2006/02/01 by D. H. Lee, D.-H. Lee, I.-S. Yuk +14 · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Core (optical fiber) #Extinction (optical mineralogy) #Fluorescence #Flux (metallurgy) #Galaxies: Formation, Evolution, Phenomena #Halo #Molecular cloud #Photon #Radiation #Wavelength #astro-ph
paper · pdf · doi:10.1086/505199
published as Astrophys.J. 644 (2006) L181-L184 · Accepted for ApJL, 4 pages, 3 figures
arxiv created 2006/02/01 · openalex publication_date 2006/06/15 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Diffuse far-ultraviolet (FUV; 1370-1670 Å) flux from the Taurus molecular cloud region has been observed with the SPEAR/FIMS imaging spectrograph. An FUV continuum map of the Taurus region, similar to the visual extinction maps, shows a distinct cloud core and halo region. The dense cloud core, where the visual extinction A v > 1.5, obscures the background diffuse FUV radiation, while scattered FUV radiation is seen in and beyond the halo region, where A v < 1.5. The total intensity of H 2 fluorescence in the cloud halo is I = 6.5 × 10 4 photons cm -2 s -1 sr -1 in the 1370-1670 Å wavelength band. A synthetic model of the H 2 fluorescent emission fits the present observation best with a hydrogen density n H = 50 cm -3 , H 2 column density N (H 2 ) = 0.8 × 10 20 cm -2 , and incident FUV intensity I UV = 0.2. H 2 fluorescence is not seen in the core, presumably because the required radiation flux to induce fluorescence is unable to penetrate the core region.