X-Ray Flare Oscillations Track Plasma Sloshing along Star-disk Magnetic Tubes in the Orion Star-forming Region

The Orion Star-Forming Region

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 members are aged <1 to a few Myr and encompass the full spectrum of stellar masses <50 M⊙, as well as brown dwarfs detected with masses as low as <0.02 M⊙ (2...

Bright X-ray Flares in Orion Young Stars from Coup: Evidence for Star-disk Magnetic Fields?

We have analyzed a number of intense X-ray flares observed in the Chandra Orion Ultradeep Project (COUP), a 13 days observation of the Orion Nebula Cluster (ONC), concentrating on the events with the highest statistics (in terms of photon flux and event duration). Analysis of the flare decay allows to determine the physical parameters of the flaring structure, in particular its size and (using ...

The chemical composition of the Orion star forming region

Aims. We re-examine the recombination/collisional emission line (RL/CEL) nebular abundance discrepancy problem in the light of recent high-quality abundance determinations in young stars in the Orion star-forming region. Methods. We re-evaluate the CEL and RL abundances of several elements in the Orion nebula and estimate the associated uncertainties, taking into account the uncertainties in th...

X-ray emission from star-forming galaxies

A Circumstellar Disk in a High-mass Star-forming Region

We present an edge-on Keplerian disk model to explain the main component of the 12.2 and 6.7 GHz methanol maser emission detected toward NGC 7538 IRS 1N. The brightness distribution and spectrum of the line of bright masers are successfully modeled with high amplification of background radio continuum emission along velocity-coherent paths through a maser disk. The bend seen in the position-vel...