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Fast and inefficient star formation due to short-lived molecular clouds and rapid feedback

机译:由于短寿命的分子云和快速反馈,快速和低效的星形形成

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摘要

The physics of star formation and the deposition of mass, momentum and energy into the interstellar medium by massive stars ('feedback') are the main uncertainties in modern cosmological simulations of galaxy formation and evolution(1,2). These processes determine the properties of galaxies(3,4) but are poorly understood on the scale of individual giant molecular clouds (less than 100 parsecs)(5,6), which are resolved in modern galaxy formation simulations(7,8). The key question is why the timescale for depleting molecular gas through star formation in galaxies (about 2 billion years)(9,10) exceeds the cloud dynamical timescale by two orders of magnitude(11). Either most of a cloud's mass is converted into stars over many dynamical times(12) or only a small fraction turns into stars before the cloud is dispersed on a dynamical timescale(13,14). Here we report high-angular-resolution observations of the nearby flocculent spiral galaxy NGC 300. We find that the molecular gas and high-mass star formation on the scale of giant molecular clouds are spatially decorrelated, in contrast to their tight correlation on galactic scales(5). We demonstrate that this decorrelation implies rapid evolutionary cycling between clouds, star formation and feedback. We apply a statistical method(15,16) to quantify the evolutionary timeline and find that star formation is regulated by efficient stellar feedback, which drives cloud dispersal on short timescales (around 1.5 million years). The rapid feedback arises from radiation and stellar winds, before supernova explosions can occur. This feedback limits cloud lifetimes to about one dynamical timescale (about 10 million years), with integrated star formation efficiencies of only 2 to 3 per cent. Our findings reveal that galaxies consist of building blocks undergoing vigorous, feedback-driven life cycles that vary with the galactic environment and collectively define how galaxies form stars.
机译:通过大规模恒星(“反馈”('反馈')的恒星形成和质量沉积的物理和质量,动量和能量的沉积是星系形成和演化的现代宇宙学模拟中的主要不确定性(1,2)。这些过程确定了星系(3,4)的性质,但在个体巨型分子云(小于100个PARSEC)(5,6)的规模上尚未理解,这在现代星系形成模拟中解决(7,8)。关键问题是为什么通过星系中的星形形成耗尽分子气体(约20亿年)(9,10)超过云动态时间尺度(11)。在许多动态时间(12)或仅在动态时间尺度(13,14)上云分散之前,大部分云的质量被转换成恒星(12)或者只有小部分变成恒星。在这里,我们报告了附近的絮状螺旋星系NGC 300的高角度分辨率观察。我们发现在巨型分子云的规模上的分子气和大质量恒星形成是空间去相关的,与金银鳞片上的紧张相关性相反(5)。我们证明,这种去相关意味着云,星形形成和反馈之间的快速进化循环。我们应用统计方法(15,16)来量化进化时间表,并发现明星形成由高效的恒星反馈来调节,这使得云分散在短时间(约150万年)。在SuperNova爆炸发生之前,从辐射和恒星风中出现快速反馈。该反馈将云寿命限制为大约一个动态时间尺度(约1000万年),其集成星形成效率仅为2%至3%。我们的研究结果表明,星系包括经历了与银河环境不同的剧烈,反馈驱动的生命周期的建筑块,并集体定义了星系的形成星星。

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  • 来源
    《Nature》 |2019年第7757期|519-522|共4页
  • 作者单位

    Heidelberg Univ Zentrum Astron Astron Rechen Inst Heidelberg Germany|Max Planck Inst Astron Heidelberg Germany;

    Max Planck Inst Extraterr Phys Garching Germany;

    Heidelberg Univ Zentrum Astron Astron Rechen Inst Heidelberg Germany;

    Liverpool John Moores Univ Astrophys Res Inst Liverpool Merseyside England;

    Heidelberg Univ Zentrum Astron Astron Rechen Inst Heidelberg Germany|Max Planck Inst Astron Heidelberg Germany;

    Heidelberg Univ Zentrum Astron Astron Rechen Inst Heidelberg Germany;

    Univ Calif Berkeley Dept Astron 601 Campbell Hall Berkeley CA 94720 USA|Texas Tech Univ Dept Phys & Astron Lubbock TX 79409 USA;

    Univ Washington Dept Astron Seattle WA 98195 USA;

    Max Planck Inst Extraterr Phys Garching Germany;

    Max Planck Inst Extraterr Phys Garching Germany|Leiden Univ Leiden Observ Leiden Netherlands;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
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