DOCSLIB.ORG

MIDI Observations of 1459 Magnya: First Attempt of Interferometric Observations of Asteroids with the VLTI ✩

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
MIDI Observations of 1459 Magnya: First Attempt of Interferometric Observations of Asteroids with the VLTI ✩ Icarus 181 (2006) 618–622 www.elsevier.com/locate/icarus Note MIDI observations of 1459 Magnya: First attempt of interferometric observations of asteroids with the VLTI ✩ Marco Delbo a,∗, Mario Gai a, Mario G. Lattanzi a, Sebastiano Ligori a, Davide Loreggia a, Laura Saba a, Alberto Cellino a, Davide Gandolfi b, Domenico Licchelli c, Carlo Blanco b, Massimo Cigna b, Markus Wittkowski d a INAF-Osservatorio Astronomico di Torino, Strada Osservatorio 20, 10025 Pino Torinese (TO), Italy b Dipartimento di Fisica e Astronomia, Università degli studi di Catania, Via S. Sofia 78, 95123 Catania, Italy c Department of Physics, University of Lecce, Via per Arnesano, 73100 Lecce, Italy d European Southern Observatory, Karl-Schwarzschild-Straße, 2 D-85748 Garching bei München, Germany Received 23 August 2005; revised 21 December 2005 Available online 17 February 2006 Abstract The Very Large Telescope Interferometer (VLTI) of the European Southern Observatory (ESO) can be used to obtain direct determination of the sizes and the albedos of asteroids. We present results of the first attempt to carry out interferometric observations of asteroids with the Mid Infrared Interferometric Instrument (MIDI) at the VLTI. Our target was 1459 Magnya. This is the only V-type asteroid known to exist in the outer main-belt, and its IRAS-albedo turns out to be rather low for an object of this taxonomic class. Interferometric fringes were not detected, very likely due to the fact that the flux emitted by the asteroid was lower than expected and below the MIDI threshold for fringe detection. However, by fitting the Standard Thermal Model to the N-band infrared flux measured by MIDI in photometric mode and to the visible absolute magnitude, obtained from quasi-simultaneous B- and V-band photometric observations, we have derived a geometric visible albedo of 0.37 ± 0.06 and an effective diameter of 17 ± 1 km. This new estimate of the albedo differs from that previously obtained by IRAS and is more consistent with the V-type taxonomic classification of 1459 Magnya. 2006 Elsevier Inc. All rights reserved. Keywords: Asteroids; Infrared observations; Photometry; Instrumentation 1. Introduction nomic classification. Whether these discrepancies are real, possibly related to short exposures to space weathering phenomena, or are simply the result of in- One of the most intriguing aspects unveiled recently from studies of small adequacies in the thermal models is not clear at present (Harris and Lagerros, (<30 km) asteroids, and particularly near-Earth asteroids (NEAs), is the dif- 2002). This has also crucial implications for the estimates of the size distribu- ficulty in making accurate albedo estimates for these objects based purely on tion of the NEA population and consequently for an assessment of the impact their taxonomic classification, using average values typically found for larger hazard these objects pose to the Earth. In fact, the albedo, along with the ab- main-belt asteroids (Harris and Lagerros, 2002). Low albedos (<0.1) are com- solute magnitude H, allows one to derive the average size of an object (Harris monly found among large main-belt asteroids displaying relatively featureless and Lagerros, 2002, and references therein). spectra (e.g., B, C, D, P types), whereas higher albedos (∼0.2–0.3) usually The direct determination of the size of small asteroids (i.e., measurement characterize objects exhibiting silicate absorption features (Q, R, S, V types). of the angular size of their disks) by means of adaptive optics or speckle inter- However, amongst small asteroids, and especially NEAs, several unusual ferometry is severely limited by their tiny apparent angular