A study of the high-inclination population in the Kuiper belt - II. The Twotinos

As the second part of our study, in this paper we proceed to explore the dynamics of the high-inclination Twotinos in the 1:2 Neptune mean motion resonance (NMMR). Depending on the inclination $i$, we show the existence of two critical eccentricities $e_a(i)$ and $e_c(i)$, which are lower limits of the eccentricity $e$ for the resonant angle $\sigma$ to exhibit libration and asymmetric libration, respectively. Accordingly, we have determined the libration centres $\sigma_0$ for inclined orbits, which are strongly dependent on $i$. With initial $\sigma=\sigma_0$ on a fine grid of $(e, i)$, the stability of orbits in the 1:2 NMMR is probed by 4-Gyr integrations. It is shown that symmetric librators are totally unstable for $i\ge30^{\circ}$; while stable asymmetric librators exist for $i$ up to $90^{\circ}$. We further investigate the 1:2 NMMR capture and retention of planetesimals with initial inclinations $i_0\le90^{\circ}$ in the planet migration model using a time-scale of $2\times10^7$ yr. We find that: (1) the capture efficiency of the 1:2 NMMR decreases drastically with the increase of $i_0$, and it goes to 0 when $i_0\ge60^{\circ}$; (2) the probability of discovering Twotinos with $i>25^{\circ}$, beyond observed values, is roughly estimated to be $\le0.1$ per cent; (3) more particles are captured into the leading rather than the trailing asymmetric resonance for $i_0\le10^{\circ}$, but this number difference appears to be the opposite at $i_0=20^{\circ}$ and is continuously varying for even larger $i_0$; (4) captured Twotinos residing in the trailing resonance or having $i>15^{\circ}$ are practically outside the Kozai mechanism, like currently observed samples.Comment: 13 pages, 10 figures, Accepted by MNRAS. Comments welcome

Preparation and characterization of a dual-layer carbon film on 6H-SiC wafer using carbide-derived carbon process with subsequent chemical vapor deposition

AbstractIt is reported that a dual-layer carbon film on SiC wafer is prepared using carbide-derived carbon (CDC) process with subsequent chemical vapor deposition (CVD). The dual-layer film includes a sub-layer of CDC and a top layer of CVD, which are prepared by chlorination of SiC and pyrolysis of CCl4 at high temperature respectively. The CDC and CVD layers are mainly amorphous. And similar dispersion effects are observed in the Raman spectra, although the D-band position of the CVD layer shifts to higher wavenumber (~1354cm−1) than that of the CDC layer (~1337cm−1). Surface chemistry analysis suggests that the unstable chemical bonds, mainly C―Cl, as well as dangling bonds in the CDC layer play an important role in promoting the nucleation of CVD carbon. The surface morphology evolvement from SiC wafer to CDC layer and to dual-layer film is investigated by atomic force microscopy [AFM] and field emission scanning electronic microscopy [FESEM]. The nanoporous surface formed in the CDC process is favorable for capturing carbon species from the gas phase and can act as a “seedbed” for the nucleation and growth of CVD layer. The primary tribological study indicates that the dual-layer film shows great advantages in friction reduction and wear resistance with comparison to SiC and CDC layer, suggesting its potential in lubrication for SiC-based moving components

Outflows from active galactic nuclei: The BLR-NLR metallicity correlation

The metallicity of active galactic nuclei (AGNs), which can be measured by emission line ratios in their broad and narrow line regions (BLRs and NLRs), provides invaluable information about the physical connection between the different components of AGNs. From the archival databases of the International Ultraviolet Explorer, the Hubble Space Telescope and the Sloan Digital Sky Survey, we have assembled the largest sample available of AGNs which have adequate spectra in both the optical and ultraviolet bands to measure the narrow line ratio [N II]/H{\alpha} and also, in the same objects, the broad-line N V/C IV ratio. These permit the measurement of the metallicities in the NLRs and BLRs in the same objects. We find that neither the BLR nor the NLR metallicity correlate with black hole masses or Eddington ratios, but there is a strong correlation between NLR and BLR metallicities. This metallicity correlation implies that outflows from BLRs carry metal-rich gas to NLRs at characteristic radial distances of ~ 1.0 kiloparsec. This chemical connection provides evidence for a kinetic feedback of the outflows to their hosts. Metals transported into the NLR enhance the cooling of the ISM in this region, leading to local star formation after the AGNs turn to narrow line LINERs. This post-AGN star formation is predicted to be observable as an excess continuum emission from the host galaxies in the near infrared and ultraviolet, which needs to be further explored.Comment: 19 pages, 13 figures, 3 tables. Accepted for publication at MNRA

