DOCSLIB.ORG

Near-Earth Asteroid Surface Roughness Depends on Compositional Class ∗ Lance A.M

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Near-Earth Asteroid Surface Roughness Depends on Compositional Class ∗ Lance A.M ARTICLE IN PRESS YICAR:8714 JID:YICAR AID:8714 /FLA [m5G; v 1.65; Prn:8/10/2008; 15:52] P.1 (1-11) Icarus ••• (••••) •••–••• Contents lists available at ScienceDirect Icarus www.elsevier.com/locate/icarus Near-Earth asteroid surface roughness depends on compositional class ∗ Lance A.M. Benner a, ,StevenJ.Ostroa, Christopher Magri b, Michael C. Nolan c, Ellen S. Howell c, Jon D. Giorgini a, Raymond F. Jurgens a, Jean-Luc Margot d, Patrick A. Taylor d, Michael W. Busch e, Michael K. Shepard f a Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA b University of Maine at Farmington, 173 High Street, Preble Hall, Farmington, ME 04938, USA c Arecibo Observatory, HC3 Box 53995, Arecibo, PR 00612, USA d Department of Astronomy, Cornell University, Ithaca, NY 14853, USA e Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA f Department of Geography and Geosciences, Bloomsburg University, Bloomsburg, PA 17815, USA article info abstract Article history: Radar observations of 214 near-Earth asteroids (NEAs) reveal a very strong correlation of circular Received 21 February 2008 polarization ratio with visible–infrared taxonomic class, establishing distinct differences in the centimeter- Revised 18 June 2008 to-several-decimeter structural complexity of objects in different spectral classes. The correlation may be due to the intrinsic mechanical properties of different mineralogical assemblages but also may reflect very different formation ages and collisional histories. The highest ratios are measured for groups Keywords: Near-Earth objects associated with achondritic igneous rocky meteorites: the E class, whose parent body may be 3103 Asteroids Eger, and the V class, derived from the mainbelt asteroid (and Dawn mission target) 4 Vesta. Asteroids, surfaces © 2008 Elsevier Inc. All rights reserved. Asteroids, composition Radar observations 1. Introduction faces, which are the outcome of complex collisional histories and reflect the mechanical properties of objects’ mineral assemblages. Meteorites are samples of small, Earth-orbit-crossing asteroids, A radar echo’s circular polarization ratio measures the wave- which in turn are primarily derived from the main asteroid belt length-scale roughness of the target’s surface (Ostro et al., 2002; (Burbine et al., 2002; Lipschutz and Schultz, 2007). The mineralogy Ostro, 2007). In almost all radar observations, a circularly polar- and meteoritic analogues of asteroids are constrained by narrow- ized signal is transmitted and the echo is measured simultaneously band optical reflectance spectra (Tholen and Barucci, 1989; Bus et in the same sense of circular polarization as transmitted (the SC al., 2002) and to a lesser extent by classification schemes based on sense) and the opposite (OC) sense. The handedness of a circu- broadband optical color indices and albedos (Burbine et al., 2002; larly polarized signal is reversed upon reflection from a smooth Lipschutz and Schultz, 2007). Asteroid classification schemes now dielectric interface, leading to dominance of the echo by the OC include some 26 spectral classes (Bus et al., 2002), in most cases polarization. Multiple scattering, subsurface reflection, wavelength- tentatively associated with meteorite types (Burbine et al., 2002; scale facets, and structure with radii of curvature near the wave- Lipschutz and Schultz, 2007). A dependence of the abundance length can produce SC echoes. Therefore, the SC/OC ratio is a of different spectral classes on heliocentric distance (Gradie and measure of the near-surface, wavelength-scale structural complex- Tedesco, 1982) probably reflects the influence of temperature on ity or “roughness.” Since the sensitivities of the two polarization the identity of condensates from the primitive solar nebula. How- channels are easily calibrated via measurement of unpolarized ra- ever, there remains great uncertainty in the relationships between dio sources, the uncertainty in SC/OC estimates is limited to the meteorite types and asteroid classes. The rare exceptions involve propagation of statistical fluctuations in receiver noise. To place asteroids visited