extensions. VLTI cases are found, including high-albedo C types (Harris and Lagerros, 2002; appears to be a promising instrument to overcome this limitation. We have pro- Veeder et al., 1989) and a number of asteroids for which the radiometric albedo posed to demonstrate the capability of VLTI to directly measure sizes of small is significantly different from the value expected on the basis of their taxo- asteroids and solve existing albedo ambiguity in some interesting cases. The main-belt Asteroid 1459 Magnya is an excellent target in this respect. This object is a unique example of a V-type asteroid in the outer main belt ✩ Based on observations with the Very Large Telescope Interferometer (VLTI) (Lazzaro et al., 2000). It might represent a rare surviving fragment from a larger, at the European Southern Observatory (ESO), obtained for the “VLTI Science differentiated and subsequently disrupted planetesimal different from Vesta. Demonstration Time” during observing period 74. According to the IRAS Minor Planet Survey (IMPS), however, its albedo is ± ± * Corresponding author. Fax: +39 011 8101930. only 0.12 0.03 and the resulting diameter is 30 3km(Tedesco et al., 1992). E-mail address: [email protected] (M. Delbo). This albedo is much lower than the value expected for a V-type asteroid (about 0019-1035/$ – see front matter 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.icarus.2006.01.001 Note / Icarus 181 (2006) 618–622 619 0.3; see Tedesco et al., 2005). In the most recent version of the IRAS data base, quisition images used for photometry of the asteroid and of the calibration Star namely the Supplemental IRAS Minor Planet Survey (SIMPS; Tedesco et al., HD10380 were carried out through the SiC filter (central wavelength 11.79 µm; 2002), Magnya’s derived diameter did not change, but the albedo was revised FWHM 2.32 µm). The calibrator was observed before and after the target aster- up to 0.22 ± 0.05. This revision of the albedo value is solely due to the use oid at 02:56 UT and 06:17 UT, at airmass 1.19 and 1.45, respectively. Its flux of a new, updated value for the visible absolute magnitude H (9.90, according is 9.76 Jy at 11.79 µm (Cohen et al., 1999). Acquisition images were obtained to the Minor Planet Center, instead of the previously adopted value of 10.6). by coadding several frames with Detector Integration Time (DIT) of 0.002 s It is worth to note, however, that the reliability of the IRAS measurement of per frame; the total on-target integration time was equal to 3.806 s for Magnya 1459 Magnya is very low: it was observed only once (over four potential sight- and to 0.926 for HD 10380. Using version 1.0 of the MIDI Interactive Analysis ings: Lazzaro et al., 2000) in the 12 and 25 µm bands (with a signal to noise (MIA) software package developed at the Max-Planck-Institut für Astronomie ratio of about 6) and has one of the highest flux overestimation corrections (MPIA) for the MIDI data reduction, we have derived a flux of 0.54 ± 0.10 Jy in the database (Tedesco et al., 1992). Our present knowledge of the size and for 1459 Magnya. From Fig. 1b and assuming the IRAS diameter of 30 km for albedo of this asteroid is thus not very accurate. 1459 Magnya was therefore 1459 Magnya, the expected flux at 11.79 µm was ∼2.5 Jy. Since the flux is selected for the first attempt of direct size determination of asteroids with the only moderately dependent on the albedo of the asteroid, the values of the mea- interferometric method at the VLTI. sured flux, about 4 times lower than the expected one, gives indication that the asteroid has a diameter about twice smaller than the IRAS nominal value (see 2. How asteroid sizes can be measured with the VLTI Section 4.2). After the acquisition of photometric images from both telescopes, MIDI combines the light of the two beams and begins searching for interfero- metric fringes. In the case of 1459 Magnya, however, fringes were not detected, The VLTI is capable of combining