Comment on "Cosmogenic neon in grains separated from individual chondrules: Evidence of precompaction exposure in chondrules" by J. P. Das, J. N. Goswami, O. V. Pravdivtseva, A. P. Meshik, and C. M. Hohenberg

U. Ott, R. Wieler, L. Huber

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Das et al. (2012) claim that in several cases nominal cosmic ray exposure ages derived from concentrations of cosmogenic Ne in individual olivine grains separated from chondrules substantially exceed exposure ages of matrix samples. Some grains were also reported to show larger apparent exposure ages than other grains from the same chondrule. The authors conclude that the excesses were caused by an exposure of chondrules to high fluences of solar energetic particles and suggest that their data provide direct evidence for a highly active phase of the early Sun, similar to what is observed in X-ray emissions of recent naked T-Tauri stars. Here, we show that the production rates of cosmogenic Ne used by Das et al. (2012) to derive nominal cosmic ray exposure ages of their olivine grains are often much too low, as the reported major element concentrations in many cases sum up to considerably less than 100% even if converted to oxides. In contrast, adopted element concentrations for matrix samples are basically self-consistent. A precompaction exposure of chondrules to a very high flux of solar energetic particles is thus not supported by the data presented by Das et al. (2012). Das et al. (2012) claim that in several cases nominal cosmic ray exposure ages derived from concentrations of cosmogenic Ne in individual olivine grains separated from chondrules substantially exceed exposure ages of matrix samples. Some grains were also reported to show larger apparent exposure ages than other grains from the same chondrule. The authors conclude that the excesses were caused by an exposure of chondrules to high fluences of solar energetic particles and suggest that their data provide direct evidence for a highly active phase of the early Sun, similar to what is observed in X-ray emissions of recent naked T-Tauri stars. Here, we show that the production rates of cosmogenic Ne used by Das et al. (2012) to derive nominal cosmic ray exposure ages of their olivine grains are often much too low, as the reported major element concentrations in many cases sum up to considerably less than 100% even if converted to oxides. In contrast, adopted element concentrations for matrix samples are basically self-consistent. A precompaction exposure of chondrules to a very high flux of solar energetic particles is thus not supported by the data presented by Das et al. (2012).

Original languageEnglish
Pages (from-to)1524-1528
Number of pages5
JournalMeteoritics and Planetary Science
Volume48
Issue number8
DOIs
Publication statusPublished - Aug 2013

Fingerprint

chondrule
neon
energetic particles
olivine
cosmic ray
cosmic rays
energetics
matrix
T Tauri stars
matrices
exposure
fluence
sun
oxide
oxides
x rays

ASJC Scopus subject areas

  • Geophysics
  • Space and Planetary Science

Cite this

@article{e1c6873ebbb84942a4847b840417f5cd,
title = "Comment on {"}Cosmogenic neon in grains separated from individual chondrules: Evidence of precompaction exposure in chondrules{"} by J. P. Das, J. N. Goswami, O. V. Pravdivtseva, A. P. Meshik, and C. M. Hohenberg",
abstract = "Das et al. (2012) claim that in several cases nominal cosmic ray exposure ages derived from concentrations of cosmogenic Ne in individual olivine grains separated from chondrules substantially exceed exposure ages of matrix samples. Some grains were also reported to show larger apparent exposure ages than other grains from the same chondrule. The authors conclude that the excesses were caused by an exposure of chondrules to high fluences of solar energetic particles and suggest that their data provide direct evidence for a highly active phase of the early Sun, similar to what is observed in X-ray emissions of recent naked T-Tauri stars. Here, we show that the production rates of cosmogenic Ne used by Das et al. (2012) to derive nominal cosmic ray exposure ages of their olivine grains are often much too low, as the reported major element concentrations in many cases sum up to considerably less than 100{\%} even if converted to oxides. In contrast, adopted element concentrations for matrix samples are basically self-consistent. A precompaction exposure of chondrules to a very high flux of solar energetic particles is thus not supported by the data presented by Das et al. (2012). Das et al. (2012) claim that in several cases nominal cosmic ray exposure ages derived from concentrations of cosmogenic Ne in individual olivine grains separated from chondrules substantially exceed exposure ages of matrix samples. Some grains were also reported to show larger apparent exposure ages than other grains from the same chondrule. The authors conclude that the excesses were caused by an exposure of chondrules to high fluences of solar energetic particles and suggest that their data provide direct evidence for a highly active phase of the early Sun, similar to what is observed in X-ray emissions of recent naked T-Tauri stars. Here, we show that the production rates of cosmogenic Ne used by Das et al. (2012) to derive nominal cosmic ray exposure ages of their olivine grains are often much too low, as the reported major element concentrations in many cases sum up to considerably less than 100{\%} even if converted to oxides. In contrast, adopted element concentrations for matrix samples are basically self-consistent. A precompaction exposure of chondrules to a very high flux of solar energetic particles is thus not supported by the data presented by Das et al. (2012).",
author = "U. Ott and R. Wieler and L. Huber",
year = "2013",
month = "8",
doi = "10.1111/maps.12167",
language = "English",
volume = "48",
pages = "1524--1528",
journal = "Meteoritics and Planetary Science",
issn = "1086-9379",
publisher = "The University of Arkansas Press",
number = "8",

}

TY - JOUR

T1 - Comment on "Cosmogenic neon in grains separated from individual chondrules

T2 - Evidence of precompaction exposure in chondrules" by J. P. Das, J. N. Goswami, O. V. Pravdivtseva, A. P. Meshik, and C. M. Hohenberg

AU - Ott, U.

