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J/AJ/114/198 The Monoceros R2 Cluster (Carpenter+ 1997)
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Properties of the Monoceros R2 Stellar Cluster
Carpenter J.M., Meyer M.R., Dougados C., Strom S.E., Hillenbrand L.A.
<Astron. J. 114, 198 (1997)>
=1997AJ....114..198C
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ADC_Keywords: Associations, stellar ; Photometry, infrared
Abstract:
We present an extensive study of the stellar population of an embedded
cluster in the MonR2 molecular cloud based upon a wide field
(~15'x15') J, H, and K band mosaic, deep near-infrared imaging at
J, H, K, and nbL' bands of the central cluster region, and
spectroscopic observations of 34 stars. By comparing the properties of
the MonR2 cluster with other star forming regions, we ultimately hope
to learn how the properties and formation of stars of various masses
are related to the local physical conditions. The K band star counts
indicate that the MonR2 cluster extends over a ~1.1pcx2.1pc area
with a FWHM cluster size of ~0.38pc. Within this region the cluster
contains ~309 stars brighter than m_K=14.5m and >~475 stars over
all magnitudes with a central stellar volume density of ~9000 stars
pc^-3^. We have further explored the properties of the cluster by
using the spectroscopic and photometric data to construct an
extinction-limited sample of 115 stars in the central 0.77pcx0.77pc
region of the cluster that is designed to contain all stars with
A_V<=11.3m and stellar masses >=0.1M_{sun}_. As a lower limit, 62% of
the stars in this sample contain a near-infrared excess at K and/or L
band. The K band excess fraction may be as high as 72% if the
accretion characteristics of the stars in the MonR2 cluster are
similar to stars in Taurus-Auriga. An initial reconnaissance of the
stellar mass function suggests that the ratio of high to low mass
stars in the extinction-limited sample is consistent with the value
expected for a Miller-Scalo IMF. We do not find compelling evidence
for mass segregation in the extinction-limited sample for stellar
masses <~2M_{sun}_, although the most massive star (~10M_{sun}_) in
the cluster appears to be forming near the cluster center. The
properties of the MonR2 cluster are similar to other rich young
clusters in the solar neighborhood, such as NGC 2024 and the
Trapezium.
(c) 1997 American Astronomical Society.
Objects:
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RA (2000) DE Designation(s)
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06 07 46.2 -06 23 09 Mon R2 = NGC 2176
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 62 512 SQIID photometry of MonR2
table2.dat 84 390 IRCAM3 photometry of MonR2
tables.tex 115 1003 AASTeX version of the tables
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Byte-by-byte Description of file: table1.dat table2.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- [CMD97] Identification number
5- 6 I2 h RAh Right ascension (1950)
7 A1 --- --- Always ':'
8- 9 I2 min RAm Right ascension (1950)
10 A1 --- --- Always ':'
11- 15 F5.2 s RAs Right ascension (1950)
17 A1 --- DE- Declination sign
18 I1 deg DEd Declination (1950)
19 A1 --- --- Always ':'
20- 21 I2 arcmin DEm Declination (1950)
22 A1 --- --- Always ':'
23- 26 F4.1 arcsec DEs Declination (1950)
29- 33 F5.2 mag Jmag ? J band magnitude
35- 38 F4.2 mag e_Jmag ? 1-sigma uncertainty in Jmag
41- 45 F5.2 mag Hmag ? H band magnitude
47- 50 F4.2 mag e_Hmag ? 1-sigma uncertainty in Hmag
53- 57 F5.2 mag Kmag ? K band magnitude
59- 62 F4.2 mag e_Kmag ? 1-sigma uncertainty in Kmag
65- 69 F5.2 mag nbL' *? nbL' band magnitude (table2.dat only)
71- 74 F4.2 mag e_nbL' ? 1-sigma uncertainty in nbL'
76- 84 A9 --- Notes *Additional notes (table2.dat only)
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Note on nbL':
The nbL' filter has a peak response at 3.6{mu}m with a full width at half
maximum transmission of 0.065{mu}m.
Note on Notes:
Cross identifications are from Beckwith et al. (1976ApJ...208..390B) and
Howard et al. (1994ApJ...425..707H).
An asterisk in this column indicates an additional note as listed below:
104 -- Stellar ?
122 -- Non-stellar at H; stellar and nebular components at K and nbL'
124 -- Extended at H and K; likely unresolved stars
129 -- Extended at H and K
151 -- Near IRS5; stellar at J and H; non-stellar at K and nbL'
156 -- Non-stellar
172 -- Non-stellar
193 -- Stellar at J?
214 -- Foreground star
233 -- Extended at H and K
235 -- Extended at K
252 -- Stellar?
254 -- Non-stellar at J and H; stellar and nebular components at K;
stellar at nbL'
291 -- Saturated at K; photometry very uncertain in all bands
301 -- Non-stellar at J; stellar and nebulous at H; stellar at K and nbL'
315 -- Non-stellar
319 -- Detected at K, but photometry unreliable
364 -- Stellar with local nebulosity at H and K
372 -- Stellar with local nebulosity at JHK
374 -- Extended at all four bands; likely unresolved stars
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Origin: AAS CD-ROM series, Volume 9, 1997 Lee Brotzman [ADS] 26-Sep-1997
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(End) [CDS] 05-Feb-1998