available online at http://meteoritics.org Cosmogenic and trapped noble gases in individual chondrules:Clues to chondrule formation

Abstract-Neon was measured in 39 individual olivine (or olivine-rich) grains separated from individual chondrules from Dhajala, Bjurbo¨le, Chainpur, Murchison, and Parsa chondrites with spallation-produced 21 Ne the result of interaction of energetic particle irradiation. The apparent 21 Ne cosmic ray exposure (CRE) ages of most grains are similar to those of the matrix with the exception of three grains from Dhajala and single grains from Bjurbo¨le and Chainpur, which show excesses, reflecting exposure to energetic particles prior to final compaction of the object. Among these five grains, one from chondrule BJ2A5 of Bjurbo¨le shows an apparent excess exposure age of approximately 20 Ma and the other four from Dhajala and Chainpur have apparent excesses, described as an ''age,'' from 2 to 17 Ma. The precompaction irradiation effects of grains from chondrules do not appear to be different from the effects seen in olivine grains extracted from the matrix of CM chondrites. As was the case for the matrix grains, there appears to be insufficient time for this precompaction irradiation by the contemporary particle sources. The apparent variations within single chondrules appear to constrain precompaction irradiation effects to irradiation by lower energy solar particles, rather than galactic cosmic rays, supporting the conclusion derived from the precompaction irradiation effects in CM matrix grains, but for totally different reasons. This observation is consistent with Chandra X-Ray Observatory data for young lowmass stars, which suggest that our own Sun may have been 10 5 times more active in an early naked T-Tauri phase (Feigelson et al. 2002).

[1] Nitrogen amount and isotopic composition have been measured in individual chondrules of six ordinary chondrites (OC) and two each of carbonaceous (CC) and enstatite chondrites (EC N of the chondrules, we propose the presence of at least three N components carried by phase Q, presolar diamonds (HL), and insoluble organic matter (IOM). The precursors of chondrules from OC and CC are different than the bulk OC and CC, which represents the different environment for their formation, compared to the bulk OC and CC. However, for EC chondrules, precursors as well as the formation environment are the same as those of enstatite chondrites.

A comprehensive photometric and spectroscopic analysis of the variable TYC 5532-1333-1 (TYC) along with an investigation of its orbital period variation is presented for the first time. The B- and V-band photometric study indicates that TYC is an intermediate contact binary with degree of contact and mass ratio of 34 per cent and ∼0.24, respectively. The derived equivalent widths from the spectroscopic study of Hα and   Na-I lines reveal phase-dependent variation and mutual correlation. Using the available times of minimum light, an investigation of orbital period variation shows a long-term decrease at a rate of 3.98 × 10 −6 d yr−1. Expected causes for such decline in the orbital period could be angular momentum loss and a quasi-sinusoidal variation due to light-time effect probably caused by a third-body companion. The minimum mass of the third body (M3) was derived to be $0.65 \, \mathrm{M}_{\odot }$. Our presented study is an attempt to evaluate and understand the evolutionary state of above-mentioned neglected contact binary.