J/ApJ/566/974 CHANDRA obs. of YSOs in OMC-2 and OMC-3 (Tsujimoto+, 2002) ================================================================================ X-ray properties of young stellar objects in OMC-2 and OMC-3 from the Chandra X-ray observatory. Tsujimoto M., Koyama K., Tsuboi Y., Goto M., Kobayashi N. =2002ApJ...566..974T ================================================================================ ADC_Keywords: X-ray sources ; Stars, pre-main sequence ; Photometry, infrared Mission_Name: Chandra Keywords: infrared: stars - SM: individual (OMC-2, OMC-3) - stars: pre-main-sequence - X-rays: stars Abstract: We report X-ray results of the Chandra observation of OMC-2 and OMC-3. A deep exposure of ~100ks detects ~400 X-ray sources in the field of view of the ACIS array, providing one of the largest X-ray catalogs in a star-forming region. Coherent studies of the source detection, time variability, and energy spectra are performed. We classify the X-ray sources into Class I, Class II, and Class III+MS based on the J-, H-, and K-band colors of their near-infrared counterparts and discuss the X-ray properties (temperature, absorption, and time variability) along these evolutionary phases. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 49 398 Results of Imaging Analysis and NIR Identification table2.dat 88 123 Results of Timing and Spectroscopic Analysis table3.dat 109 23 Best-fit Values of Two-Temperature Thin-Thermal Plasma Model -------------------------------------------------------------------------------- See also: J/ApJ/567/423 : CHANDRA obs. of YSOs in Monoceros R2 (Kohno+, 2002) Byte-by-byte Description of file: table1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 4 A4 --- [TKT2002] Object source identification (1) 6- 23 A18 --- Name Object name (hhmmss.ss-ddmmss.s) (2) 25- 29 I5 ct XCts X-ray photon counts in 0.5-8.0keV band 31- 35 F5.2 --- HR Hardness ratio (3) 37- 42 F6.3 mag J-H ? The (J-H) color (4) 44- 49 F6.3 mag H-K ? The (H-K) color (4) -------------------------------------------------------------------------------- Note (1): Results of X-ray imaging analysis and 2MASS correlation are listed for all the detected X-ray sources. I1-I354 and S1-S11 are detected in the total band image (0.5-8.0keV) image of the ACIS-I and the ACIS-S2. I355-I369 and S12-S13 are detected only in the hard band (2.0-8.0keV) image of the ACIS-I and the ACIS-S2. I370-I385 are detected only in the soft band (0.5-2.0keV) image of the ACIS-I. No new source was detected in the soft band image of the ACIS-S2. Note (2): Sources are named after their position in the equinox J2000. Note (3): Defined as (H-S)/(H+S) where H and S are photon counts in the hard band (2.0-8.0keV) and in the soft band (0.5-2.0keV) respectively. Note (4): In CIT color system derived from 2MASS J, H, and K_s_ band photometry (see Carpenter, 2001AJ....121.2851C). -------------------------------------------------------------------------------- Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 4 A4 --- [TKT2002] Object source identification (1) 6 A1 --- f_[TKT2002] [d] Indicates source with time-variability 8- 12 F5.3 --- UProb Upper probability (2) 14- 17 F4.2 10+22/cm2 NH Column density 19- 22 F4.2 10+22/cm2 e_NH Lower 1{sigma} confidence level to NH 24- 27 F4.2 10+22/cm2 E_NH Upper 1{sigma} confidence level to NH 29- 33 F5.2 keV Temp Temperature (3) 35- 38 F4.2 keV e_Temp Lower 1{sigma} confidence level to Temp 40- 44 F5.2 keV E_Temp Upper 1{sigma} confidence level to Temp 46- 49 F4.2 [Sun] Z Metallicity relative to solar photospheric from Morrison & McCammon, 1983ApJ...270..119M (3) 52- 55 F4.2 [Sun] e_Z Lower 1{sigma} confidence level to Z 57- 60 F4.2 [Sun] E_Z Upper 1{sigma} confidence level to Z 62- 67 F6.2 10+22W XLum X-ray luminosity in units of 10+29erg/s (4) 69- 74 F6.2 10+22W