Results 21 to 30 of about 3,875,215 (299)
Ne II Observations of Gas Motions in Compact and Ultracompact H II Regions [PDF]
, 2008 We present high spatial and spectral resolution observations of 16 Galactic compact and ultracompact H II regions in the [Ne II] 12.8 mu m fine-structure line.
Greathouse, Thomas K. +4 more
core +2 more sources
H II regions with He II emission [PDF]
Publications of the Astronomical Society of the Pacific, 1991 H II regions which exhibit surprisingly strong nebular He II λ4686 emission, with I(λ4686)/I (Hβ) as high as 0.3 in some cases. The He II emission in-these objects is associated with a rather diverse set of stars, with WO stars, very early WN stars, and luminous X-ray binaries involved, and in one case what appears to be a normal O-type star. Extension
Donald R. Garnett +3 more
openaire +1 more source
Topology and Sizes of HII Regions during Cosmic Reionization [PDF]
, 2011 We use the results of large-scale simulations of reionization to explore methods for characterizing the topology and sizes of HII regions during reionization. We use four independent methods for characterizing the sizes of ionized regions.
Alvarez, Marcelo A +4 more
core +2 more sources
Ultraviolet through far-infrared spatially resolved analysis of the recent star formation in M81 (NGC 3031) [PDF]
, 2006 The recent star formation (SF) in the early-type spiral galaxy M81 is characterized using imaging observations from the far-ultraviolet to the far-infrared. We compare these data with models of the stellar, gas, and dust emission for subgalactic regions.
Bendo, George J. +15 more
core +2 more sources
Stellar associations powering H II regions
Astronomy & AstrophysicsNewly formed stars profoundly affect their environment by depositing energy and momentum into the surrounding gas. However, only a fraction of the stellar feedback is retained in the cloud, and observational constraints are needed to improve our ...
Scheuermann Fabian +29 more
doaj +1 more source
The Astrophysical Journal, 1968 H II regions expansion around O, B and A stars due to interstellar hydrogen ionization by stellar radiation ...
R. C. Newman, W. I. Axford
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The observational signature of the first H ii regions [PDF]
Monthly Notices of the Royal Astronomical Society, 2009 13 pages, 7 figures, published in ...
Greif, Thomas H. +3 more
openaire +2 more sources
MMT observations of new extremely metal-poor emission-line galaxies in the Sloan Digital Sky Survey
, 2007 We present 6.5-meter MMT spectrophotometry of 20 H II regions in 13 extremely metal-poor emission-line galaxies selected from the Data Release 5 of the Sloan Digital Sky Survey to have [O III] 4959/Hbeta < 1 and [N II] 6583/Hbeta < 0.05.
Stasinska G. +2 more
core +1 more source
Massive Star Formation in the Ultraviolet Observed with the Hubble Space Telescope
Galaxies, 2020 Spectroscopic observations of a massive star formation in the ultraviolet and their interpretation are reviewed. After a brief historical retrospective, two well-studied resolved star clusters and the surrounding H II regions are introduced: NGC 2070 in ...
Claus Leitherer
doaj +1 more source
The Astrophysical JournalWe employ observations of the 205 μ m [N ii ] fine structure (FS) line and radio recombination line (RRL) emission to derive the electron density in 10 well-known H ii regions. The combination of these two spectral lines (the RRL–FS line method) provides
Paul. F. Goldsmith +4 more
doaj +1 more source