skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: DIFFERENT ORIGINS OR DIFFERENT EVOLUTIONS? DECODING THE SPECTRAL DIVERSITY AMONG C-TYPE ASTEROIDS

Abstract

Anhydrous pyroxene-rich interplanetary dust particles (IDPs) have been proposed as surface analogs for about two-thirds of all C-complex asteroids. However, this suggestion appears to be inconsistent with the presence of hydrated silicates on the surfaces of some of these asteroids, including Ceres. Here, we report the presence of enstatite (pyroxene) on the surface of two C-type asteroids (Ceres and Eugenia) based on their spectral properties in the mid-infrared range. The presence of this component is particularly unexpected in the case of Ceres, because most thermal evolution models predict a surface consisting of hydrated compounds only. The most plausible scenario is that Ceres’ surface has been partially contaminated by exogenous enstatite-rich material, possibly coming from the Beagle asteroid family. This scenario questions a similar origin for Ceres and the remaining C-types, and it possibly supports recent results obtained by the Dawn mission (NASA) that Ceres may have formed in the very outer solar system. Concerning the smaller D  ∼ 200 km C-types such as Eugenia, both their derived surface composition (enstatite and amorphous silicates) and low density (<1.5 g cm{sup −3}) suggest that these bodies accreted from the same building blocks, namely chondritic porous, pyroxene-rich IDPs and volatiles (mostly water ice), and that amore » significant volume fraction of these bodies has remained unaffected by hydrothermal activity likely implying a late accretion. In addition, their current heliocentric distance may best explain the presence or absence of water ice at their surfaces. Finally, we raise the possibility that CI chondrites, Tagish-Lake-like material, or hydrated IDPs may be representative samples of the cores of these bodies.« less

Authors:
; ; ; ; ; ;  [1];  [2];  [3];  [4]; ; ;  [5]; ;  [6];  [7];  [8];  [9]
  1. Aix Marseille Univ, CNRS, LAM, Laboratoire d’Astrophysique de Marseille, Marseille (France)
  2. Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)
  3. UJF-Grenoble 1, CNRS-INSU, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG), UMR 5274, Grenoble F-38041 (France)
  4. Department of Earth and Planetary Sciences and Planetary Geosciences Institute, University of Tennessee, Knoxville, TN 37996-1410 (United States)
  5. Institut d’Astrophysique Spatiale, CNRS, UMR-8617, Université Paris-Sud, bâtiment 121, F-91405 Orsay Cedex (France)
  6. Laboratoire Lagrange, UNS-CNRS, Observatoire de la Cote d’Azur, Boulevard de l’Observatoire-CS 34229, F-06304 Nice Cedex 4 (France)
  7. Carl Sagan Center at the SETI Institute, Mountain View, CA 94043 (United States)
  8. IMCCE, Observatoire de Paris, 77 avenue Denfert-Rochereau, F-75014 Paris Cedex (France)
  9. SMIS Beamline, Soleil Synchrotron, BP48, L’Orme des Merisiers, F-91192 Gif sur Yvette Cedex (France)
Publication Date:
OSTI Identifier:
22663992
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (Online); Journal Volume: 153; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTEROIDS; ASTROPHYSICS; CARBON COMPLEXES; CHONDRITES; DATA ANALYSIS; ENSTATITE; EVOLUTION; METEOROIDS; NASA; PLANETS; POROUS MATERIALS; SILICATES; SOLAR SYSTEM; SURFACES; WATER