coherently the light collected by the either automatically by the instrument, or by our subsequent off-line analysis. four 8-meter Unit Telescopes (UTs) and by the 1.8-meter Auxiliary Telescopes We have carefully checked the performance of all subsystems of the VLTI at the (ATs). Currently, a three-beam, near-IR instrument (AMBER) and a two-beam time of the fringe search and did not notice any irregularities. The non-detection mid-IR instrument (MIDI; Leinert et al., 2003) are available. For a general of fringes was very likely caused by the flux value below the current sensitiv- technical overview of the VLTI, see, for instance, Glindemann et al. (2003). ity limit of MIDI for fringe detection (1 Jy). With such a low flux, detection Details of the VLTI instruments can also be found on the ESO web pages: of interferometric fringes appears below the instrument threshold, whatever the http://www.eso.org/projects/vlti/. visibility amplitude. However, as for any non-detection, we cannot completely According to the Van Cittert-Zernicke theorem, the Fourier transform of the rule out a technical failure of one of the subsystems. brightness distribution of the astronomical source gives its visibility function V(u,v)= V(Bx /λ, By /λ),whereBx and By are the components along two orthogonal directions of the interferometer’s baseline projected on the plane of 3.2. B- and V-band photometric observations the sky, λ is the wavelength of the monochromatic light, and u and v are the − spatial frequencies measured in radians 1. Quasi-simultaneous photometric observations of 1459 Magnya, through the In the case of a uniform circular disk of angular diameter θ, the ampli- B and V Johnson filters, were carried out at M.G. Fracastoro station of the Cata- tude of the visibility function at a monochromatic wavelength λ is given by: nia Astrophysical Observatory, in order to determine the rotational phase of the |VUD|=|2J1(πBθ/λ)/(πBθ/λ)|,whereJ1 is the first-order Bessel function asteroid at the time of VLTI observations and to derive a reliable absolute mag- of first kind and B is the length of the projected baseline.
Load more

Recommended publications
  • 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]
  • The Mineralogy of Middle- and Outer-Belt Vestoids
    Lunar and Planetary Science XXXIX (2008) 2270.pdf THE MINERALOGY OF MIDDLE- AND OUTER-BELT VESTOIDS. T. H. Burbine1, P. C. Buchanan2 and R. P. Binzel3, 1Department of Astronomy, Mount Holyoke College, 50 College Street, South Hadley, MA 01075, USA ([email protected]), 2Kilgore College, 1100 Broadway, Kilgore, TX 75662, USA (pbu- [email protected]), 3Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA ([email protected]). Introduction: Asteroid 4 Vesta is commonly (a=3.01 AU) [14], 10537 1991 RY16 (a=2.85 AU) thought to have a basaltic crust due to its spectral simi- [14], 21238 1995 WV7 (a=2.54 AU) [15,16], and larity in the visible and near-infrared to the HED me- 40521 1999 RL5 (a=2.53 AU) [10]. teorites (howardites, eucrites, and diogenites) [1,2]. Roig et al. [10] have calculated that some of the Vesta is located in the inner main-belt with a semi- middle-belt Vestoids could be fragments of Vesta. major axis (a) of 2.36 AU and is one of the few aster- The calculated probability is a function of the size of oids that can be persuasively linked to a group of me- the object since a larger size reduces the efficiency of teorites [3]. the Yarkovsky effect. Roig et al. [10] found that there HEDs are a clan of achondritic meteorites that have is a low probability (~1%) that 21238 1995 WV7 (~5 continuous variations in mineralogy and chemistry [4]. km in diameter) is a fragment of Vesta; however, Eucrites are composed primarily of anorthitic plagio- 40521 1999 RL5 (~3 km in diameter) has a much clase and low-Ca pyroxene with augite exsolution la- higher probability to be related to Vesta due to its mellae, whereas diogenites are predominately mag- slightly smaller estimated diameter.
