Pabst C H M, Goicoechea J R, Teyssier D, Berné O, Higgins R D, Chambers E T, Kabanovic S, Güsten R, Stutzki J, Tielens A G G M
Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, Netherlands.
Instituto de Fisica Fundamental, CSIC, Calle Serrano 121-123, 28006 Madrid, Spain.
Astron Astrophys. 2020 Jul 1;639. doi: 10.1051/0004-6361/202037560. eCollection 2020 Jul.
The Orion Molecular Cloud is the nearest massive-star forming region. Massive stars have profound effects on their environment due to their strong radiation fields and stellar winds. Stellar feedback is one of the most crucial cosmological parameters that determine the properties and evolution of the interstellar medium in galaxies.
We aim to understand the role that feedback by stellar winds and radiation play in the evolution of the interstellar medium. Velocity-resolved observations of the [C ] 158m fine-structure line allow us to study the kinematics of UV-illuminated gas. Here, we present a square-degree-sized map of [C ] emission from the Orion Nebula complex at a spatial resolution of 16″ and high spectral resolution of 0.2kms, covering the entire Orion Nebula (M42) plus M43 and the nebulae NGC 1973, 1975, and 1977 to the north. We compare the stellar characteristics of these three regions with the kinematics of the expanding bubbles surrounding them.
We use [C ] 158m line observations over an area of 1.2deg in the Orion Nebula complex obtained by the upGREAT instrument onboard SOFIA.
The bubble blown by the O7V star Ori C in the Orion Nebula expands rapidly, at 13kms. Simple analytical models reproduce the characteristics of the hot interior gas and the neutral shell of this wind-blown bubble and give us an estimate of the expansion time of 0.2 Myr. M43 with the B0.5V star NU Ori also exhibits an expanding bubble structure, with an expansion velocity of 6kms. Comparison with analytical models for the pressure-driven expansion of H regions gives an age estimate of 0.02 Myr. The bubble surrounding NGC 1973, 1975, and 1977 with the central B1V star 42 Orionis expands at 1.5kms, likely due to the over-pressurized ionized gas as in the case of M43. We derive an age of 0.4 Myr for this structure.
We conclude that the bubble of the Orion Nebula is driven by the mechanical energy input by the strong stellar wind from Ori C, while the bubbles associated with M43 and NGC 1977 are caused by the thermal expansion of the gas ionized by their central later-type massive stars.
猎户座分子云是距离最近的大质量恒星形成区域。大质量恒星因其强烈的辐射场和恒星风对其周围环境有着深远影响。恒星反馈是决定星系中星际介质性质和演化的最关键宇宙学参数之一。
我们旨在了解恒星风和辐射反馈在星际介质演化中所起的作用。对[CⅡ]158μm精细结构线进行速度分辨观测，使我们能够研究紫外线照射气体的运动学。在此，我们展示了一幅来自猎户座星云复合体的[CⅡ]发射的平方度大小的地图，其空间分辨率为16″，光谱分辨率为0.2km/s，覆盖了整个猎户座星云（M42）加上M43以及北部的星云NGC 1973、1975和1977。我们将这三个区域的恒星特征与围绕它们的膨胀气泡的运动学进行比较。
我们使用了由平流层红外天文台（SOFIA）上的upGREAT仪器在猎户座星云复合体中1.2°区域获得的[CⅡ]158μm线观测数据。
猎户座星云中由O7V型恒星θ1 Ori C吹出的气泡以13km/s的速度快速膨胀。简单的解析模型再现了这个由恒星风吹出的气泡的热内部气体和中性壳层的特征，并给出了0.2百万年的膨胀时间估计。拥有B0.5V型恒星NU Ori的M43也呈现出一个膨胀气泡结构，膨胀速度为6km/s。与HⅡ区压力驱动膨胀的解析模型比较，得出年龄估计为0.02百万年。围绕着NGC 1973、1975和1977且中心为B1V型恒星42 Orionis的气泡以1.5km/s的速度膨胀，可能与M43情况一样是由于过压的电离气体所致。我们得出这个结构的年龄为0.4百万年。
我们得出结论，猎户座星云的气泡是由来自θ1 Ori C的强烈恒星风输入的机械能驱动的，而与M43和NGC 1977相关的气泡是由其中心晚型大质量恒星电离的气体的热膨胀引起的。
