玻钻之争
What we know about the Americans killed in the Israel-Hamas war_我的网站
A | “超级地球”是一类不同于我们太阳系中任何行星的行星。它们的质量比地球大，但不超过其质量的10倍。 At least 14 Americans have been killed as the Israel-Hamas conflict continues, according to President Joe Biden."As we continue to account for the horrors of the appalling terrorist assault against Israel this weekend and the hundreds of innocent civilians who were murdered, we are seeing the immense scale and reach of this tragedy," he said in a statement on Monday.The statement continued, "It's heart-wrenching. These families have been torn apart by inexcusable hatred and violence...My heart goes out to every family impacted by the horrible events of the past few days."It's currently unclear how many Americans are among those missing or might have been taken hostage, but Biden said in a statement on Monday that it's "likely" American citizens are being held hostage by Hamas.Here's what we know about the U.S. victims so far:
Hayim Katsman, 32
The first American citizen identified is 32-year-old Hayim Katsman, who had been living in Israel, his mother told ABC News.Hannah Katsman said she initially thought her son had been taken hostage, but later learned he had been killed when Hamas militants burst into his apartment.She said he and a female neighbor were hiding in a closet when they were found. The neighbor was released but her son was shot dead and his body was found in his apartment, she said."[I've] been getting so many messages from people who worked with Hayim or who knew him, or who met him during their travels and how warm he was, how open," Hannah Katsman told ABC News. "He was a very accepting person and [a] very loyal friend, good sense of humor. He took things in stride."According to the University of Washington's Henry M. Jackson School of International Studies, Hayim Katsman received his Ph.D. in 2021 with his research focusing on "the interrelations of religion and politics in the Middle-East, focusing on Israel/Palestine."。这意味着它们的质量比地球大，但又比海王星和天王星这样的冰冷气态巨行星轻。它们可以由气体、岩石或两者的组合组成。关键事实天文学家通常通过观察行星在经过其宿主恒星前时阻挡了多少光线来发现和研究系外行星，这种技术被称为“凌日法”。GJ 1252 b是一颗距离地球约65光年的系外行星，其半径是地球的1.18倍，于2020年被美国宇航局的凌日系外行星调查卫星（TESS）用这种方法发现。这项新研究中的天文学家在斯皮策太空望远镜退役前对这颗系外行星进行了观测，并能够近距离观察这颗行星和它的大气。利用斯皮策望远镜，研究小组检测到了次蚀。这发生在一颗行星经过一颗恒星后面时，行星的光线被阻挡。行星的光线来自于其自身的红外辐射（或热量），以及从恒星反射的光线。寻找宇宙中生命迹象的天文学家们关注系外行星的一些不同细节。这些细节中有许多是系外行星和地球之间的比较，因为地球仍然是我们已经确认存在生命的唯一行星。GJ 1252 b并不比地球大多少。然而，它的温度要高得多，因为它离它的恒星更近。此外，正如天文学家在这项研究中发现的那样，它缺乏很多大气层。
B | 天文学家和研究报告的共同作者、马克斯-普朗克天文研究所系外行星大气物理学部主任Laura Kreidberg说：“我们刚刚开始了解岩质行星能够保持其大气层的频率，以及在什么情况下。这一测量结果表明，对于最热的行星，厚厚的大气层通常不太可能存在。”为了确定这颗系外行星的大气层（如果有的话）可能是什么样的，天文学家测量了GJ 1252 b的红外辐射，因为它的光线在一次次的日食中被遮挡。这些观测结果揭示了这颗行星炙热的白天温度，估计高达2242华氏度（1228摄氏度）。事实上，GJ 1252 b是如此之热，以至于金、银和铜都会在这颗行星上融化。这个系外行星的预期温度，与大气模型相比，表明它的表面压力可能低于10bar （作为参考，地球的表面压力约为1bar ）。虽然这颗行星的炙热温度将使大气层难以长期稳定，但这颗系外行星可能有一个密度像地球的大气层，一个密度比地球高10倍的大气层，甚至没有任何大气层。鉴于其极端的温度和低的表面压力，这个团队的天文学家们预测，GJ 1252 b可能根本没有大气层。这是目前科学家对其大气层有如此清晰认识的最小的系外行星。GJ 1252b是一颗系外行星，它首先被TESS探测到，然后在2020年望远镜任务结束之前，用斯皮策望远镜进行了更彻底的调查。随着使用詹姆斯-韦伯太空望远镜（JWST）的进一步探索，研究人员可以对这颗行星的大气层进行更严格的限制，这是一种令人兴奋的可能性。“当时，斯皮策是已知宇宙中唯一能够进行此类测量的设施。现在，斯皮策已被关闭，但JWST就在那里，在这些波长下，它比斯皮策要敏感得多。因此，我们用斯皮策做的困难的事情，现在我们可以开始用JWST轻松地完成，而且是对更多数量的岩质行星，”Crossfield说。“JWST的红外观测有可能揭示出像这样的热的岩石行星的表面特性。不同类型的岩石有不同的光谱特征，所以我们有可能了解到GJ 1252b是由什么类型的岩石构成的，”Kreidberg补充说。用JWST进一步研究GJ 1252 b对科学家来说是一种令人兴奋的可能性，因为确认这样一颗小而热的系外行星上有大气层是非常有趣的，因为探索像这样一颗完全没有大气层的行星的组成也是非常迷人的。
C | 由Crossfield领导的堪萨斯大学的一个小组领导了这项研究，发现了关于GJ 1252b大气层的奇怪的新细节。这项研究发表在《天体物理学杂志通讯》上。
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