Giant H II regions in M101. I. X-ray analysis of hot gas

Wei Sun, Yang Chen, Li Feng, You Hua Chu, C. H. Rosie Chen, Q. Daniel Wang, Jiang Tao Li

Research output: Contribution to journalArticlepeer-review


We performed a Chandra X-ray study of three giant H II regions (GHRs), NGC5461, NGC5462, and NGC5471, in the spiral galaxy M101. The X-ray spectra of the three GHRs all contain a prominent thermal component with a temperature of ∼ 0.2 keV. In NGC5461, the spatial distribution of the soft (<1.5 keV) X-ray emission is generally in agreement with the extent of H1105, the most luminous H II region therein, but extends beyond its southern boundary, which could be attributed to outflows from the star cloud between H1105 and H1098. In NGC5462, the X-ray emission is displaced from the H II regions and a ridge of blue stars; the Hα filaments extending from the ridge of star cloud to the diffuse X-rays suggest that hot gas outflows have occurred. The X-rays from NGC5471 are concentrated at the B-knot, a "hypernova remnant" candidate. Assuming a Sedov-Taylor evolution, the derived explosion energy, on the order of 1052 erg, is consistent with a hypernova origin. In addition, a bright source in the field of NGC5462 has been identified as a background active galactic nucleus, instead of a black hole X-ray binary in M101.

Original languageEnglish (US)
Article number61
JournalAstrophysical Journal
Issue number1
StatePublished - Nov 20 2012


  • Hii regions
  • ISM: bubbles
  • ISM: kinematics and dynamics
  • X-rays: ISM
  • galaxies: individual (M101)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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