    [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]
  • On the V-Type Asteroids Outside the Vesta Family. I. Interplay Of
    Astronomy & Astrophysics manuscript no. carruba September 16, 2018 (DOI: will be inserted by hand later) On the V-type asteroids outside the Vesta family I. Interplay of nonlinear secular resonances and the Yarkovsky effect: the cases of 956 Elisa and 809 Lundia V. Carruba1, T. A. Michtchenko1 , F. Roig2, S. Ferraz-Mello1, and D. Nesvorn´y3, 1 IAG, Universidade de S˜ao Paulo, S˜ao Paulo, SP 05508-900, Brazil e-mail: [email protected] 2 Observat´orio Nacional, Rio de Janeiro, RJ 20921-400, Brazil e-mail: [email protected] 3 Southwest Research Institute, Department of Space Studies, Boulder, Colorado 80302 e-mail: [email protected] Received May 2nd 2005; accepted June 22nd 2005. Abstract. Among the largest objects in the main belt, asteroid 4 Vesta is unique in showing a basaltic crust. It is also the biggest member of the Vesta family, which is supposed to originate from a large cratering event about 1 Gyr ago (Marzari et al. 1996). Most of the members of the Vesta family for which a spectral classification is available show a V-type spectra. Due to their characteristic infrared spectrum, V-type asteroids are easily distinguished. Before the discovery of 1459 Magnya (Lazzaro et al. 2000) and of several V-type NEA (Xu 1995), all the known V-type asteroids were members of the Vesta family. Recently two V-type asteroids, 809 Lundia and 956 Elisa, (Florczak et al. 2002) have been discovered well outside the limits of the family, near the Flora family. We currently know 22 V-type asteroids outside the family, in the inner asteroid belt (see Table 2).
    [Show full text]
  • The Minor Planet Bulletin
    THE MINOR PLANET BULLETIN OF THE MINOR PLANETS SECTION OF THE BULLETIN ASSOCIATION OF LUNAR AND PLANETARY OBSERVERS VOLUME 36, NUMBER 3, A.D. 2009 JULY-SEPTEMBER 77. PHOTOMETRIC MEASUREMENTS OF 343 OSTARA Our data can be obtained from http://www.uwec.edu/physics/ AND OTHER ASTEROIDS AT HOBBS OBSERVATORY asteroid/. Lyle Ford, George Stecher, Kayla Lorenzen, and Cole Cook Acknowledgements Department of Physics and Astronomy University of Wisconsin-Eau Claire We thank the Theodore Dunham Fund for Astrophysics, the Eau Claire, WI 54702-4004 National Science Foundation (award number 0519006), the [email protected] University of Wisconsin-Eau Claire Office of Research and Sponsored Programs, and the University of Wisconsin-Eau Claire (Received: 2009 Feb 11) Blugold Fellow and McNair programs for financial support. References We observed 343 Ostara on 2008 October 4 and obtained R and V standard magnitudes. The period was Binzel, R.P. (1987). “A Photoelectric Survey of 130 Asteroids”, found to be significantly greater than the previously Icarus 72, 135-208. reported value of 6.42 hours. Measurements of 2660 Wasserman and (17010) 1999 CQ72 made on 2008 Stecher, G.J., Ford, L.A., and Elbert, J.D. (1999). “Equipping a March 25 are also reported. 0.6 Meter Alt-Azimuth Telescope for Photometry”, IAPPP Comm, 76, 68-74. We made R band and V band photometric measurements of 343 Warner, B.D. (2006). A Practical Guide to Lightcurve Photometry Ostara on 2008 October 4 using the 0.6 m “Air Force” Telescope and Analysis. Springer, New York, NY. located at Hobbs Observatory (MPC code 750) near Fall Creek, Wisconsin.
