Open AccessHighly ionized plasma in the Large Magellanic Cloud: evidence for outflows and a possible galactic wind ★
Author(s) -
Lehner N.,
Howk J. C.
Publication year - 2007
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2007.11631.x
Subject(s) - physics , astrophysics , space telescope imaging spectrograph , large magellanic cloud , milky way , galactic halo , stars , galaxy , astronomy , intergalactic travel , ionization , halo , ion , hubble space telescope , redshift , quantum mechanics
Based on an analysis of the interstellar highly ionized species C iv , Si iv , N v and O vi observed in the Far Ultraviolet Spectroscopic Explorer ( FUSE ) and Hubble Space Telescope /Space Telescope Imaging Spectrograph ( HST /STIS) E140M spectra of four hot stars in the Large Magellanic Cloud (LMC), we find evidence for a hot LMC halo fed by energetic outflows from the LMC disc and even possibly an LMC galactic wind. Signatures for such outflows are the intermediate‐ and high‐velocity components ( v LSR ≳ 100 km s −1 ) relative to the LMC disc observed in the high‐ and low‐ion absorption profiles. The stellar environments produce strong, narrow ( T ≲ 2 × 10 4 K) components of C iv and Si iv associated with the LMC disc; in particular they are likely signatures of H ii regions and expanding shells. Broad components are observed in the profiles of C iv , Si iv and O vi with their widths implying hot, collisionally ionized gas at temperatures of a few times 10 5 K. There is a striking similarity in the O vi /C iv ratios for the broad LMC and high‐velocity components, suggesting much of the material at v LSR ≳ 100 km s −1 is associated with the LMC. The velocity of the high‐velocity component is large enough to escape altogether the LMC, polluting the intergalactic space between the LMC and the Milky Way. The observed high‐ion ratios of the broad LMC and high‐velocity components are consistent with those produced in conductive interfaces; such models are also favoured by the apparent kinematically coupling between the high and the weakly ionized species.