Show simple item record

dc.contributor.authorESPEY, BRIAN RUSSELL
dc.date.accessioned2008-06-10T13:58:16Z
dc.date.available2008-06-10T13:58:16Z
dc.date.issued1995
dc.date.submitted1995en
dc.identifier.citationKriss, 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.issn51373
dc.identifier.otherY
dc.identifier.otherYen
dc.identifier.urihttp://hdl.handle.net/2262/17227
dc.descriptionPUBLISHEDen
dc.description.abstractWe 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.extentL7-L10en
dc.format.extent210644 bytes
dc.format.mimetypeapplication/pdf
dc.language.isoenen
dc.publisherAmerican Astronomical Societyen
dc.relation.ispartofseries454en
dc.rightsYen
dc.subjectPhysicsen
dc.titleThe far-ultraviolet spectrum of NGC 4151 as observed with the Hopkins ultraviolet telescope on Astro-2en
dc.typeJournal Articleen
dc.type.supercollectionscholarly_publicationsen
dc.type.supercollectionrefereed_publicationsen
dc.identifier.peoplefinderurlhttp://people.tcd.ie/espeyb


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record