Chandra/ACIS-I study of the X-ray properties of the NGC 6611 and M16 stellar population

Abstract

Mechanisms regulating the origin of X-rays in YSOs and the correlation with their evolutionary stage are under debate. Studies of the X-ray properties in young clusters allow to understand these mechanisms. One ideal target for this analysis is the Eagle Nebula (M16), with its central cluster NGC6611. At 1750 pc from the Sun, it harbors 93 OB stars, together with a population of low-mass stars from embedded protostars to disk-less Class III objects, with age <= 3Myrs. We study an archival 78 ksec Chandra/ACIS-I observation of NGC6611, and two new 80ksec observations of the outer region of M16, one centered on the Column V, and one on a region of the molecular cloud with ongoing star-formation. We detect 1755 point sources, with 1183 candidate cluster members (219 disk-bearing and 964 disk-less). We study the global X-ray properties of M16 and compare them with those of the Orion Nebula Cluster. We also compare the level of X-ray emission of Class II and Class III stars, and analyze the X-ray spectral properties of OB stars. Our study supports the lower level of X-ray activity for the disk-bearing stars with respect to the disk-less members. The X-ray Luminosity Function (XLF) of M16 is similar to that of Orion, supporting the universality of the XLF in young clusters. 85% of the O stars of NGC6611 have been detected in X-rays. With only one possible exception, they show soft spectra with no hard component, indicating that mechanisms for the production of hard X-ray emission in O stars are not operating in NGC 6611.

Accepted in ApJ

References in corpus (15)

• The young stellar population in M17 revealed by Chandra
• The VLT-FLAMES Survey of Massive Stars: Stellar parameters and rotational velocities in NGC3293, NGC4755 and NGC6611
• A Chandra Study of the Rosette Star-Forming Complex. I. The Stellar Population and Structure of the Young Open Cluster NGC 2244
• Correlation between the spatial distribution of the circumstellar disks and the massive stars in the open cluster NGC 6611. Compiled catalog and cluster parameters
• X-ray properties of protostars in the Orion Nebula
• Embedded Star Formation in the Eagle Nebula with Spitzer/GLIMPSE
• ACIS-I observations of NGC2264. Membership and X-ray properties of PMS stars
• The XMM-Newton survey of the ELAIS-S1 field. I: Number counts, angular correlation function and X-ray spectral properties
• X-ray Flares in Orion Low Mass Stars
• An X-ray Census of Young Stars in the Massive Southern Star-Forming Complex NGC 6357
• Correlation between the spatial distribution of circumstellar disks and massive stars in the young open cluster NGC 6611. II: Cluster members selected with Spitzer/IRAC
• Chandra Observations of the Eagle Nebula. I. Embedded Young Stellar Objects near the Pillars of Creation
• X-Rays From Massive OB Stars: Thermal Emission From Radiative Shocks
• Discovery of magnetic fields in the very young, massive stars W601 (NGC 6611) and OI 201 (NGC 2244)
• Early-type objects in NGC6611 and Eagle Nebula

Cited by in corpus (18)

• A Magnetic Confinement vs. Rotation Classification of Massive-Star Magnetospheres
• Overview of the Massive Young Star-Forming Complex Study in Infrared and X-ray (MYStIX) Project
• The Massive Star-forming Regions Omnibus X-ray Catalog
• The Apache Point Observatory Catalog of Optical Diffuse Interstellar Bands
• The stellar contents and star formation in the NGC 7538 region
• M17 MIR: A massive protostar with multiple accretion Outbursts
• Pre-main sequence stars older than 8 Myr in the Eagle Nebula
• The early evolution of young massive clusters: The kinematic history of NGC6611 / M16
• Discovery of X-ray emission from young suns in the Small Magellanic Cloud
• A JVLA survey of the high frequency radio emission of the massive magnetic B- and O-type stars
• Pre-main-sequence population in NGC 1893 region: X-ray properties
• On the possible common origin of M16 and M17
• X-ray emission in the enigmatic CVSO 30 system
• Irradiated Interfaces in the Ara OB1, Carina, Eagle Nebula, and Cyg OB2 Massive Star Formation Regions
• X-ray observations of eight young open star clusters : I. Membership and X-ray Luminosity
• Hadronic acceleration in the young star cluster NGC 6611 inside the M16 region unveiled by Fermi-LAT: constraints on the acceleration efficiency
• A CCD Search for Variable Stars in the Open Cluster NGC 6611
• Evidence of triggered star formation in the Pillars of Creation from JWST observations