by rendezvous spacecraft: the ∼15-km-diameter the results below in context, Mercury, Venus, and the Moon have ∼ NEA 433 Eros (Veverka et al., 1997) and the several-hundred- SC/OC 0.1 and Mars has a ratio of about 0.3, although for each meter-long NEA 25143 Itokawa (Fujiwara et al., 2006)areboth object, there are local variations. mineralogically akin to ordinary chondrites. Similarly, there is only limited information about the physical characteristics of NEA sur- 2. Results Here we report 3.5- and 13-cm-wavelength radar observations * Corresponding author. Fax: +1 818 354 9476. of 214 near-Earth asteroids (Figs. 1, 2; Tables 1, 2, and 3) that re- E-mail address: [email protected] (L.A.M. Benner). veal a very strong correlation between circular polarization ratio 0019-1035/$ – see front matter © 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.icarus.2008.06.010 Please cite this article in press as: Benner, L.A.M., et al. Near-Earth asteroid surface roughness depends on compositional class. Icarus (2008), doi:10.1016/j.icarus.2008.06.010 ARTICLE IN PRESS YICAR:8714 JID:YICAR AID:8714 /FLA [m5G; v 1.65; Prn:8/10/2008; 15:52] P.2 (1-11) 2 L.A.M. Benner et al. / Icarus ••• (••••) •••–••• Table 1 Summary of asteroid SC/OC distributions by spectral class. Spectral Near-Earth Main-belt class SC/OC SC/OC Mean SD Range Number Mean SD Range Number C 0.285 0.120 0.40 17 0.098 0.056 0.22 25 E 0.892 0.079 0.23 6 0.67 0.226 0.32 2 F 0.15 – – 1 0.058 0.101 0.26 6 G 0.102 0.080 0.20 5 M 0.143 0.055 0.11 3 0.153 0.097 0.23 6 O0.21––1 PD 0.188 0.019 0.04 4 0.096 0.062 0.18 9 S 0.270 0.079 0.40 70 0.198 0.094 0.35 27 V 0.603 0.088 0.23 6 0.28 – – 1 X 0.674 0.436 0.90 5 ? 0.339 0.284 1.48 101 Notes. Main-belt asteroid results are from Magri et al. (2007a) except for the two E-class MBAs, which are from Shepard et al. (2008b). “?” indicates objects with un- known taxonomies. “X” refers to the degenerate E, M, and P objects (Tholen and Barucci, 1989; Bus et al., 2002). Table 2 lists SC/OC estimates in decreasing order Fig. 1. Distribution of NEA SC/OC versus absolute magnitude. Spectral classes are and Table 3 lists SC/OC for objects ordered by catalog number and provisional des- indicated with different letters and colors. We adopt the classes described in Tholen ignation. A histogram for the NEAs appears in Fig. 3. NEA SC/OC estimates range and Barucci (1989), which identifies 14 groups based on the shape of their visible from zero to 1.5, with a mean of 0.34 ± 0.25 and a median of 0.26. spectra and their albedos. S, Q, K, and L subclasses within the taxonomy in Bus et al. (2002) have been grouped into the S class. Dark C and B objects are labeled as “C.” Of the 214 objects in the radar sample, estimates of VIS/IR spectral class are are associated with the enstatite achondrites (Zellner et al., 1977; available for 113. Gaffey et al., 1992; Clark et al., 2004), also known as aubrites, whose composition is predominantly the orthopyroxene enstatite (MgSiO3). Aubrites contain white enstatite crystals up to ten cen- timeters in diameter and small amounts of olivine, plagioclase, clinopyroxene, sulfides, and nickel–iron metal (Zellner et al., 1977; Clark et al., 2004), which suggests that they cooled underground under highly reducing conditions (McSween, 1999). Most aubrites consist of angular pieces or fragments in a softer matrix (Sears, 1995) and some are fragile (Hutchison, 2006). The bulk of classified targets in the tables are C or S, which include carbonaceous and ordinary chondrite analogues (Burbine et al., 2002; Lipschutz and Schultz, 2007), respectively, as well as stony-iron analogues. Chondrites are undifferentiated, consti- tute the vast majority (∼80%) of meteorite falls, and are derived from asteroids that never melted (Lipschutz and Schultz, 2007). Our C and S targets have SC/OC from ∼0.1 to ∼0.5. The lowest SC/OC targets include our sample’s handful of objects in the M spectral class (SC/OC from 0.1 to 0.2), which includes iron me- teorite and enstatite–chondrite analogues (Burbine et al., 2002; Rivkin et al., 2002), and four members of the P class, which are Fig. 2. Distribution of NEA SC/OC versus absolute magnitude including estimated standard errors on SC/OC. Standard errors are 1σ and are estimated using methods thought to be dark, primitive, carbonaceous objects from the outer given in Ostro (2007). For objects observed on multiple dates, errors give the range main belt (Bell et al., 1989). The X group is a degenerate class of SC/OC. comprised of E, M, and P objects that have nearly indistinguish- able VIS/IR spectra and which can be separated primarily by their and visible-infrared (VIS/IR) taxonomic class, as well as unexpected optical albedos (Tholen and Barucci, 1989). Our five X objects in- diversity in the decimeter-scale roughness of NEA surfaces. clude two with SC/OC = 1.1, one with SC/OC = 0.7, and two with NEA SC/OC estimates range from zero to 1.5, with a mean of SC/OC ∼ 0.2. 