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天文学家发现“灾难性变量”系统：证实了几十年前的预测_我的网站

A |     需要说明的是，这并不是科学记者的夸张之词。

B | 天文学家称这些系统为灾难性变星是一个恰当的描述。

C | 这个术语描述了一个白矮星和一个次级“正常”恒星的配对，前者是一颗曾经强大的恒星的密集残余物，后者跟太阳类似但质量可能较小。

D | 在这对组合的紧密轨道上，白矮星由于其极端的引力而从较大的恒星上吸走恒星物质。    NEW YORK -- Bloomberg Philanthropies unveiled a $50 million initiative Wednesday to help cities address global issues, including climate change, by launching programs proven effective in other cities around the world.The Bloomberg Cities Idea Exchange will give city governments grants for startup costs and technical support, as well as sponsor trips and webinars to inform leaders about new programs.“Cities are a force for change on all of the big challenges we’re facing, and we’ve long worked to spread the best ideas globally,” Michael R. Bloomberg, founder of Bloomberg LP and Bloomberg Philanthropies, said in a statement. “This new Bloomberg Cities Idea Exchange will intensify and expand those efforts, bringing new muscle and rigor to the replication process.”The new initiative, announced at the Bloomberg CityLab conference in Washington on Wednesday, formalizes a process that CityLab has used for years. As former mayor of New York City, Bloomberg knows the importance of seeking out ideas that other cities have already proven, said James Anderson, who leads Bloomberg Philanthropies’ Government Innovation Program.“He understood the unique opportunity that city leaders have to drive progress locally, but also contribute to driving around global issues like climate change,” Anderson told The Associated Press in an interview. “We looked around and we understood very quickly that many city halls did not have the capacity they needed to find solutions and to implement them locally, to make them more ambitious and move their cities and the world forward.”They decided that philanthropy could play an important role in helping cities launch innovative programs and then unlock further funding from governments or other donors, Anderson said.The Bloomberg Cities Idea Exchange builds on the success of programs like an environmental initiative in Lincoln, Nebraska, that turns wood waste into a charcoal-like material called biochar that reduces the amount of carbon dioxide released into the atmosphere.In 2022, the city received a $400,000 grant from Bloomberg Philanthropies to launch the program and it has already made a difference in the city, said Lincoln Mayor Leirion Gaylor Baird. The biochar — which the city produces from trees blown down in storms or damaged by the emerald ash borer beetle — traps carbon, conserves water and improves the soil.“We have ambitious climate action goals,” Gaylor Baird said. “And we’re looking for innovative solutions to help us sequester carbon and improve quality of life and also just deal with some of the impacts of changing weather patterns.”Without the Bloomberg Philanthropies grant, Lincoln would not have been able to launch the biochar initiative so quickly, Gaylor Baird said. Or receive a $100,000 grant from the Nebraska Forest Service.Mattias Gustafsson, co-founder of the consulting firm EcoTopic and the project manager of the Stockholm Biochar Initiative, which the Lincoln project is modeled after, said he is “proud and amazed” to see the idea replicated around the world. In the United States, Cincinnati and Minneapolis have also launched biochar projects, along with Helsinki, Darmstadt, Germany, Helsingborg, Sweden, and Sandnes, Norway – all with help from Bloomberg Philanthropies.“Cities are really crucial for fighting climate change because they have a different angle coming in,” Gustafsson said. “Cities are not trying to make a profit. They are trying to do something good for their citizens.”The Bloomberg Cities Idea Exchange is designed to help cities in that effort, Anderson said. Numerous projects, highlighted by Bloomberg Philanthropies' Global Mayors Challenge, have already been replicated by cities around the world.The Providence Talks program in Rhode Island, which helps young children learn by increasing the number of words they hear each day, has been adopted by Birmingham, Alabama. The Visor Urbano program in Guadalajara, Mexico, which allows businesses to receive licenses completely online, has already expanded to 100 other cities in Mexico and will soon launch in other Latin American cities. Anderson said that city officials receive so much real time feedback from their residents that they are always looking for new ideas to help them do their jobs better.“They don’t spend as much time giving speeches and engaging in partisanship because they’re in the business of delivering services that people count on every single day,” he said. “There’s an accountability to residents to bring solutions that make a difference in their lives that are visible and measurable. And the cities understand that sometimes those ideas can come from entrepreneurs at home and other times it’s great to steal those ideas from the city down the street.”____Associated Press coverage of philanthropy and nonprofits receives support through the AP’s collaboration with The Conversation US, with funding from Lilly Endowment Inc. The AP is solely responsible for this content. For all of AP’s philanthropy coverage, visit https://apnews.com/hub/philanthropy.。

E | 周三发表在《自然》上的新灾难性变量的发现其特点是一颗大小为太阳1/100的白矮星和一颗更大的恒星--约是太阳质量的10%并挤在一个木星大小的球体中。这对恒星距离地球约3000光年，其被标记为ZTF J1813+4251。它是在兹威基瞬变设施拍摄的图像中被发现，这是一项广域调查，其使用加州帕洛玛天文台的一台望远镜并依次拍摄数百张天空图像。兹威克瞬变设施目录使天文学家能寻找恒星亮度的快速变化。这就是研究人员发现这对奇特的星体的方式。“这是一个特殊的系统，”麻省理工学院的天体物理学家Kevin Burdge说道。他指出，这是已知的行为最优美的灾难性变数之一。Burdge和他的同事们搜索了茨威基的数据以试图在深黑的太空中找到灯塔。他们希望看到有规律的眨眼特征--Burdge通常在寻找快速的眨眼，这是因为它们往往是一对恒星快速运行的信号。研究小组看到ZTF J1813+4251每51分钟闪烁一次。据悉，这是其中一颗恒星从另一颗恒星前面经过并使其光线变暗。闪烁的时间跟迄今为止发现的灾难性变星的最短轨道相吻合。通过用夏威夷和西班牙的其他望远镜以及天基望远镜进行观测，这使得研究人员对恒星变得更加集中，并能更准确地测量它发出的光线。

F | 不过这引发了一个难题。Burdge在一份新闻稿中指出：“有一颗恒星看起来像太阳，但是太阳无法进入一个短于8小时的轨道。

G | ”太阳的质量使它无法拥有如此紧密的轨道。那么为什么这颗木星大小的恒星会这样做呢？Burdge和研究小组已经确定的解释是，这颗白矮星一直在吞噬其伙伴星的一大块氢。这留下了一个更密集的氦气核心，而这有助于稳定紧密的轨道。简而言之，研究小组是在这一过程的中间阶段观察这对恒星的，当时白矮星已经剥去了大部分的氢。剥离后的白矮星留下了一个吸积盘，它像土星环一样围绕着核心。“这是一个罕见的案例，我们在从氢到氦的吸积过程中抓住了其中的一个系统，”Burdge说道。在12亿颗恒星中，该算法挑出了我们迄今发现的最有趣的灾难性变数之一。

H | 这一幸运的发现有助于支持早先提出的关于大灾变体过渡到超短轨道的理论，该理论是在近四十年前提出的--现在我们知道这确实发生了。该小组还进行了模拟以确定ZTF J1813+4251的最终命运。他们预测，在约7000万年后，这对天体将更快地围绕对方运行，每18分钟做一次完整的循环。

I | 尽管人们不会看到它，但一旦激光干涉仪空间天线(LISA)在2030年代末的某个时候进入轨道，那么研究人员将能更详细地研究这个灾难性的变量。这一系列卫星将被用来探测引力波--这些恒星舞伴将产生引力波。

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Published on:21:57:07