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 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 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 2001ApJ...547L.141H
Damiani et al., Paper II 2003ApJ...588.1009D 2003ApJ...588.1009D, Cat. J/ApJ/588/1009
(End) James Marcout, Patricia Vannier [CDS] 02-Jul-2004