Chandra
Orion Ultradeep Project
The Embedded Young Stars of OMC-1
Here is the COUP image of the southern known as the OMC 1-South cloud core (for comparison the same area observed with VLT in the near-infrared is shown on the right handside; McCaughrean 2005). Chandra detected in this region the most embedded X-ray source in the COUP survey (COUP 632), a protostar with AV~500 visual magnitudes of absorption. Chandra unveiled 18 new X-ray sources without infrared counterpart, which are embedded Young Stellar Objects of OMC-1.
Below is the COUP lightcurve and spectrum of the brightest X-ray source in the OMC 1-South cloud core (COUP 554). This embedded young star is very powerful in high-energy penetrating X-rays, which produces a bubble of slightly-ionized gas around the star.
Here is the COUP image of the northern core known as the Becklin-Neugebauer-Kleinman-Low region, which harbors the closest and infrared-brightest cluster of high-mass protostars (for comparison the same area observed with VLT in the near-infrared is shown on the right handside; McCaughrean 2005). We detect X-ray sources close to four of these luminous protostars, but arising maybe from low-mass companions rather than wind emission from these massive protostars. The BN Object is detected but, surprisingly, is much fainter in X-rays than a previously unknown flaring companion star less than an arcsecond away. COUP gives the first direct estimate of the low-mass population of the BN cluster, about 50 stars, which is fewer than expected.
The full paper on COUP embedded Young Stars of OMC-1 is:
Chandra Orion Ultradeep Project census of X-ray stars in the BN-KL and OMC-1S regions
N. Grosso, E. D. Feigelson, K. V. Getman, L. Townsley, P. Broos, E. Flaccomio, M. J. McCaughrean, G. Micela, S. Sciortino, J. Bally, N. Smith, A. A. Muench, G. Garmire, F. Palla
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The Embedded Young Stars of OMC-1
The Chandra X-ray telescope
and detectors have great sensitivity for hard X-ray photons above ~3 keV,
energies which penetrate through sufficient interstellar material to peer
deep into the cores of molecular clouds where stars are forming today.
Some COUP sources are so heavily absorbed that even the largest ground-based
infrared telescopes can not detect them. Also useful, the soft X-ray
absorption gives direct measure of the intervening column density for each
source.
Over sixty COUP sources are found within the two molecular cores behind the Orion Nebula, known collectively as Orion Molecular Core 1. This is the first direct measurement of the low-mass population of the OMC-1 South cluster. They have absorptions ranging from 1022 to 1024 cm-2, equivalent to AV~5-500 visual magnitudes of absorption.
Over sixty COUP sources are found within the two molecular cores behind the Orion Nebula, known collectively as Orion Molecular Core 1. This is the first direct measurement of the low-mass population of the OMC-1 South cluster. They have absorptions ranging from 1022 to 1024 cm-2, equivalent to AV~5-500 visual magnitudes of absorption.
Here is the COUP image of the southern known as the OMC 1-South cloud core (for comparison the same area observed with VLT in the near-infrared is shown on the right handside; McCaughrean 2005). Chandra detected in this region the most embedded X-ray source in the COUP survey (COUP 632), a protostar with AV~500 visual magnitudes of absorption. Chandra unveiled 18 new X-ray sources without infrared counterpart, which are embedded Young Stellar Objects of OMC-1.
Below is the COUP lightcurve and spectrum of the brightest X-ray source in the OMC 1-South cloud core (COUP 554). This embedded young star is very powerful in high-energy penetrating X-rays, which produces a bubble of slightly-ionized gas around the star.
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Here is the COUP image of the northern core known as the Becklin-Neugebauer-Kleinman-Low region, which harbors the closest and infrared-brightest cluster of high-mass protostars (for comparison the same area observed with VLT in the near-infrared is shown on the right handside; McCaughrean 2005). We detect X-ray sources close to four of these luminous protostars, but arising maybe from low-mass companions rather than wind emission from these massive protostars. The BN Object is detected but, surprisingly, is much fainter in X-rays than a previously unknown flaring companion star less than an arcsecond away. COUP gives the first direct estimate of the low-mass population of the BN cluster, about 50 stars, which is fewer than expected.
The full paper on COUP embedded Young Stars of OMC-1 is:
Chandra Orion Ultradeep Project census of X-ray stars in the BN-KL and OMC-1S regions
N. Grosso, E. D. Feigelson, K. V. Getman, L. Townsley, P. Broos, E. Flaccomio, M. J. McCaughrean, G. Micela, S. Sciortino, J. Bally, N. Smith, A. A. Muench, G. Garmire, F. Palla
Back to the COUP home page