J/ApJ/882/L22ivo://CDS.VizieR/J/ApJ/882/L22doi:10.26093/cds/vizier.18829022CDSPalomba E.D'Aversa E.Sato T.M.Longobardo A.Dirri F.Aoki S.,Orton G.Sindoni G.Oliva F.Carrozzo G.Kasaba Y.2021-07-05T08:30:56Z2021-03-08T12:42:42ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frasteroidsinfrared-astronomyspectroscopyPlagioclase feldspars are among the most prevalent minerals in the solar system, and are present in many chondritic and achondritic meteorite families. Nevertheless, spectral features of plagioclases have never been unambiguously and directly observed in remote observations of asteroids. We report here the detection of an absorption band at 12.2{mu}m on Vesta spectra provided by ground-based spectral observations at the Subaru Telescope. This signature represents the first direct evidence of a widespread presence of crystalline Ca-rich plagioclase on Vesta and reveals that its regolith is comminuted to a very fine grain size, smaller than a few tens of microns, indicating that the mechanical brecciation process has been very effective. The crystalline nature of plagioclase strongly suggests that impacts alone cannot be the sole mechanism for regolith formation on Vesta and a milder process, such as thermal fatigue, should be invoked as an important and concomitant process Thermal fatigue should be considered a very effective process in regolith production and rejuvenation not only for near-Earth asteroids but even for large asteroids located in the main belt.2019ApJ...882L..22Phttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/882/L22CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/MNRAS/456/248 : (4) Vesta adopted polarimetric light curves (Cellino+, 2016)J/A+A/623/A6 : VLT/SPHERE/ZIMPOL images of Vesta (Fetick+, 2019)J/AJ/159/264 : Obs. of 10 Vesta asteroids with WISE/NEOWISE (Jiang+, 2020)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/882/L22https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/882/L22http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/882/L22https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/882/L22https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/882/L22http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/882/L22GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapInfrareddefaultJ/ApJ/882/L22/laboCombined table from original tablesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintWavenum[624.85/3332.56] Wavenumbercm**-1em.wavenumberdoubleGraineucrite NWA7854 or howardite NWA2698stat.fit.paramcharlambda[3.00069/16.00372] Wavelengthumem.wldoubleem[0.874/0.992] Emissivityphys.emissivitydoubleJ/ApJ/882/L22/emissivityCombined table from original tablesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDateDate of the observation'Y-M-D'time.epochcharlambda[7.67/13.1] Wavelengthumem.wlfloatem[0.81/0.96]? Emissivityphys.emissivityfloatnullablee_em[0.007/0.08]? Uncertainty in emstat.errorfloatnullableTssTss parameterstat.fit.paramcharGEglob. emiss. parameterstat.fit.paramcharGRglob. rough. parameterstat.fit.paramcharGFglob. fact. parameterstat.fit.paramchar