• Title/Summary/Keyword: Photometry

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THE GALACTIC OPEN CLUSTER NGC 6531 (M21)

  • PARK BYEONG-GON;SUNG HWANKYUNG;KANG YONG HEE
    • Journal of The Korean Astronomical Society
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    • v.34 no.3
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    • pp.149-155
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    • 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.

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UBVI CCD PHOTOMETRY OF OPEN CLUSTER NGC 2324

  • KYEONG JAE-MANN;BYUN YONG-IK;SUNG EON-CHANG
    • Journal of The Korean Astronomical Society
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    • v.34 no.3
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    • pp.143-147
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    • 2001
  • UBVI CCD photometry of open cluster NGC 2324 is presented. C-M diagrams of this cluster show well-defined main sequence with a red giant clump centered at B - V =1.05, V =13.45. We derived the major cluster characteristics; E(B - V)=0.17$\pm$0.12 from color-color diagram and mean color of red giant clump stars, (m - M)o=13.1$\pm$0.1 from zero age main sequence fitting, and [Fe/H]$\~$-0.32 from comparison the theoretical model developed by Bertelli et al. (1994) to the observed C-M diagrams. We estimate the age of NGC 2324 to be log t$\~$8.8 by applying isochrone fitting and morphological age index method.

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STELLAR CONTENTS AND GLOBULAR CLUSTER CANDIDATES IN THE SCULPTOR GROUP GALAXY NGC 300

  • KIM SANG CHUL;SUNG HWANKYUNG;LEE MYUNG GYOON
    • Journal of The Korean Astronomical Society
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    • v.35 no.1
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    • pp.9-28
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    • 2002
  • We present UBVI CCD photometry of the stellar contents and globular cluster(GC) candidates in the spiral galaxy NGC 300 in the Sculptor group. Color-magnitude diagrams for 18 OB associations having more than 30 member stars are presented. The slope of the initial mass function for the bright stars in NGC 300 is estimated to be ${\Gamma}= -2.6{\pm} 0.3$. Assuming the distance to NGC 300 of (m - M)o = 26.53 $\pm$ 0.07, the mean absolute magnitude of three brightest blue stars is obtained to be < $M_v^{BSG}$ (3) > = -8.95 mag. We have performed search for GCs in NGC 300 and have found 17 GC candidates in this galaxy. Some characteristics of these GC candidates are discussed.

A Photometric Study of the Young Open Cluster IC 1805

  • Sung, Hwankyung;Lim, Beomdu;Bessell, M.S.;Hur, Hyeonoh;Yi, Jonghyuk;Chun, Moo-Young
    • The Bulletin of The Korean Astronomical Society
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    • v.40 no.2
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    • pp.41.2-41.2
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    • 2015
  • We have performed deep wide-field CCD photometry of the young open cluster IC 1805 in the famous star forming region W4, and obtained photometric data for more than 91,000 stars in the field of IC 1805 based on observations with the 3.6m CFHT and the AZT-22 1.5m telescope at Maidanak Astronomical Observatory in Uzbekistan. The photometric data cover an area $43^{\prime}{\times}45^{\prime}$ which is far larger and far deeper than any other optical observations made for the cluster. In order to select the young stellar objects with mid-IR excess emission, we have performed mid-IR photometry of the cluster using the archival images obtained with the Spitzer Space Telescope IRAC and MIPS instruments. From a preliminary analysis of the data, we determined the reddening law ($R_V=3.02{\pm}0.05$), distance modulus ($V_0-M_V=11.9{\pm}0.2$), and the spatial distribution of members.

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On the Multiple Stellar Populations in the Globular Cluster NGC 6388

  • Roh, Dong-Goo;Lee, Young-Wook;Lim, Dongwook;Han, Sang-Il
    • The Bulletin of The Korean Astronomical Society
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    • v.38 no.2
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    • pp.63.2-63.2
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    • 2013
  • Unlike the conventional wisdom, observations made during the past decade have revealed that many globular clusters possess more than one stellar population. Here, we have discovered evidence for multiple red giant branches (RGBs) in the globular cluster NGC 6388 from the narrow-band Calcium and Str$\ddot{o}$mgren b & y (Caby) photometry. In order to confirm the difference in Calcium abundance, we have acquired the low resolution spectroscopy for these RGB stars. In this paper, we will present results of our photometry and hand in the preliminary results of spectroscopic observations.