0.34 ± 0.25 and a median of 0.26, and 12% (26/214) have SC/OC How can the striking correlation of SC/OC with spectral class exceeding 0.6, indicating that decimeter-scale surface roughness be understood? One possibility is that mineralogy has played a among NEAs is relatively common.
Load more

Recommended publications
  • Dynamical Evolution of the Hungaria Asteroids ⇑ Firth M
    Icarus 210 (2010) 644–654 Contents lists available at ScienceDirect Icarus journal homepage: www.elsevier.com/locate/icarus Dynamical evolution of the Hungaria asteroids ⇑ Firth M. McEachern, Matija C´ uk , Sarah T. Stewart Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, MA 02138, USA article info abstract Article history: The Hungarias are a stable asteroid group orbiting between Mars and the main asteroid belt, with high Received 29 June 2009 inclinations (16–30°), low eccentricities (e < 0.18), and a narrow range of semi-major axes (1.78– Revised 2 August 2010 2.06 AU). In order to explore the significance of thermally-induced Yarkovsky drift on the population, Accepted 7 August 2010 we conducted three orbital simulations of a 1000-particle grid in Hungaria a–e–i space. The three simu- Available online 14 August 2010 lations included asteroid radii of 0.2, 1.0, and 5.0 km, respectively, with run times of 200 Myr. The results show that mean motion resonances—martian ones in particular—play a significant role in the destabili- Keywords: zation of asteroids in the region. We conclude that either the initial Hungaria population was enormous, Asteroids or, more likely, Hungarias must be replenished through collisional or dynamical means. To test the latter Asteroids, Dynamics Resonances, Orbital possibility, we conducted three more simulations of the same radii, this time in nearby Mars-crossing space. We find that certain Mars crossers can be trapped in martian resonances, and by a combination of chaotic diffusion and the Yarkovsky effect, can be stabilized by them.
    [Show full text]
  • AAS SFMC Manuscript Format Template
    AAS 13-484 PASSIVE SORTING OF ASTEROID MATERIAL USING SOLAR RADIATION PRESSURE D. García Yárnoz,* J. P. Sánchez Cuartielles,† and C. R. McInnes ‡ Understanding dust dynamics in asteroid environments is key for future science missions to asteroids and, in the long-term, also for asteroid exploitation. This paper proposes a novel way of manipulating asteroid material by means of solar radiation pressure (SRP). We envisage a method for passively sorting material as a function of its grain size where SRP is used as a passive in-situ ‘mass spec- trometer’. The analysis shows that this novel method allows an effective sorting of regolith material. This has immediate applications for sample return, and in- situ resource utilisation to separate different regolith particle sizes INTRODUCTION Asteroids have lately become prime targets for space exploration missions. This interest is jus- tified as asteroids are among the least evolved bodies in the Solar System and they can provide a better understanding of its formation from the solar nebula. Under NASA’s flexible path plan,1 asteroids have also become one of the feasible “planetary” surfaces to be visited by crewed mis- sions, with the benefit of not requiring the capability to land and take-off from a deep gravity well. In addition, they may well be the most affordable source of in-situ resources to underpin future space exploration ventures. Considerable efforts have been made in the study of the perturbing forces and space environ- ment around cometary and asteroid bodies.2, 3 These forces and harsh environments need to be considered and will have direct implications for the operations of spacecraft around and on small bodies.
