Thesis Figures


Chapter 3: Neutral Gas Imaging and Spectroscopy



Representative Green Bank H I 21cm spectra over the survey region. Each grid square is 2°x2°, and represents 144 pointings of the 140-ft. telescope where fully mapped -- pointings which by no means have identical spectra. Outlines of the map region are shown along with VLA and WISP survey field boundaries. Principal Pleiads are marked with blue circles, Coudé Feed survey stars with red diamonds. Right ascension is marked across the top in hours, and declination on the right side in degrees. The brightness temperature units of the spectra are convertable to H I column density when integrated over velocity, using the factor 1 K km s-1 = 1.823x1018 cm-2 (Dickey & Lockman 1990). Integrated column densities for these profiles can range above 1021 cm-2, but this must be divided among the multiple velocity components seen in most sightlines; thus in most cases the H I is unlikely to be optically thick.



Right ascension - velocity slice of Green Bank H I 21cm emission at [1950] +23°35', showing velocity structure as a function of position. The color bar indicates brightness temperature in Kelvins. The sharp divergence of the two main features at 3h41m occurs at a position half a degree west of the densest part of the Merope cloud.



Declination - velocity slice of Green Bank H I 21cm emission at [1950] 3h41m, showing velocity structure as a function of position. The color bar indicates brightness temperature in Kelvins. The sharp divergence of the two main features at +23°35' occurs at a position half a degree west of the densest part of the Merope cloud.



IRAS 100µm emission over the Green Bank survey region. Many of the faint cirruslike filaments have counterparts in H I 21cm emission. The display scale is logarithmic, with the colorbar indicating the log of the surface brightness in MJy sr-1.



Green Bank H I 21cm emission at +10 km s-1. Structures at this velocity, corresponding to the ``red'' narrow CNM component, show good agreement with IRAS morphology. The color bar indicates brightness temperature in Kelvins.



Green Bank H I 21cm emission at 0 km s-1. Many complex structures are revealed at this velocity which appear related to general IRAS wisps, though the exact relation to the central nebulosity is unclear. Emission at this velocity generally corresponds to the broad WNM component. The color bar indicates brightness temperature in Kelvins.



Green Bank H I 21cm emission at -6 km s-1. Structures at this velocity, corresponding to the ``blue'' narrow CNM component, show little agreement with the morphology of the central nebula, but may instead depict shocked gas in the cloud-cluster interaction. The color bar indicates brightness temperature in Kelvins.



Green Bank H I 21cm contours over IRAS 100µm emission, showing the correlations between various elements in Figs. \ref{Fig:gbiras} - \ref{Fig:gb-6kms}. Top: +10 km s-1; Middle: 0 km s-1; Bottom: -6 km s-1. While some agreement is apparent at all three velocities, the best match for the central nebula occurs at +10 km s-1.



Green Bank H I 21cm RA-DEC maps showing, in left-to-right order, velocities of -10.4, -8.8, -7.8, -6.3, -5.2, -3.7, -2.7, -1.1, -0.1, +1.5, +2.5, +4.0, +5.1, +6.6, +7.6, +9.2, +10.2, +11.8, +12.8, and +14.3 km s-1. The color bar shows brightness temperatures from -2 to 50 K.



Green Bank H I 21cm RA-VEL maps showing, in left-to-right order, declinations of +19°55', +20°25', +20°55', +21°25', +21°55', +22°25', +22°55', +23°25', +23°55', +24°25', +24°55', +25°25', +25°55', +26°25', +26°55', +27°25', +27°55', +28°25', +28°55', and +29°25'. The color bar shows brightness temperatures from -2 to 50 K.



Green Bank H I 21cm DEC-VEL maps showing, in left-to-right order, right ascensions of 4h29m, 4h27m, 4h25m, 4h22m, 4h20m, 4h18m, 4h16m, 4h13m, 4h11m, 4h09m, 4h07m, 4h05m, 4h02m, 4h00m, 3h58m, 3h56m, 3h54m, 3h51m, 3h49m, 3h47m, 3h45m, 3h43m, 3h40m, 3h38m, 3h36m, 3h34m, 3h32m, 3h29m, 3h27m, 3h25m, 3h23m, 3h21m, 3h18m, 3h16m, 3h14m, 3h12m, 3h10m, 3h07m, and 3h06m. The color bar shows brightness temperatures from -2 to 50 K.



