Discovery of hard X-rays from a cluster of protostars

Katsuji Koyama, Kenji Hamaguchi, Shiro Ueno, Naoto Kobayashi, Eric D. Feigelson

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113 Scopus citations


We report on the detection of hard X-rays from protostar candidates (Class I sources) in the R Coronae Australia (R CrA) molecular cloud. The hard X-rays are found even in the quiescent states with extremely high temperature of about 6 keV. One of the sources, probably the embedded far-infrared source R1, exhibited a powerful X-ray flare. These phenomena are similar to, but with a significantly higher temperature than, those seen in T Tauri stars. The flare spectrum is unusual, showing a broadened or double emission-line structure between 6.2 and 6.8 keV. Since X-rays are unexpected from current protostellar theory, these ASCA observations should have a significant impact on our understanding of star formation and the earliest phases of stellar evolution.

Original languageEnglish (US)
Pages (from-to)L87-L92
JournalPublications of the Astronomical Society of Japan
Issue number5
StatePublished - 1996

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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