• Title/Summary/Keyword: open clusters and associations

Search Result 33, Processing Time 0.129 seconds

INITIAL LUMINOSITY FUNCTION AND INITIAL MASS FUNCTION FOR OPEN CLUSTERS AND ASSOCIATIONS

  • Lee, See-Woo;Chun, Moo-Young
    • Journal of The Korean Astronomical Society
    • /
    • v.21 no.1
    • /
    • pp.37-55
    • /
    • 1988
  • Combining the luminosity functions of main sequence stars in 3 associations and 22 open clusters, the initial luminosity function and mass function for these clusters are derived. For stars of m > $0.6m_{\odot}$, they are well consistent with those for the field stars.

  • PDF

A PHOTOMETRIC STUDY OF FIVE OPEN CLUSTERS IN THE SDSS

  • Ryu, Jin-Hyuk;Lee, Myung-Gyoon
    • Journal of The Korean Astronomical Society
    • /
    • v.44 no.5
    • /
    • pp.177-193
    • /
    • 2011
  • We present a photometric study of five open clusters (Czernik 5, Alessi 53, Berkeley 49, Berkeley 84, and Pfleiderer 3) in the Sloan Digital Sky Survey. The position and size of these clusters are determined using the radial number density profiles of the stars, and the member stars of the clusters are selected using the proper motion data in the literature. We estimate the reddening, distance and age of the clusters based on the isochrone fitting in the color-magnitude diagram. The foreground reddenings for these clusters are estimated to be E(B - V ) = 0.71 - 1.55 mag. The distances to these clusters are derived to be 2.0 - 4.4 kpc, and their distances from the Galactic center range from 7.57 kpc to 12.35 kpc. Their ages are in the range from 250 Myr to 1 Gyr. Berkeley 49 and Berkeley 84 are located in the Orion spur, Czernik 5 is in the Perseus arm, and Pfleiderer 3 and Alessi 53 are located beyond the Perseus arm.

BOAO PHOTOMETRIC SURVEY OF GALACTIC OPEN CLUSTERS. I. BERKELEY 14, COLLINDER 74, BIURAKAN 9, and NGC 2355

  • ANN H. B.;LEE M. G.;CHUN M. Y.;KIM S.-L.;JEON Y.-B.;PARK B.-G.;YUK I.-S.;SUNG H.;LEE S. H.
    • Journal of The Korean Astronomical Society
    • /
    • v.32 no.1
    • /
    • pp.7-16
    • /
    • 1999
  • Open clusters are useful tools to investigate the structure and evolution of the Galactic disk. We have started a long-term project to obtain UBVI CCD photometry of open clusters which were little studied before, using the Doyak 1.8 m telescope of Bohyunsan Optical Astronomy Observatory in Korea. The primary goals of this project are (1) to make a catalog of UBVI photometry of open clusters, (2) to make an atlas of open clusters, and (3) to survey and monitor variable stars in open clusters. Here we describe this project and report the first results based on preliminary analysis of the data on four open clusters in the survey sample: Be 14, Cr 74, Biu 9, and NGC 2355. Isochrone fitting of the color-magnitude diagrams of the clusters shows that all of them are intermediate age to old (0.3-1.6 Gyrs) open clusters with moderate metallicity.

  • PDF

PHOTOMETRIC EVOLUTION OF OPEN CLUSTERS AND ASSOCIATIONS

  • LEE SEE-WOO;PARK WON-KEE
    • Journal of The Korean Astronomical Society
    • /
    • v.26 no.1
    • /
    • pp.47-64
    • /
    • 1993
  • The photometric evolution of cluster stars are examined for six synthetic clusters in the age range from $2.4\times10^6\;yr\;to\;7.6\times10^8yr$ by using the detailed evolutionary model calculation, and their results are compared with the observed integrated absolute magnitude and colors of 47 clusters. The reasonable agreements of the observed photometric parameters with the synthetic evolutionary sequences imply that there is a general form of time-dependent IMF including the noncoeval formation of stars and its detailed function is changed slightly with various environmental conditions of each primordial cloud.

