J/AJ/149/127 The SOS project. IV. NGC 1624 and NGC 1931 (Lim+, 2015)
The Sejong Open cluster Survey (SOS).
IV. The young open clusters NGC 1624 and NGC 1931.
Lim B., Sung H., Bessell M.S., Kim J.S., Hur H., Park B.-G.
<Astron. J., 149, 127 (2015)>
=2015AJ....149..127L 2015AJ....149..127L
ADC_Keywords: Clusters, open ; Photometry, UBVRI ; Photometry, H-alpha
Keywords: dust, extinction - stars: luminosity function, mass function -
open clusters and associations: individual: (NGC 1624,NGC 1931)
Abstract:
Young open clusters located in the outer Galaxy provide us with an
opportunity to study star formation activity in a different
environment from the solar neighborhood. We present a UBVI and
Hα photometric study of the young open clusters NGC 1624 and NGC
1931 that are situated toward the Galactic anticenter. Various
photometric diagrams are used to select the members of the clusters
and to determine the fundamental parameters. NGC 1624 and NGC 1931
are, on average, reddened by <E(B-V)≥0.92±0.05 and 0.74±0.17mag,
respectively. The properties of the reddening toward NGC 1931 indicate
an abnormal reddening law (RV,cl=5.2±0.3). Using the zero-age main
sequence fitting method we confirm that NGC 1624 is 6.0±0.6kpc away
from the Sun, whereas NGC 1931 is at a distance of 2.3±0.2kpc. The
results from isochrone fitting in the Hertzsprung-Russell diagram
indicate the ages of NGC 1624 and NGC 1931 to be less than 4 and
1.5-2.0Myr, respectively. We derived the initial mass function (IMF)
of the clusters. The slope of the IMF (ΓNGC1624=-2.0±0.2
and ΓNGC1931=-2.0±0.1) appears to be steeper than that of
the Salpeter/Kroupa IMF. We discuss the implication of the derived IMF
based on simple Monte-Carlo simulations and conclude that the property
of star formation in the clusters does not seem to be significantly
different from that in the solar neighborhood.
Description:
The present work on NGC 1624 and NGC 1931 is the fifth paper of the
Sejong Open cluster Survey (SOS) project which was initiated to
provide homogeneous photometric data for many open clusters. The
overview of the SOS project can be found in Sung et al.
(2013JKAS...46..103S 2013JKAS...46..103S; Paper 0).
The observations of NGC 1624 were made on 2006 November 24, using the
AZT-22 1.5m telescope (f/7.74) at Maidanak Astronomical Observatory
(MAO) in Uzbekistan. All imaging data were acquired using Fairchild
486 CCD camera (SNUCam) with the standard Bessell UBVI filters. The
field of view (FOV) is about 18.1'*18.1'.
