scholarly journals Widespread carbon-bearing materials on near-Earth asteroid (101955) Bennu

Science ◽  
2020 ◽  
Vol 370 (6517) ◽  
pp. eabc3522 ◽  
Author(s):  
Amy A. Simon ◽  
Hannah H. Kaplan ◽  
Victoria E. Hamilton ◽  
Dante S. Lauretta ◽  
Humberto Campins ◽  
...  
Keyword(s):  
Near Infrared ◽  
Absorption Feature ◽  
Space Weathering ◽  
Spectral Slope ◽  
Main Belt ◽  
Recent Exposure ◽  
Spatially Resolved ◽  
Near Infrared Spectra ◽  
Bearing Materials ◽  
Carbonate Materials

Asteroid (101955) Bennu is a dark asteroid on an Earth-crossing orbit that is thought to have assembled from the fragments of an ancient collision. We use spatially resolved visible and near-infrared spectra of Bennu to investigate its surface properties and composition. In addition to a hydrated phyllosilicate band, we detect a ubiquitous 3.4-micrometer absorption feature, which we attribute to a mix of organic and carbonate materials. The shape and depth of this absorption feature vary across Bennu’s surface, spanning the range seen among similar main-belt asteroids. The distribution of the absorption feature does not correlate with temperature, reflectance, spectral slope, or hydrated minerals, although some of those characteristics correlate with each other. The deepest 3.4-micrometer absorptions occur on individual boulders. The variations may be due to differences in abundance, recent exposure, or space weathering.

Characterization of the craters’ surface at Ryugu using NIR spectroscopy

2021 ◽  
Author(s):  
Lucie Riu ◽  
Cédric Pilorget ◽  
Ralph Milliken ◽  
Kohei Kitazato ◽  
Tomoki Nakamura ◽  
...  
Keyword(s):  
Near Infrared ◽  
Spectral Characteristics ◽  
Solar Heating ◽  
Absorption Feature ◽  
Space Weathering ◽  
Near Surface ◽  
Exposure Age ◽  
Reflectance Factor ◽  
Subsurface Material ◽  
Band Depth

<div> <p>Asteroid Ryugu was observed up close for almost a year and a half by the instruments on-board the Japanese Aerospace eXploration Agency (JAXA) Hayabusa2 spacecraft. It has been shown that in the near-infrared wavelength ranges, the asteroid exhibits relatively homogeneous spectral characteristics: including a very low reflectance factor, a slight red slope towards longer wavelengths, and a narrow and weak absorption feature centered at 2.72 <span>μ</span>m. Numerous craters have been identified at the surface of Ryugu. These features provide good candidates for studying more recently exposed near-surface material to further assess potential spectral/compositional heterogeneities of Ryugu. We present here the results of a spectral survey of all previously identified and referenced craters (Hirata et al. 2020) based on reflectance data acquired by the NIRS3 spectrometer. Globally, we find that the spectral properties inside and outside of craters are very similar, indicating that subsurface material is either compositionally similar to material at the surface that has a longer exposure age or that material at Ryugu’s optical surface is spectrally altered over relatively short timescales by external factors such as space weathering. The 2.72 <span>μ</span>m band depth, present on the overall surface, exhibits a slight anti-correlation with the reflectance factor selected at 2 <span>μ</span>m, which could indicate different surface properties (<em>e.g.</em>, grain size and/or porosity) or different alteration processes (<em>e.g.</em>, space weathering, shock metamorphism and/or solar heating). We identified four different spectral classes based on their reflectance factor at 2 <span>μ</span>m and 2.72 <span>μ</span>m absorption strength. The most commonly spectral behavior associated with crater floors, is defined by a slightly lower reflectance at 2 <span>μ</span>m and deeper band depth. These spectral characteristics are similar to those of subsurface material excavated by the Hayabusa2 small carry-on impactor (SCI) experiment, suggesting these spectral characteristics may represent materials with a younger surface exposure age. Conversely, these materials may have experienced significant solar heating and desiccation to form finer grains that subsequently migrated towards and preferentially accumulated in areas of low geopotential, such as craters floors. Detailed analyses of the returned samples of Ryugu that are now being investigated at the curation facility in ISAS will allow for further testing of these formation and alteration hypotheses.<span> </span></p> </div>

scholarly journals Space weathering of asteroids: similarities and discrepancies between Main Belt asteroids and NEOs

2006 ◽  
Vol 2 (S236) ◽  
pp. 239-242 ◽  
Author(s):  
S. Marchi ◽  
P. Paolicchi ◽  
M. Lazzarin ◽  
S. Magrin
Keyword(s):  
Ion Flux ◽  
Space Weathering ◽  
The Sun ◽  
Spectral Slope ◽  
Main Belt ◽  
Complex Objects ◽  
General Behavior ◽  
The Poor ◽  
C Complex ◽  
Near Earth Objects

AbstractA sample of 35 C–complex objects is present among near–Earth objects. In spite of the poor statistics, some striking differences compared to Main Belt asteroids can be established: for instance the percentage of near–Earth objects (NEOs) showing hydration features is very small. Moreover the spectral slope of C–complex NEOs seems to be anti–correlated with the exposure to the ion flux coming from the Sun, in contrast with the general behavior of C–complex Main Belt asteroids (and of most asteroids, in general). We discuss some possible implications and suggest some preliminary partial explanations.

