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首页> 外文期刊>The Astrophysical journal >INTERSTELLAR HELIUM TRAPPED WITH THE COLLISA EXPERIMENT ON THE MIR SPACE STATION-IMPROVED ISOTOPE ANALYSIS BY IN VACUO ETCHING
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INTERSTELLAR HELIUM TRAPPED WITH THE COLLISA EXPERIMENT ON THE MIR SPACE STATION-IMPROVED ISOTOPE ANALYSIS BY IN VACUO ETCHING

机译：真空刻蚀法研究星际氦气对科里萨实验的MIR空间站改进同位素分析

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摘要

We have redetermined the helium isotopic composition of the local interstellar cloud (LIC) in the framework of the Swiss-Russian Collection of Interstellar Atoms (COLLISA) collaboration. Based on in vacuo etching analyses of foils that have been exposed to the interstellar neutral particle flux on board the Mir space station, we obtain (~3He/~4He)_(LIC) = (1.62 ± 0.29) x 10~(-4). This is the most precise determination of the He isotopic composition of the LIC, with errors being lower by more than a factor of 2 compared to an earlier experiment on similar foils and compared to the analysis of interstellar pick-up ions. Comparing our improved result with current models of Galactic chemical evolution reveals that close to 100% of all Galactic low-mass stars must have undergone extra mixing associated with cool bottom processing. The ~3He abundance relative to ~4He in the LIC is within the uncertainty identical to the value of (1.66 ± 0.06) x 10~(-4) inferred for the protosolar cloud (PSC), showing that no significant evolution of the ~3He abundance took place since 4.6 Gyr ago at the solar distance (～8 kpc) from the Galactic center. Our value sets new rigorous constraints on Galactic evolution models. Since the Big Bang nucleosynthesis theory predicts a value of ≤(1.1 ± 0.2) x 10~(-4), a noticeable increase of the relative abundance of ~3He has apparently occurred in the Galaxy before the formation of the solar system, but, contrary to earlier expectations, only a modest or negligible increase is registered after the formation of the solar system.
机译：我们已经在瑞士-俄罗斯星际原子收集（COLLISA）合作的框架中重新确定了本地星际云（LIC）的氦同位素组成。根据对暴露于和平号空间站上星际中性粒子通量的箔进行真空蚀刻分析，我们得出（〜3He /〜4He）_（LIC）=（1.62±0.29）x 10〜（-4 ）。这是LIC中He同位素组成的最精确测定，与早期类似箔片上的实验相比，与星际吸收离子分析相比，其误差降低了2倍以上。将我们的改进结果与现有的银河系化学演化模型进行比较后发现，近100％的银河系低质量恒星必须经过与冷塔底处理相关的额外混合。 LIC中〜3He相对于〜4He的丰度在不确定度内，该值与针对原云（PSC）推断的（1.66±0.06）x 10〜（-4）的值相同，表明〜3He没有明显的演化自4.6吉尔以来，在距银河系中心太阳距离（〜8 kpc）处发生了丰度。我们的价值为银河演化模型设定了新的严格约束。由于Big Bang核合成理论预测的值≤（1.1±0.2）x 10〜（-4），因此在太阳系形成之前，银河系中已经明显发生了〜3He相对丰度的明显增加，但是，与早先的预期相反，太阳系形成后仅出现了适度或微不足道的增加。

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