J/AJ/128/1254 VLT 3.8µm Trapezium catalog (Lada+, 2004)
Deep 3.8 micron observations of the Trapezium cluster.
Lada C.J., Muench A.A., Lada E.A., Alves J.F.
<Astron. J., 128, 1254-1264 (2004)>
=2004AJ....128.1254L 2004AJ....128.1254L
ADC_Keywords: Photometry, infrared ; Clusters, open ; Infrared sources
Keywords: circumstellar matter - infrared: stars -
open clusters and associations: individual (Trapezium) -
stars: low-mass, brown dwarfs
Abstract:
We present deep 3.8µm L' imaging observations of the Trapezium
cluster in Orion obtained with the ESO VLT. We use these observations
to (1) search for infrared excess emission and evidence for
protoplanetary disks associated with the faint, substellar population
of this young cluster and (2) investigate the nature and extent of a
recently discovered population of deeply embedded sources located in
dense molecular gas behind the cluster. We detected 38 L' sources with
substellar luminosities. In addition, we detected 24 L' sources that
were spectroscopically classified as substellar objects in previous
studies. Examining the infrared colors of all these sources, we
determine an infrared excess fraction of 50%±20% from the J, H,
Ks and L' colors for both the luminosity-selected and
spectroscopically selected substellar samples.
Description:
We obtained deep imaging of the Trapezium cluster in the L' band at
3.78µm using the Infrared Spectrometer And Array Camera at the VLT
UT1 telescope. In order to obtain the best seeing conditions at
Paranal, the observing program was carried out in service mode and
data acquisition took place during several nights of good seeing
during the southern summer of 2002.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 98 496 VLT 3.8 Micron Trapezium Catalog
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See also:
J/ApJ/573/366 : Infrared photometry of Trapezium cluster (Muench+, 2002)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- [LML2004] Sequential running number (1)
7- 9 I3 --- n_L'mag Detection/photometry flag (2)
11- 12 I2 h RAh Hour of right ascension (J2000) (3)
14- 15 I2 min RAm Minute of right ascension (J2000) (3)
17- 22 F6.3 s RAs Second of right ascension (J2000) (3)
24 A1 --- DE- Sign of the declination (J2000) (3)
25- 26 I2 deg DEd Degree of declination (J2000) (3)
28- 29 I2 arcmin DEm Arcminute of declination (J2000) (3)
31- 35 F5.2 arcsec DEs Arcsecond of declination (J2000) (3)
37 I1 --- PosFlag [0/2] Astrometry flag (4)
39- 44 A6 --- IName Image name (5)
46- 53 F8.3 pix Xpos ? X pixel on image
55- 62 F8.3 pix Ypos ? Y pixel on image
64- 67 F4.2 arcsec a_L'mag ? Beam size of photometry
69- 74 F6.3 mag L'mag ?=99.000 The VLT L' (3.80µm) magnitude
76- 81 F6.3 mag e_L'mag ?=-1.000 Error in L'mag
83- 88 A6 --- MLLA Optical identification (6)
90- 92 A3 --- [HC2000] Infrared identification (7)
94- 98 A5 --- [H97b] Optical identification (8)
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Note (1): Sequential running number. Visual binaries unresolved in VLT data
have the letters "ab" appended to their running number.
Note (2): Detection/Photometry flag:
-13 = Saturated on VLT images.
-1 = Known source fell into negative "chop" image.
0..3 = Number of VLT detections of a cataloged source. A "0" indicates
known infrared source undetected in VLT L' data. For stars in image
overlaps (f_n=1-3), the average L' photometry is quoted with the
reported error corresponding to the 1σ standard deviation of
the set of magnitudes.
9 = L'-band detection lacking previous IR detection.
10 = Source resolved at L' but unresolved in previous near-IR data
(e.g., Muench et al., 2002 Cat. J/ApJ/573/366).
Note (3): Coordinates derived from an astrometric solution to the 2MASS
coordinate system as of the Point Source Catalog.
The 2MASS coordinates system is aligned to the ACT catalog.
Note (4): Astrometry flag indicating the internal error of astrometry as
derived from source in overlap frames. The relevant values of
this flag are as follows:
0 = Astrometry from single source. If detection/photometry flag (f_n) equals
0, then astrometry is from Muench et al., 2002 Cat. J/ApJ/573/366)
NTT data linearly shifted to match the World Coordinate System of the
relevant VLT L' image. Astrometric error is ∼0.1".
1 = Averaged astrometry from L' images has large internal error (>0.2").
2 = Average of positions in overlapped Lp images that has small (<0.2")
relative dispersion.
Note (5): Image name: to preserve astrometric information, the X-Y pixel
location of each source is preserved relative to a particular
reduced image whose name (L1-L6) is listed here.
Note (6): Cross-reference to the Muench et al. (2002, Cat. J/ApJ/573/366)
FLWO-NTT catalog. The sequential running number and catalog specifier
are collapsed into a single cross-reference (e.g., 00273A).
Note (7): Cross-reference to the Hillenbrand & Carpenter (2000, Cat.
J/ApJ/540/236) Keck Trapezium catalog.
Note (8): Cross-reference to the Hillenbrand (1997AJ....113.1733H 1997AJ....113.1733H) ONC optical
catalog. The sequential running number and catalog specifier are
collapsed into a single cross-reference (e.g., 488a).
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Marianne Brouty [CDS] 15-Feb-2005