    [Show full text]
  • Polarimetric Survey of Main-Belt Asteroids V
    A&A 599, A114 (2017) Astronomy DOI: 10.1051/0004-6361/201628485 & c ESO 2017 Astrophysics Polarimetric survey of main-belt asteroids V. The unusual polarimetric behavior of V-type asteroids? R. Gil-Hutton1; 2, C. López-Sisterna1, and M. F. Calandra1 1 Grupo de Ciencias Planetarias, Complejo Astronómico El Leoncito, UNLP-UNC-UNSJ-CONICET, Av. España 1512 sur, J5402DSP San Juan, Argentina e-mail: [email protected] 2 Universidad Nacional de San Juan, J. I. de la Roza 590 oeste, 5400 Rivadavia, San Juan, Argentina Received 10 March 2016 / Accepted 20 December 2016 ABSTRACT Aims. We present the results of a polarimetric survey of main-belt asteroids at Complejo Astronómico El Leoncito (CASLEO), San Juan, Argentina. The aims of this survey are to increase the database of asteroid polarimetry, to estimate diversity in polarimet- ric properties of asteroids that belong to different taxonomic classes, and to search for objects that exhibit anomalous polarimetric properties. Methods. The data were obtained using the CASPROF and CASPOL polarimeters at the 2:15 m telescope. The CASPROF polarimeter is a two-hole aperture polarimeter with rapid modulation and CASPOL is a polarimeter based on a CCD detector, which allows us to observe fainter objects with better signal-to-noise ratio. Results. The survey began in 1995 and data on a large sample of asteroids were obtained until 2012. A second period began in 2013 using a polarimeter with a more sensitive detector in order to study small asteroids, families, and special taxonomic groups. We obtained 55 polarimetric measurements for 28 V-type main belt asteroids, all of them polarimetrically observed for the first time.
    [Show full text]
  • Mineralogies and Source Regions of Near-Earth Asteroids ⇑ Tasha L
    Icarus 222 (2013) 273–282 Contents lists available at SciVerse ScienceDirect Icarus journal homepage: www.elsevier.com/locate/icarus Mineralogies and source regions of near-Earth asteroids ⇑ Tasha L. Dunn a, , Thomas H. Burbine b, William F. Bottke Jr. c, John P. Clark a a Department of Geography-Geology, Illinois State University, Normal, IL 61790, United States b Department of Astronomy, Mount Holyoke College, South Hadley, MA 01075, United States c Southwest Research Institute, Boulder, CO 80302, United States article info abstract Article history: Near-Earth Asteroids (NEAs) offer insight into a size range of objects that are not easily observed in the Received 8 October 2012 main asteroid belt. Previous studies on the diversity of the NEA population have relied primarily on mod- Revised 8 November 2012 eling and statistical analysis to determine asteroid compositions. Olivine and pyroxene, the dominant Accepted 8 November 2012 minerals in most asteroids, have characteristic absorption features in the visible and near-infrared Available online 21 November 2012 (VISNIR) wavelengths that can be used to determine their compositions and abundances. However, formulas previously used for deriving compositions do not work very well for ordinary chondrite Keywords: assemblages. Because two-thirds of NEAs have ordinary chondrite-like spectral parameters, it is essential Asteroids, Composition to determine accurate mineralogies. Here we determine the band area ratios and Band I centers of 72 Meteorites Spectroscopy NEAs with visible and near-infrared spectra and use new calibrations to derive the mineralogies 47 of these NEAs with ordinary chondrite-like spectral parameters. Our results indicate that the majority of NEAs have LL-chondrite mineralogies.
    [Show full text]
  • Multiple Asteroid Systems: Dimensions and Thermal Properties from Spitzer Space Telescope and Ground-Based Observations Q ⇑ F
    Icarus 221 (2012) 1130–1161 Contents lists available at SciVerse ScienceDirect Icarus journal homepage: www.elsevier.com/locate/icarus Multiple asteroid systems: Dimensions and thermal properties from Spitzer Space Telescope and ground-based observations q ⇑ F. Marchis a,g, , J.E. Enriquez a, J.P. Emery b, M. Mueller c, M. Baek a, J. Pollock d, M. Assafin e, R. Vieira Martins f, J. Berthier g, F. Vachier g, D.P. Cruikshank h, L.F. Lim i, D.E. Reichart j, K.M. Ivarsen j, J.B. Haislip j, A.P. LaCluyze j 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, USA 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, USA j Physics and Astronomy Department, University of North Carolina, Chapel Hill, NC 27514, USA article info abstract Article history: We collected mid-IR spectra from 5.2 to 38 lm using the Spitzer Space Telescope Infrared Spectrograph Available online 2 October 2012 of 28 asteroids representative of all established types of binary groups.
