2006/10/20 by Alaina L. Henry, Alaina Henry, Jean L. Turner +6 · 4 citations
Physics and Astronomy · #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/510358
published as Astron.J.133:757-767,2007 · 26 pages, 7 figures. Accepted for publication in AJ
arxiv created 2006/10/20 · openalex publication_date 2007/01/18 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We present high spectral resolution ( v ∼ 12-16 km s -1 ) Brackett line spectroscopy of the blue compact dwarf galaxy Henize 2-10 made with NIRSPEC on the Keck telescope. The spatial resolution is seeing-limited, at 1''. We detect two distinct kinematic features separated by approximately 3'', with heliocentric velocities of ∼860 and ∼890 km s -1 . In addition to a narrow core, the line profiles also display a broad, low-intensity feature on the blue side of the centroid, which we attribute to an outflow. This may be a sign of aging in the clusters. We compare to archival high-resolution Very Large Array data at 1.3 cm and find that the centimeter-wavelength emission is resolved into six sources. These radio sources are organized into two larger groups, which we associate with the two kinematic peaks in the Brackett spectrum. We estimate a Lyman continuum rate of at least 7 × 10 52 s -1 , with a corresponding stellar mass of 6 × 10 6 M ⊙ required to ionize the nebulae. We also estimate the size of the nebulae from the radio continuum brightness and find that the observed sources probably contain many H II regions in smaller, unresolved clumps. Brackett line profiles have supersonic line widths but, aside from the blue wing, are comparable to line widths observed in Galactic ultracompact H II regions, which are excited by a single star or a few stars.