간행물
천문학회지 KCI 등재 SCOPUS Journal of The Korean Astronomical Society
- 발행기관 한국천문학회
- 자료유형 학술지
- 간기 반년간
- ISSN 1225-4614 (Print)2288-890X (Online)
- 수록기간 1968 ~ 2024
- 주제분류 자연과학 > 천문학 자연과학 분류의 다른 간행물
- 십진분류KDC 440DDC 520
권호리스트/논문검색
제50권 제3호 (2017년 6월) 5건
1.
2017.06
구독 인증기관 무료, 개인회원 유료
Hee-Jae Lee, Hong-Kyu Moon, Myung-Jin Kim, Chun-Hwey Kim, Josef Durech, Young-Jun Choi, Young-Seok Oh, Jintae Park, Dong-Goo Roh, Hong-Suh Yim, Sang-Mok Cha, Yongseok Lee
We conduct BVRI and R band photometric observations of asteroid (5247) Krylov from January 2016 to April 2016 for 51 nights using the Korea Microlensing Telescope Network (KMTNet). The color indices of (5247) Krylov at the light curve maxima are determined as B - V = 0:841 0:035, V -R = 0:4180:031, and V -I = 0:8710:031 where the phase angle is 14.1◦. They are acquired after the standardization of BVRI instrumental measurements using the ensemble normalization technique. Based on the color indices, (5247) Krylov is classi ed as a S-type asteroid. Double periods, that is, a primary period P1 = 82:188 0:013 h and a secondary period P2 = 67:13 0:20 h are identi ed from period searches of its R band light curve. The light curve phases with P1 and this indicate that it is a typical Non-Principal Axis (NPA) asteroid. We discuss the possible causes of its NPA rotation.
4,000원
2.
2017.06
구독 인증기관 무료, 개인회원 유료
The presence of blue stragglers pose challenges to standard stellar evolution theory, in the sense that explaining their presence demands a complex interplay between stellar evolution and cluster dynamics. In the meantime, mass transfer in binary systems and stellar collisions are widely studied as a blue straggler formation channel. We explore properties of the Galactic open clusters where blue stragglers are found, in attempting to estimate the relative importance of these two favored processes, by comparing them with those resulting from open clusters in which blue stragglers are absent as of now. Unlike previous studies which require a sophisticated process in understanding the implication of the results, this approach is straightforward and has resulted in a supplementary supporting evidence for the current view on the blue straggler formation mechanism. Our main findings are as follows: (1) Open clusters in which blue stragglers are present have a broader distribution with respect to the Z-axis pointing towards the North Galactic Pole than those in which blue stragglers are absent. The probability that two distributions with respect to the Z-axis are drawn from the same distribution is 0.2%. (2) Average values of log10(t) of the clusters with blue stragglers and those without blue stragglers are 8.58 ± 0.232 and 7.52 ± 0.285, respectively. (3) The clusters with blue stragglers tend to be relatively redder than the others, and are distributed broader in colors. (4) The clusters with blue stragglers are likely brighter than those without blue stragglers. (5) Finally, blue stragglers seem to form in condensed clusters rather than simply dense clusters. Hence, we conclude that mass transfer in binaries seems to be a relatively important physical mechanism of the generation of blue stragglers in open clusters, provided they are sufficiently old.
4,000원
3.