NEAR-INFRARED SPECTRA OF HIGH-ALBEDO OUTER MAIN-BELT ASTEROIDS

2015 ◽  
Vol 149 (2) ◽  
pp. 37
Author(s):  
Toshihiro Kasuga ◽  
Fumihiko Usui ◽  
Mai Shirahata ◽  
Daisuke Kuroda ◽  
Takafumi Ootsubo ◽  
...  
Keyword(s):  
Infrared Spectra ◽  
Near Infrared ◽  
Main Belt ◽  
Near Infrared Spectra

HIGH-ALBEDO C-COMPLEX ASTEROIDS IN THE OUTER MAIN BELT: THE NEAR-INFRARED SPECTRA

2013 ◽  
Vol 146 (1) ◽  
pp. 1 ◽  
Author(s):  
Toshihiro Kasuga ◽  
Fumihiko Usui ◽  
Takafumi Ootsubo ◽  
Sunao Hasegawa ◽  
Daisuke Kuroda
Keyword(s):  
Infrared Spectra ◽  
Near Infrared ◽  
Main Belt ◽  
Near Infrared Spectra ◽  
C Complex

scholarly journals Space Weathering of S-Complex Asteroids Manifested in the UV/Blue: Recent Insights and Future Directions

2015 ◽  
Vol 10 (S318) ◽  
pp. 201-205
Author(s):  
Faith Vilas ◽  
Amanda R. Hendrix
Keyword(s):  
Spectral Reflectance ◽  
Near Infrared ◽  
Uv Absorption ◽  
Reflectance Spectra ◽  
Absorption Feature ◽  
Space Weathering ◽  
The Moon ◽  
Future Directions ◽  
Absorption Features ◽  
Weathering Effects

AbstractSpace weathering affects reflectance spectra of the Moon and S-complex asteroids by spectral bluing (increasing reflectance with decreasing wavelength) of their surface materials at UV/blue (less than 400 nm) wavelengths. This spectral bluing is attributed to a degradation of the UV absorption feature seen in spectral reflectance of olivine as a result of the creation of nanophase (npFe0) iron. We have modeled the effect of the addition of small amounts of npFe0 intimately mixed with particles from a hypothetical material and a terrestrial basalt. The addition of 0.0001% npFe0 affects the reflectance at these UV/blue wavelengths, while the addition of 0.01% is required to see the visible/near infrared reddening and diminution of VNIR absorption features. Thus, the UV/blue spectral reflectance characteristics allow earlier detection of the onset of space weathering effects.

scholarly journals Near-Infrared Spectra of ARP 220: Spatially Resolved CO Absorption in the Inner Kiloparsec

1995 ◽  
Vol 110 ◽  
pp. 2610 ◽  
Author(s):  
L. Armus ◽  
G. Neugebauer ◽  
B. T. Soifer ◽  
K. Matthews
Keyword(s):  
Infrared Spectra ◽  
Near Infrared ◽  
Spatially Resolved ◽  
Near Infrared Spectra

Spectroscopic study of Ceres' collisional family candidate members: taxonomic classification and comparison to Ceres' surface.

2021 ◽  
Author(s):  
Fernando Tinaut-Ruano ◽  
Julia de Leon ◽  
Eri Tatsumi ◽  
Batiste Rousseau ◽  
Juan Luis Rizos
Keyword(s):  
Near Infrared ◽  
Asteroid Belt ◽  
Space Weathering ◽  
Spectral Slope ◽  
Dynamical Study ◽  
Royal Astronomical Society ◽  
La Palma ◽  
The Family ◽  
Visible Spectra ◽  
Main Asteroid Belt

<p>Despite the observed signs of large impacts on the surface of Ceres, there is no confirmed collisional family associated with this dwarf planet. Carruba et al. (2016) carried out a dynamical study in the ‘pristine region’ of the main asteroid belt and proposed a sample of 156 asteroids as candidates to be members of a Ceres’ collisional family. Our main objective in this work is to study the spectral link between Ceres and a total of 14 observed asteroids among the family candidate samples proposed by Carruba et al. (2016) to explore their potential membership to the collisional family.</p> <p>For this aim we obtained visible spectra of these 14 asteroids using the OSIRIS spectrograph at the 10.4m Gran Telescopio de Canarias (GTC), located at the El Roque de los Muchachos Observatory (La Palma, Spain), managed by the Instituto de Astrofísica de Canarias (IAC). We reduced the raw images and extracted the spectra with a semi-automatic Python-based pipeline. After that, we computed spectral slopes in two different wavelength ranges: one in the visible (490-800 nm) and one in the visible-near-infrared (800-920 nm) to compare the obtained values with those in Ceres’ surface already Ncomputed by Rousseau et al. (2020) using the spectrometer onboard the NASA Dawn spacecraft.</p> <p>We present the spectra and the taxonomy of 14 observed asteroids, their taxonomy, and calculated slopes. We concluded that only one asteroid could be compatible with an origin in a primitive collision at Ceres. We have also found a hydration band at 700 nm, also found in the surroundings of crater Occattor (Rizos et al. 2019). On the other hand, we have also found a relation between the spectral slope of the craters in Ceres’ surface and their age in both wavelength ranges. This behavior could be related to space weathering.</p> <p>Exploring the sample as a whole, the variability in member’s taxonomy and the differences in their spectral slopes makes us conclude that they cannot be considered as members of a collisional family of Ceres. However, the presence of a hydration band in one of the asteroids could be proof that such a family may have existed.</p> <p> </p> <p> </p> <p>Bibliography:</p> <p>Carruba, V., Nesvorný, D., Marchi, S., & Aljbaae, S. 2016, Monthly Notices of the Royal Astronomical Society, 458, 1117</p> <p>Rousseau, B., De Sanctis, M. C., Raponi, A., et al. 2020, A&A, 642, A74</p> <p>Rizos, J. L., de León, J., Licandro, J., et al. 2019, Icarus, 328, 69</p>

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