    [Show full text]
  • The Compositional Diversity of Non-Vesta Basaltic Asteroids
    The compositional diversity of non-Vesta basaltic asteroids The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Citation Leith, Thomas B. et al. "The compositional diversity of non-Vesta basaltic asteroids." Icarus 295 (October 2017): 61-73 © 2017 Elsevier As Published http://dx.doi.org/10.1016/j.icarus.2017.05.007 Publisher Elsevier BV Version Author's final manuscript Citable link https://hdl.handle.net/1721.1/127640 Terms of Use Creative Commons Attribution-NonCommercial-NoDerivs License Detailed Terms http://creativecommons.org/licenses/by-nc-nd/4.0/ The compositional diversity of non-Vesta basaltic asteroids Thomas B. Leitha,b, Nicholas A. Moskovitza, Rhiannon G. Maynec, Francesca E. DeMeod, Driss Takire, Brian J. Burta,d, Richard P. Binzeld, Dimitra Pefkoud aLowell Observatory, Flagstaff, AZ, 86001, USA bHarvard-Smithsonian Center for Astrophysics, Cambridge, MA, 02138, USA cMonnig Meteorite Collection, Texas Christian University, Fort Worth, TX, 76129, USA dMassachusetts Institute of Technology, Cambridge, MA, 02139, USA eAstrogeology Science Center, United States Geological Survey, Flagstaff, AZ, 86001, USA Abstract We present near-infrared (0.78-2.45 µm) reflectance spectra for nine middle and outer main belt (a > 2:5 AU) basaltic asteroids. Three of these objects are spectrally distinct from all classifications in the Bus-DeMeo system and could represent spectral end members in the existing taxonomy or be representatives of a new spectral type. The remainder of the sample are classified as V- or R- type. All of these asteroids are dynamically detached from the Vesta collisional family, but are too small to be intact differentiated parent bodies, implying that they originated from differentiated planetesimals which have since been destroyed or ejected from the solar system.
    [Show full text]
  • Asteroid Research Data Primer
    Asteroid Research Data Primer: A Case Study of one Team in the Exploration of the Moon and Asteroids by Secondary Students (ExMASS) Program Jimmy Newland & Jennifer Wang, Bellaire High School, Houston, TX This document is meant to be a starting point for student researchers when it comes to questions and research techniques in asteroid science. This document was written by the Bellaire High School student team leader during the 2014-2015 school year, Jennifer Wang, and the team’s teacher, Mr. Jimmy Newland. Speaking from personal experience – as a high schooler with a limited skill set and even more limited knowledge base – finding a suitable research topic is one of the biggest challenges presented by the ExMASS research program. The dearth of easily attainable data on asteroids only increases the difficulty. The Jet Propulsion Laboratory (JPL) has wonderful data on a large range of asteroids, but this data is incomplete in regards to most asteroids, because not enough studies have been performed, or some points remain controversial. Presented below is an account of how we acquired a topic and the subsequent data for our project - hypothesizing the former existence of a differentiated protoplanet in the 5:2 Kirkwood Gap between Mars and Jupiter. To start students off, the ExMASS program has several required readings: a general introduction to asteroids, including information about meteorite types, asteroid formation, mineralogy, relation to meteorites and various other properties. Whereas this information is essential to form a basic understanding, it is mostly facts and history – which is nowhere near detailed enough to help find a research topic.
