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
제52권 제5호 (2019년 10월) 5건
1.
2019.10
구독 인증기관 무료, 개인회원 유료
We conducted a survey of open clusters within 1 kpc from the Sun using the astrometric and photometric data of the Gaia Data Release 2. We found 655 cluster candidates by visual inspection of the stellar distributions in proper motion space and spatial distributions in l b space. All of the 655 cluster candidates have a well de ned main-sequence except for two candidates if we consider that the main sequence of very young clusters is somewhat broad due to di erential extinction. Cross-matching of our 653 open clusters with known open clusters in various catalogs resulted in 207 new open clusters. We present the physical properties of the newly discovered open clusters. The majority of the newly discovered open clusters are of young to intermediate age and have less than 50 member stars.
4,600원
2.
2019.10
구독 인증기관 무료, 개인회원 유료
It is known that the number of astronomers of a country registered to the International As- tronomical Union (IAU) is correlated with that country’s gross domestic product (GDP). However, the robustness of this relationship could be doubted, as the fraction of astronomers joining the IAU differs from country to country. Here we revisit this correlation by using more recent data, updated as of 2017. We find a similar correlation by using the total number of astronomers and astrophysicists with PhD degrees that are working in each country, instead of adopting the number of IAU members. We confirm the existence of the correlation. We also confirm the existence of two subgroups within this correlation. One group consists of advanced European countries having a long history of modern astronomy, while the other group consists of countries having experienced recent rapid economic development. In order to determine the cause for the correlation, we obtained the long-term variations of the number of as- tronomers, population, and the GDP for a number of countries. We find that the number of astronomers per capita for recently developing countries has increased more rapidly as GDP per capita increased, than that for fully developed countries. We collected demographic data of the Korean astronomical community and find that it has experienced recent rapid growth. From these findings we estimate the proper size of the Korean astronomical community by considering Korea economic power and population. The current number of PhD astronomers working in Korea is approximately 310, but it should be 550 in order for it to be comparable and competitive to the sizes of the Spanish, Canadian, and Japanese astronomical communities. If current trends continue, this number will be reached by 2030. In order to be comparable to the German, French, and Italian communities, there should be 800 PhD astronomers in Korea. We discuss ways to overcome the vulnerability of the Korean astronomical community, based on the statistics of national R&D expenditure structure in comparison with that of other major advanced countries.
4,600원
3.
2019.10
구독 인증기관 무료, 개인회원 유료
We present IR ux density measurements, models of the broadband SED, and results of SED modeling for the Pulsar Wind Nebula (PWN) 3C 58. We nd that the Herschel ux density seems to be slightly lower than suggested by interpolation of previous measurements in nearby wavebands, implying that there may be multiple electron populations in 3C 58. We model the SED using a simple stationary one-zone and a more realistic time-evolving multi-zone scenario. The latter includes variations of ow properties in the PWN (injected energy, magnetic eld, and bulk speed), radiative energy losses, adiabatic expansion, and di usion, similar to previous PWN models. From the modeling, we nd that a PWN age of 2900{5400 yrs is preferred and that there may be excess emission at 1011 Hz. The latter may imply multiple populations of electrons in the PWN.
4,000원
4.
2019.10
구독 인증기관 무료, 개인회원 유료
There is evidence that the luminosities of Type Ia supernova (SN Ia) depend on their environments. While the impact of this trend on estimating cosmological parameters is widely acknowledged, the origin of this correlation is still under debate. In order to explore this problem, we first construct the YONSEI (YOnsei Nearby Supernova Evolution Investigation) SN catalog. The catalog consists of 1231 spectroscopically confirmed SNe Ia over a wide redshift range (0.01 < z < 1.37) from various SN surveys and includes light-curve fit data from two independent light-curve fitters, SALT2 and MLCS2k2. For a sample of 674 host galaxies, we use the stellar mass and the star formation rate data in Kim et al. (2018). We find that SNe Ia in low-mass and star-forming host galaxies are 0.062 ± 0.009 mag and 0.057 ± 0.010 mag fainter than those in high-mass and passive hosts, after light-curve corrections with SALT2 and MLCS2k2, respectively. When only local environments of SNe Ia (e.g., locally star-forming and locally passive) are considered, this luminosity difference increases to 0.081 ± 0.018 mag for SALT2 and 0.072 ± 0.018 mag for MLCS2k2. Considering the significant difference in the mean stellar population age between the two environments, this result suggests that the luminosity evolution of SNe Ia with redshift is most likely the origin of the environmental dependence.
6,300원
5.
2019.10
구독 인증기관 무료, 개인회원 유료
In this paper we introduce a software package, the Very long baseline interferometry Network SIMulator (VNSIM), which provides an integrated platform assisting radio astronomers to design Very Long Baseline Interferometry (VLBI) experiments and evaluate the network performance, with a userfriendly interface. Though VNSIM is primarily motivated by the East Asia VLBI Network, it can also be used for other VLBI networks and generic interferometers. The software package not only integrates the functionality of plotting (u; v) coverage, scheduling the observation, and displaying the dirty and CLEAN images, but also adds new features including sensitivity calculations for a given VLBI network. VNSIM provides exible interactions on both command line and graphical user interface and o ers friendly support for log reports and database management. Multi-processing acceleration is also supported, enabling users to handle large survey data. To facilitate future developments and updates, all simulation functions are encapsulated in separate Python modules, allowing independent invoking and testing. In order to verify the performance of VNSIM, we performed simulations and compared the results with other simulation tools, showing good agreement.
4,000원
