- ... stars
- Tables 1, 3, 4 and 6 are only available in electronic form at http://www.edpsciences.org
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- ... Center
- See
cxc.harvard.edu
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- ...
sources
-
where
;
Si and Ais are the
number of counts in the ith source region and its area,
respectively. B and Ab are the background counts and relative
extraction area, respectively. The background was taken for the present
purpose as uniform within the FOV.
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- ...(Damiani et al. 1997)
- Available at: http://www.astropa.unipa.it/progetti_ricerca/PWDetect
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- ... keV
- The choice of energy is not crucial: the ratio
between the effective area at the source position and on the optical
axis, which is the quantity we use to define the effective exposure
time, has only a small dependence on energy.
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- ... spectroscopy#
- The Rebull et al. (2002), catalog was
updated following private communication from L. Rebull.
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- ... (JHKs
- Note that in the following we neglect
the small differences among NIR photometric systems and, in particular,
that between the 2MASS Ks and the standard K bands.
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- ...
track
- This latter condition was required by the convergence
of the isochrones at higher masses and by the observed spread of stars
in the "cluster locus'', at least in part due to uncertainties.
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- ... Y06)
- Note that the source is missed by
2MASS because, at the 2MASS spatial resolution, it is blended with a
nearby source.
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- ...
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- Although Y06 report that C-MM 1
has no NIR counterpart, we associate it with 2MASS source
06411792+0929011 (offset = 1.5'').
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- ... interval
- Events
with energies below 0.5 keV were not used because of uncertainties in
the calibration resulting from the time-dependent degradation of the
ACIS quantum efficiency at low energies.
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- ... acceptable
- For source #241 we changed the 2T
model (
%,
kT1=0.0577.80.022 keV,
kT2=0.571.300.30 keV,
)
to a 1T model (
%,
kT=0.600.840.38 keV,
). For source #104 we changed
the 1T model (
%,
kT=0.430.730.29 keV,
)
to a
model
(n.p. = 32%,
and reasonable temperatures). For
sources #97 and #127 we changed from
models (p=68% and
p=21%, kT=54 keV and kT=19 keV, both with unconstrained
uncertainties) to 1T models (p=97% and p=56%, kT=4.7 keV and
kT=3.5 keV).
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- ...
cases
- Sources #190, #340, #352, #375, #391.
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- ...
)
- For this source we adopted the
spectral type (K2) from Dahm & Simon (2005) and the photometry
(
)
from Lamm et al. (2004). Independent photometry and
spectral types are available from Rebull et al. (2002), Lamm et al. (2004), and
Dahm & Simon (2005). The
color ranges between 0.55 and 0.62 and
spectral types between G9 and K2. The possible range in
is thus
,
i.e. between
9 and
46 times the value derived from the X-ray spectrum, considering
its 90% confidence interval.
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- ...)
- We excluded 14 sources identified as stars by
Barger et al. (2003).
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- ... objects
- Mean
value and 1
uncertainty result from repeating the experiment 10 times, each time varying the position of simulated extragalactic
sources.
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- ...
diagrams
- The NIR photometry of the CDFN sources was taken from
2Mass.
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- ...(Schreyer et al. 2003)
- The ACIS spectrum indicates
(90% confidence interval),
corresponding to
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- ... stars
- #7, #51, #110, #128,
#130, #171, #224, #248, #258, and #267.
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- ... neighborhood
- This is justified by the low equatorial
longitude of NGC 2264:
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- ... cm
- With the chosen value of
,
taking
and d=760 pc (the assumed distance of
NGC 2264), we obtain
,
in agreement with the median of values
measured for NGC 2264 members.
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- ... non-members
- The fraction of non-members is expected to be
higher among X-ray sources with
and ages
yr.
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- ... considered
- Four of
these X-ray sources were actually identified with MIR and/or mm sources
in Sect. 3.3. Because these catalogs are not spatially
complete, we here treat them as unidentified for uniformity.
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- ... HRI
- In Table
3 our ACIS source # 376 is associated with HRI source
138 due to the large uncertainty of the HRI positions; the HRI source
is, however, closer to the brighter ACIS source #375, with which it is
most likely associated.
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- ...
1.9
- 80% interval of the
power indexes reported by Alexander et al. (2003) for the sources in the CDFN
that we would have detected in our ACIS data and for which the
1
uncertainty in the index is lower than 0.1.
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- ...
ONC
- Note that the COUP observation, obtained with Chandra ACIS, was 850 ks long. The temperatures are thus derived from
a spectrum that has been integrated in time over a period that is 8.5
times longer than that of our NGC 2264 observation.
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- ...spectrum
- Our
is based on
,
derived here from
published photometry and spectral type. Herbst & Moran (2005) derive their
value from
E(B-V)=0.1. This E(B-V) should, however, imply
cm-2 assuming
and depending on
the assumed
ratio in the range
.
Herbst & Moran (2005) assume solar abundances and kT=2.7 keV, the latter based
on the uncertain (due to statistics) hardness ratio. The count to flux
conversion factor we used (Eq. (1)) was derived from
sources with 50 to 100 counts, which were fit with APEC models with
subsolar abundances and median kT of 1.0 keV. Note that our harness
ratio analysis (cf. Fig. 16) actually indicates a
very cool spectrum,
keV, with large uncertainties.
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- ... uncertainties
- In this section
uncertainties quoted for quantities derived by SD05 are
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while for our results we quote 90% confidence intervals.
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