- Email: [email protected]
The main parameters of 25 un-studied open star clusters
Available online at www.sciencedirect.com
New Astronomy 13 (2008) 370–374 www.elsevier.com/locate/newast
The main parameters of 25 un-studied open star clusters A.L. Tadross * National Research Institute of Astronomy and Geophysics, Department of Astronomy, Helwan, Cairo 11421, Egypt Received 6 September 2007; received in revised form 24 October 2007; accepted 15 November 2007 Available online 22 November 2007 Communicated by G.F. Gilmore
Abstract This paper is a continuation of a series, aiming to determine the main parameters of rarely or un-studied open star clusters using Near-IR JHK photometry. Cluster center coordinates, angular diameter, distances, reddening, age, and metallicity are estimated for 25 un-studied open clusters, most of them in the first quadrant. A morphological analysis of 2MASS database (the digital ‘‘Two Micron All Sky Survey”) has been used. Ó 2007 Elsevier B.V. All rights reserved. PACS: 91.10.Lh; 95.80.+p; 95.85.Jq; 97.10.Zr; 98.20.Di Keywords: Galaxy: open clusters and associations; General; Individuals; Stars: Hertzsprung–Russell diagram
1. Introduction The 2MASS1 Surveys has proven to be a powerful tool in the analysis of the structure and stellar content of open clusters (cf. Bonatto and Bica, 2003; Bica et al., 2003). Using this database, we could determine the fundamental parameters of 25 open star clusters, which were never studied insofar. The only information known about these clusters are the coordinates and the apparent diameters, which taken from WEBDA2 site; listed here in Table 1. Therefore, the present study introduces the first photometric analysis of the CMDs of these clusters. This paper is a part of our continuation series in determining the main photometrical properties of rarely or un-studied open clusters using 2MASS database. Relevant examples are NGC 1883 (Tadross, 2005a), NGC 2059
*
1 2
Tel.: +20 2 25560645; fax: +20 2 25548020. E-mail addresses: [email protected], [email protected]. http://www.ipac.caltech.edu/2MASS. http://www.univie.ac.at/webda.
1384-1076/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.newast.2007.11.006
(Tadross, 2005b), NGC 7086 (Tadross, 2005c); NGC 7296 (Tadross, 2006); and Pismis 3 (Tadross, 2007). 2. Reductions procedure Data extraction have been performed using the known tool of VizieR.3 The data have been extracted at a preliminary radius of about 20 arcmin from the obtained cluster center (cf. Tadross, 2007 and references therein). We assumed that all the clusters in our sample must fulfill the following two conditions: (1) to be clearly separated from the background field and have good blue images on the Digitized Sky Surveys (DSS)4 as shown in the example of Fig. 1 and (2) have enough members with prominent CM-diagrams as shown in Fig. 2. To derive better cluster center coordinates, the cluster center is taken at the maximum stellar density of the
3 4
http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=2MASS. http://cadcwww.dao.nrc.ca/cadcbin/getdss.
A.L. Tadross / New Astronomy 13 (2008) 370–374
371
Table 1 Clusters’ coordinates and diameters obtained from Webda Cluster
ah
m s
Skiff 2 Luginbuhl-Skiff 1 BH 47 BH 60 IC 4291 BH 218 Collinder 351 Ruprecht 168 Czernik 37 Ruprecht 135 Ruprecht 169 NGC 6507 Ruprecht 138 Ruprecht 137 ESO 522-05 Turner 2 NGC 6625 Dias 6 Ruprecht 142 Ruprecht 171 NGC 6645 NGC 6647 ESO 524-01 NGC 6737 ESO 525-08
4:58:11 6:14:48 8:42:31 9:15:53 13:36:54 17:16:12 17:49:04 17:52:46 17:53:16 17:58:12 17:59:23 17:59:50 17:59:54 18:00:17 18:12:53 18:17:12 18:22:49 18:30:27 18:32:12 18:32:12 18:32:37 18:32:49 18:56:39 19:02:17 19:27:17
d° 0 00
G. Long.°
G. Lat.°
Diameter
+43:01:00 +12:52:24 48:06:00 50:01:00 62:05:30 39:24:00 28:45:00 28:26:00 27:22:00 11:39:00 24:46:00 17:27:00 24:41:00 25:14:00 24:21:48 18:49:30 11:57:42 12:19:40 12:14:00 16:03:00 16:53:00 17:13:42 26:57:48 18:32:48 23:34:48
162.999 197.314 266.628 271.657 308.224 347.925 0.621 1.238 2.213 16.421 5.151 11.554 5.282 4.848 7.001 12.11 19.043 19.588 19.870 16.480 15.784 15.246 9.063 17.431 15.117
0.140 2.093 3.582 0.708 0.312 0.676 0.707 1.085 0.638 6.234 0.518 3.028 0.579 0.927 3.001 1.324 0.799 1.022 1.358 3.116 3.787 3.564 12.991 10.658 18.027
5 7 12 2 6 5 7 4 3 4 3 14 6 5 4 7 16 8 6 12 14 ? 6 8 5
Fig. 2. An example for estimating the reddening, distance modulus, and age of the cluster ‘‘IC 4291”. The solar metallicity isochrones of Bonatto et al. (2004) have been used. E(J H) = 0.20 mag, m-M = 11.8 mag, and age = 800 Myr.