Essay: Reflecting on Subsistence and Breaking Through Conundrums -- Readings of SUI Jianguo\u27s Arts 生存的自省与困境的突围 -- 隋建国艺术读解

This essay by Jia Fangzhou about artist Sui Jianguo is scripted in Chinese. The essay was published in journal Art Observation 美术观察 in 1993 (issue No.3). (Jerry Wu\u2723).https://digital.kenyon.edu/zhoudocs/1247/thumbnail.jp

Essay: Traces and Paths 印迹与途径

This essay of the artist (first page of the file) is scripted in Chinese. On the second page of the file, a brief artistic bibliography of SU is included. The article(s) was(were) published in journal Art Observation 美术观察” in 1996 (issue No. 3). (Jerry Wu\u2723).https://digital.kenyon.edu/zhoudocs/1248/thumbnail.jp

Chandra observation of Abell 1689: New determination of mass distribution and comparison to lensing measurements

We present a new estimate of the projected X-ray mass of Abell 1689 observed with Chandra, in an attempt to clarify the issue of whether or not there exists a discrepancy between X-ray and gravitational lensing mass estimates claimed in previous investigations based on {\it Einstein}, {\it ROSAT} and {\it ASCA} observations. A particular attention is paid to examining if there is an offset between X-ray centroid and central dominant cD galaxy, which may be an indicator of the presence of local dynamical activities of intracluster gas in the central core and therefore, explain the discrepancy between X-ray and lensing mass estimates, if any. The unprecedentedly high spatial resolution achieved by Chandra allows us to precisely localize the X-ray centroid of Abell 1689, which appears to coincide perfectly with the central cD galaxy. This fact, along with the symmetry and regularity of the X-ray surface brightness and temperature distributions, suggests that Abell 1689 is a fully-relaxed cluster. We thus employ hydrostatic equilibrium hypothesis to determine the projected mass profile of Abell 1689, and compare it with the results obtained by different lensing techniques available in the literature. Our analysis confirms the existance of the discrepancy of a factor of $\sim2$ between X-ray and lensing mass estimates in the central region of $r\approx0.2$ Mpc, although the two methods yield essentially consistent result on large radii. If the perfect coincidence between the X-ray center and the cD galaxy of Abell 1689 detected by Chandra observation is not a projection effect, the central mass discrepancy between X-ray and lensing measurements may pose a challenge to our conventional understanding of dynamical evolution of the intracluster gas in the central regions of clusters.Comment: 26 pages, 7 figures, Accepted for publication in the Astrophysical Journa

Aqua­chlorido{μ-6,6′-dieth­oxy-2,2′-[1,2-phenyl­enebis(nitrilo­methyl­idyne)]diphenolato}copper(II)sodium(I) N,N-dimethyl­formamide solvate

In the heterometallic dinuclear title compound, [CuNa(C24H22N2O4)Cl(H2O)]·C3H7NO, the CuII ion is coord­inated in a square-planar geometry by two N atoms and two O atoms of the 6,6′-dieth­oxy-2,2′-[1,2-phenyl­enebis(nitrilo­methyl­­idyne)]diphenolate ligand. The NaI ion is hexa­coordinated by four O atoms of the ligand, defining the equatorial plan, and by one O atom of the water mol­ecule and one Cl atom occuping axial positions. The CuII and NaI ions are bridged by two phenolate O atoms