Related papers: Orion Outlying Clouds
Magnetic fields permeate the interstellar medium and are important in the star formation process. Determining the 3D magnetic fields of molecular clouds will allow us to better understand their role in the evolution of these clouds and…
Massive stars have a strong impact on their local environments. However, how stellar feedback regulates star formation is still under debate. In this context, we studied the chemical properties of 80 dense cores in the Orion molecular cloud…
When observed with sufficiently high spatial resolution and sensitivity, star formation regions are unusually complex X-ray sources. Low-mass protostars and T Tauri stars, Herbig Ae/Be stars, OB and Wolf-Rayet stars are seen at levels $28…
The spectra of Herbig Haro objects are usually characteristic of ionization and excitation in shock-heated gas, whether an internal shock in an unsteady outflow or a bow shock interface with the interstellar medium. We examine the…
We report the discovery of the oldest stellar substructure in the Orion star forming region (OSFR), the Orion relic filament. The relic filament is physically associated with the OSFR as demonstrated by Gaia DR2 photometry and astrometry,…
We suggest that the Orion A cloud is gravitationally collapsing on large scales, and is producing the Orion Nebula Cluster due to the focusing effects of gravity acting within a finite cloud geometry. In support of this suggestion, we show…
We performed new comprehensive $^{13}$CO($J$=2--1) observations toward NGC 2024, the most active star forming region in Orion B, with an angular resolution of $\sim$100'' obtained with NANTEN2. We found that the associated cloud consists of…
Understanding the initial properties of star-forming material and how they affect the star formation process is key. From an observational point of view, the feedback from young high-mass stars on future star formation properties is still…
The Orion Nebula Cluster and the molecular cloud in its vicinity have been observed with the ACIS-I detector on board the Chandra X-ray Observatory with 23 hours exposure. We detect 1075 X-ray sources: 91% are spatially associated with…
We have made continuum and spectral line observations of several outflow sources in the Mon OB1 dark cloud (NGC 2264) using the Heinrich Hertz Telescope (HHT) and ARO 12m millimeter-wave telescope. This study explores the kinematics and…
Hierarchical structure from stellar clusters, to subgroups, to associations and star complexes is discussed in the context of the Orion stellar grouping and its origin. The analogous structure in gas clouds is also reviewed, with an…
As a stellar group forms within its parent molecular cloud, new members first appear in the deep interior. These overcrowded stars continually diffuse outward to the cloud boundary, and even beyond. Observations have so far documented only…
I compare theoretical models of massive star formation with observations of the Orion Hot Core, which harbors one of the closest massive protostars. Although this region is complicated, many of its features (size, luminosity, accretion…
We have extended the work of Papers I and II of this series to determine at higher spatial resolution the properties of the embedded Orion-S Molecular Cloud that lies within the ionized cavity of the Orion Nebula and of the thin ionized…
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. Velocity-resolved observations of the [CII]…
Strong winds and ultraviolet (UV) radiation from O-type stars disrupt and ionize their molecular core birthplaces, sweeping up material into parsec-size shells. Owing to dissociation by starlight, the thinnest shells are expected to host…
We have investigated the formation and kinematics of sub-mm continuum cores in the Orion A molecular cloud. A comparison between sub-mm continuum and near infrared extinction shows a continuum core detection threshold of $A_V\sim$ 5-10 mag.…
The existence of multiple layers in the inner Orion Nebula has been revealed using data from an Atlas of spectra at 2" and 12 km/s resolution. These data were sometimes grouped over Samples of 10"x10"to produce high Signal to Noise spectra…
This work extends previous kinematic studies of young stars in the Head of the Orion A cloud (OMC-1/2/3/4/5). It is based on large samples of infrared, optical, and X-ray selected pre-main sequence stars with reliable radial velocities and…
We report on the discovery of a mid-infrared source at a projected distance of only 1200 AU from the O9.5 V star sigma Orionis. The spatially resolved, fan-shaped morphology and the presence of an ionization front, as well as evidence in…