    [Show full text]
  • New Voyage to Rendezvous with a Small Asteroid Rotating with a Short Period
    Hayabusa2 Extended Mission: New Voyage to Rendezvous with a Small Asteroid Rotating with a Short Period M. Hirabayashi1, Y. Mimasu2, N. Sakatani3, S. Watanabe4, Y. Tsuda2, T. Saiki2, S. Kikuchi2, T. Kouyama5, M. Yoshikawa2, S. Tanaka2, S. Nakazawa2, Y. Takei2, F. Terui2, H. Takeuchi2, A. Fujii2, T. Iwata2, K. Tsumura6, S. Matsuura7, Y. Shimaki2, S. Urakawa8, Y. Ishibashi9, S. Hasegawa2, M. Ishiguro10, D. Kuroda11, S. Okumura8, S. Sugita12, T. Okada2, S. Kameda3, S. Kamata13, A. Higuchi14, H. Senshu15, H. Noda16, K. Matsumoto16, R. Suetsugu17, T. Hirai15, K. Kitazato18, D. Farnocchia19, S.P. Naidu19, D.J. Tholen20, C.W. Hergenrother21, R.J. Whiteley22, N. A. Moskovitz23, P.A. Abell24, and the Hayabusa2 extended mission study group. 1Auburn University, Auburn, AL, USA ([email protected]) 2Japan Aerospace Exploration Agency, Kanagawa, Japan 3Rikkyo University, Tokyo, Japan 4Nagoya University, Aichi, Japan 5National Institute of Advanced Industrial Science and Technology, Tokyo, Japan 6Tokyo City University, Tokyo, Japan 7Kwansei Gakuin University, Hyogo, Japan 8Japan Spaceguard Association, Okayama, Japan 9Hosei University, Tokyo, Japan 10Seoul National University, Seoul, South Korea 11Kyoto University, Kyoto, Japan 12University of Tokyo, Tokyo, Japan 13Hokkaido University, Hokkaido, Japan 14University of Occupational and Environmental Health, Fukuoka, Japan 15Chiba Institute of Technology, Chiba, Japan 16National Astronomical Observatory of Japan, Iwate, Japan 17National Institute of Technology, Oshima College, Yamaguchi, Japan 18University of Aizu, Fukushima, Japan 19Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA 20University of Hawai’i, Manoa, HI, USA 21University of Arizona, Tucson, AZ, USA 22Asgard Research, Denver, CO, USA 23Lowell Observatory, Flagstaff, AZ, USA 24NASA Johnson Space Center, Houston, TX, USA 1 Highlights 1.
    [Show full text]
  • Potential Resources on and from the Asteroids/Comets; Threats
    ASTEROIDS AND COMETS: POTENTIAL RESOURCES LECTURE 21 NEEP 533 HARRISON H. SCHMITT EROS C-TYPE NASA/NEAR SHOEMAKER/APL 11X11X34 KM ASTEROIDS IN GENERAL 1.3 GM/CM3 MAIN BELT ASTEROIDS BETWEEN JUPITER AND MARS NEAR EARTH ASTEROIDS SOME MAY BE SPENT COMETS EARTH CROSSING ASTEROIDS SOME MAY BE SPENT COMETS “CENTAUR” ASTEROIDS BETWEEN JUPITER AND URANUS CHIRON, 1979 VA, AND 133P/ELST-PIZARRO ALSO HAVE COMET- LIKE BEHAVIOR “TROJAN” ASTEROIDS JUPITER’S ORBIT AND CONTROLLED BY IT GENERAL CHARACTERISTICS RUBBLE PILES (?) NO ASTEROID >150M ROTATES FASTER THAN ONE REVOLUTION PER 2 HOURS CALCULATED LIMIT FOR RUBBLE TO STAY TOGETHER 1998 KY26 IS 30M IN DIAMETER, ROTATES IN 10.7 MIN. AND MAY BE SOLID MAY BE A TRANSITION IN ORBITAL CHARACTERISTICS