cluster’s area. The location of the cluster center is found by fitting a Gaussian to the profiles of star counts in right ascension a and declination d (cf. Tadross, 2005b,c) as
shown in the example of Fig. 3. The present clusters centers’ coordinates have been found very close to what obtained from WEBDA, see Table 2. Within concentric shells in equal incremental steps from the cluster center, stellar density is performed out to the preliminary radius. The real radius (genuine border) of the cluster can be defined at that point which reaches enough stability of the background density, and covers all the cluster area. At that radius, the JHK photometric data would be extracted and taken into account for estimating the clusters’ properties. An example, for estimating
Fig. 1. An example for the image of ‘‘IC 4291” as taken from Digitized Sky Surveys (DSS). North is up, east on the left.
Fig. 3. An example for estimating the cluster center coordinates of ‘‘IC 4291”.
372
A.L. Tadross / New Astronomy 13 (2008) 370–374
Table 2 Cluster data Cluster
ah
m s
Skiff 2 Luginbuhl-Skiff 1 BH 47 BH 60 IC 4291 BH 218 Collinder 351 Ruprecht 168 Czernik 37 Ruprecht 135 Ruprecht 169 NGC 6507 Ruprecht 138 Ruprecht 137 ESO 522-05 Turner 2 NGC 6625 Dias 6 Ruprecht 142 Ruprecht 171 NGC 6645 NGC 6647 ESO 524-01 NGC 6737 ESO 525-08
4:58:14 6:14:47 8:42:33 9:15:53 13:36:56 17:16:12 17:49:00 17:52:47 17:53:16 17:58:12 17:59:22 17:59:50 17:59:56 18:00:16 18:12:53 18:17:11 18:22:50 18:30:26 18:32:11 18:32:11 18:32:37 18:32:50 18:56:37 19:02:20 19:27:16
d° 0 00
Diam. (0 )
Age (Gyr)
EB-V (mag)
m-M (mag)
Dist. (pc)
Rgc (kpc)
X (pc)
Y (pc)
Z (pc)
+43:00:48 +12:52:15 48:05:13 50:00:38 62:05:45 39:24:04 28:44:09 28:25:56 27:21:44 11:39:10 24:46:01 17:27:02 24:40:57 25:13:39 24:21:50 18:49:27 11:57:42 12:19:41 12:13:47 16:02:59 16:53:08 17:13:56 26:57:39 18:32:59 23:34:35
5 3 15.4 4.2 5.6 5.6 8.4 5.2 3.6 6 5.2 13.2 6 5.6 4.4 7.6 15.4 6 6.6 11.4 14.8 13 6 8.8 6
0.90 0.25 0.80 0.40 0.80 0.40 0.16 2.00 0.60 0.50 1.00 0.40 2.00 0.80 3.20 0.10 0.50 0.60 0.40 3.20 0.40 1.60 3.20 0.50 1.00
0.18 0.57 0.73 0.67 0.61 0.88 0.70 1.06 1.03 1.10 0.66 0.85 0.18 0.67 1.82 0.36 1.21 0.91 0.91 0.12 0.36 0.54 0.30 0.76 0.36
11.8 13.0 12.6 11.2 11.8 11.2 11.2 10.5 12.1 12.3 11.3 11.2 10.0 11.4 10.7 10.7 11.7 11.8 12.0 10.4 10.8 12.2 12.5 12.3 11.4
2125 ± 100 3150 ± 145 2465 ± 110 1325 ± 60 1790 ± 82 1215 ± 55 1310 ± 60 820 ± 35 1730 ± 80 1850 ± 85 1390 ± 60 1230 ± 55 930 ± 40 1450 ± 65 660 ± 30 1190 ± 55 1335 ± 60 1580 ± 70 1735 ± 80 1140 ± 50 1245 ± 55 2200 ± 100 2800 ± 130 2120 ± 95 1640 ± 75
6.37 5.35 6.03 7.17 7.53 7.28 7.19 7.68 6.77 6.74 7.12 7.3 7.57 7.06 7.84 7.34 7.25 7.03 6.89 7.41 7.31 6.4 5.75 6.51 6.93
2032 3005 145 38 1107 1188 1310 820 1728 1764 1384 1203 926 1445 654 1163 1262 1488 1631 1092 1195 2119 2694 1988 1505
621 937 2456 1324 1406 254 14 18 67 520 125 246 86 123 80 250 435 530 590 323 338 577 430 624 407
5 115 154 16 10 14 16 16 19 201 13 65 9 23 35 27 19 28 41 62 82 137 629 392 507
The columns display, respectively, cluster name, cluster center coordinates, diameter, age, reddening, distance modulus, distance from the sun, distance from the galactic center, the projected distances on the galactic plane from the sun, and the distance from galactic plane.
