[tel-00726959, v1] Caractériser le milieu interstellaire ... - HAL - INRIA

H. S. Liszt and J. Pety: Imaging diffuse clouds: bright and dark gas mapped in CO-12˚30'b=100.65 0.6110.70.55.78CO0.51δ (J2000)-13˚00' 0.45B1730-1300.5 0.550.60.65-13˚30'0.450.750.7T r* [Kelvin]nw quadrant0 0.417h36m 17h34m 17h32mα (J2000)-12˚50'20.403.2B1730HCNx9.12tel-00726959, version 1 - 31 Aug 2012δ(J2000)-13˚00'-13˚10'B1730-13017h34m 17h33m3 017h32mα(J2000)32e -τ -1C 2 Hx19.11CO(1-0)0HCO-1+H I-20 10V LSR (KM S -1 )Fig. 4. The sky field around the position of B1730-130, as in Fig. 2. The emission profile labeled “nw quadrant” is an average over that portion ofthe map. The emission profile labeled 〈otf CO〉 is the mean over the entire region mapped in CO.seen strongly in molecular absorption or CO emission but a redshiftedCO emission component overlaying the red side of theH I line core is present to the Northeast as indicated in Fig. 9.5. Three complex fields at low-moderate latitude5.1. B0212+735 (b ∼ 12 ◦ )B0212+735 (Fig. 10) sits in a mild trough with E B−V ≈ 0.76 magin a region of substantial reddening at moderate galactic latitudeb = 12 ◦ . It has three molecular absorption components whosebalance is entirely opposite to that of H I. Whereas most ofthe atomic absorption toward B0212+725 occurs in a deep andbroad feature at v < ∼ 10 km s −1 , most of the molecules are concentratedin a narrower-lined feature at v ≈ 4kms −1 . An obviousmolecular absorption feature at 0-velocity is, very unusually, notapparent in H I. It seems possible that the low velocity resolutionof the H I profile (1 km s −1 ) is responsible. The only otherpublished example of this phenomenon is toward B0727-115(Lequeux et al. 1993).The CO emission line kinematics have been color coded atlower left in Fig. 10 to display the observed behavior in onepanel. The gray-scale background represents the integrated intensityof the gas at 1.5−5 kms −1 ; higher resolution mappingwith the IRAM 30 m telescope to be discussed in a forthcomingpaper indicates that the feature is compound but this is notapparent in the present dataset. The blue contours represent theCO profile integral at −16 km s −1 ≤ v ≤−9.5 kms −1 ; consistentwith the prominence of this gas in H I, it is almost as widely distributedover the field as the stronger emission at 1.5−5 kms −1(Table 2: 26% vs. 34%) even if it is barely seen toward the continuum.The profile labeled “A” at upper right is an example.The green contours represent the profile integral at −2 kms −1 ≤v ≤ 1kms −1 and an example is shown at upper right as profile“B”. Emission from this gas occurs only at the eastern edgeof the map area.5.2. B0224+671 (b ∼ 6 ◦ )This line of sight toward B0224+671 (Fig. 11) samples the twolower-velocity features seen toward B0212+735 but at substantiallylower galactic latitude b = 6.2 ◦ ,seeTable1. The extinctionis large in this field as are the H I and inferred H 2 column densities.CO emission is weak on a per-component basis towardthe continuum target but fairly total large values of W CO are attainedoverall.The integrated CO emission is compact but rather formlessbecause it is the sum of many kinematic components.Paradoxically, the strongest molecular features seen toward andnear B0224+671 are not widely distributed over the map areaas shown in the middle panel at right in Fig. 11 comparingthe profile toward B0224+671 with the unweighted averageof all profiles denoted “〈otf〉”: the strongest emission peak, atthe red edge of the CO emission profile toward B0224+671A58, page 7 of 23