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HST NIC3 PHOTOMETRY OF METAL-RICH GLOBULAR CLUSTERS PALOMAR 6, LILLER 1, AND 47 TUC (NGC 104)

  • Lee, Jae-Woo
    • Journal of Astronomy and Space Sciences
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    • v.21 no.3
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    • pp.167-180
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    • 2004
  • We present HST NIC3 photometry of metal-rich globular clusters Palomar 6, Liller 1 and 47 Tuc (NGC 104). We discuss the interstellar reddening law for the HST NICMOS F110W/F160W photometric system which depends on the temperature of the source. The distance moduli and interstellar reddening values for Palomar 6 and Liller 1 are estimated by comparing the magnitudes and colors of RHB stars in the clusters with those of 47 Tuc. We obtain $(m-M)_0=14.48$mag and E(B-V)=1.34mag for Palomar 6 and $(m-M)_0=15.17$mag and E(B-V)=2.50 mag for Liller 1.

CCD PHOTOMETRY USING MULTIPLE COMPARISON STARS

  • Kim, Yong-gi;Andronov, Ivan L.;Jeon, Young-Beom
    • Journal of Astronomy and Space Sciences
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    • v.21 no.3
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    • pp.191-200
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    • 2004
  • The accuracy of CCD observations obtained at the Korean 1.8m telescope has been studied. Seventeen comparison stars in the vicinity of the cataclysmic variable BG CMi have been measured. The 'artificial' star has been used instead of the 'control' star, what made possible to increase accuracy estimates by a factor of 1.3-2.1 times for 'good' and 'cloudy' nights, respectively. The algorithm of iterative determination of accuracy and weights of few comparison stars contributing to the artificial star, has been presented. The accuracy estimates for 13-mag stars are around $0.^m002$ mag for exposure times of 30 sec.

CCD Photometry of the Globular Cluster M30

  • Yim, Hong-Seo;Chun, Mun-Suk
    • Bulletin of the Korean Space Science Society
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    • 1993.04a
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    • pp.14.2-14
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    • 1993
  • We present UBV CCD Photometry of the very metal-poor globular duster M3O,covering a region of r f 100 arcsec from the duster center. The data was obtained from the 40 inch telescope at Mt Soomlo Siding Spring Observator in August 1992. We used DAOPHOT CCD reudction package for data reduction to obtain Color-Magnitude Diagram(CMD). We have determined some fludamental parameters of the globular Ouster such as metal abundance, helium abundance and distance from the CMD. finally, we have attempted to determine the age of M3O using the revised Yale isochrones.

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VRI SURFACE PHOTOMETRY OF THE SPIRAL GALAXIES NGC 531, NGC 536, AND NGC 542 IN HCG10 (HCG10에 속한 나선은하 NGC 531, NGC 536, NGC 542의 VRI CCD 표면측광)

  • SONG WOO-MI;ANN HONG BAE
    • Publications of The Korean Astronomical Society
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    • v.14 no.1
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    • pp.1-8
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    • 1999
  • We performed VRI CCD surface photometry of three spiral galaxies of HCG10 in order to understand the effect of interactions in the compact group. The morphology of the largest member NGC 536 seems to be normal but its bulge is thought to be of an oblate spheroid. The central surface brightness of the disk of NGC 536 is much fainter than that of disks of nearby spiral galaxies. The morphologies of NGC 531 and NGG 542 appear to be affected by interactions which lead to a warped disk in NGC 531 and a slightly bent disk in NGC 542. NGC 531 have a boxy bulge and a Freeman Type II disk both of which strongly suggest the presence of a bar in the galaxy. There is a break in the slope of the luminosity profile of NGC 542 which is dominated by the disk component.

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VARIABLE STARS IN THE OPEN CLUSTER M29

  • KIM SEUNG-LEE;SEE SEE-WOO
    • Journal of The Korean Astronomical Society
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    • v.29 no.1
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    • pp.31-41
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    • 1996
  • We present results of time-series CCD photometry for 178 stars in the young open cluster M29 (=NGC6913). Total 1036 V-band CCD frames were collected for five nights between August 12 and September 13, 1994. The photometric precision is about 7.6 mmag for 9th-10th mag stars in M29 with exposure times of 30 seconds. From the dispersion diagram and the light curves, one detached eclipsing binary (HD194378) and two suspected variables are newly discovered. $A\;\gamma\;Cas$ type variable, V1322 Cyg, which has been known as a member of M29, did not show any light variations during the period of present observations, indicating that it passed the steady phase without the eruption during our observing runs.

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