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Masatoshi Taga & Masanori Iye 《Monthly notices of the Royal Astronomical Society》1998,299(1):111-117
In this paper we show the positional oscillation of a massive object in a dense stellar system by numerical N -body simulations. We found that the central massive object, which at first is placed at rest at the centre of the surrounding spherical stellar system, promptly departs from the centre and rotates in accordance with the rotation of the stellar system, if the stellar system has an appreciable rotation. This oscillatory motion continues for a long time because of the absence of dynamical friction. Such a long-lasting oscillation may explain the asymmetric structure observed in the centres of M31 and NGC 4486B, may cause the secular flow of gaseous elements distributed in the central regions of galaxies on to the massive object, and may ignite activity in the centres of galaxies. 相似文献
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Masanori Iye Tatsuo Ueda Masafumi Noguchi Shinko Aoki 《Astrophysics and Space Science》1983,89(2):363-376
A new scheme has been devised to calculate discrete unstable global shearing spiral modes of gaseous disk models of galaxies. The scheme makes use of the Legendre expansion of eigen functions and the problem of stability analysis is reduced to an eigenvalue problem of an infinite matrix. The spiral patterns of these shearing wave solutions of linearized equations change their form in the course of time due to the differential rotation of the equilibrium disk. These shearing wave solutions are presumed to have intermediate characteristics between so-called density-waves and material arms. Comparison between these shearing modes and the non-shearing normal modes for a series of disk models is presented. 相似文献
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Masatoshi Taga & Masanori Iye 《Monthly notices of the Royal Astronomical Society》1998,299(4):1132-1138
In this paper we investigate, by linear modal analysis, the one-armed dynamical instability of a two-dimensional fluid disc that has a massive object at its centre. The model of the disc is chosen to avoid the artificial instabilities that originate from the unrealistic disc configurations that have been adopted in previous studies. We find a one-armed instability for which the central massive object is displaced from the centre, which is generally called the 'eccentric instability'. However, to excite the eccentric instability, the mass of the central object should be appreciably smaller than that of the disc, and this mass ratio is far smaller than what was originally proposed. The instability shown in this paper is likely to be excited in a stellar system with a central massive object, e.g. a galactic nucleus harbouring a massive black hole, and further studies are desirable via techniques such as numerical simulations. 相似文献
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Tae-Soo Pyo Masahiko Hayashi Naoto Kobayashi Alan T. Tokunaga Hiroshi Terada Miwa Goto Takuya Yamashita Yoichi Itoh Hideki Takami Naruhisa Takato Yutaka Hayano Wolfgang Gaessler Yukiko Kamata Yosuke Minowa Masanori Iye 《Astrophysics and Space Science》2003,287(1-4):21-24
We present high angular resolution spectra taken along the jets from L1551 IRS 5 and DG Tau obtained with the Subaru Telescope. The position-velocity diagrams of the [Fe II] λ 1.644 μmemission line revealed remarkably similar characteristics for the two sources, showing two distinct velocity components separated from each other in both velocity and space with the entire emission range blueshifted with respect to the stellar velocity. The high velocity component (HVC) has a velocity of –200 ––300 km s-1 with a narrow line width, while the low velocity component (LVC) is around –100 km s-1 exhibitinig a broad line width. The HVC is located farther away from the origin and is more extended than the LVC. Our results suggest that the HVC is a well-collimated jet originating from the region close to the star, while the LVC is a widely-opened wind accelerated in the region near the inner edge of the accretion disk. 相似文献
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Takato Naruhisa Fuse Tetsuharu Gaessler Wolfgang Goto Miwa Kanzawa Tomio Kobayashi Naoto Minowa Yosuke Oya Shin Pyo Tae-Soo Saint-Jacque D. Takami Hideki Terada Hiroshi Hayano Yutaka Iye Masanori Kamata Yukiko Tokunaga A. T. 《Earth, Moon, and Planets》2003,92(1-4):183-191
We have measured near-infrared colorsof the binary Kuiper Belt object (KBO)1998 WW31 using the Subaru Telescope withadaptive optics. The satellite was detectednear its perigee and apogee(0.18“ and 1.2” apart from the primary).The primary and the satellite have similar H–Kcolors, while the satellite is redder thanthe primary in J–H. Combined with the Rband magnitude previously published byVeillet et al., 2002, the color of the primaryis consistent with that of optically red KBOs. Thesatellite's R-, J-, H-colors suggest thepresence of ～1 μm absorption band dueto rock-forming minerals. If the surface of thesatellite is mainly composed by olivine, thesatellite's albedo is higher value than the canonicallyassumed value of 4%. 相似文献
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Masanori Iye 《Astrophysics and Space Science》1989,160(1-2):149-157
The concept of the active support system for JNLT is summarized. Performance of the force sensor, the optical wavefront analyzer, and the actuator under development for JNLT is reported. The results of a series of active optics experiments carried out by assembling these elements to support, measure, and actively correct a 62 cm thin mirror are described.Paper presented at the symposium on the JNLT and Related Engineering Development, Tokyo, November 29–December 2, 1988. 相似文献
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Preliminary results of spectroscopic studies of selected Seyfert galaxies employing a new Cassegrain echelle spectrograph completed at ESO are presented. Subjects reported are the asymmetric profiles of narrow emission lines, spatial variation of narrow emission line profiles, and the interstellar absorption lines.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984. 相似文献
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