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巴纳德B行星可能有外星生命，距离地球6光年。_我的网站

A | 据外国媒体报道，科学家最新的研究发现，一颗巨大的超级行星离地球只有6光年远，这可能孕育着原始的生命形式。

B | 巴纳德B（GJ699B）是最近发现的一颗绕着巴纳德运行的超级地球行星，它是离地球第二近的恒星系统。    STOCKHOLM -- A ban on gasoline and diesel-fueled cars from a commercial district of Stockholm's downtown in 2025 will be the first for a European capital, a city official said Thursday.The ban will take effect in a 20-block area of shops, pedestrian walkways and a few homes in order to curb pollution, reduce noise and encourage use of electric vehicles said Lars Strömgren, the city council member for the Greens who's in charge of the Swedish capital's transportation. Many European capitals have restrictions on gasoline and diesel cars, but Strömgren says Stockholm’s complete ban would be a first. “We need to eliminate the harmful exhaust gases from (gasoline) and diesel cars. That’s why we are introducing the most ambitious low-emission zone to date,” Strömgren told The Associated Press. The idea is to create an "environmental zone” where only electric vehicles will be allowed. There will be some exceptions such as for emergency vehicles and transportation for the disabled.In its budget for 2024, the left-leaning, environmentally-focused city council on Tuesday unveiled the plan for the target area just north of the city’s famed Old Town. The municipal government controls a majority in the council, so the vote set for Nov. 23 is expected to be a formality. “We are pretty proud, I must say,” Strömgren said, adding that gradual expansion of the environmental zone would be decided in the first half of 2025.One of the city’s main cab companies, Taxi Stockholm, said its transition to emission-free vehicles is moving at a fast pace. The company’s acting chief executive Pernilla Samuelsson said it's emission-free vehicles now make up 30% of its fleet - almost seven times more than last year. “In other words, the transition is going fast and it is already being driven forward by the industry,” Samuelson said.Some aren't convinced things will go smoothly. Nike Örbrink from the opposition Christian Democrats told the Aftonbladet newspaper that some are concerned the plan would hurt businesses and the hotel industry.Other European capitals harbor similar ambitions. The Dutch capital, Amsterdam, is aiming for all transport in the city, including automobiles, to be emissions-free by 2030.The mayor of Paris wanted to ban all diesel cars before next year’s Olympics, and gasoline cars by 2030, but has run up against resistance.Currently, any diesel cars built before 2006 and gasoline cars built before 1997 are banned in Paris and 77 surrounding towns for 12 hours a day on weekdays. The ban will expand in 2025 for diesel cars built before 2011 and pre-2006 gasoline vehicles.___Jan Olsen reported from Copenhagen, Denmark. AP writers Mike Corder in Amsterdam, The Netherlands and Angela Charlton in Paris, France contributed.。这颗行星被认为是非常冷的，其表面温度与木卫二相似，大约在零下150度。然而，研究人员说，它可能有一个巨大的热铁/镍核心，地热活动非常活跃，这将有助于促进生命。维拉诺瓦大学的天体物理学家爱德华·桂南在美国天文学会第223届年会上说，核热活动可能支持地表下的“生命带”，这种现象类似于南极洲地下湖泊中的现象。我们注意到欧罗巴的表面温度与巴纳德B的相似，由于潮汐加热，欧罗巴冰的表面下可能有一个液态海洋。

C | 他还指出，如果存在水，核热活动（火山羽流、火山口等）可能在冰面下形成液态水的“生活区”。它非常像结冰的欧罗巴卫星，它是由潮汐活动而不是地热能加热的。

D | 巴纳德的恒星系统将是我们未来研究和分析的重点。

E | 巴纳德最显著的特点是，它是离太阳最近的两个恒星系统之一，而且其中有行星。这项研究的共同作者斯科特·恩格尔强调，这项研究支持开普勒先前的任务数据，这些数据可以推断行星在整个星系中非常常见，可能高达数百亿颗。同时，巴纳德恒星的年龄大约是太阳的两倍——90亿年，而太阳的年龄是46亿年。宇宙要想形成地球大小的行星需要很长的时间，甚至比太阳现在的年龄还要长。

F | 巴纳德B是地球质量的三倍，绕着红矮星巴纳德运行233天。它的轨道距离与水星绕太阳的轨道距离大致相同。当它经过巴纳德星球的雪线时，它变暗了。”这些观测将帮助我们了解大气层、表面结构和系外行星的潜在生存能力，”恩格尔说。虽然巴纳德B的表面温度约为零下150摄氏度，但科学家们仍然相信，地球冰冻表面下的液态水区域可能是生命形式的滋生地。外行星是一颗岩石行星，至少是地球的3.2倍大。巴纳德距离地球只有六光年，在天文距离上非常接近，它的亮度是太阳的0.0035倍。

G | 离太阳最近的恒星是半人马座α星，它由离地球四光年的三颗引力束缚的恒星组成。据报道，巴纳德B行星的存在是通过使用不同的陆基望远镜和天文仪器20年来发现的。其中之一是西班牙卡门尼天文台最先进的行星探测器。

H | 即使是今天最强大的望远镜也不能直接成像巴纳德B。巴纳德星的名字来自于1916年发现它的耶克斯天文台的爱德华·艾默生·巴纳德。虽然巴纳德离地球只有六光年远，但它是人类肉眼看不见的。如果你把半人马座阿尔法星系的三颗恒星作为一个单位，那么巴纳德是离地球第二近的恒星。这是一颗暗的，低质量的M4矮星，亮度只有太阳的0.0035倍。相关辐射数据表明，它的直径仅为太阳直径的20%，质量仅为太阳最近恒星的17%。大多数恒星属于M矮星，它们很弱，很难用肉眼观察，就像半人马座的邻居一样。巴纳德的明星都很老了。他们是在恒星爆炸怀孕期间出生的。当时，星际金属含量已达到目前的水平，星际金属含量仅为太阳含量的10%。它的年龄也证实了它有一个更长的旋转周期130天。

I | 随着年龄的增长，其转速逐渐减慢。相反，太阳自转周期平均为25.4天，相当于巴纳德恒星自转周期的五分之一。巴纳德恒星仍有一些磁场活动，偶尔会有磁场能量释放的耀斑。它有一个像太阳一样活跃的X射线日冕，最高温度为200万摄氏度。巴纳德恒星内部的低温条件和微弱的能量产生率使它成为一颗不可思议的“长寿星”。事实上，在银河系中还没有发现已经灭绝的M矮星。

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