Skip to main content

污软件app下载免费

云雨直播成版人
Rugheimer
小狐仙app下载免费
Kaltenegger

To sort out the biological intricacies of Earth-like planets, astronomers have developed computer models that examine how ultraviolet radiation from other planets’ nearby suns may affect those worlds, according to new research published June 10 in Astrophysical Journal.

“Depending on the intensity, ultraviolet radiation can be both useful and harmful to the origin of life,” says Lisa Kaltenegger, Cornell associate professor of astronomy and the director of Cornell’s new Carl Sagan Institute: Pale Blue Dot and Beyond. “We are trying to ascertain how much radiation other young Earths would get and what that could mean for the possibility for life.”

The study, “UV Surface Environment of Earth-like Planets Orbiting FGKM Stars Through Geological Evolution,” was prepared by lead author Sarah Rugheimer, Cornell research associate at the Carl Sagan Institute; Antigona Segura of Universidad Nacional Autonoma de Mexico; Dimitar Sasselov of the Harvard Smithsonian Center for Astrophysics; and Kaltenegger.

“We’re going to see all kinds of planets in all kinds of stages in their own evolution, but we wanted to take four kinds of epochs from Earth history, as samples of what we might see,” said Rugheimer. “With the next generation of missions, we expect to observe a wide diversity of extrasolar planets.”

Borrowing from deep into Earth’s history, Rugheimer and co-authors modeled the first epoch, a pre-biotic world with a carbon dioxide-dominated atmosphere, similar to early Earth 3.9 billion years ago. The second epoch – about 2 billion years ago – spawned the first whiff of oxygen, an active biosphere and the process of biosynthesis. Oxygen started to rise from the first cyanobacteria to the 1 percent concentration of current levels.

“It’s not just the amount of ultraviolet radiation, but also the specific types of ultraviolet radiation which will impact biology,” Rugheimer said. “We consider which wavelengths are most damaging to DNA and other biomolecules in addition to just looking at the total amount of radiation.”

Multicellular life started about 800 million years ago, and the group modeled a third epoch, where oxygen rose to about 10 percent of today’s levels. The fourth epoch corresponds to modern Earth, where the atmosphere features a carbon dioxide ratio of about 355 parts per million with current oxygen levels.

The researchers noted that for all epochs after the rise of oxygen the hottest and coolest stars have less biologically effective radiation. For the hottest stars, this is due to increased ozone shielding from higher UV environments, and for the coolest stars this is due to less absolute UV flux.

Rugheimer, who conducted the research while she was a doctoral student at Harvard University, explained that astrobiology draws researchers across disciplines and noted: “This work provides a link from the astrophysical conditions we expect to find on other planets to the origin-of-life experiments happening on here on Earth.”

The Simons Foundation provided funding for this research.

临汾茂恒盛机械有限公司

十堰台东大服务有限公司
咪咪直播成版人 久草app污下载安装 七秒鱼app下载免费 成版人快手成版人 Kitty直播app下载免费 暖暖直播成版人 豆奶视频app污下载安装 IAVBOBOapp污下载安装 斗艳直播app下载免费 冈本视频app污下载安装 朵朵直播app下载免费 享受直播app下载免费 黄瓜直播成版人 蚪音成版人 豆奶视频成版人 嘿嘿连载成版人 微杏app污下载安装 f2富二代app污下载安装 丝瓜草莓视频app下载免费 粉色视频成版人 番茄视频成版人 花粥直播成版人 桃花直播app下载免费 咪哒直播成版人 小酒窝直播成版人 成人直播成版人 米老鼠直播app下载免费 丝瓜视频污成版人 奶茶视频app污下载安装 小猪视频app污下载安装 葫芦娃app下载免费 米老鼠直播app污下载安装 含羞草实验研究所成版人 芭乐成版人 探花直播app污下载安装 享爱app下载免费 69热app下载免费 恋夜秀场成版人 小狐仙直播成版人 铁牛视频成版人 草榴短视频app污下载安装 AVnightapp污下载安装 青草视频成版人 初见直播成版人 暖暖直播成版人 JAV名优馆app污下载安装 左手视频app污下载安装 黄瓜app下载免费 蝶恋花app污下载安装 小狐仙视频app下载免费 杏吧直播app污下载安装 葫芦娃app污下载安装 后宫视频app下载免费 杏趣直播app下载免费 红楼直播成版人 一对一直播成版人 7秒鱼直播app下载免费 探探直播成版人 压寨直播成版人 繁花直播app下载免费 草榴直播成版人 九尾狐视频app污下载安装 仙人掌成版人 ML聚合app下载免费 探花直播成版人 萝卜视频成版人 豆奶app下载免费 香蜜直播app污下载安装 春水堂app污下载安装 灭火卫视成版人 香蕉成版人 粉色成版人 富二代f2短视频app下载免费 小狐仙直播app下载免费 夜魅直播app污下载安装 草榴直播app下载免费 蜜柚直播app下载免费 富二代f2短视频app污下载安装 BB直播成版人 小v视频成版人 草莓直播成版人 尤蜜视频app下载免费 春水堂视频app下载免费 性福宝成版人 水果视频app下载免费 d2天堂成版人 套路直播app污下载安装 s8视频成版人 成版人茄子视频app污下载安装 IAVBOBO成版人 铁牛app污下载安装 初恋直播成版人 仙人掌成版人 九尾狐视频app下载免费 小奶猫app污下载安装 烟花直播成版人 富二代f2app下载免费 草鱼app污下载安装 成版人短视频app下载免费 fi11含羞草成版人 草莓直播app污下载安装 91香蕉成版人 ML聚合直播app污下载安装 丝瓜视频污成版人 葡萄视频app污下载安装 豆奶短视频app污下载安装 含羞草视频app污下载安装 月光直播app污下载安装 蘑菇视频app下载免费 午夜神器app下载免费 金鱼直播app下载免费 蝶恋花直播app污下载安装 抖阴直播app下载免费 左手视频成版人 月色直播app污下载安装 成版人快手app污下载安装 千层浪直播app污下载安装 向日葵视频app污下载安装 茶馆视频app污下载安装 幸福宝app污下载安装 彩云直播app污下载安装 JAV名优馆app下载免费 大小姐直播成版人 快猫app下载免费 泡泡直播成版人 盘她直播app污下载安装 盘她s直播app污下载安装 柚子直播app污下载安装 桃花直播app污下载安装 享爱直播app污下载安装 小怪兽直播app污下载安装 7秒鱼app污下载安装 云上花直播app下载免费 微杏app污下载安装 兔子直播app污下载安装 茄子直播成版人 蜜蜂视频app污下载安装 菠萝菠萝蜜视频成版人 小奶狗视频成版人 小怪兽直播成版人 月色直播app下载免费 遇见直播app污下载安装 盘她直播成版人 小奶狗成版人 91直播app下载免费 花粥直播app下载免费 四虎app下载免费 iavboboapp下载免费 fi11含羞草成版人 污软件成版人 秋葵视频app污下载安装