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Figure 1:
The Galactic rotation curve toward Galactic longitude of
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Figure 2: The spiral arm pattern of the Milky Way Galaxy (Cordes & Lazio 2002; Taylor & Cordes 1993). The names of the spiral arms and the line of sight (LOS) toward Wd 1 are indicated. |
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Figure 3: H I emission profile averaged over an area of a few arcminutes towards Wd 1. The locations of the spiral arms as listed in Table 1 are indicated. The Local arm is indicated at 0 km s-1. |
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Figure 4: H I absorption profiles of four radio bright H II regions in the vicinity of Wd 1. To make the individual components better comparable we plotted the relative absorption - the ratio of absorbed emission to total emission - as a function of radial velocity. The dotted vertical lines indicate the systemic velocities of the H II regions (Russeil 2003), which, within their uncertainties, are in excellent agreement with the absorption peaks. |
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Figure 5: H I channels images averaged together to demonstrate in which spiral arms Wd 1 is absorbed. For the individual arms we averaged over: +5 to -1 km s-1 (Local arm), -10 to -20 km s-1 (Sagittarius arm), -32 to -45 km s-1 (Scutum-Crux arm), -85 to -102 km s-1 (Norma arm), and -110 to -125 km s-1 (Tangent Point). In these images white denotes high and black weak emission. The radio continuum emission of Wd 1 is indicated by the white contours. |
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Figure 6: Three views of the two small expanding bubbles, B1 and B2, around Wd 1, indicated by dashed and dotted ellipses respectively. Longitude-velocity slices are displayed at the top and bottom and the velocity-latitude slices in the left and right panels. The HI channel map at about -55 km s-1 in longitude-latitude is shown in the centre, with Wd 1 indicated by the white contours. The bright emission in the velocity slices mark the gas at the far edge of Scutum-Crux I. In these images black represents low and white high intensity. |
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Figure 7: H I channelmap at a radial velocity of -55 km s-1 from the SGPS. Black contours go from 20 K to 90 K in steps of 10 K. Grayish contours indicate the 1420 MHz continuum emission. The location of Wd 1 is indicated. |
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Figure 8: Radio continuum emission at 1420 MHz around Wd 1 taken from the end channels of the SGPS H I observations. Contours are at 11, 17, 23, and 40 K (black) and 80, 120, and 160 K (white). The dotted ellipses enclose SNRs and H II regions that are believed to be beyond the Tangent point. The location of Wd 1 is indicated. |
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Figure 9: H I absorption profiles of one radio bright H II region (G338.9+0.4) and three bright SNRs in the vicinity of Wd 1. |
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Figure 10: Radio continuum spectrum of the H II region, produced by the members of Wd 1. |
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