AU - Wieler, R.

AU - Huber, L.

PY - 2013/8

Y1 - 2013/8

N2 - Das et al. (2012) claim that in several cases nominal cosmic ray exposure ages derived from concentrations of cosmogenic Ne in individual olivine grains separated from chondrules substantially exceed exposure ages of matrix samples. Some grains were also reported to show larger apparent exposure ages than other grains from the same chondrule. The authors conclude that the excesses were caused by an exposure of chondrules to high fluences of solar energetic particles and suggest that their data provide direct evidence for a highly active phase of the early Sun, similar to what is observed in X-ray emissions of recent naked T-Tauri stars. Here, we show that the production rates of cosmogenic Ne used by Das et al. (2012) to derive nominal cosmic ray exposure ages of their olivine grains are often much too low, as the reported major element concentrations in many cases sum up to considerably less than 100% even if converted to oxides. In contrast, adopted element concentrations for matrix samples are basically self-consistent. A precompaction exposure of chondrules to a very high flux of solar energetic particles is thus not supported by the data presented by Das et al. (2012). Das et al. (2012) claim that in several cases nominal cosmic ray exposure ages derived from concentrations of cosmogenic Ne in individual olivine grains separated from chondrules substantially exceed exposure ages of matrix samples. Some grains were also reported to show larger apparent exposure ages than other grains from the same chondrule. The authors conclude that the excesses were caused by an exposure of chondrules to high fluences of solar energetic particles and suggest that their data provide direct evidence for a highly active phase of the early Sun, similar to what is observed in X-ray emissions of recent naked T-Tauri stars. Here, we show that the production rates of cosmogenic Ne used by Das et al. (2012) to derive nominal cosmic ray exposure ages of their olivine grains are often much too low, as the reported major element concentrations in many cases sum up to considerably less than 100% even if converted to oxides. In contrast, adopted element concentrations for matrix samples are basically self-consistent. A precompaction exposure of chondrules to a very high flux of solar energetic particles is thus not supported by the data presented by Das et al. (2012).

AB - Das et al. (2012) claim that in several cases nominal cosmic ray exposure ages derived from concentrations of cosmogenic Ne in individual olivine grains separated from chondrules substantially exceed exposure ages of matrix samples. Some grains were also reported to show larger apparent exposure ages than other grains from the same chondrule. The authors conclude that the excesses were caused by an exposure of chondrules to high fluences of solar energetic particles and suggest that their data provide direct evidence for a highly active phase of the early Sun, similar to what is observed in X-ray emissions of recent naked T-Tauri stars. Here, we show that the production rates of cosmogenic Ne used by Das et al. (2012) to derive nominal cosmic ray exposure ages of their olivine grains are often much too low, as the reported major element concentrations in many cases sum up to considerably less than 100% even if converted to oxides. In contrast, adopted element concentrations for matrix samples are basically self-consistent. A precompaction exposure of chondrules to a very high flux of solar energetic particles is thus not supported by the data presented by Das et al. (2012). Das et al. (2012) claim that in several cases nominal cosmic ray exposure ages derived from concentrations of cosmogenic Ne in individual olivine grains separated from chondrules substantially exceed exposure ages of matrix samples. Some grains were also reported to show larger apparent exposure ages than other grains from the same chondrule. The authors conclude that the excesses were caused by an exposure of chondrules to high fluences of solar energetic particles and suggest that their data provide direct evidence for a highly active phase of the early Sun, similar to what is observed in X-ray emissions of recent naked T-Tauri stars. Here, we show that the production rates of cosmogenic Ne used by Das et al. (2012) to derive nominal cosmic ray exposure ages of their olivine grains are often much too low, as the reported major element concentrations in many cases sum up to considerably less than 100% even if converted to oxides. In contrast, adopted element concentrations for matrix samples are basically self-consistent. A precompaction exposure of chondrules to a very high flux of solar energetic particles is thus not supported by the data presented by Das et al. (2012).

UR - http://www.scopus.com/inward/record.url?scp=84883265358&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84883265358&partnerID=8YFLogxK

U2 - 10.1111/maps.12167

DO - 10.1111/maps.12167

M3 - Article

AN - SCOPUS:84883265358

VL - 48

SP - 1524

EP - 1528

JO - Meteoritics and Planetary Science

JF - Meteoritics and Planetary Science

SN - 1086-9379

IS - 8

ER -