An Orbital Window into the Ancient Sun’s Mass
An Orbital Window into the Ancient Sun’s Mass
复制标题
了解古代太阳质量的轨道窗口
DOI：
10.3847/2041-8213/aaf219
复制
发表时间：
2018
期刊：
影响因子：
--
通讯作者：
G. Laughlin
中科院分区：
文献类型：
--
作者：
C. Spalding;W. Fischer;G. Laughlin
太阳的长期演化模型表明，它的光度在20亿至40亿年前大幅降低，这与古代地球和火星地质记录中温暖和潮湿条件的大量证据不一致。对于这个所谓的“年轻太阳暗淡悖论”，典型的解决方案考虑了地球和火星大气成分的变化，虽然很有吸引力，但这些想法的地质验证通常缺乏-特别是对于火星。对于年轻太阳的暗淡悖论，一个可能的未被探索的解决方案是，太阳在其一生中只是失去了百分之几的质量。如果是正确的，这将减缓，甚至可能抵消，从恒定质量模型预期的亮度增加。然而，这一假设是具有挑战性的测试。在这里，我们提出了一个新的观测代理太阳的古代质量，可以很容易地从地球和火星上的沉积岩的积累模式测量。我们证明了太阳系行星的轨道参数在一个频率下经历准周期振荡，由长期模式g2 − g5给出，该频率与太阳的质量近似线性地成比例。因此，通过研究古代盆地中沉积物积累的节奏，可以将质量恒定的太阳和质量更大的古代太阳的情况区分开来，精确度超过1%。这种方法提供了一种验证或证伪早期太阳大质量假说的途径。
Models of the Sun’s long-term evolution suggest that its luminosity was substantially reduced 2–4 billion years ago, which is inconsistent with substantial evidence for warm and wet conditions in the geological records of both ancient Earth and Mars. Typical solutions to this so-called “faint young Sun paradox” consider changes in the atmospheric composition of Earth and Mars, and, while attractive, geological verification of these ideas is generally lacking—particularly for Mars. One possible underexplored solution to the faint young Sun paradox is that the Sun has simply lost a few percent of its mass during its lifetime. If correct, this would slow, or potentially even offset, the increase in luminosity expected from a constant-mass model. However, this hypothesis is challenging to test. Here, we propose a novel observational proxy of the Sun’s ancient mass that may be readily measured from accumulation patterns in sedimentary rocks on Earth and Mars. We show that the orbital parameters of the Solar System planets undergo quasi-cyclic oscillations at a frequency, given by secular mode g2 − g5, that scales approximately linearly with the Sun’s mass. Thus by examining the cadence of sediment accumulation in ancient basins, it is possible distinguish between the cases of a constant-mass Sun and a more massive ancient Sun to a precision of greater than about 1 percent. This approach provides an avenue toward verification, or of falsification, of the massive early Sun hypothesis.