An Arcminute-Resolution Imaging Study of the H-alpha & [S II] Emission of the ISM from the Local Perseus Arm Using the Virginia Tech Spectral-Line Survey

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dc.contributor.authorNelson, Keith Phillipen
dc.contributor.committeechairSimonetti, John H.en
dc.contributor.committeememberDennison, Brian K.en
dc.contributor.committeememberArav, Nahumen
dc.contributor.committeememberMizutani, Tetsuroen
dc.contributor.departmentPhysicsen
dc.date.accessioned2014-03-14T20:15:08Zen
dc.date.adate2011-09-09en
dc.date.available2014-03-14T20:15:08Zen
dc.date.issued2011-08-08en
dc.date.rdate2011-09-09en
dc.date.sdate2011-08-12en
dc.description.abstractThe Virginia Tech Spectral-Line Survey (VTSS) is a series of 10-degree wide, arcminute-resolution images of the warm ionized interstellar medium (WIM) within the Milky Way for declinations greater than -15 degrees. The Wisconsin Hydrogen-Alpha Mapper (WHAM) studies the kinematics and distribution of this same material on an angular scale of one degree. Comparing the spatially-resolved images of the VTSS with WHAM's high spectral resolution images shows that the ISM's characteristics appear to be very similar at both degree and arcminute scales --- we see similar structures, and notice the same [S II]/H-alpha trend between those structures at both degree and arcminute scales. VTSS fields show three basic types of structures --- compact clouds with diameters greater than several degrees, those that are 1-degree or less in diameter, and extended filaments that differ from the clouds by spanning several degrees in length but having thicknesses of only a few tens of arcminutes. The latter two morphological types cannot be observed by WHAM. Additionally, VTSS data confirms that the [S II] intensity values are directly proportional to H-alpha intensities, a result that is also observed at degree resolutions. Finally, VTSS data show that [S II]/H-alpha ratios are, on average, nearly six times higher in the filaments. This would indicate that collisional excitation of singly-ionized sulfur ions is the dominant emission source within filaments. In clouds, the lower [S II]/H-alpha values observed are evidence that the H-alpha recombination line of photo-excited neutral hydrogen dominates. Because automating the VTSS was a key part of obtaining many of the images used in this project, I begin with a discussion of general observatory automation. I then address the specific processes and techniques used in automating the VTSS before discussing data collection and reduction techniques.en
dc.description.degreePh. D.en
dc.identifier.otheretd-08122011-114753en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-08122011-114753/en
dc.identifier.urihttp://hdl.handle.net/10919/28638en
dc.publisherVirginia Techen
dc.relation.haspartNelson_KP_D_2011.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectISMen
dc.subjectH-alphaen
dc.subject[S II]en
dc.subjectWIMen
dc.subjectWHAMen
dc.subjectAutomated Telescopesen
dc.titleAn Arcminute-Resolution Imaging Study of the H-alpha & [S II] Emission of the ISM from the Local Perseus Arm Using the Virginia Tech Spectral-Line Surveyen
dc.typeDissertationen
thesis.degree.disciplinePhysicsen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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