A FUSE Survey of Interstellar O VI Absorption in the Small Magellanic Cloud

Дата и время публикации : 2002-01-21T21:09:57Z

Авторы публикации и институты :
Charles G. Hoopes (JHU)
Kenneth R. Sembach (STScI)
J. Christopher Howk (JHU)
Blair D. Savage (Wisconsin)
Alex W. Fullerton (JHU)

Оригинал статьи :http://arxiv.org/abs/astro-ph/0201351v1

Скачать pdf : http://arxiv.org/pdf/astro-ph/0201351v1

Ссылка на журнал-издание: Ссылка на журнал-издание не найдена
Коментарии к статье: Accepted for publication in the ApJ. 23 pages, 5 figures, 5 tables
Первичная категория: astro-ph

Все категории : astro-ph

Краткий обзор статьи: We present the results of a FUSE survey of O VI 1031.93 Angstrom and 1037.62 Angstrom absorption toward 18 OB stars in the Small Magellanic Cloud (SMC). We detect O VI along every sight line. The average value of the O VI column density in the SMC is log <N(O VI)>=14.53. This value is 1.7 times higher than the average value for the Milky Way halo (perpendicular to the Galactic plane) of log N_perp(O VI)=14.29 found by FUSE, even though the SMC has much lower metallicity than the Galaxy. The column density in the SMC is higher along sight lines that lie close to star-forming regions, in particular NGC 346 in the northern part of the SMC. The standard deviation of the column densities for sight lines outside of NGC 346 is +/- 27%, somewhat lower than the deviation seen in the Milky Way halo. The lowest O VI column densities, log N(O VI)~14.3, occur in the central region and in the southeastern “Wing” of the galaxy. Even these low column densities are as high as the Milky Way average, establishing the presence of a substantial, extended component of coronal gas in the SMC. The O VI absorption is always shifted to higher velocities than the main component of lower ionization gas. The O VI line widths are broader than expected for pure thermal broadening. We discuss several mechanisms that may be able to explain the observed properties of the hot gas, including supershells, a galactic fountain, and the infall of gas previously stripped from the SMC by tidal interactions with the Milky Way and the Large Magellanic Cloud. If a fountain produces the hot gas, the mass flux per unit surface area is ~0.02 M_sun/yr/kpc2.

Category: Physics