e_XLum Lower 1{sigma} confidence level to XLum 76- 81 F6.2 10+22W E_XLum Upper 1{sigma} confidence level to XLum 83- 88 A6 --- Class Classification based on J, H, K_s_ magnitude of 2MASS counterpart (G1) -------------------------------------------------------------------------------- Note (1): Results of timing and spectroscopic analysis are listed for all the "bright2" sources. Best-fit parameters of thin-thermal plasma model fitting are tabulated regardless whether the fit is accepted or rejected. Note (2): Defined as the integral from {alpha} to infinity of {Chi}_{nu}_^2^(x) dx where the {Chi}_{nu}_^2^(x) value and the degree of freedom of the fit is {alpha} and {nu}. Fits with the upper probability larger than 0.01 are "accepted" while those less than or equal to 0.01 are "rejected". Even the "best-fit" parameters of rejected fittings represent values of some physical meaning or approximated values. We thus use these values in the same way with the accepted ones. Note (3): The best fit value of temperature and metallicity are searched for in the range of less than 20keV and 5 solar respectively. Note (4): In the 0.5-8.0keV band and corrected for absorption. -------------------------------------------------------------------------------- Byte-by-byte Description of file: table3.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 4 A4 --- [TKT2002] Object source identification (1) 6- 9 F4.2 10+22/cm2 NH Column density 11- 14 F4.2 10+22/cm2 e_NH Lower 1{sigma} confidence level to NH 16- 19 F4.2 10+22/cm2 E_NH Upper 1{sigma} confidence level to NH 21- 24 F4.2 keV TempL Lower temperature component value (2) 26- 29 F4.2 keV e_TempL Lower 1{sigma} confidence level to TempL 31- 34 F4.2 keV E_TempL Upper 1{sigma} confidence level to TempL 36- 40 F5.2 keV TempH Higher temperature component value (2) 42- 45 F4.2 keV e_TempH Lower 1{sigma} confidence level to TempH 47- 51 F5.2 keV E_TempH Upper 1{sigma} confidence level to TempH 53- 56 F4.2 [Sun] Z Metallicity relative to solar photospheric of Morrison & McCammon, 1983ApJ...270..119M (2) 58- 61 F4.2 [Sun] e_Z Lower 1{sigma} confidence level to Z 63- 66 F4.2 [Sun] E_Z Upper 1{sigma} confidence level to Z 68- 72 F5.2 10+22W XLumL Lower component X-ray luminosity in units of 10+29erg/s (3) 74- 78 F5.2 10+22W e_XLumL Lower 1{sigma} confidence level to XLumL 80- 84 F5.2 10+22W E_XLumL Upper 1{sigma} confidence level to XLumL 86- 90 F5.2 10+22W XLumH Higher component X-ray luminosity in units of 10+29erg/s (3) 92- 96 F5.2 10+22W e_XLumH Lower 1{sigma} confidence level to XLumH 98-102 F5.2 10+22W E_XLumH Upper 1{sigma} confidence level to XLumH 104-109 A6 --- Class Classification based on J, H, K_s_ magnitude of 2MASS counterpart (G1) -------------------------------------------------------------------------------- Note (1): Accepted fits are listed. Note (2): The absorption and the metallicity of the higher temperature component is fixed to be the same with those of the lower temperature component. The best fit value of temperature and metallicity are searched for in the range of less than 20keV and 5 solar respectively. Note (3): In the 0.5-8.0keV band and corrected for absorption. -------------------------------------------------------------------------------- Global notes: Note (G1): Classification: I = class I; II = class II; III+MS = class III+MS; others = source which are out of these groups. no data = source can not be classified due to their lack of a NIR counterpart. -------------------------------------------------------------------------------- History: * 25-Apr-2002: From electronic version of the journal * 28-Dec-2006: Table1 corrected, from erratum published in 2003 ApJ, 585, 602 ================================================================================ (End) Greg Schwarz [AAS], Patricia Bauer [CDS] 25-Apr-2002