The observations of NGC 1624 and NGC 1931 were made on 2011 October
29, using the Kuiper 61" telescope (f/13.5) of Steward Observatory
(SO) on Mt. Bigelow in Arizona, USA. We obtained images with the
Mont4k CCD camera and 5 filters (Bessell U, Harris BV, Arizona I, and
Hα). The FOV is about 9.7'*9.7'. Later, additional images of NGC
1931 were taken on 2013 February 5, without the Hα filter.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 135 3727 Photometric data for NGC 1624 (2015-06-02 version)
table5.dat 135 1508 Photometric data for NGC 1931 (2015-06-02 version)
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See also:
B/ocl : Optically visible open clusters and Candidates (Dias+ 2002-2014)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/MNRAS/438/1451 : UBVIHa photometry of IC 1848 (Lim+, 2014; Paper II)
J/ApJ/764/172 : UBVRI photometry of stars toward NGC 1931 (Pandey+, 2013)
J/AJ/145/46 : UBVIc photometry in Westerlund 1 (Lim+, 2013)
J/AJ/145/37 : UBVI and Ha CCD photometry of NGC 6231 (Sung+, 2013)
J/AJ/143/41 : UBVIc photometry of star clusters Tr14 and Tr16 (Hur+, 2012)
J/MNRAS/411/2530 : UBVRIJHK photometry in NGC1624 (Jose+, 2011)
J/AJ/138/1116 : A Spitzer view of NGC 2264 (Sung+, 2009)
J/AJ/135/441 : VRIHa photometry in NGC 2264 (Sung+, 2008)
J/AJ/128/1684 : NGC 2264: VRIHa photometry (Sung+, 2004)
J/AJ/127/1014 : CCD UBVRIHa photometry in NGC 3603 (Sung+, 2004)
J/AJ/120/333 : UBVRI and Ha in NGC 6530 (Sung+, 2000)
J/MNRAS/310/982 : UBVI CCD Photometry of M11 - II. (Sung+ 1999)
J/AJ/115/734 : NGC 6231 UBVRI and Ha photometry (Sung+ 1998)
J/AJ/114/2644 : UBVRIHa photometry of NGC2264 (Sung+, 1997)
Byte-by-byte Description of file: table[45].dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Star [1/3727] Number of the star (in cluster)
6- 7 I2 h RAh Hour of Right Ascension (J2000)
9- 10 I2 min RAm Minute of Right Ascension (J2000)
12- 16 F5.2 s RAs Second of Right Ascension (J2000)
18 A1 --- DE- Sign of the Declination (J2000)
19- 20 I2 deg DEd Degree of Declination (J2000)
22- 23 I2 arcmin DEm Arcminute of Declination (J2000)
25- 28 F4.1 arcsec DEs Arcsecond of Declination (J2000)
30- 35 F6.3 mag Vmag [10.8/22.5]? V-band magnitude
37- 42 F6.3 mag Imag [9.4/20.3]? I-band magnitude
44- 48 F5.3 mag V-I ? The (V-I) color index
50- 54 F5.3 mag B-V ? The (B-V) color index
56- 61 F6.3 mag U-B ? The (U-B) color index
63- 68 F6.3 mag Ha-C ? The Hα color index (C=(V+I)/2)
70- 74 F5.3 mag e_Vmag ? The uncertainty in Vmag
76- 80 F5.3 mag e_Imag ? The uncertainty in Imag
82- 86 F5.3 mag e_V-I ? The uncertainty in V-I
88- 92 F5.3 mag e_B-V ? The uncertainty in B-V
94- 98 F5.3 mag e_U-B ? The uncertainty in U-B
100-104 F5.3 mag e_Ha-C ? The uncertainty in Ha-C
106 I1 --- o_Vmag [0/4] Number of observations for Vmag
108 I1 --- o_Imag [0/5] Number of observations for Imag
110 I1 --- o_V-I [0/4] Number of observations for V-I
112 I1 --- o_B-V [0/4] Number of observations for B-V
114 I1 --- o_U-B [0/4] Number of observations for U-B
116 I1 --- o_Ha-C [0/2] Number of observations for Ha-C
118-133 A16 --- 2MASS The 2MASS identifier (HHMMSSss+DDMMSSs, J2000)
135 A1 --- Ha [Hh] Hα emission status (1)
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Note (1): The Hα emission flag is defined as follows:
H = Hα emission star;
h = Hα emission star candidate.
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History:
* 23-Apr-2015: From electronic version of the journal, 18 rows only
in each table
* 02-Jun-2015: Complete tables (3727 rows for NGC 1624, and 1508 for NGC 1931)
References:
Sung et al., Paper 0, 2013JKAS...46..103S 2013JKAS...46..103S
Lim et al., Paper I, 2011JKAS...44...39L 2011JKAS...44...39L
Lim et al., Paper II, 2014MNRAS.438.1451L 2014MNRAS.438.1451L, Cat. J/MNRAS/438/1451
Lim et al., Paper III, 2014MNRAS.443..454L 2014MNRAS.443..454L
(End) Sylvain Guehenneux [CDS] 23-Apr-2015