J/A+A/488/211 Infrared photometry of NGC 1893 (Caramazza+, 2008)
Circumstellar Disks in the Outer Galaxy: the Star Forming Region NGC 1893.
Caramazza M., Micela G., Prisinzano L., Rebull L., Sciortino S.,
Stauffer J.R.
<Astron. Astrophys. 488, 211 (2008)>
=2008A&A...488..211C 2008A&A...488..211C
ADC_Keywords: Clusters, open ; Stars, pre-main sequence ; Photometry, infrared
Keywords: stars: pre-main sequence - stars: circumstellar matter -
Galaxy: open cluster and association: individual: NGC 1893 -
stars: formation
Abstract:
The independence of the star formation processes with respect to the
environmental conditions is controversial. In particular it is not
clear whether star formation in the outer Galaxy, where the
environmental conditions are, theoretically, less conducive, occurs in
the same way as in the inner Galaxy. We investigate the population of
NGC 1893, a young cluster (∼3-4Myr) in the outer part of the Galaxy
(galactic radius >11kpc) in order to explore the effects of
environmental conditions on star forming regions. We present the
infrared observations obtained with the IRAC camera on board of the
Spitzer Space Telescope and analyze the color-color diagrams to
establish the membership of stars with excesses. We also merge this
information with that obtained from Chandra ACIS-I observations, in
order to identify the Class III population. We find that the cluster
is very rich, with 242 PMS Classical T-Tauri stars and 7 Class 0/I
stars. Moreover we identify 110 Class III candidate cluster members in
the ACIS-I field of view. We estimate a disk fraction for NGC 1893 of
about 67%, similar to fraction calculated for nearby star forming
regions of the same age. Although the environmental conditions are not
favorable, star formation can clearly be very successful in the outer
Galaxy, allowing creation of a very rich cluster like NGC 1893.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 125 15277 Coordinates and magnitudes of sources in our catalog
table4.dat 48 818 Parameters of cluster members
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See also:
J/MNRAS/379/1237 : VIcJHK photometry of NGC1893 Halpha sources (Maheswar+ 2007)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- ID Identification number
9 I1 h RAh Right ascension (J2000)
11- 12 I2 min RAm Right ascension (J2000)
14- 18 F5.2 s RAs Right ascension (J2000)
22 A1 --- DE- Declination sign (J2000)
23- 24 I2 deg DEd Declination (J2000
26- 27 I2 arcmin DEm Declination (J2000)
29- 33 F5.2 arcsec DEs Declination (J2000)
37- 41 F5.2 mag Kmag ? K magnitude
45- 48 F4.2 mag e_Kmag ? Error in K magnitude
52- 57 F6.3 mag [3.6] ? Magnitude at 3.6um
61- 65 F5.3 mag e_[3.6] ? Error in [3.6] magnitude
69- 74 F6.3 mag [4.5] ? Magnitude at 4.5um
78- 82 F5.3 mag e_[4.5] ? Error in [4.5] magnitude
86- 91 F6.3 mag [5.8] ? Magnitude at 5.8um
95- 99 F5.3 mag e_[5.8] ? Error in [5.8] magnitude
103-108 F6.3 mag [8.0] ? Magnitude at 8.0um
112-116 F5.3 mag e_[8.0] ? Error in [8.0] magnitude
120-125 F6.3 --- Sharp DAOPHOT Sharp parameter (1)
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Note (1): the "sharp" parameter is close to zero for isolated stars;
significantly negative for bad pixels and cosmic rays;
significantly positive for blended or non-stellar objects.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- ID Identification number
9- 13 F5.2 mag [3.6] Magnitude at 3.6um
17- 21 F5.2 mag [4.5] Magnitude at 4.5um
25- 29 F5.2 mag [5.8] ? Magnitude at 5.8um
33- 37 F5.2 mag [8.0] ? Magnitude at 8.0um
42 I1 --- Class [0/3]? T Tau Class flag (1)
47- 48 I2 --- Xray [-1/1] X-ray emission flag (2)
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Note (1): Class flag as follows:
0 = Class 0/I Protostars
2 = Classical T-Tauri stars
3 = Weak-lined T-Tauri
Note (2): X-ray flag as follows:
-1 = Stars out of the ACIS field of view
1 = X-ray sources
0 = Stars without X-ray emission in the ACIS field of view
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Acknowledgements:
Marilena Caramazza, mcarama(at)astropa.unipa.it
(End) Marilena Caramazza [INAF-OAPA, Italy], Patricia Vannier [CDS] 13-Jun-2008