Schmidt Bj features in VLA mosaic vicinity. The data values have been ``folded'' to show a greater dynamic range. Display parameters are similar to those in Figs. \ref{Fig:smos_str} & \ref{Fig:smos_nstr}. Crosses mark Coudé Feed survey stars, small circles indicate White et al. (1997) stars, and large circles mark major Pleiads. These marks are to aid the eye in comparing nebular features with those in Figs. \ref{Fig:vlasd_iras100} - \ref{Fig:vlasd_69}.



IRAS 100µm features in VLA mosaic vicinity. The display scale is logarithmic, ranging from 6 to 350 MJy sr-1. The symbols are described in Fig. \ref{Fig:vlasd_schmidt}.



H I 21cm emission at +10 km s-1 in VLA mosaic vicinity. The VLA survey region is shown inset in Green Bank data. The display scale is linear, ranging from 0 to 40 milliJanskys per (30'')2 pixel. The symbols are described in Fig. \ref{Fig:vlasd_schmidt}.



H I 21cm emission at 0 km s-1 in VLA mosaic vicinity. The VLA survey region is shown inset in Green Bank data. The display scale is linear, ranging from 0 to 80 milliJanskys per (30'')2 pixel. The symbols are described in Fig. \ref{Fig:vlasd_schmidt}.



H I 21cm emission at -6 km s-1 in VLA mosaic vicinity. The VLA survey region is shown inset in Green Bank data. The display scale is linear, ranging from 0 to 30 milliJanskys per (30'')2 pixel. The symbols are described in Fig. \ref{Fig:vlasd_schmidt}.



VLA H I 21cm RA-DEC maps showing, in left-to-right order, velocities of -10.3, -9.0, -7.7, -6.4, -5.2, -3.9, -2.6, -1.3, 0.0, +1.3, +2.6, +3.9, +5.2, +6.4, +7.7, +9.0, +10.3, +11.6, +12.9, and +14.2 km s-1. The colorbar shows values of -100 to 600 milliJankys per (30'')2 pixel.



VLA H I 21cm RA-VEL maps showing, in left-to-right order, declinations of +23°57', +24°02', +24°06', +24°11', +24°16', +24°20', +24°25', +24°30', +24°34', +24°39', +24°44', +24°48', +24°53', +24°58', +25°02', +25°07', +25°12', +24°16', +25°21', and +25°26'. The colorbar shows values of -100 to 600 milliJankys per (30'')2 pixel.



VLA H I 21cm DEC-VEL maps, in left-to-right order, right ascensions of 3h49m17s, 3h49m00s, 3h48m43s, 3h48m26s, 3h48m09s, 3h47m52s, 3h47m35s, 3h47m19s, 3h47m02s, 3h46m45s, 3h46m28s, 3h46m11s, 3h45m54s, 3h45m37s, 3h45m20s, 3h45m03s, 3h44m46s, 3h44m29s, 3h44m12s, and 3h43m55s. The colorbar shows values of -100 to 600 milliJankys per (30'')2 pixel.



Detail of optical filaments near Merope (23 Tauri). This linear-scale Schmidt Bj closeup shows nebular structure in the vicinity of the star, where the measured radial brightness profile has been subtracted (see Fig. \ref{Fig:schmidt_nfps}). The rays and rings are stellar PSF artifacts, and the two diagonal lines are telescopic scattered light. The remaining structure however is real. The narrowest wisps resolved here are some 8'' = 1000 AU across, and might be detectable in H I 21cm emission with a higher-resolution interferometric survey of sufficient sensitivity.



The distribution on the sky of sightlines of this Coudé Feed survey in comparison to those of White et al. (1997). The WISP and VLA survey fields are shown.



The interstellar Na I D-line absorption spectra for the first 25 observations (continued in Fig. \ref{Fig:raorder_2}). Stars are shown in order of increasing right ascension (from west to east). The D2 line is shown solid, the D1 line dotted. The latter, which is naturally weaker, has been scaled up by an arbitrary factor of 1.7 in optical depth in all plots in order to compare the two directly. Generally they agree quite well. Some occasional wavelength calibration errors are visible as slight shifts between the two D-line profiles. One star, Eta (=25) Tauri, was observed at two different resolutions.



Interstellar Na I D-line absorption spectra, continued from Fig. \ref{Fig:raorder_1}.



Na I absorption and H I emission toward known and possible cluster members. Known members are on the left, and other stars which have suitable proper motions are on the right. For the latter group, computed photometric distances are given in parsecs in the lower right corner of each plot, and the stars are sorted by these possible distances.



Na I absorption and H I emission toward nonmembers with photometric distances less than the adopted cluster distance of 130 pc. Stars are shown in presumed distance order.



Na I absorption and H I emission toward nonmembers with photometric distances greater than the adopted cluster distance of 130 pc. Stars are shown in presumed distance order.