AND / OR COMPOSITION BETWEEN SOME ASTEROIDS AND COMETS • S-TYPE OTHER ASTEROIDS – INNER ASTEROID BELT – EVIDENCE OF HEATING AND DIFFERENTIATION – 29 TELESCOPIC SPECTRA (Binzel, et al., 1996) • INTERMEDIATE BETWEEN S-TYPE AND ORDINARY CHONDRITES – 1. DISTINCT ROCK TYPES VS DIVERSE LARGER BODIES – 2. ABUNDANCE OF OPAQUE MATERIALS – 3. FRESH SURFACES (MOST LIKELY) • BASALTIC ACHONDRITES (6%) – 4 VESTA AT 2.36 AU [MAIN BELT PARENT (?)] – TOUTATIS - NEA (RADAR STUDY) • 4.5X2.4X1.9KM, 2.1 GM/CM3, TWO ROTATIONS, I.E., TUMBLING (5.4 AND 7.3 DAYS) – 1459 MAGNYA AT 3.15 AU [FRAGMENT OF LARGER BODY (?)] EROS • (Lazzaro, et al, 2000, Science, 288) C-TYPE (REVISED BY GRS DATA) 11X11X33 KM 2.7 GM/CM3 5.27 HR ROTATION NASA/NEAR SHOEMAKER/APL OTHER ASTEROIDS • D-TYPE CARBONACEOUS CHONDRITE (BEYOND MAIN BELT ASTEROIDS) – TAGISH
    [Show full text]
  • (3 I" Richard P. Binzel, 1 (.: , FINAL REPORT for NASA GRANT
    f i I j .t t_ (3 i" _(.: _,_ Richard P. Binzel, 1 FINAL REPORT FOR NASA GRANT NAG5-3939 RECONNAISSANCE OF NEAR-EARTH OBJECTS Richard P. Binzel (MIT) Principal Investigator Summa_: NASA sponsorship of asteroid research for this grant has resulted in 31)publications and major new results relating near- Earth asteroids _o known meteorite groups, most especially ordina_ chondrites. Analysis of observations continues. Research Objectives What ar_ the relationships between asteroids, comets, and meteorites? All represent primordial sanples from the early solar system, but how have their thermal, collisional, and dynamical evolution differed over the age of the solar system? Achieving such a fundamental understanding of the interrelationships of solar system small bodies has been a cornerstone for work in planetary science over the past three decades and continues to be of highest priority Asteroids, comets, and meteorite source bodies all traverse near-Earth space and are therefore accessible to groundbased observations despite their typically small sizes. As has been demonstrated by rJearly three decades of work, spectroscopic observations represent the most fundamental technique for measuring the physical properties of small solar system bodies. Over visible wavelengths, near-Earth objects observed to date have been found to display a wide range of distinctive spectral properties which appear to span the range between primitive (perhaps cometary) compositions to highly differentiated materials (likely formed in the asteroid belt). In addition, many apparent comet->asteroid transition objects (e.g. 4015 Wilson-Harr_ngton) have been discovered and are in need of substantial follow- up physical study. Thus, the study (,f near-Earth objects is _ for achieving the fundamental science goals of understanding the relationships between asteroids, comets, and meteorites.