Fig. 4. An example for estimating the true radius of ‘‘IC 4291” using the projected density distribution. The dashed line represents the fitting of King (1962). The length of the error-bars denote errors resulting from p sampling statistics, in accordance with Poisson distribution (¼ 1= N , where N is the number of stars used in the density estimation at that point). The arrow represents the point at which the radius of the cluster is obtained.
the true radius is explained in Fig. 4. Before counting stars inside the defined area, we applied a cutoff of photometric completeness limit at J < 16:5 mag to avoid over-sampling, i.e. avoiding the spatial variations in the number of faint stars which are numerous, affected by large errors, and may include spurious detections (Bonatto et al., 2004). Also, we restricted to stars with observational uncertainties J ;H ;K < 0:2 mag. The CMDs comprising stars inside radii of 10 , 20 , and 30 from the derived cluster center. The simultaneous fitting of solar metallicity isochrones of Bonatto et al. (2004) were attempted on the J ðJ H Þ and K ðJ KÞ diagrams for the inner stars, as these should be less contaminated by the field stars. If the number of stars were not enough for an accepted fitting, the next larger area would be included, and so on. RV ¼ 3:2; AAVJ ¼ 0:276; AAKV ¼ 0:118; and EEJH ¼ 0:33 have BV been used for reddening and absorption transformations according to Dutra et al. (2002) and references therein. EJK 1:6 0:15, which was derived from absorption EJ H rations in Schlegel et al. (1998). Following the above procedure, the cluster center coordinates, the diameter, age, reddening, distance modulus, distance from the sun, distance from the galactic center, Rgc , and the projected distances on the galactic plane from the Sun, X ; Y , and the distance from galactic plane, Z
A.L. Tadross / New Astronomy 13 (2008) 370–374
373
Fig. 5. The color-magnitude diagrams and isochrone fits for the first half of the clusters of our sample; note that IC 4291 has been shown in a separate diagram of Fig. 2.
of all our clusters’ sample have been estimated and listed in Table 2. The color-magnitude diagrams and the isochrone fits for all the clusters can be seen in Figs. 5 and 6 (all data will be available at WEBDA). Acknowledgements This publication makes use of data products from the Two Micron All Sky Survey 2MASS, which is a joint
project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. Catalogues from CDS/SIMBAD (Strasbourg), and Digitized Sky Survey DSS images from the Space Telescope Science Institute have been employed. Many thanks to the referee; his comments are very appreciated.
374
A.L. Tadross / New Astronomy 13 (2008) 370–374
Fig. 6. The color-magnitude diagrams and isochrone fits for the second half of the clusters of our sample.
References Bica, E., Bonatto, Ch., Dutra, C.M., 2003. A&A 405, 991. Bonatto, Ch., Bica, E., 2003. A&A 405, 525. Bonatto, Ch., Bica, E., Girardi, L., 2004. A&A 415, 571. Dutra, C., Santiago, B., Bica, E., 2002. A&A 381, 219. King, I., 1962. AJ 67, 471.
Schlegel, Tadross, Tadross, Tadross, Tadross, Tadross,
D., Finkbeiner, D., Davis, M., 1998. ApJ 500, 525. A.L., 2005a. BASI 33, 421. A.L., 2005b. JKAS 38, 357. A.L., 2005c. JKAS 38, 423. A.L., 2006. AN 327, 714. A.L., 2007. arXiv. 0705, 29v2.
