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J/ApJ/567/423       CHANDRA obs. of YSOs in Monoceros R2     (Kohno+, 2002)

Chandra observations of high-mass young stellar objects in the Monoceros R2 molecular cloud. Kohno M., Koyama K., Hamaguchi K. <Astrophys. J. 567, 423 (2002)> =2002ApJ...567..423K
ADC_Keywords: Stars, pre-main sequence ; X-ray sources Keywords: stars: early-type - stars: individual (Monoceros R2) - stars: pre-main-sequence - X-rays: stars Abstract: We observed the Monoceros R2 molecular cloud with the ACIS-I array on board the Chandra X-Ray Observatory. From the central 3.2'x3.2' region, we detect 154 sources above the detection limit of ∼5x10-16erg/s/cm2 with a 100ks exposure. About 85% of the X-ray sources are identified with an infrared counterpart, including four high-mass stars in the zero-age main-sequence (ZAMS) and/or premain-sequence (PMS) phase. The X-ray spectra of the high-mass ZAMS and PMS stars are represented by a thin thermal plasma model of a temperature above ∼2keV. The X-rays are time variable and exhibit rapid flares. This high-temperature plasma and flaring activity is similar to that seen in low-mass PMS stars and is contrary to the behavior observed in high-mass main-sequence stars.The X-ray luminosity increases as the intrinsic K-band flux increases. However, the X-ray luminosity saturates at a level of ∼1031erg/s. We conclude that high-mass ZAMS and PMS stars emit X-rays, possibly because of magnetic activity such as that of low-mass stars. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 118 154 CHANDRA X-ray sources in the Monoceros R2 region
See also: J/AJ/114/198 : The Monoceros R2 Cluster (Carpenter+ 1997) J/ApJ/566/974 : CHANDRA obs. of YSOs in OMC-2 and OMC-3 (Tsujimoto+, 2002) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 3 I3 --- [KKH2002] Source number 5- 6 I2 h RAh Hour of Right Ascension (J2000) (1) 8- 9 I2 min RAm Minute of Right Ascension (J2000) (1) 11- 15 F5.2 s RAs Second of Right Ascension (J2000) (1) 17 A1 --- DE- Sign of the Declination (J2000) (1) 18- 19 I2 deg DEd Degree of Declination (J2000) (1) 21- 22 I2 arcmin DEm Arcminute of Declination (J2000) (1) 24- 27 F4.1 arcsec DEs Arcsecond of Declination (J2000) (1) 29- 31 I3 ct Cts CHANDRA counts 33- 37 F5.1 % VarPr Variable probability (2) 39- 42 F4.1 kT Temp ? Temperature 44 A1 --- l_Temp Limit flag on the 90% confidence limit 45- 47 F3.1 kT e_Temp ? The 90% confidence value on Temp or lower limit if E_Temp is given 49- 52 F4.1 kT E_Temp ? The upper 90% confidence limit on Temp 54 A1 --- f_Temp [fg] Flag on Temp (3) 56- 59 F4.1 [cm-3] LogEM Log of the emission measure 61- 64 F4.1 [cm-3] e_LogEM The lower 90% confidence limit on LogEM 66- 69 F4.1 [cm-3] E_LogEM The upper 90% confidence limit on LogEM 71- 74 F4.1 10+22cm-2 NH Hydrogen column density 76- 79 F4.1 10+22cm-2 e_NH The lower 90% confidence limit on NH 81- 85 F5.1 10+22cm-2 E_NH The upper 90% confidence limit on NH 87- 90 F4.1 10-15mW/m2 Flux Observed 0.5-10.0 keV band flux in 10-15erg/cm2/s 92- 95 F4.1 [10-7W] LogLX Log of the absorption-corrected 0.5-10.0keV band luminosity in erg/s 97-100 F4.1 [10-7W] e_LogLX The lower 90% confidence limit on LogLX 102-105 F4.1 [10-7W] E_LogLX The upper 90% confidence limit on LogLX 107-109 I3 --- IRNum ? IR counterpart number (4) 111-117 A7 --- IRName IR source name (5)
Note (1): Mean position error is 0.15". Note (2): Obtained by Kolmogorov-Smirnov test to 0.5-10keV band. Note (3): Flags on Temp: f = fixed; g = The best-fit values of kT not determined to be below 20keV, hence we assume the temperatures are 20keV for estimation of the other parameters. Note (4): Source numbers are from Carpenter et al. (1997, Cat. J/AJ/114/198). Note (5): From Beckwith et al. (1976ApJ...208..390B), Howard et al. (1994ApJ...425..707H) and Capenter et al. (1997, Cat. J/AJ/114/198).
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Bauer [CDS] 25-Apr-2002
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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