    [Show full text]
  • Observation of Near-Earth Object (1566) Icarus and the Split Candidate 2007 MK6
    PPS07-P07 JpGU-AGU Joint Meeting 2017 Observation of near-earth object (1566) Icarus and the split candidate 2007 MK6 *Seitaro Urakawa1, Katsutoshi Ohtsuka2, Shinsuke Abe3, Daisuke Kinoshita4, Hidekazu Hanayama 5, Takeshi Miyaji5, Shin-ichiro Okumura1, Kazuya Ayani6, Syouta Maeno6, Daisuke Kuroda5, Akihiko Fukui5, Norio Narita5,7,8, George HASHIMOTO9, Yuri SAKURAI9, Sayuri Nakamura9, Jun Takahashi10, Tomoyasu Tanigawa11, Otabek Burhonov12, Kamoliddin Ergashev12, Takashi Ito5, Fumi Yoshida5, Makoto Watanabe13, Masataka Imai14, Kiyoshi Kuramoto14, Tomohiko Sekiguchi15 , MASATERU ISHIGURO16 1. Japan Spaceguard Association, 2. Tokyo Meteor Network, 3. Nihon University, 4. National Central University, 5. National Astronomical Observatory of Japan, 6. Bisei Observatory, 7. Astrobiology Center, 8. University of Tokyo, 9. Okayama University, 10. University of Hyogo, 11. Sanda Shounkan Highschool, 12. Ulugh Beg Astronomical Institute Uzbekistan Academy of Science , 13. Okayama University of Science, 14. Hokkaido University, 15. Hokkaido University of Education, 16. Seoul National University Background & Aim: A numerical simulation proposes that the origin of near-Earth object 2007 MK6 (hereafter, MK6) is a near-Earth object (1566) Icarus (hereafter, Icarus) [1]. In addition to it, the orbital parameters of the daytime Taurid-Perseid meteor swarm are in good agreement with those of Icarus. Thus, it is considered that MK6 is split from the parent object Icarus by a rotational fission and/or an impact event, and the produced dust became to the daytime Taurid-Perseid meteor swarm. To confirm such a hypothesis, we need to obtain the observational evidence that the color indices of Icarus and MK6 are same. Moreover, if MK6 split by the rotational fission due to the YORP effect, the rotation period of Icarus would be shorten compared with the past rotation period.
    [Show full text]
  • Multiple Asteroid Systems: Dimensions and Thermal Properties from Spitzer Space Telescope and Ground-Based Observations*
    Multiple Asteroid Systems: Dimensions and Thermal Properties from Spitzer Space Telescope and Ground-Based Observations* F. Marchisa,g, J.E. Enriqueza, J. P. Emeryb, M. Muellerc, M. Baeka, J. Pollockd, M. Assafine, R. Vieira Martinsf, J. Berthierg, F. Vachierg, D. P. Cruikshankh, L. Limi, D. Reichartj, K. Ivarsenj, J. Haislipj, A. LaCluyzej a. Carl Sagan Center, SETI Institute, 189 Bernardo Ave., Mountain View, CA 94043, USA. b. Earth and Planetary Sciences, University of Tennessee 306 Earth and Planetary Sciences Building Knoxville, TN 37996-1410 c. SRON, Netherlands Institute for Space Research, Low Energy Astrophysics, Postbus 800, 9700 AV Groningen, Netherlands d. Appalachian State University, Department of Physics and Astronomy, 231 CAP Building, Boone, NC 28608, USA e. Observatorio do Valongo/UFRJ, Ladeira Pedro Antonio 43, Rio de Janeiro, Brazil f. Observatório Nacional/MCT, R. General José Cristino 77, CEP 20921-400 Rio de Janeiro - RJ, Brazil. g. Institut de mécanique céleste et de calcul des éphémérides, Observatoire de Paris, Avenue Denfert-Rochereau, 75014 Paris, France h. NASA Ames Research Center, Mail Stop 245-6, Moffett Field, CA 94035-1000, USA i. NASA/Goddard Space Flight Center, Greenbelt, MD 20771, United States j. Physics and Astronomy Department, University of North Carolina, Chapel Hill, NC 27514, U.S.A * Based in part on observations collected at the European Southern Observatory, Chile Programs Numbers 70.C-0543 and ID 72.C-0753 Corresponding author: Franck Marchis Carl Sagan Center SETI Institute 189 Bernardo Ave. Mountain View CA 94043 USA [email protected] Abstract: We collected mid-IR spectra from 5.2 to 38 µm using the Spitzer Space Telescope Infrared Spectrograph of 28 asteroids representative of all established types of binary groups.
