http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Miocchi, P. (검색결과 3 건)
- 무료
- 기관 내 무료
- 유료
-
Miocchi, P.,Pasquato, M.,Lanzoni, B.,Ferraro, F. R.,Dalessandro, E.,Vesperini, E.,Alessandrini, E.,Lee, Y.-W. IOP Publishing 2015 The Astrophysical journal Vol.799 No.1
<P>We present semi-analytical models and simplified N-body simulations with 10(4) particles aimed at probing the role of dynamical friction (DF) in determining the radial distribution of blue straggler stars (BSSs) in globular clusters. The semi-analytical models show that DF (which is the only evolutionary mechanism at work) is responsible for the formation of a bimodal distribution with a dip progressively moving toward the external regions of the cluster. However, these models fail to reproduce the formation of the long-lived central peak observed in all dynamically evolved clusters. The results of N-body simulations confirm the formation of a sharp central peak, which remains as a stable feature over time regardless of the initial concentration of the system. In spite of noisy behavior, a bimodal distribution forms in many cases, with the size of the dip increasing as a function of time. In the most advanced stages, the distribution becomes monotonic. These results are in agreement with the observations. Also, the shape of the peak and the location of the minimum (which, in most of cases, is within 10 core radii) turn out to be consistent with observational results. For a more detailed and close comparison with observations, including a proper calibration of the timescales of the dynamical processes driving the evolution of the BSS spatial distribution, more realistic simulations will be necessary.</P>
-
-
GLOBULAR CLUSTERS HOSTING INTERMEDIATE-MASS BLACK HOLES: NO MASS-SEGREGATION BASED CANDIDATES
Pasquato, Mario,Miocchi, Paolo,Won, Sohn Bong,Lee, Young-Wook American Astronomical Society 2016 The Astrophysical journal Vol.823 No.2
<P>Recently, both stellar mass segregation and binary fractions were uniformly measured on relatively large samples of Galactic globular clusters (GCs). Simulations show that both sizable binary-star populations and intermediate-mass black holes (IMBHs) quench mass segregation in relaxed GCs. Thus mass segregation in GCs with a reliable binary-fraction measurement is a valuable probe to constrain IMBHs. In this paper we combine mass-segregation and binary-fraction measurements from the literature to build a sample of 33 GCs (with measured core binary fractions), and a sample of 43 GCs (with binary-fraction measurements in the area between the core radius and the half-mass radius). Within both samples we try to identify IMBH-host candidates. These should have relatively low mass segregation, a low binary fraction (<5%), and a short (<1 Gyr) relaxation time. Considering the core-binary-fraction sample, no suitable candidates emerge. If the binary fraction between the core and the half-mass radius is considered, two candidates are found, but this is likely due to statistical fluctuations. We also consider a larger sample of 54 GCs where we obtained an estimate of the core binary fraction using a predictive relation based on metallicity and integrated absolute magnitude. Also in this case no suitable candidates are found. Finally, we consider the GC core-to half-mass radius ratio, which is expected to be larger for GCs containing either an IMBH or binaries. We find that GCs with large core-to half-mass radius ratios are less mass-segregated (and show a larger binary fraction), confirming the theoretical expectation that the energy sources responsible for the large core are also quenching mass segregation.</P>
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