Citation Formats

Vernazza, P., Marsset, M., Groussin, O., Lamy, P., Jorda, L., Mousis, O., Delsanti, A., Castillo-Rogez, J., Beck, P., Emery, J., Brunetto, R., Djouadi, Z., Dionnet, Z., Delbo, M., Carry, B., Marchis, F., Zanda, B., and Borondics, F., E-mail: pierre.vernazza@lam.fr. DIFFERENT ORIGINS OR DIFFERENT EVOLUTIONS? DECODING THE SPECTRAL DIVERSITY AMONG C-TYPE ASTEROIDS. United States: N. p., 2017. Web. doi:10.3847/1538-3881/153/2/72.
Vernazza, P., Marsset, M., Groussin, O., Lamy, P., Jorda, L., Mousis, O., Delsanti, A., Castillo-Rogez, J., Beck, P., Emery, J., Brunetto, R., Djouadi, Z., Dionnet, Z., Delbo, M., Carry, B., Marchis, F., Zanda, B., & Borondics, F., E-mail: pierre.vernazza@lam.fr. DIFFERENT ORIGINS OR DIFFERENT EVOLUTIONS? DECODING THE SPECTRAL DIVERSITY AMONG C-TYPE ASTEROIDS. United States. doi:10.3847/1538-3881/153/2/72.
Vernazza, P., Marsset, M., Groussin, O., Lamy, P., Jorda, L., Mousis, O., Delsanti, A., Castillo-Rogez, J., Beck, P., Emery, J., Brunetto, R., Djouadi, Z., Dionnet, Z., Delbo, M., Carry, B., Marchis, F., Zanda, B., and Borondics, F., E-mail: pierre.vernazza@lam.fr. Wed . "DIFFERENT ORIGINS OR DIFFERENT EVOLUTIONS? DECODING THE SPECTRAL DIVERSITY AMONG C-TYPE ASTEROIDS". United States. doi:10.3847/1538-3881/153/2/72.
@article{osti_22663992,
title = {DIFFERENT ORIGINS OR DIFFERENT EVOLUTIONS? DECODING THE SPECTRAL DIVERSITY AMONG C-TYPE ASTEROIDS},
author = {Vernazza, P. and Marsset, M. and Groussin, O. and Lamy, P. and Jorda, L. and Mousis, O. and Delsanti, A. and Castillo-Rogez, J. and Beck, P. and Emery, J. and Brunetto, R. and Djouadi, Z. and Dionnet, Z. and Delbo, M. and Carry, B. and Marchis, F. and Zanda, B. and Borondics, F., E-mail: pierre.vernazza@lam.fr},
abstractNote = {Anhydrous pyroxene-rich interplanetary dust particles (IDPs) have been proposed as surface analogs for about two-thirds of all C-complex asteroids. However, this suggestion appears to be inconsistent with the presence of hydrated silicates on the surfaces of some of these asteroids, including Ceres. Here, we report the presence of enstatite (pyroxene) on the surface of two C-type asteroids (Ceres and Eugenia) based on their spectral properties in the mid-infrared range. The presence of this component is particularly unexpected in the case of Ceres, because most thermal evolution models predict a surface consisting of hydrated compounds only. The most plausible scenario is that Ceres’ surface has been partially contaminated by exogenous enstatite-rich material, possibly coming from the Beagle asteroid family. This scenario questions a similar origin for Ceres and the remaining C-types, and it possibly supports recent results obtained by the Dawn mission (NASA) that Ceres may have formed in the very outer solar system. Concerning the smaller D  ∼ 200 km C-types such as Eugenia, both their derived surface composition (enstatite and amorphous silicates) and low density (<1.5 g cm{sup −3}) suggest that these bodies accreted from the same building blocks, namely chondritic porous, pyroxene-rich IDPs and volatiles (mostly water ice), and that a significant volume fraction of these bodies has remained unaffected by hydrothermal activity likely implying a late accretion. In addition, their current heliocentric distance may best explain the presence or absence of water ice at their surfaces. Finally, we raise the possibility that CI chondrites, Tagish-Lake-like material, or hydrated IDPs may be representative samples of the cores of these bodies.},
doi = {10.3847/1538-3881/153/2/72},
journal = {Astronomical Journal (Online)},
number = 2,
volume = 153,
place = {United States},
year = {Wed Feb 01 00:00:00 EST 2017},
month = {Wed Feb 01 00:00:00 EST 2017}
}
  • The discovery circumstances of the near-earth asteroids (NEAs) were modeled in order to investigate the observational selection effects associated with NEAs. It is suggested that these selection effects are responsible for the apparent overabundance of S types among the NEAs and that this overabundance is in part a result of the larger phase darkening of the C types over the S types. The large phase angles and preferential phase darkening of the C type NEAs force some of them below the threshold of detectability (in a magnitude-limited survey), thus exaggerating the number of S type NEAs. 23 refs.
  • We present a spectroscopic analysis of the H{sub α} profiles of hydrogen-rich Type II supernovae. A total of 52 Type II supernovae having well-sampled optical light curves and spectral sequences were analyzed. Concentrating on the H{sub α} P-Cygni profile we measure its velocity from the FWHM of the emission and the ratio of absorption to emission (a/e) at a common epoch at the start of the recombination phase, and search for correlations between these spectral parameters and photometric properties of the V-band light curves. Testing the strength of various correlations we find that a/e appears to be the dominant spectralmore » parameter in terms of describing the diversity in our measured supernova properties. It is found that supernovae with smaller a/e have higher H{sub α} velocities, more rapidly declining light curves from maximum during the plateau and radioactive tail phase, are brighter at maximum light, and have shorter optically thick phase durations. We discuss possible explanations of these results in terms of physical properties of Type II supernovae, speculating that the most likely parameters that influence the morphologies of H{sub α} profiles are the mass and density profile of the hydrogen envelope, together with additional emission components due to circumstellar interaction.« less
