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J/A+A/468/379       XMM Optical Monitor Survey of TMC        (Audard+, 2007)

The XMM-Newton Optical Monitor Survey of the Taurus Molecular Cloud. Audard M., Briggs K.R., Grosso N., Guedel M., Scelsi L., Bouvier J., Telleschi A. <Astron. Astrophys. 468, 379 (2007)> =2007A&A...468..379A
ADC_Keywords: Surveys ; Molecular clouds ; X-ray sources ; Ultraviolet ; Photometry Keywords: stars: coronae - stars: flare - stars: formation - stars: pre-main sequence - surveys - X-rays: stars Abstract: The Optical Monitor (OM) on-board XMM-Newton obtained optical/ultraviolet data for the XMM-Newton Extended Survey of the Taurus Molecular Cloud (XEST), simultaneously with the X-ray detectors. With the XEST OM data, we study the optical and ultraviolet properties of TMC members, and to perform correlative studies between the X-ray and OM light curves. In particular, we aim to determine whether accretion plays a significant role in the optical/ultraviolet and X-ray emissions. The Neupert effect in stellar flares is also investigated. Coordinates, average count rates and magnitudes were extracted from OM images, together with light curves with low time resolution (a few kiloseconds). For a few sources, OM FAST mode data were also available, and we extracted OM light curves with high time resolution. The OM data were correlated with Two Micron All Sky Survey (2MASS) data and with the XEST catalogue in the X-rays. The XEST OM catalogue contains 2,148 entries of which 1,893 have 2MASS counterparts. However, only 98 entries have X-ray counterparts, of which 51 are known TMC members and 12 additional are TMC candidates. The OM data indicate that accreting stars are statistically brighter in the U band than non-accreting stars after correction for extinction, and have U-band excesses, most likely due to accretion. The OM emission of accreting stars is variable, probably due to accretion spots, but it does not correlate with the X-ray light curve, suggesting that accretion does not contribute significantly to the X-ray emission of most accreting stars. In some cases, flares were detected in both X-ray and OM light curves and followed a Neupert effect pattern, in which the optical/ultraviolet emission precedes the X-ray emission of a flare, whereas the X-ray flux is proportional to the integral of the optical flux. Description: Full catalogue of XMM-Newton Optical Monitor Survey done in the framework of the XMM-Newton Extended Survey of the Taurus Molecular Cloud (XEST). The catalogue gives for each line, source number, OM coordinates (after corrections from a cross-correlation with 2MASS), positional error, XEST OM identification, 2MASS cross-identification when available and offset between the OM coordinates and 2MASS coordinates, XEST X-ray identification and offset between the OM and X-ray coordinates, average magnitude and its uncertainty, OM filter flag, and detection significance. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file catalog.dat 122 2148 OM (Optical Monitor of XMM-Newton) Catalogue
See also: J/A+A/325/647 : High-resolution spectra south of Taurus (Neuhaeuser+ 1997) J/A+AS/124/449 : Young stars south of Taurus-Auriga (Magazzu+ 1997) J/ApJS/101/117 : UBVRIJHKLMNQ photometry in Taurus-Auriga (Kenyon+ 1995) J/A+A/468/353 : XMM-Newton Extended Survey of Taurus (Guedel+, 2007) Byte-by-byte Description of file: catalog.dat
Bytes Format Units Label Explanations
1- 4 I4 --- Seq OM source number 8- 9 I2 h RAh Right ascension (J2000.0) 11- 12 I2 min RAm Right ascension (J2000.0) 14- 18 F5.2 s RAs Right ascension (J2000.0) 22 A1 --- DE- Declination sign (J2000.0) 23- 24 I2 deg DEd Declination (J2000.0) 26- 27 I2 arcmin DEm Declination (J2000.0) 29- 32 F4.1 arcsec DEs Declination (J2000.0) 37- 40 F4.2 arcsec ePos Position mean error 44- 52 A9 --- XESTOM XEST OM identification 56- 71 A16 --- 2MASS 2MASS (Cat. II/246) cross-identification 75- 78 F4.2 arcsec Off2M ? Offset between OM and 2MASS positions 82- 87 A6 --- XEST XEST X-ray cross-identification 91- 94 F4.2 arcsec OffX ? Offset between OM and X-ray positions 98-102 F5.2 mag mag Magnitude in Filter (U, UVW1 or UVW2) 106-109 F4.2 mag e_mag Magnitude uncertainty 113 I1 --- Filter [0/2] OM filter (0=U, 1=UVW1, 2=UVW2) for the magnitude 117-122 F6.1 --- Signi Detection significance
Acknowledgements: Marc Audard, Marc.Audard(at)
(End) Marc Audard [ISDC & Observatoire de Geneve, Switzerland] 01-Jun-2007
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