New Astronomy 13 (2008) 370–374 www.elsevier.com/locate/newast
The main parameters of 25 un-studied open star clusters A.L. Tadross * National Research Institute of Astronomy and Geophysics, Department of Astronomy, Helwan, Cairo 11421, Egypt Received 6 September 2007; received in revised form 24 October 2007; accepted 15 November 2007 Available online 22 November 2007 Communicated by G.F. Gilmore
Abstract This paper is a continuation of a series, aiming to determine the main parameters of rarely or un-studied open star clusters using Near-IR JHK photometry. Cluster center coordinates, angular diameter, distances, reddening, age, and metallicity are estimated for 25 un-studied open clusters, most of them in the first quadrant. A morphological analysis of 2MASS database (the digital ‘‘Two Micron All Sky Survey”) has been used. Ó 2007 Elsevier B.V. All rights reserved. PACS: 91.10.Lh; 95.80.+p; 95.85.Jq; 97.10.Zr; 98.20.Di Keywords: Galaxy: open clusters and associations; General; Individuals; Stars: Hertzsprung–Russell diagram
1. Introduction The 2MASS1 Surveys has proven to be a powerful tool in the analysis of the structure and stellar content of open clusters (cf. Bonatto and Bica, 2003; Bica et al., 2003). Using this database, we could determine the fundamental parameters of 25 open star clusters, which were never studied insofar. The only information known about these clusters are the coordinates and the apparent diameters, which taken from WEBDA2 site; listed here in Table 1. Therefore, the present study introduces the first photometric analysis of the CMDs of these clusters. This paper is a part of our continuation series in determining the main photometrical properties of rarely or un-studied open clusters using 2MASS database. Relevant examples are NGC 1883 (Tadross, 2005a), NGC 2059
*
1 2
Tel.: +20 2 25560645; fax: +20 2 25548020. E-mail addresses: [email protected], [email protected]. http://www.ipac.caltech.edu/2MASS. http://www.univie.ac.at/webda.
1384-1076/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.newast.2007.11.006
(Tadross, 2005b), NGC 7086 (Tadross, 2005c); NGC 7296 (Tadross, 2006); and Pismis 3 (Tadross, 2007). 2. Reductions procedure Data extraction have been performed using the known tool of VizieR.3 The data have been extracted at a preliminary radius of about 20 arcmin from the obtained cluster center (cf. Tadross, 2007 and references therein). We assumed that all the clusters in our sample must fulfill the following two conditions: (1) to be clearly separated from the background field and have good blue images on the Digitized Sky Surveys (DSS)4 as shown in the example of Fig. 1 and (2) have enough members with prominent CM-diagrams as shown in Fig. 2. To derive better cluster center coordinates, the cluster center is taken at the maximum stellar density of the
3 4
http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=2MASS. http://cadcwww.dao.nrc.ca/cadcbin/getdss.
A.L. Tadross / New Astronomy 13 (2008) 370–374
371
Table 1 Clusters’ coordinates and diameters obtained from Webda Cluster
ah
m s
Skiff 2 Luginbuhl-Skiff 1 BH 47 BH 60 IC 4291 BH 218 Collinder 351 Ruprecht 168 Czernik 37 Ruprecht 135 Ruprecht 169 NGC 6507 Ruprecht 138 Ruprecht 137 ESO 522-05 Turner 2 NGC 6625 Dias 6 Ruprecht 142 Ruprecht 171 NGC 6645 NGC 6647 ESO 524-01 NGC 6737 ESO 525-08
4:58:11 6:14:48 8:42:31 9:15:53 13:36:54 17:16:12 17:49:04 17:52:46 17:53:16 17:58:12 17:59:23 17:59:50 17:59:54 18:00:17 18:12:53 18:17:12 18:22:49 18:30:27 18:32:12 18:32:12 18:32:37 18:32:49 18:56:39 19:02:17 19:27:17
d° 0 00
G. Long.°
G. Lat.°
Diameter
+43:01:00 +12:52:24 48:06:00 50:01:00 62:05:30 39:24:00 28:45:00 28:26:00 27:22:00 11:39:00 24:46:00 17:27:00 24:41:00 25:14:00 24:21:48 18:49:30 11:57:42 12:19:40 12:14:00 16:03:00 16:53:00 17:13:42 26:57:48 18:32:48 23:34:48
162.999 197.314 266.628 271.657 308.224 347.925 0.621 1.238 2.213 16.421 5.151 11.554 5.282 4.848 7.001 12.11 19.043 19.588 19.870 16.480 15.784 15.246 9.063 17.431 15.117
0.140 2.093 3.582 0.708 0.312 0.676 0.707 1.085 0.638 6.234 0.518 3.028 0.579 0.927 3.001 1.324 0.799 1.022 1.358 3.116 3.787 3.564 12.991 10.658 18.027
5 7 12 2 6 5 7 4 3 4 3 14 6 5 4 7 16 8 6 12 14 ? 6 8 5
Fig. 2. An example for estimating the reddening, distance modulus, and age of the cluster ‘‘IC 4291”. The solar metallicity isochrones of Bonatto et al. (2004) have been used. E(J H) = 0.20 mag, m-M = 11.8 mag, and age = 800 Myr.