  • Cuprous oxide films have been deposited on quartz substrates by a sol-gel method under various annealing temperatures. The X-ray diffraction analysis and Raman scattering show that all the films are of pure Cu{sub 2}O phase. From comparison of photoluminescence with 488 and 325 nm laser excitations, the electronic transition energies and intensities present the annealing-temperature dependent behavior. The electronic band structures of the Cu{sub 2}O film annealed at 800 °C, especially for the contribution of exciton series and high energy transitions, have been investigated by temperature dependent transmittance. The extracted refraction index and the high frequency dielectric constant both abruptly decrease untilmore » the temperature rises up to 100 K. Six transitions can be clearly identified and the red shift trend of E{sub o3}-E{sub o5} transition energies with increasing the temperature can be found. Moreover, the anomalous behavior takes place at about 200 K from the E{sub o6} transition. The singularities indicate that the change in the crystalline and electronic band structure occurs as the temperature near 100 K and 200 K for the film.« less
  • Type Ibn supernovae (SNe) are a small yet intriguing class of explosions whose spectra are characterized by low-velocity helium emission lines with little to no evidence for hydrogen. The prevailing theory has been that these are the core-collapse explosions of very massive stars embedded in helium-rich circumstellar material (CSM). We report optical observations of six new SNe Ibn: PTF11rfh, PTF12ldy, iPTF14aki, iPTF15ul, SN 2015G, and iPTF15akq. This brings the sample size of such objects in the literature to 22. We also report new data, including a near-infrared spectrum, on the Type Ibn SN 2015U. In order to characterize the classmore » as a whole, we analyze the photometric and spectroscopic properties of the full Type Ibn sample. We find that, despite the expectation that CSM interaction would generate a heterogeneous set of light curves, as seen in SNe IIn, most Type Ibn light curves are quite similar in shape, declining at rates around 0.1 mag day{sup −1} during the first month after maximum light, with a few significant exceptions. Early spectra of SNe Ibn come in at least two varieties, one that shows narrow P Cygni lines and another dominated by broader emission lines, both around maximum light, which may be an indication of differences in the state of the progenitor system at the time of explosion. Alternatively, the spectral diversity could arise from viewing-angle effects or merely from a lack of early spectroscopic coverage. Together, the relative light curve homogeneity and narrow spectral features suggest that the CSM consists of a spatially confined shell of helium surrounded by a less dense extended wind.« less
  • Type Ibn supernovae (SNe) are a small yet intriguing class of explosions whose spectra are characterized by low-velocity helium emission lines with little to no evidence for hydrogen. The prevailing theory has been that these are the core-collapse explosions of very massive stars embedded in helium-rich circumstellar material (CSM). We report optical observations of six new SNe Ibn: PTF11rfh, PTF12ldy, iPTF14aki, iPTF15ul, SN 2015G, and iPTF15akq. This brings the sample size of such objects in the literature to 22. We also report new data, including a near-infrared spectrum, on the Type Ibn SN 2015U. In order to characterize the classmore » as a whole, we analyze the photometric and spectroscopic properties of the full Type Ibn sample. Here, we find that, despite the expectation that CSM interaction would generate a heterogeneous set of light curves, as seen in SNe IIn, most Type Ibn light curves are quite similar in shape, declining at rates around 0.1 mag day -1 during the first month after maximum light, with a few significant exceptions. Early spectra of SNe Ibn come in at least two varieties, one that shows narrow P Cygni lines and another dominated by broader emission lines, both around maximum light, which may be an indication of differences in the state of the progenitor system at the time of explosion. Alternatively, the spectral diversity could arise from viewing-angle effects or merely from a lack of early spectroscopic coverage. Finally, together, the relative light curve homogeneity and narrow spectral features suggest that the CSM consists of a spatially confined shell of helium surrounded by a less dense extended wind.« less