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
제49권 제3호 (2016년 6월) 5건
1.
2016.06
구독 인증기관 무료, 개인회원 유료
We obtain the first complete CCD light curves (LCs) of the contact binary AP UMi in the VRI bands and analyzed them by means of the PHOEBE code. A spotted model is applied to treat the asymmetry in the LCs. The LC morphology clearly shows the O’Connell effect and the solution shows an influence of star spots on both components. Such effect of star spots is common between the RS CVn and W UMa chromospherically active stars. Based on the obtained solution of the LCs we investigate the evolutionary state of the components and conclude that the system is a pre-intermediate contact binary (f = 0.29) with mass ratio q = 0.38, and it is an A-type W UMa system where the less massive secondary component is cooler than the more massive primary one.
4,000원
2.
2016.06
구독 인증기관 무료, 개인회원 유료
I.-G. Shin, Y.-H. Ryu, A. Udalski, M. Albrow, S.-M. Cha, J.-Y. Choi, S.-J. Chung, C. Han, K.-H. Hwang, Y. K. Jung, D.-J. Kim, S.-L. Kim, C.-U. Lee, Y. Lee, B.-G. Park, H. Park, R. W. Pogge, J. C. Yee, P. Pietrukowicz, P. Mroz, S. Koz lowski, R. Poleski, J. Skowron, I. Soszynski, M. K. Szymanski, K. Ulaczyk, L. Wyrzykowski, M. Pawlak, A. Gould
We report the characterization of a massive (mp = 3:91:4Mjup) microlensing planet (OGLE- 2015-BLG-0954Lb) orbiting an M dwarf host (M = 0:33 0:12M ) at a distance toward the Galactic bulge of 0:6+0:4 0:2 kpc, which is extremely nearby by microlensing standards. The planet-host projected separation is a? 1:2AU. The characterization was made possible by the wide- eld (4 deg2) high cadence ( = 6 hr1) monitoring of the Korea Microlensing Telescope Network (KMTNet), which had two of its three telescopes in commissioning operations at the time of the planetary anomaly. The source crossing time t = 16 min is among the shortest ever published. The high-cadence, wide- eld observations that are the hallmark of KMTNet are the only way to routinely capture such short crossings. High-cadence resolution of short caustic crossings will preferentially lead to mass and distance measurements for the lens. This is because the short crossing time typically implies a nearby lens, which enables the measurement of additional e ects (bright lens and/or microlens parallax). When combined with the measured crossing time, these e ects can yield planet/host masses and distance.
4,000원
3.
2016.06
구독 인증기관 무료, 개인회원 유료
The Toothbrush radio relic associated with the merging cluster 1RXS J060303.3 is presumed to be produced by relativistic electrons accelerated at merger-driven shocks. Since the shock Mach number inferred from the observed radio spectral index, Mradio 2:8, is larger than that estimated from X-ray observations, MX . 1:5, we consider the re-acceleration model in which a weak shock of Ms 1:2 - 1:5 sweeps through the intracluster plasma with a preshock population of relativistic electrons. We nd the models with a power-law momentum spectrum with the slope, s 4:6, and the cutoff Lorentz factor, e;c 7-8104 can reproduce reasonably well the observed pro les of radio uxes and integrated radio spectrum of the head portion of the Toothbrush relic. This study con rms the strong connection between the ubiquitous presence of fossil relativistic plasma originated from AGNs and the shock-acceleration model of radio relics in the intracluster medium.
4,000원
4.
2016.06
구독 인증기관 무료, 개인회원 유료
Augmenting the Wide Field Infrared Survey Telescope (WFIRST) microlensing campaigns with intensive observations from a ground-based network of wide-field survey telescopes would have several major advantages. First, it would enable full two-dimensional (2-D) vector microlens parallax measurements for a substantial fraction of low-mass lenses as well as planetary and binary events that show caustic crossing features. For a significant fraction of the free-floating planet (FFP) events and all caustic-crossing planetary/binary events, these 2-D parallax measurements directly lead to complete solutions (mass, distance, transverse velocity) of the lens object (or lens system). For even more events, the complementary ground-based observations will yield 1-D parallax measurements. Together with the 1-D parallaxes from WFIRST alone, they can probe the entire mass range M & M⊕. For luminous lenses, such 1-D parallax measurements can be promoted to complete solutions (mass, distance, transverse velocity) by high-resolution imaging. This would provide crucial information not only about the hosts of planets and other lenses, but also enable a much more precise Galactic model. Other benefits of such a survey include improved understanding of binaries (particularly with low mass primaries), and sensitivity to distant ice-giant and gas-giant companions of WFIRST lenses that cannot be detected by WFIRST itself due to its restricted observing windows. Existing ground-based microlensing surveys can be employed if WFIRST is pointed at lower-extinction fields than is currently envisaged. This would come at some cost to the event rate. Therefore the benefits of improved characterization of lenses must be weighed against these costs.
4,800원
5.
2016.06
구독 인증기관 무료, 개인회원 유료
[Fe II] emission lines are prominent in the infrared (IR) and important as diagnostic tools for radiative atomic shocks. We investigate the emission characteristics of [Fe II] lines using a shock code developed by Raymond (1979) with updated atomic parameters. We rst review general characteristics of the IR [Fe II] emission lines from shocked gas, and derive their uxes as a function of shock speed and ambient density. We have compiled available IR [Fe II] line observations of interstellar shocks and compare them to the ratios predicted from our model. The sample includes both young and old supernova remnants in the Galaxy and the Large Magellanic Cloud and several Herbig-Haro objects. We nd that the observed ratios of the IR [Fe II] lines generally fall on our grid of shock models, but the ratios of some mid- IR lines, e.g., [Fe II] 35.35 m=[Fe II] 25.99 m, [Fe II] 5.340 m=[Fe II] 25.99 m, and [Fe II] 5.340 m=[Fe II] 17.94 m, are signi cantly o set from our model grid. We discuss possible explanations and conclude that while uncertainties in the shock modeling and the observations certainly exist, the uncertainty in atomic rates appears to be the major source of discrepancy.
4,600원
