J/ApJ/733/113 IRAC observations of IC 1795 (Roccatagliata+, 2011)
Disk evolution in OB associations: deep Spitzer/IRAC observations of IC 1795.
Roccatagliata V., Bouwman J., Henning T., Gennaro M., Feigelson E.,
Kim J.S., Sicilia-Aguilar A., Lawson W.A.
<Astrophys. J., 733, 113 (2011)>
=2011ApJ...733..113R 2011ApJ...733..113R
ADC_Keywords: YSOs ; Associations, stellar ; Photometry, infrared ;
X-ray sources
Keywords: ISM: individual objects (W3) - X-rays: stars -
open clusters and associations: individual (W3 IC1795) -
protoplanetary disks - stars: formation - stars: pre-main sequence
Abstract:
We present a deep Spitzer/Infrared Array Camera (IRAC) survey of the
OB association IC 1795 carried out to investigate the evolution of
protoplanetary disks in regions of massive star formation. Combining
Spitzer/IRAC data with Chandra/Advanced CCD Imaging Spectrometer
observations, we find 289 cluster members. An additional 340 sources
with an infrared excess, but without X-ray counterpart, are classified
as cluster member candidates. Both surveys are complete down to
stellar masses of about 1M☉. We present pre-main-sequence
isochrones computed for the first time in the Spitzer/IRAC colors. The
age of the cluster, determined via the location of the Class III
sources in the [3.6]-[4.5]/[3.6] color-magnitude diagram, is in the
range of 3-5Myr. As theoretically expected, we do not find any
systematic variation in the spatial distribution of disks within 0.6pc
of either O-type star in the association. However, the disk fraction
in IC 1795 does depend on the stellar mass: sources with masses
>2M☉ have a disk fraction of ∼20%, while lower mass objects
(2-0.8M☉) have a disk fraction of ∼50%. This implies that disks
around massive stars have a shorter dissipation timescale.
Description:
IC 1795 was observed in 2007 September with all 4 IRAC channels
centered at 3.6um, 4.5um, 5.8um, 8.0um, respectively.
Our X-ray catalog was generated from a mosaic of Chandra observations
consisting of the seven exposures of W3 presented by Feigelson &
Townsley (2008ApJ...673..354F 2008ApJ...673..354F) and an additional exposure of IC 1795.
This is a 50.0ks exposure obtained on 2007 December 4 centered on
J022633.6+620035.9 with the 4-CCD ACIS Imaging Array.
Out of 593 sources detected in Spitzer/IRAC ch1 and ch2 without an
X-ray counterpart, we find 248 IRAC excess sources ([3.6]-[4.5]≥0.2);
classified as cluster member candidates (tables 4 and 5).
The final catalog of the IC 1795 cluster members is in Table 3 (and 2).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 74 277 Spitzer/IRAC sources with Chandra counterparts
table3.dat 128 277 Optical, near-infrared and IRAC/Spitzer fluxes
of the IRAC/Spitzer sources with X-ray counterpart
table4.dat 48 248 Cluster member candidates: designation and
positions of IRAC sources with excess without
X-ray counterpart
table5.dat 128 248 Cluster member candidates: IRAC sources with excess
without X-ray counterpart
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See also:
B/chandra : The Chandra Archive Log (CXC, 1999-2012)
II/297 : AKARI/IRC mid-IR all-sky Survey (ISAS/JAXA, 2010)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/A+A/514/A2 : AKARI/HIP and AKARI/2MASS samples (Ita+, 2010)
J/A+A/501/539 : RMS survey. 6cm observations of YSOs (Urquhart+, 2009)
J/ApJ/660/1532 : Spitzer/IRAC-MIPS survey of NGC 2244 (Balog+, 2007)
J/ApJ/654/338 : Spitzer photometry in W3 molecular cloud (Ruch+, 2007)
J/AJ/129/393 : UBV photometry in W3 (Oey+, 2005)
J/AJ/126/1423 : MSX 8.3um fluxes of star-forming regions (Kraemer+, 2003)
J/A+AS/124/205 : W3 star-forming region 345 GHz survey (Helmich+ 1997)
Byte-by-byte Description of file: table[24].dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- ID Identification; IRAC- (HHMMSSss+DDMMSSs)
18 A1 --- f_ID Flag on source (1)
20- 28 F9.6 deg RAdeg Right Ascension in decimal degrees (J2000)
30- 33 F4.2 10-4deg e_RAdeg Error in RAdeg
35- 43 F9.6 deg DEdeg Declination in decimal degrees (J2000)
45- 48 F4.2 10-4deg e_DEdeg Error in DEdeg
50 A1 --- Exc [X~-] Infrared excess code (2)
52- 74 A23 --- Disk Disk classification (only for table 2)
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Note (1): Flag as follows:
a = Source position in IRAC/channel 2.
b = Source position in IRAC/channel 3.
c = The counterparts at different wavelengths were found using a different
matching procedure.
d = IRAC source with 2 X-ray counterparts ("X binary").
e = IRAC source with 3 X-ray counterparts.
Note (2): IR excess code (in table2 only) as follows:
X = [3.6]-[4.5]>0.2mag;
- = [3.6]-[4.5]<0.1mag;
∼ = 0.1<[3.6]-[4.5]<0.2mag.
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Byte-by-byte Description of file: table[35].dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- ID Identification; IRAC- (HHMMSSss+DDMMSSs)
18- 23 F6.4 mJy FV ? V band flux density (3)
25- 31 F7.4 mJy FI ? I band flux density (3)
33- 41 F9.4 mJy FJ ? 2MASS J band flux density (4)
43- 50 F8.4 mJy FH ? 2MASS H band flux density (4)
52- 60 F9.4 mJy FK ? 2MASS Ks band flux density (4)
62- 70 F9.4 mJy F3.6 ? Spitzer/IRAC 3.6 micron band flux density
72- 77 F6.4 mJy e_F3.6 ? Uncertainty in F3.6 (5)
79- 87 F9.4 mJy F4.5 ? Spitzer/IRAC 4.5 micron band flux density
89- 94 F6.4 mJy e_F4.5 ? Uncertainty in F4.5 (5)
96-104 F9.4 mJy F5.8 ? Spitzer/IRAC 5.8 micron band flux density
106-111 F6.4 mJy e_F5.8 ? Uncertainty in F5.8 (5)
113-121 F9.4 mJy F8.0 ? Spitzer/IRAC 8.0 micron band flux density
123-128 F6.4 mJy e_F8.0 ? Uncertainty in F8.0 (5)
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Note (3): In table 3, from Jose et al. (in prep).
Note (4): From the 2MASS catalog (Skrutskie et al. 2006, Cat. VII/233),
selecting only sources flagged 'AAA'.
Note (5): The IRAC flux errors refer to the covariance matrix calculated
from the "best-fit" of the PRF (Point Response Function) to the data
and do not include calibration uncertainty (∼10% of the flux).
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Nomenclature notes:
These objects are <[RBH2011] IRAC JHHMMSSss+DDMMSSs> in Simbad.
History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 14-Nov-2012