Scholarlink

<p>Stars and planets form within cold, dark molecular clouds. In these dense regions, where starlight cannot penetrate, cosmic rays (CRs) are the dominant source of ionization—driving interstellar chemistry, setting the gas temperature and enabling coupling to magnetic fields. Together, these effects regulate the collapse of clouds and the onset of star formation. Despite this importance, the CR ionization rate, <i>ζ</i>, has never been measured directly. Instead, this fundamental parameter has been loosely inferred from indirect chemical tracers and uncertain assumptions, limiting our understanding of star formation physics. Here we report the direct detection of CR-excited vibrational H<sub>2</sub> emission, using James Webb Space Telescope observations of the starless core Barnard 68 (B68). The observed emission pattern matches theoretical predictions for CR excitation precisely, confirming a decades-old theoretical proposal long considered observationally inaccessible. This result enables direct measurement of <i>ζ</i>, effectively turning molecular clouds into natural, light-year-sized, CR detectors. It opens a transformative observational window into the origin, propagation and role of CRs in star formation and galaxy evolution.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Direct detection of cosmic-ray-excited H2 in interstellar space

  • 期刊论文

  • 发表日期：

    2026年2月3日

查看全文
  • Shmuel Bialy,
  • Amit Chemke,
  • David A. Neufeld,
  • James Muzerolle Page,
  • Alexei V. Ivlev,
  • Sirio Belli,
  • Brandt A. L. Gaches,
  • Benjamin Godard,
  • Thomas G. Bisbas,
  • Paola Caselli,
  • Arshia M. Jacob,
  • Marco Padovani,
  • Christian Rab,
  • Kedron Silsbee,
  • Troy A. Porter,
  • Ekaterina I. Makarenko

摘要

Stars and planets form within cold, dark molecular clouds. In these dense regions, where starlight cannot penetrate, cosmic rays (CRs) are the dominant source of ionization—driving interstellar chemistry, setting the gas temperature and enabling coupling to magnetic fields. Together, these effects regulate the collapse of clouds and the onset of star formation. Despite this importance, the CR ionization rate, ζ, has never been measured directly. Instead, this fundamental parameter has been loosely inferred from indirect chemical tracers and uncertain assumptions, limiting our understanding of star formation physics. Here we report the direct detection of CR-excited vibrational H2 emission, using James Webb Space Telescope observations of the starless core Barnard 68 (B68). The observed emission pattern matches theoretical predictions for CR excitation precisely, confirming a decades-old theoretical proposal long considered observationally inaccessible. This result enables direct measurement of ζ, effectively turning molecular clouds into natural, light-year-sized, CR detectors. It opens a transformative observational window into the origin, propagation and role of CRs in star formation and galaxy evolution.