Related papers: Overview of the Orion Complex
The Orion Complex is a notable star forming region, that it is fragmented into several different populations that have substantial difference in their phase space. I propose a model that attempts to explain the how the Complex has evolved…
In this chapter we review the properties of the Orion outlying clouds at b < -21 degrees. These clouds are located far off the Orion giant molecular cloud complex and are in most cases small cometary-shaped clouds, with their head pointing…
The Orion Nebula is one of the most frequently observed nearby (<1 kiloparsec) star forming regions and, consequently, the subject of a large bibliography of observations and interpretation. The summary in this chapter is bounded spatially…
The Orion OB1 Association, at a distance of roughly 400 pc and spanning over ~200 deg^2 on the sky, is one of the largest and nearest OB associations. With a wide range of ages and environmental conditions, Orion is an ideal laboratory for…
The giant molecular cloud Orion A is the closest massive star-forming region to earth ($d\sim400$ pc). It contains the rich Orion Nebula Cluster (ONC) in the North, and low-mass star-forming regions (L1641, L1647) to the South. To get a…
Massive stars born in star clusters terminate star cluster formation by ionizing the surrounding gas. This process is considered to be prevalent in young star clusters containing massive stars. The Orion Nebula is an excellent example…
The Orion Molecular Complex is the nearest site of ongoing high-mass star formation, making it one of the most extensively studied molecular complexes in the Galaxy. We have developed a new technique for mapping the 3D distribution of dust…
The Orion complex is arguably the most studied star-forming region in the Galaxy. While stars are still being born in the Orion nebula, the oldest part was believed to be no more than 13 Myr old. In order to study the full hierarchy of star…
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]…
The star forming region of the Orion Nebula (ONC) is ideal to study the stellar dynamics of young stars in a clustered environment. Using Gaia DR2 we search for the pre-main sequence stars with unusually high proper motions that may be…
The Orion Nebula Cluster (ONC) is the most massive region of active star formation within a kpc of the Sun. Using Gaia DR3 parallaxes and proper motions, we examine the bulk motions of stars radially and tangentially relative to the cluster…
We examine the pattern of star birth in the Orion Nebula Cluster (ONC), with the goal of discerning the cluster's formation mechanism. Outside of the Trapezium, the distribution of stellar masses is remarkably uniform, and is not accurately…
The Orion Nebula Cluster (ONC) is the nearest site of ongoing massive star formation, which allows us to study the kinematics and dynamics of the region in detail and constrain star formation theories. Using HST ACS/WFPC2/WFC3IR and Keck II…
General properties of the Orion star-forming region are discussed, with a focus on the dense Orion Nebula Cluster (ONC). This cluster contains between 2500 and 4500 objects located within a few parsecs of the eponymous Trapezium stars. Its…
A census of classical T Tauri stars and Herbig Ae/Be stars has been performed around the Orion-Eridanus Superbubble which is ionized and created by the Ori OB1 association. This sample is used to study the spatial distribution of newborn…
Using proper motion data for 894 stars in the Orion Nebula Cluster (ONC) compiled by Jones & Walker in 1988, we search for binaries with apparent separations in the range 1000-5000 AU, and find an upper limit of three. Using a Monte Carlo…
The spatial morphology and dynamical status of a young, still-forming stellar cluster provide valuable clues on the conditions during the star formation event and the processes that regulated it. We analyze the Orion Nebula Cluster (ONC),…
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…
The OB associations, which are fossil star formation regions, retain the end-products of the star formation process in an open, unobscured environment. Observations of the low mass stars in OB associations provide a far clearer picture of…
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…