    [Show full text]
  • Polarimetric and Photometric Observations of Neas with the 1.6M Pirka Telescope
    PPS03-P17 Japan Geoscience Union Meeting 2018 Polarimetric and Photometric observations of NEAs with the 1.6m Pirka Telescope *Ryo Okazaki1, Tomohiko Sekiguchi1, Akari Kamada1, Masateru Ishiguro2, Hiroyuki Naito3, Masataka Imai4, Tatsuharu Ono4 1. Hokkaido University of Education, 2. Seoul National University, 3. Nayoro Observatory, 4. Hokkaido University Polarimetric observations of 3 near-Earth asteroids, 2000 PD3, 2012 TC4 and (3200) Phaethon, were carried out in 2017 using the 1.6m Pirka telescope at the Nayoro Observatory, Hokkaido, as well as BVRIphotometric color observations were conducted for 2000 PD3. Polarimetry is a useful method for investigating asteroids’ physical properties such as the albedo, regolith particle size and taxonomy of asteroids. In general, Pr (the linear polarization degree) exhibits a strong dependence on the phase angle (Sun-Target-Observer’s angle, α). 2000 PD3 In order to understand Pmax (maximum Polarization degree) , we attempted to obtain polarimetric data at different phase angles (α=22°-120°). A geometric albedo of pv=0.26±0.06% were derived from a limited αrange ( 25°-84°) which is in good agreement with that of S-type asteroids. BVRI photometric data (B-V=0.132±0.002mag,V-R=0.114±0.002mag,V-I=0.180±0.002mag) supports S-type classification. 2012 TC4 In October 2017, 2012 TC4 approached to the Earth at about 50,000 km of the closest distance. A fast rotation period about 0.2 hours (Ryan and Ryan, 2017) indicates a monolithic suraface layer which is not covered with a rubble pile. The liner polarization Pr=5.62±5.26% (α=34°) in the R-band is in close accord with that of C-type asteroids, although October run was performed under bad weather.
    [Show full text]
  • Projekt Brána Do Vesmíru
    Projekt Brána do vesmíru Hvězdárna Valašské Meziříčí, p. o. Krajská hvezdáreň v Žiline Súčasnosť a budúcnosť výskumu medziplanetárnej hmoty RNDr. Peter Vereš, PhD. University of Hawaii / Univerzita Komenského Ako sa objavila MPH ● Pôvodne iba nehybná hviezdna sféra ● Mesiac a Slnko ● Bludné planéty viditeľné voľným okom Starovek => novovek Piazzi ● 1.1.1801 ● Objekt pozorovaný 41 dní ● Stratený...predpoklad, medzi Marsom a Jupiterom ● Laplace – nemožné nájsť ● Gauss (24) vynašiel metódu, vypočítal, Ceres bol nájdený... Halley ● Kométy, odjakživa považované za poslov zlých správ, vysvetlené ako atmosferické javy ● ● ● ● Názov Kometes (dlhovlasá) ● 1577 Brahe = paralaxa, ďalej ako Mesiac ● Edmond Halley si všimol periodicitu kométy 1531, 1607, 1682 = návrat v 1758 Meteory ● Zaznamenané v -1809, - 687 (Lyridy) ● Ernst Chladni 1794 Kniha o pôvode Pallasovho železa ● 1798 Brandes, Benzenberg, paralaxa 400 meteorov, 22 spoločných ● 1803 dážď / Paríž, priznanie kozmického pôvodu ● 1833 USA dážď 20/s, LEO ● 1845/46 rozpad kométy Biela, dažde Andromedíd (72, 85, 93, 99) ● 1861 = Kirkwood, súvis rojov s kométami ● 1866 Schiaparelli: Swift-Tuttle (Perzeidy), Tempel (Leonidy) ● 1899 Adams vypočítal, že Jupiter narušil dráhu kométy, dážď nebol 1833, rytina, Leonidy 1998, foto, Leonidy, AGO Modra MPH a Slnečná sústava ● Slnko ● planéty (8) ● trpasličie planéty /Ceres, Pluto, Haumea, Makemake, Eris ● MPH = asteroidy, kométy, prach, plyn, .... Vznik a vývoj asteroidov ● -4571mil. rokov – vznik Sl. sús. ● Akrécia hmoty – nehomogenity, planetesimály, „viskózna
    [Show full text]
  • Discovery of Earth's Quasi-Satellite
