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J/ApJ/606/466      X-ray variability in NGC 2516                   (Wolk+, 2004)

Coronal variability in the young cluster NGC 2516. Wolk S.J., Harnden F.R.JR, Murray S.S., Adams N.R., Damiani F., Flaccomio E., Micela G., Sciortino S., Jeffries R.D. <Astrophys. J., 606, 466-482 (2004)> =2004ApJ...606..466W
ADC_Keywords: Clusters, open ; X-ray sources Keywords: open clusters and associations: individual (NGC 2516) - stars: coronae - X-rays: stars Abstract: NGC 2516 has been observed by Chandra several times in order to correct the plate scale of the spacecraft's focal plane instruments. Because of this, Chandra has observed NGC 2516 with all four imaging arrangements available. In addition, NGC 2516 has been observed as part of the High Resolution Camera (HRC) guaranteed time program and is scheduled for return plate scale calibration visits. This makes it the best cluster to study for long-term variability. NGC 2516 is about 140Myr old and less than 400pc away. In our first paper, Harnden et al., 2001ApJ...547L.141H, we discussed the detection of 150 X-ray sources (42% of which are identified as cluster members) in the calibration data taken during the orbital activation phase of the Chandra mission. In our second paper, Damiani et al., 2003, Cat. J/ApJ/588/1009, we combined all the extant data sets and detected 284 sources, more than half of which are considered likely cluster members. In this our third paper, we further explore techniques of combining Advanced CCD Imaging Spectrometer (ACIS) and HRC Chandra data for timing analysis. We have been able to combine almost 70ks of observation time, spread over five epochs, to study variability in this cluster on multiple timescales. We find that while stochastic variability rates are about the same for all objects in the sample, the timescale for detecting variability is shorter for late-type stars. Both stochastic and flare variability rates seen in NGC 2516 are similar to those seen in younger clusters IC 348, NGC 1333, and M42. Description: Chandra observations of NGC 2516 performed from 1999 through 2001 form a very heterogeneous data set. This data set is composed of three HRC observations, two ACIS-I observations, and two ACIS-S observations, all made on a common center. An eighth observation, also with ACIS-S3 at the aim point, was made slightly off the field center to improve the boresight solution. In Paper II (Damiani et al., 2003, Cat. J/ApJ/588/1009), we detailed our method of analysis of the eight independent observations. Objects: -------------------------------------- RA (2000) DE Designation(s) -------------------------------------- 07 58 18 -60 52.0 NGC 2516 -------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 77 103 X-ray variability analysis versus spectral type
See also: J/ApJ/588/1009 : Chandra X-ray observations of NGC 2516 (Damiani+, 2003) J/AJ/123/290 : UBVI CCD photometry of NGC 2516 (Sung+, 2002) J/A+A/312/818 : NGC 2516 X-ray sources (Dachs+, 1996) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 2 A2 --- Cat Category (1) 4- 6 I3 --- [DFM2003] Sequential number (see J/ApJ/588/1009) 9 I1 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) 20 A1 --- DE- Declination sign (J2000.0) 21- 22 I2 deg DEd Declination (J2000.0) 24- 25 I2 arcmin DEm Declination (J2000.0) 27- 30 F4.1 arcsec DEs Declination (J2000.0) 32- 34 A3 --- Bin [Yes/No ] Binary ? 36- 43 A8 --- ACISBr ACIS brightness 46- 55 A10 --- ACISVar ACIS variability (2) 58- 65 A8 --- HRCBr HRC brightness 68- 77 A10 --- HRCVar HRC variability (2)
Note (1): Categories as follows: B = B Stars A = A Stars F = F Stars G = G Stars K = K Stars M = M Stars nm = Non-members nc = No Counterpart Note (2): "QL" indicates a change in the quiescent level
History: From electronic version of the journal References: Harnden et al. Paper I 2001ApJ...547L.141H Damiani et al., Paper II 2003ApJ...588.1009D, Cat. J/ApJ/588/1009
(End) James Marcout, Patricia Vannier [CDS] 02-Jul-2004
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