We report on the results of the Chandra ACIS-I observation on the central region of the Monoceros R2 cloud ( Mon R2 ) , a high-mass star-forming region ( SFR ) at a distance of 830 pc .
With a deep exposure of \sim 100 ks , we detected 368 X-ray sources , \sim 80 % of which were identified with the near-infrared ( NIR ) counterparts .
We systematically analyzed the spectra and time variability of most of the X-ray emitting sources and provided a comprehensive X-ray source catalog for the first time .
Using the J - , H - , and K -band magnitudes of the NIR counterparts , we estimated the evolutionary phase ( classical T Tauri stars and weak-lined T Tauri stars ) and the mass of the X-ray emitting sources , and analyzed the X-ray properties as a function of the age and mass .
We found a marginal hint that classical T Tauri stars have a slightly higher temperature ( 2.4 keV ) than that of weak-lined T Tauri stars ( 2.0 keV ) .
A significant fraction of the high- and intermediate-mass sources have a time variability and high plasma temperatures ( 2.7 keV ) similar to those of low-mass sources ( 2.0 keV ) .
We performed the same analysis for other SFRs , the Orion Nebula Cluster and Orion Molecular Cloud-2/3 , and obtained similar results to Mon R2 .
This supports the earlier results of this observation obtained by Kohno et al .
( 2002 , ApJ , 567 , 423 ) and Preibisch et al .
( 2002 , A & A , 392 , 945 ) that high- and intermediate-mass young stellar objects emit X-rays via magnetic activity .
We also found a significant difference in the spatial distribution between X-ray and NIR sources .