    Meteoritics & Planetary Science 39, Nr 8, 1251–1255 (2004) Abstract available online at http://meteoritics.org Discovery of Earth’s quasi-satellite Martin CONNORS,1* Christian VEILLET,2 Ramon BRASSER,3 Paul WIEGERT,4 Paul CHODAS,5 Seppo MIKKOLA,6 and Kimmo INNANEN3 1Athabasca University, Athabasca AB, Canada T9S 3A3 2Canada-France-Hawaii Telescope, P. O. Box 1597, Kamuela, Hawaii 96743, USA 3Department of Physics and Astronomy, York University, Toronto, ON M3J 1P3 Canada 4Department of Physics and Astronomy, University of Western Ontario, London, ON N6A 3K7, Canada 5Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, USA 6Turku University Observatory, Tuorla, FIN-21500 Piikkiö, Finland *Corresponding author. E-mail: [email protected] (Received 18 February 2004; revision accepted 12 July 2004) Abstract–The newly discovered asteroid 2003 YN107 is currently a quasi-satellite of the Earth, making a satellite-like orbit of high inclination with apparent period of one year. The term quasi- satellite is used since these large orbits are not completely closed, but rather perturbed portions of the asteroid’s orbit around the Sun. Due to its extremely Earth-like orbit, this asteroid is influenced by Earth’s gravity to remain within 0.1 AU of the Earth for approximately 10 years (1997 to 2006). Prior to this, it had been on a horseshoe orbit closely following Earth’s orbit for several hundred years. It will re-enter such an orbit, and make one final libration of 123 years, after which it will have a close interaction with the Earth and transition to a circulating orbit.
    [Show full text]
  • Twenty Years of Toutatis
    EPSC Abstracts Vol. 6, EPSC-DPS2011-297, 2011 EPSC-DPS Joint Meeting 2011 c Author(s) 2011 Twenty Years of Toutatis M.W. Busch (1), L.A.M. Benner (2), D.J. Scheeres (3), J.-L. Margot (1), C. Magri (4), M.C. Nolan (5), and J.D. Giorgini (2) (1) Department of Earth and Space Sciences, UCLA, Los Angeles, California, USA (2) Jet Propulsion Laboratory, Pasadena, California, USA (3) Aerospace Engineering Sciences, University of Colorado, Boulder, Colorado, USA (4) University of Maine at Farmington, Farmington, Maine, USA (5) Arecibo Observatory, Arecibo, Puerto Rico, USA Abstract Near-Earth asteroid 4179 Toutatis is near a particularly if the moments of inertia are 4:1 orbital resonance with the Earth. consistent with a uniform internal density. Following its discovery in 1989, Toutatis Toutatis’ last close-Earth-approach for was observed extensively with the Arecibo several decades will be in December 2012, and Goldstone radars during flybys in 1992, when it will be 0.046 AU away. We will 1996, 2000, 2004, and 2008. The 1992 and make predictions for what radar 1996 data show that Toutatis is a bifurcated observations at that time should see. object with overall dimensions of 4.6 x 2.3 x 1.9 km and a surface marked with prominent impact craters. Most significantly, Toutatis References is in a non-principal-axis tumbling rotation [1] Hudson, R.S. and Ostro, S.J.: Shape and non-principal state, spinning about its long axis with a axis spin state of asteroid 4179 Toutatis, Science 270 84-86, period of 5.41 days while that axis precesses 1995.
    [Show full text]
  • Earth's Recurrent Quasi-Satellite?
    2002 AA: Earth’s recurrent quasi-satellite ? Pawel Wajer To cite this version: Pawel Wajer. 2002 AA: Earth’s recurrent quasi-satellite ?. Icarus, Elsevier, 2009, 200 (1), pp.147. 10.1016/j.icarus.2008.10.018. hal-00510967 HAL Id: hal-00510967 https://hal.archives-ouvertes.fr/hal-00510967 Submitted on 23 Aug 2010 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Accepted Manuscript 2002 AA29: Earth’s recurrent quasi-satellite ? Paweł Wajer PII: S0019-1035(08)00381-3 DOI: 10.1016/j.icarus.2008.10.018 Reference: YICAR 8801 To appear in: Icarus Received date: 11 April 2008 Revised date: 20 October 2008 Accepted date: 23 October 2008 Please cite this article as: P. Wajer, 2002 AA29: Earth’s recurrent quasi-satellite ?, Icarus (2008), doi: 10.1016/j.icarus.2008.10.018 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
    [Show full text]