Hideyoshi Arakida

Surface heterogeneity of 2005 UD from photometric observations

Context. The recently discovered Apollo-type near-Earth asteroid 2005 UD has been suggested to be a fragment of (3200) Phaethon. Aims. To test this hypothesis, we carried out photometric observations of 2005 UD using the 1-m telescope at Lulin Observatory. Methods. Multi-color photometry was used to compare the surface properties of (3200) Phaethon and 2005 UD. Surface-color variation due to the rotation was also examined. Results. The time-resolved differential photometry showed clear brightness variation, and the lightcurve was fitted with a rotation period of 5.23 h and an amplitude of 0.44 mag. Using this rotational lightcurve, we derived the surface colors of 2005 UD. The surface of 2005 UD exhibits colors similar to those of F- and B-type asteroids, which is consistent with (3200) Phaethon. Furthermore, the (R - I) color of 2005 UD shows variation during the rotation of the body. Conclusions. The similarity of surface colors between (3200) Phaethon and 2005 UD observationally supports the hypothesis that 2005 UD is likely to be a fragment of (3200) Phaethon. A simple explanation for the inhomogeneity of the surface is that we see the surface and subsurface of the precursor object. Another explanation is the topographical structure that such as a large crater causes on this heterogeneous surface.

Note on the Perihelion/Periastron Advance Due to Cosmological Constant

We will comment on the perihelion/periastron advance of celestial bodies due to the cosmological constant Λ. It is well known that the cosmological constant Λ causes the perihelion/periastron shift; however, there seems to still exist a discrepancy among the various derived precession formulae. We will point out that the expression

Secular Increase of the Astronomical Unit : a Possible Explanation in Terms of the Total Angular-Momentum Conservation Law

\Delta\omega_{\varLambda} = (\pi c^{2} \varLambda a^{3}/(GM))\sqrt{1 - e^{2}}

Effect of the cosmological constant on the bending of light and the cosmological lens equation

is the general formula for any orbital eccentricity e and the expression ΔωΛ=(πc2Λa3/(GM))(1−e2)3 comes from the nearly circular (e≪1) approximation.

Time Delay in Robertson-McVittie Spacetime and its Application to Increase of Astronomical Unit

Aims. We show a possible explanation for the recently reported secular increase of the Astronomical Unit (AU) by Krasinsky and Brumberg (2004). Methods. The mechanism proposed is analogous to the tidal acceleration in the Earth-Moon system, which is based on the conservation of the total angular momentum and we apply this scenario to the Sun-planets system. Results. Assuming the existence of some tidal interactions that transfer the rotational angular momentum of the Sun and using reported value of the positive secular trend in the astronomical unit, d dt AU = 15±4 (m/cy), the suggested change in the period of rotation of the Sun is about 3 ms/cy in the case that the orbits of the eight planets have the same “expansion rate.” This value is suffi ciently small, and at present it seems there are no observational data which exclude this possibility. Effects of the change in the Sun’s moment of inertia is also investigated. It is pointed out that the ch ange in the moment of inertia due to the radiative mass loss by the Sun may be responsible for the secular increase of AU, if the orbital “expansion” is happening only in the inner planets system.

Quasi-Hilda Comet 147P/Kushida-Muramatsu Another long temporary satellite capture by Jupiter

Graduate School of Science and Technology, Hirosaki University, Hirosaki, Aomori 036-8561 Japan(Dated: December 26, 2011)We revisit the effect of cosmological constant Λ on the light deflection and its role in the cosmolog-ical lens equation. First, we re-examine the motion of photon in the Schwarzschild spacetime, andexplicitly describe the trajectory of photon and deflection angle αup to the second-order in G. Thenthe discussion is extended to the contribution of the cosmological constant Λ in the Schwarzschild-deSitter or Kottler spacetime. Contrary to the previous arguments, we emphasize the following points:(a) the cosmological constant Λ does appear in the orbital equation of light, (b) nevertheless thebending angle of light αdoes not change its form even if Λ 6= 0 since the contribution of Λ is thor-oughly absorbed into the definition of the impact parameter, and (c) the effect of Λ is completelyinvolved in the angular diameter distance D

Light deflection and Gauss–Bonnet theorem: definition of total deflection angle and its applications

Abstract We investigated the light propagation by means of the Robertson–McVittie solution which is considered to be the spacetime around the gravitating body embedded in the FLRW (Friedmann–Lemaitre–Robertson–Walker) background metric. We concentrated on the time delay and derived the correction terms with respect to the Shapiro’s formula. To relate with the actual observation and its reduction process, we also took account of the time transformations; coordinate time to proper one, and conversely, proper time to coordinate one. We applied these results to the problem of increase of astronomical unit reported by Krasinsky and Brumberg [Krasinsky, G.A., Brumberg, V.A., 2004. Celest. Mech. Dyn. Astrn. 90, 267]. However, we found the influence of the cosmological expansion on the light propagation does not give an explanation of observed value, d AU / d t = 15 ± 4 [m/century] in the framework of Robertson–McVittie metric.

Diffusive Propagation of High Energy Cosmic Rays in Galaxy: Effect of Hall Drift

Context. The quasi-Hilda comets (QHCs), being in unstable 3:2 Jovian mean motion resonance, are considered a major cause of temporary satellite capture (TSC) by Jupiter. Though the QHCs may be escaped Hilda asteroids, their origin and nature have not yet been studied in su cient detail. Of particular interest are long TSCs/orbiters. Orbiters n in which at least one full revolution about the planet is completed n are rare astronomical events; only four have been known to occur in the last several decades. Every case has been associated with a QHC: 82P/Gehrels 3; 111P/Helin-Roman-Crockett; P/1996 R2 (Lagerkvist); and the possibly QHC-derived D/1993 F2 (Shoemaker-Levy 9, SL9). Aims. We focus on long TSC/orbiter events involving QHCs and Jupiter. Thus we survey the known QHCs, searching for further long TSCs/orbiters over the past century. Methods. First, we conrmed the long TSC/orbiter events of 82P, 111P, and 1996 R2 in order to test our method against previous work, applying a general N-body Newtonian code. We then used the same procedure to survey the remaining known QHCs and search for long TSC/orbiter events. Results. We newly identied another long TSC/orbiter: 147P/Kushida-Muramatsu from 1949 May 14 +97days 106days n1961 July 15. Our result is veried by integrations of 243 cloned orbits which take account of the present orbital uncertainty of this comet. The event involves an L2 ! L1 transition as with 82P and 1996 R2; this may represent a distinct subtype of TSCs from QHC derived (L1 !) longer captures exemplied by 111P and (probably) SL9, though this classication is still only based on a small database of TSCs. Conclusions. This is the third long TSC and the fth orbiter to be found, thus long TSC/orbiter events involving Jupiter have occurred once per decade. Two full revolutions about Jupiter were completed and the capture duration was 12:17 +0:29 0:27 years; both these numbers rank 147P as third among long TSC/orbiter events, behind SL9 and 111P. This study also conrms the importance of the QHC region as a dynamical route into and out of Jovian TSC, via the Hill’s sphere.

Apollo asteroid 2005 UD: split nucleus of (3200) Phaethon?

In this paper, we re-examine the light deflection in the Schwarzschild and the Schwarzschild–de Sitter spacetime. First, supposing a static and spherically symmetric spacetime, we propose the definition of the total deflection angle