2017.06
구독 인증기관 무료, 개인회원 유료
Jihey Shin, Hyunjin Shim, Ho Seong Hwang, Jongwan Ko, Jong Chul Lee, Yousuke Utsumi, Narae Hwang, Byeong-Gon Park
We study the angular correlation function of bright (Ks ≤ 19.5) Extremely Red Objects (EROs) selected in the Subaru GTO 2 deg2 field. By applying the color selection criteria of R − Ks > 5.0, 5.5, and 6.0, we identify 9055, 4270, and 1777 EROs, respectively. The number density is consistent with similar studies on the optical − NIR color selected red galaxies. The angular correlation functions are derived for EROs with different limiting magnitude and different R −Ks color cut. When we assume that the angular correlation function w() follows a form of a power-law (i.e., w() = A−), the value of the amplitude A was larger for brighter EROs compared to the fainter EROs. The result suggests that the brighter, thus more massive high-redshift galaxies, are clustered more strongly compared to the less massive galaxies. Assuming that EROs have redshift distribution centered at hzi ∼ 1.1 with z = 0.15, the spatial correlation length r0 of the EROs estimated from the observed angular correlation function ranges ∼ 6-10 h−1Mpc. A comparison with the clustering of dark matter halos in numerical simulation suggests that the EROs are located in most massive dark matter halos and could be progenitors of L∗ elliptical galaxies.
4,000원
4.
2017.06
구독 인증기관 무료, 개인회원 유료
We present the characteristics and the performance of the new CCD camera system, SNUCAM- II (Seoul National University CAMera system II) that was installed on the Lee Sang Gak Telescope (LSGT) at the Siding Spring Observatory in 2016. SNUCAM-II consists of a deep depletion chip covering a wide wavelength from 0.3 μm to 1.1 μm with high sensitivity (QE at > 80% over 0.4 to 0.9 μm). It is equipped with the SDSS ugriz lters and 13 medium band width (50 nm) lters, enabling us to study spectral energy distributions (SEDs) of diverse objects from extragalactic sources to solar system objects. On LSGT, SNUCAM-II offers 15.7 15.7 arcmin eld-of-view (FOV) at a pixel scale of 0.92 arcsec and a limiting magnitude of g = 19.91 AB mag and z=18.20 AB mag at 5σ with 180 sec exposure time for point source detection.
4,000원
5.
2017.06
구독 인증기관 무료, 개인회원 유료
Sang Chul Kim, Jaemann Kyeong, Hong Soo Park, Ilseung Han, Joon Hyeop Lee, Dae-Sik Moon, Youngdae Lee, Seongjae Kim
We present a BV I optical photometric study of the old open cluster Ruprecht 6 using the data obtained with the SMARTS 1.0 m telescope at the CTIO, Chile. Its color-magnitude diagrams show the clear existence of the main-sequence stars, whose turn-o point is located around V 18:45 mag and B - V 0:85 mag. Three red clump (RC) stars are identi ed at V = 16:00 mag, I = 14:41 mag and B - V = 1:35 mag. From the mean Ks-band magnitude of RC stars (Ks = 12:39 0:21 mag) in Ruprecht 6 from 2MASS photometry and the known absolute magnitudes of the RC stars (MKS = - :595 0:025 mag), we obtain the distance modulus to Ruprecht 6 of (m -M)0 = 13:84 0:21 mag (d = 5:86 0:60 kpc). From the (J - Ks) and (B - V ) colors of the RC stars, comparison of the (B - V ) and (V - I) colors of the bright stars in Ruprecht 6 with those of the intrinsic colors of dwarf and giant stars, and the PARSEC isochrone ttings, we derive the reddening values of E(B - V ) = 0:42 mag and E(V - I) = 0:60 mag. Using the PARSEC isochrone ttings onto the color-magnitude diagrams, we estimate the age and metallicity to be: log(t) = 9:50 0:10 (t = 3:16 0:82 Gyr) and [Fe/H] = -0:42 0:04 dex. We present the Galactocentric radial metallicity gradient analysis for old (age > 1 Gyr) open clusters of the Dias et al. catalog, which likely follow a single relation of [Fe/H] = (-0:034 0:007)RGC + (0:190 0:080) (rms = 0.201) for the whole radial range or a dual relation of [Fe/H] = (-0:077 0:017)RGC + (0:609 0:161) (rms = 0.152) and constant ([Fe/H] -0:3 dex) value, inside and outside of RGC 12 kpc, respectively. The metallicity and Galactocentric radius (13:28 0:54 kpc) of Ruprecht 6 obtained in this study seem to be consistent with both of the relations.
4,600원
