性，以及差异和闭合相是波长的函数。我们使用了CO发射的简单LTE环模型来重现频谱和CO线位移。我们的干涉数据表明，恒星在我们的空间分辨率下略有解析，半径为10.58+-2.65 rsun。圆盘的K频段连续发射倾向于63+-1 deg，位置角度为116+-1 deg，为116+-1 deg和4+-0.8 mas（0.5+-0+-0+-0.1.1 au）。 CO线发射内的可见性增加，表明CO在尘埃播出半径内发射。通过对CO BandHead Spectrum进行建模，我们得出CO是从热（t = 1900-2800 K）和密集（NCO =（0.9-9-9）x10^21^21 cm^-2）的气体中发出的。对连续体的CO线位移的分析使我们能够推断出CO是从0.10+-0.02 au的区域散发出的，远距离粉尘呈现半径内。 CO线排放区域的倾斜度和位置角与尘土盘的倾斜度和位置角度一致。我们在空间上解析的干涉测量值证实了内盘无尘区域内的CO RO振动发射。传统的圆盘模型排除了Herbig Aebe恒星尘埃淹没地区的CO的存在。因此，需要计算无尘内盘的性质的最内向圆盘区域的临时模型。

51 Oph is a Herbig Ae/Be star that exhibits strong near-infrared CO ro-vibrational emission at 2.3 micron, most likely originating in the innermost regions of a circumstellar disc. We aim to obtain the physical and geometrical properties of the system by spatially resolving the circumstellar environment of the inner gaseous disc. We used the second-generation VLTI/GRAVITY to spatially resolve the continuum and the CO overtone emission. We obtained data over 12 baselines with the auxiliary telescopes and derive visibilities, and the differential and closure phases as a function of wavelength. We used a simple LTE ring model of the CO emission to reproduce the spectrum and CO line displacements. Our interferometric data show that the star is marginally resolved at our spatial resolution, with a radius of 10.58+-2.65 Rsun.The K-band continuum emission from the disc is inclined by 63+-1 deg, with a position angle of 116+-1 deg, and 4+-0.8 mas (0.5+-0.1 au) across. The visibilities increase within the CO line emission, indicating that the CO is emitted within the dust-sublimation radius.By modelling the CO bandhead spectrum, we derive that the CO is emitted from a hot (T=1900-2800 K) and dense (NCO=(0.9-9)x10^21 cm^-2) gas. The analysis of the CO line displacement with respect to the continuum allows us to infer that the CO is emitted from a region 0.10+-0.02 au across, well within the dust-sublimation radius. The inclination and position angle of the CO line emitting region is consistent with that of the dusty disc. Our spatially resolved interferometric observations confirm the CO ro-vibrational emission within the dust-free region of the inner disc. Conventional disc models exclude the presence of CO in the dust-depleted regions of Herbig AeBe stars. Ad hoc models of the innermost disc regions, that can compute the properties of the dust-free inner disc, are therefore required.

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