dc.contributor.author | ESPEY, BRIAN RUSSELL | |
dc.date.accessioned | 2008-06-10T13:58:16Z | |
dc.date.available | 2008-06-10T13:58:16Z | |
dc.date.issued | 1995 | |
dc.date.submitted | 1995 | en |
dc.identifier.citation | Kriss, Gerard A.; Davidsen, Arthur F.; Zheng, Wei; Kruk, Jeffrey W.; Espey, Brian R., The far-ultraviolet spectrum of NGC 4151 as observed with the Hopkins ultraviolet telescope on Astro-2 in Astrophysical Journal Letters, 454, 1995, pp. L7-L10. | en |
dc.identifier.issn | 51373 | |
dc.identifier.other | Y | |
dc.identifier.other | Y | en |
dc.identifier.uri | http://hdl.handle.net/2262/17227 | |
dc.description | PUBLISHED | en |
dc.description.abstract | We observed NGC 4151 on six separate occasions at intervals of 1 to 3 days using the Hopkins Ultraviolet Telescope during the flight of Astro-2 aboard the space shuttle Endeavour in 1995 March. The far-UV spectra cover the spectral range from the interstellar cutoff at 912 to 1840 A with a resolution of 2--4 A. The mean spectrum, representing 4752 s of integration time, has a signal-to-noise ratio of approximately 30, and it shows profound differences compared to that obtained during the flight of Astro-1 in 1990 December. The continuum, 5.3 x 10-13 erg cm-2 s-1 A-1 at 1455 A, is 5 times brighter, the brightest UV flux ever observed for NGC 4151. All high-ionization absorption lines have strengthened considerably---S VI lambda lambda 933, 945, C III lambda 977, O VI lambda lambda 1032, 1038, N V lambda lambda 1239, 1243, Si IV lambda lambda 1394, 1403, and C IV lambda lambda 1548, 1551. The Lyman series absorption lines have also increased in strength, with the bulk of the absorption requiring a neutral hydrogen column density of 5 x 1017 cm-2 covering only 78% of the UV source with an effective Doppler parameter of 350 km s-1. However, up to 5 x 1020 cm-2 of neutral hydrogen that fully covers the source could be present in gas with a thermal Doppler parameter of 20 km s-1. Single-zone photoionization models of warm absorbing gas are unable to account for both the X-ray absorbing material and the UV-absorbing gas, largely because of the wide range of ionization states present in the UV and the X-ray. | en |
dc.format.extent | L7-L10 | en |
dc.format.extent | 210644 bytes | |
dc.format.mimetype | application/pdf | |
dc.language.iso | en | en |
dc.publisher | American Astronomical Society | en |
dc.relation.ispartofseries | 454 | en |
dc.rights | Y | en |
dc.subject | Physics | en |
dc.title | The far-ultraviolet spectrum of NGC 4151 as observed with the Hopkins ultraviolet telescope on Astro-2 | en |
dc.type | Journal Article | en |
dc.type.supercollection | scholarly_publications | en |
dc.type.supercollection | refereed_publications | en |
dc.identifier.peoplefinderurl | http://people.tcd.ie/espeyb | |