JWST MIRI/MRS Observations of Tau042021

We present JWST MIRI MRS observations of the edge-on protoplanetary disk around the young
sub-solar mass star Tau 042021, acquired as part of the Cycle 1 GO program "Mapping Inclined
Disk Astrochemical Signatures (MIDAS)." These data resolve the mid-IR spatial distributions of H2,
revealing X-shaped emission extending to 200 au above the disk midplane with a semi-opening angle
of 35 +/- 5 degrees. We do not velocity-resolve the gas in the spectral images, but the measured semi-opening
angle of the H2 is consistent with an MHD wind origin. A collimated, bipolar jet is seen in forbidden
emission lines from [Ne II], [Ne III], [Ni II], [Fe II], [Ar II], and [S III]. Extended H2O and CO emission
lines are also detected, reaching diameters between 90 and 190 au, respectively. Hot molecular
emission is not expected at such radii, and we interpret its extended spatial distribution as scattering
of inner disk molecular emission by dust grains in the outer disk surface. H I recombination lines,
characteristic of inner disk accretion shocks, are similarly extended, and are likely also scattered light
from the innermost star-disk interface. Finally, we detect extended PAH emission at 11.3 microns cospatial
with the scattered light continuum, making this the first low-mass T Tauri star around which
extended PAHs have been confirmed, to our knowledge. MIRI MRS line images of edge-on disks provide
an unprecedented window into the out
ow, accretion, and scattering processes within protoplanetary
disks, allowing us to constrain the disk lifetimes and accretion and mass loss mechanisms.

本研究展示了年轻亚太阳质量恒星Tau 042021周围侧向原行星盘的詹姆斯·韦布空间望远镜（James Webb Space Telescope, JWST）中红外仪器中分辨率光谱仪（Mid-Infrared Instrument Medium-Resolution Spectrometer, MIRI MRS）观测数据，该观测作为第1周期通用观测（General Observer, GO）项目“倾斜盘天体化学特征测绘（Mapping Inclined Disk Astrochemical Signatures, MIDAS）”的一部分开展。这些数据解析了H₂的中红外空间分布，揭示出延伸至盘面上方200天文单位（au）的X形发射结构，其半张角为35±5度。本研究未对光谱图像中的气体进行速度解析，但测得的H₂半张角与磁流体动力学（Magnetohydrodynamics, MHD）风起源模型相符。在[Ne II]、[Ne III]、[Ni II]、[Fe II]、[Ar II]及[S III]的禁戒发射线中可观测到准直双极喷流。同时还探测到延展的H₂O与CO发射线，其直径分别介于90至190天文单位之间。此类半径范围内本不应观测到热分子发射，我们将其延展空间分布解释为外盘表面尘埃颗粒对内侧盘分子发射的散射作用。表征内盘吸积激波特征的氢原子复合线同样呈现延展分布，其大概率同样源自星盘最内侧界面的散射光。最后，本研究在11.3微米波段探测到与散射光连续谱共空间分布的延展多环芳烃（Polycyclic Aromatic Hydrocarbons, PAH）发射；据我们所知，这是首个被证实存在延展多环芳烃的低质量T Tauri星。侧向原行星盘的MIRI MRS光谱图像为原行星盘内的外流、吸积及散射过程提供了前所未有的观测窗口，有助于我们约束盘寿命、吸积与质量损失机制。