  • PDF

FUNDAMENTAL PARAMETERS OF NGC 2509 BASED ON 2MASS DATA

  • Tadross, A.L.
    • Journal of The Korean Astronomical Society
    • /
    • v.38 no.3
    • /
    • pp.357-363
    • /
    • 2005
  • A deep stellar analysis is introduced for the poorly studied open cluster NGC 2509. The Near-IR database of the digital Two Micron All Sky Survey (2MASS) has been used to re-estimate and refine the fundamental parameters of the cluster, i.e. age, reddening, distance, and diameter. As well as, luminosity function, mass function, total mass, relaxation time, and mass segregation of NGC 2509 have been estimated here for the first time..

KINEMATICAL FOCUS ON NGC 7086

  • Tadross, A.L.
    • Journal of The Korean Astronomical Society
    • /
    • v.38 no.4
    • /
    • pp.423-428
    • /
    • 2005
  • The main physical parameters; the cluster center, distance, radius, age, reddening, and visual absorbtion; have been re-estimated and improved for the open cluster NGC 7086. The metal abundance, galactic distances, membership richness, luminosity function, mass function, and the total mass of NGC 7086 have been examined for the first time here using Monet et al. (2003) catalog.

THE GALACTIC OPEN CLUSTER NGC 6531 (M21)

  • PARK BYEONG-GON;SUNG HWANKYUNG;KANG YONG HEE
    • Journal of The Korean Astronomical Society
    • /
    • v.34 no.3
    • /
    • pp.149-155
    • /
    • 2001
  • UBV RI and H$\alpha$ photometry has been performed for the open cluster NGC 6531. A total of 56 bright main sequence (MS) members were selected from their positions in photometric diagrams. We also classified 7 pre-main sequence (PMS) stars and 6 PMS candidates with Ha: emission from H$\alpha$ photometry. We determined a reddening of < E(B - V) >= 0.29 $\pm$ 0.03 and a distance modulus of Vo - Mv = 10.5 for the cluster. From the comparison of our photometric results to theoretical evolution models, we derived a MS turnoff age of 7.5 Myr and a PMS age spread of $\~$4 Myr. The IMF slope $\Gamma$, calculated in the mass range of 0.45 $\le$ log m $\le$ 1.35 is a steep value of $\Gamma$ = -1.8 $\pm$ 0.6.

  • PDF

PHYSICAL PARAMETERS OF THE OLD OPEN CLUSTER TRUMPLER 5

  • KIM SANG CHUL;SUNG HWANKYUNG
    • Journal of The Korean Astronomical Society
    • /
    • v.36 no.1
    • /
    • pp.13-19
    • /
    • 2003
  • We present a study of the old open cluster Trumpler 5 (Tr 5), based on the CDS archival data. From the color-magnitude diagrams of Tr 5, we have found the positions of main-sequence turn-off (MSTO) and red giant clump (RGC) stars. Using the mean magnitude of the RGC stars, we have estimated the reddening toward Tr 5, E(B - V) = 0.60 $\pm$ 0.10. Using the stars common in two data sets and the theoretical isochrones of Padova group, we have estimated the distance modulus $V_o - M_v = 12.64 {\pm} 0.20 (d = 3.4 {\pm} 0.3 kpc)$, the metallicity [Fe/H) = -0.30 $\pm$ 0.10, and the age of 2.4 $\pm$ 0.2 Gyr (log t = 9.38). These metallicity and distance values are consistent with the relation between the metallicity and the Galactocentric distance of other old open clusters, for which we obtain the slope of ${\Delta}[Fe/H]/ R_{gc} = -0.064 {\pm} 0.010\;dex\;kpc^{-1}$.

NO OPEN CLUSTER IN THE RUPRECHT 93 REGION

  • Cheon, So-Ra;Sung, Hwan-Kyung;Bessell, M.S.
    • Journal of The Korean Astronomical Society
    • /
    • v.43 no.4
    • /
    • pp.115-121
    • /
    • 2010
  • UBVI CCD photometry is obtained for the Ruprecht 93 (Ru 93)region. We are unable to confirm the existence of an intermediate-age open cluster in Ru 93 from the spatial distribution of blue stars. On the other hand, we find two young star groups in the observed field: the nearer one (Ru 93 group) comprises the field young stars in the Sgr-Car arm at $d{\approx}2.1$ kpc, while the farther one (WR 37 group) is the young stars around WR 37 at $d{\approx}4.8$ kpc. We derive an abnormal extinction law ($R_V$ = 3.5) in the Ruprecht 93 region.