    [Show full text]
  • Lucy F. Lim1, M. Antonietta Barucci2, Humberto Campins3, Philip R
    THE GLOBAL THERMAL INFRARED SPECTRUM OF BENNU: COMPARISON WITH SPITZER IRS ASTEROID SPECTRA Lucy F. Lim1, M. Antonietta Barucci2, Humberto Campins3, Philip R. Christensen4, Beth Clark5, Marco Delbo6, Joshua P. Emery7, Victoria E. Hamilton8, Javier Licandro9, Dante S. Lauretta10, and The OSIRIS-REx Team (1) NASA/GSFC (2) Paris Observatory Meudon (3) University of Central Florida, (4) Arizona State University, (5) Ithaca College, (6) CNRS, France (7) Univ of Tennessee- EPS, Knoxville, (8) Southwest Research Ins_tute Boulder, (9) Ins_tuto de Astro`sica de Canarias, (10) University of Arizona, Lunar and Planetary Laboratory SPITZER IRS ASTEROID SPECTRA BENNU AND LOW-ALBEDO ASTEROIDS AND COMETS BENNU: OTES VS. SPITZER IRS The Spitzer Space Telescope Infrared Spectrograph (“IRS”; Houck et al. 2004) observed dozens of asteroids and other small bodies during Bennu (thermal model 1) Emery et al., LPSC 2010 its cryogenic mission, 2003 to 2009, in a thermal-IR spectral range (5.2 to 38 microns) similar to that covered by OSIRIS-REx OTES. Bennu (thermal model 2) Targets included asteroids with a variety of sizes, VNIR spectral Bennu (thermal model 1) types, and dynamical characteristics (e.g., Barucci et al. 2008). Here we discuss the initial OTES spectra of (101955) Bennu (Hamilton et Bennu (thermal model 2) Bennu (2007 Spitzer IRS data) al., this meeting) in the context of the Spitzer data set. Bennu (200% contrast) Many low-albedo main-belt asteroids such as 24 Themis and 65 Cybele (Hargrove et al. 2012, 2015; Licandro et al. 2011) show emissivity “plateau" maxima in the 10-micron region rather than the 3200 Phaethon minima typical of silicate minerals and meteorites in the laboratory.
    [Show full text]
  • The Minor Planet Bulletin Is Open to Papers on All Aspects of 6500 Kodaira (F) 9 25.5 14.8 + 5 0 Minor Planet Study
    THE MINOR PLANET BULLETIN OF THE MINOR PLANETS SECTION OF THE BULLETIN ASSOCIATION OF LUNAR AND PLANETARY OBSERVERS VOLUME 32, NUMBER 3, A.D. 2005 JULY-SEPTEMBER 45. 120 LACHESIS – A VERY SLOW ROTATOR were light-time corrected. Aspect data are listed in Table I, which also shows the (small) percentage of the lightcurve observed each Colin Bembrick night, due to the long period. Period analysis was carried out Mt Tarana Observatory using the “AVE” software (Barbera, 2004). Initial results indicated PO Box 1537, Bathurst, NSW, Australia a period close to 1.95 days and many trial phase stacks further [email protected] refined this to 1.910 days. The composite light curve is shown in Figure 1, where the assumption has been made that the two Bill Allen maxima are of approximately equal brightness. The arbitrary zero Vintage Lane Observatory phase maximum is at JD 2453077.240. 83 Vintage Lane, RD3, Blenheim, New Zealand Due to the long period, even nine nights of observations over two (Received: 17 January Revised: 12 May) weeks (less than 8 rotations) have not enabled us to cover the full phase curve. The period of 45.84 hours is the best fit to the current Minor planet 120 Lachesis appears to belong to the data. Further refinement of the period will require (probably) a group of slow rotators, with a synodic period of 45.84 ± combined effort by multiple observers – preferably at several 0.07 hours. The amplitude of the lightcurve at this longitudes. Asteroids of this size commonly have rotation rates of opposition was just over 0.2 magnitudes.
    [Show full text]