cluster’s area. The location of the cluster center is found by fitting a Gaussian to the profiles of star counts in right ascension a and declination d (cf. Tadross, 2005b,c) as
shown in the example of Fig. 3. The present clusters centers’ coordinates have been found very close to what obtained from WEBDA, see Table 2. Within concentric shells in equal incremental steps from the cluster center, stellar density is performed out to the preliminary radius. The real radius (genuine border) of the cluster can be defined at that point which reaches enough stability of the background density, and covers all the cluster area. At that radius, the JHK photometric data would be extracted and taken into account for estimating the clusters’ properties. An example, for estimating
Fig. 1. An example for the image of ‘‘IC 4291” as taken from Digitized Sky Surveys (DSS). North is up, east on the left.
Fig. 3. An example for estimating the cluster center coordinates of ‘‘IC 4291”.
372
A.L. Tadross / New Astronomy 13 (2008) 370–374
Table 2 Cluster data Cluster
ah
m s
Skiff 2 Luginbuhl-Skiff 1 BH 47 BH 60 IC 4291 BH 218 Collinder 351 Ruprecht 168 Czernik 37 Ruprecht 135 Ruprecht 169 NGC 6507 Ruprecht 138 Ruprecht 137 ESO 522-05 Turner 2 NGC 6625 Dias 6 Ruprecht 142 Ruprecht 171 NGC 6645 NGC 6647 ESO 524-01 NGC 6737 ESO 525-08
4:58:14 6:14:47 8:42:33 9:15:53 13:36:56 17:16:12 17:49:00 17:52:47 17:53:16 17:58:12 17:59:22 17:59:50 17:59:56 18:00:16 18:12:53 18:17:11 18:22:50 18:30:26 18:32:11 18:32:11 18:32:37 18:32:50 18:56:37 19:02:20 19:27:16
d° 0 00
Diam. (0 )
Age (Gyr)
EB-V (mag)
m-M (mag)
Dist. (pc)
Rgc (kpc)
X (pc)
Y (pc)
Z (pc)
+43:00:48 +12:52:15 48:05:13 50:00:38 62:05:45 39:24:04 28:44:09 28:25:56 27:21:44 11:39:10 24:46:01 17:27:02 24:40:57 25:13:39 24:21:50 18:49:27 11:57:42 12:19:41 12:13:47 16:02:59 16:53:08 17:13:56 26:57:39 18:32:59 23:34:35
5 3 15.4 4.2 5.6 5.6 8.4 5.2 3.6 6 5.2 13.2 6 5.6 4.4 7.6 15.4 6 6.6 11.4 14.8 13 6 8.8 6
0.90 0.25 0.80 0.40 0.80 0.40 0.16 2.00 0.60 0.50 1.00 0.40 2.00 0.80 3.20 0.10 0.50 0.60 0.40 3.20 0.40 1.60 3.20 0.50 1.00
0.18 0.57 0.73 0.67 0.61 0.88 0.70 1.06 1.03 1.10 0.66 0.85 0.18 0.67 1.82 0.36 1.21 0.91 0.91 0.12 0.36 0.54 0.30 0.76 0.36
11.8 13.0 12.6 11.2 11.8 11.2 11.2 10.5 12.1 12.3 11.3 11.2 10.0 11.4 10.7 10.7 11.7 11.8 12.0 10.4 10.8 12.2 12.5 12.3 11.4
2125 ± 100 3150 ± 145 2465 ± 110 1325 ± 60 1790 ± 82 1215 ± 55 1310 ± 60 820 ± 35 1730 ± 80 1850 ± 85 1390 ± 60 1230 ± 55 930 ± 40 1450 ± 65 660 ± 30 1190 ± 55 1335 ± 60 1580 ± 70 1735 ± 80 1140 ± 50 1245 ± 55 2200 ± 100 2800 ± 130 2120 ± 95 1640 ± 75
6.37 5.35 6.03 7.17 7.53 7.28 7.19 7.68 6.77 6.74 7.12 7.3 7.57 7.06 7.84 7.34 7.25 7.03 6.89 7.41 7.31 6.4 5.75 6.51 6.93
2032 3005 145 38 1107 1188 1310 820 1728 1764 1384 1203 926 1445 654 1163 1262 1488 1631 1092 1195 2119 2694 1988 1505
621 937 2456 1324 1406 254 14 18 67 520 125 246 86 123 80 250 435 530 590 323 338 577 430 624 407
5 115 154 16 10 14 16 16 19 201 13 65 9 23 35 27 19 28 41 62 82 137 629 392 507
The columns display, respectively, cluster name, cluster center coordinates, diameter, age, reddening, distance modulus, distance from the sun, distance from the galactic center, the projected distances on the galactic plane from the sun, and the distance from galactic plane.
