J/AJ/126/1665 NICMOS observations of NGC 2024 (Liu+, 2003)
Hubble Space Telescope NICMOS observations of the embedded cluster in NGC 2024:
constraints on the initial mass function and binary fraction .
Liu W.M., Meyer M.R., Cotera A.S., Young E.T.
<Astron. J. 126, 1665 (2003)>
=2003AJ....126.1665L 2003AJ....126.1665L
ADC_Keywords: Clusters, open ; Photometry ; Stars, double and multiple
Keywords: binaries: visual -
open clusters and associations: individual (NGC 2024) -
stars: formation - stars: luminosity function, mass function -
stars: pre-main-sequence
Abstract:
We present an analysis of NICMOS observations of the embedded cluster
associated with NGC 2024. An analysis of the cluster color-magnitude
diagram (CMD) using the models of D'Antona & Mazzitelli and Baraffe et
al. (published in 1997MmSAI..68..807D 1997MmSAI..68..807D and 1998, Cat. J/A+A/337/403,
respectively) indicates that the ratio of intermediate-mass
(1.0-10.0M☉) to low-mass (0.1-1.0M☉) stars is consistent
with the stellar initial mass function (IMF) for the field. In
addition to the CMD analysis, we present results on the multiplicity
of stars in the region. Three companions (in a sample of 95 potential
primaries) were found, with angular separations between 0.4" and 1.0",
translating to a projected linear separation of 184-460AU for an
estimated distance of 460pc. The completeness of binary detections is
assessed using recovery fractions calculated by a series of tests
using artificially generated companions to potential primaries in the
data frames. We find that the binary fraction in NGC 2024 is
consistent with that of Duquennoy & Mayor (published in
1991A&A...248..485D 1991A&A...248..485D) for solar neighborhood stars over the range of
separations and companion masses appropriate for our survey.
Description:
Images of the young embedded cluster associated with NGC 2024 were
obtained on 1998 January 17 using camera 3 of NICMOS (NIC3) on HST.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 92 98 Objects Dectected in J and H Bands
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- [LMC2003] Sequential designation, N-NNa (1)
7- 13 F7.3 pix Xpix The X pixel coordinate
15- 19 F5.1 pix Ypix The Y pixel coordinate
21 I1 h RAh Hour of right ascension (J2000)
23- 24 I2 min RAm Minute of right ascension (J2000)
26- 30 F5.2 s RAs Second of right ascension (J2000)
32 A1 --- DE- Sign of the declination (J2000)
33 I1 deg DEd Degree of declination (J2000)
35- 36 I2 arcmin DEm Arcminute of declination (J2000)
38- 41 F4.1 arcsec DEs Arcsecond of declination (J2000)
43- 47 F5.2 mag Jmag ? The J-band magnitude
49- 52 F4.2 mag e_Jmag ? Error in Jmag
54- 59 F6.3 mag Hmag ? The H-band magnitude
61- 64 F4.2 mag e_Hmag ? Error in Jmag
66- 67 I2 --- BSC ? Beck, Simon, & Close (2003ApJ...583..358B 2003ApJ...583..358B)
identification, Cl* NGC 2024 BSC NN in Simbad
68 A1 --- --- [,]
69- 70 I2 --- BSC2 ? BSC number of the companion
72- 92 A21 --- Note Additional notes
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Note (1): N is the frame number, NNa the identification
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Bauer [CDS] 21-Nov-2003