Fig. 4. An example for estimating the true radius of ‘‘IC 4291” using the projected density distribution. The dashed line represents the fitting of King (1962). The length of the error-bars denote errors resulting from p sampling statistics, in accordance with Poisson distribution (¼ 1= N , where N is the number of stars used in the density estimation at that point). The arrow represents the point at which the radius of the cluster is obtained.
the true radius is explained in Fig. 4. Before counting stars inside the defined area, we applied a cutoff of photometric completeness limit at J < 16:5 mag to avoid over-sampling, i.e. avoiding the spatial variations in the number of faint stars which are numerous, affected by large errors, and may include spurious detections (Bonatto et al., 2004). Also, we restricted to stars with observational uncertainties J ;H ;K < 0:2 mag. The CMDs comprising stars inside radii of 10 , 20 , and 30 from the derived cluster center. The simultaneous fitting of solar metallicity isochrones of Bonatto et al. (2004) were attempted on the J ðJ H Þ and K ðJ KÞ diagrams for the inner stars, as these should be less contaminated by the field stars. If the number of stars were not enough for an accepted fitting, the next larger area would be included, and so on. RV ¼ 3:2; AAVJ ¼ 0:276; AAKV ¼ 0:118; and EEJH ¼ 0:33 have BV been used for reddening and absorption transformations according to Dutra et al. (2002) and references therein. EJK 1:6 0:15, which was derived from absorption EJ H rations in Schlegel et al. (1998). Following the above procedure, the cluster center coordinates, the diameter, age, reddening, distance modulus, distance from the sun, distance from the galactic center, Rgc , and the projected distances on the galactic plane from the Sun, X ; Y , and the distance from galactic plane, Z
A.L. Tadross / New Astronomy 13 (2008) 370–374
373
Fig. 5. The color-magnitude diagrams and isochrone fits for the first half of the clusters of our sample; note that IC 4291 has been shown in a separate diagram of Fig. 2.
of all our clusters’ sample have been estimated and listed in Table 2. The color-magnitude diagrams and the isochrone fits for all the clusters can be seen in Figs. 5 and 6 (all data will be available at WEBDA). Acknowledgements This publication makes use of data products from the Two Micron All Sky Survey 2MASS, which is a joint
project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. Catalogues from CDS/SIMBAD (Strasbourg), and Digitized Sky Survey DSS images from the Space Telescope Science Institute have been employed. Many thanks to the referee; his comments are very appreciated.
374
A.L. Tadross / New Astronomy 13 (2008) 370–374
Fig. 6. The color-magnitude diagrams and isochrone fits for the second half of the clusters of our sample.
References Bica, E., Bonatto, Ch., Dutra, C.M., 2003. A&A 405, 991. Bonatto, Ch., Bica, E., 2003. A&A 405, 525. Bonatto, Ch., Bica, E., Girardi, L., 2004. A&A 415, 571. Dutra, C., Santiago, B., Bica, E., 2002. A&A 381, 219. King, I., 1962. AJ 67, 471.
Schlegel, Tadross, Tadross, Tadross, Tadross, Tadross,
D., Finkbeiner, D., Davis, M., 1998. ApJ 500, 525. A.L., 2005a. BASI 33, 421. A.L., 2005b. JKAS 38, 357. A.L., 2005c. JKAS 38, 423. A.L., 2006. AN 327, 714. A.L., 2007. arXiv. 0705, 29v2.