4,331 research outputs found

    An HI interstellar bubble surrounding WR85 and RCW118

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    We analyze the distribution of the interstellar matter in the environs of the Wolf-Rayet star LSS3982 (= WR85, WN6+OB?) linked to the optical ring nebula RCW118. Our study is based on neutral hydrogen 21cm-line data belonging to the Southern Galactic Plane Survey (SGPS). The analysis of the HI data allowed the identification of a neutral hydrogen interstellar bubble related to WR 85 and the 25' diameter ring nebula RCW118. The HI bubble was detected at a systemic velocity of -21.5 km/s, corresponding to a kinematical distance of 2.8+/-1.1 kpc, compatible with the stellar distance. The neutral stucture is about 25' in radius or 21+/-8 pc, and is expanding at 9+/-2 km/s. The associated ionized and neutral masses amount to 3000 Mo. The CO emission distribution depicts a region lacking CO coincident in position and velocity with the HI structure. The 9'.3 diameter inner optical nebula appears to be related to the approaching part of the neutral atomic shell. The HI void and shell are the neutral gas counterparts of the optical bubble and have very probably originated in the action of the strong stellar wind of the central star during the O-type and WR phases on the surrounding interstellar medium. The HI bubble appears to be in the momentun conserving stage.Comment: 9 pages, 7 figures, accepted in MNRA

    Milky Way Kinematics: Measurements at the Subcentral Point of the Fourth Quadrant

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    We use atomic hydrogen (HI) data from the Southern Galactic Plane Survey to study the kinematics of the fourth quadrant of the Milky Way. By measuring the terminal velocity as a function of longitude throughout the fourth Galactic quadrant we have derived the most densely sampled rotation curve available for the Milky Way between 3 < R < 8 kpc. We determine a new joint rotation curve fit for the first and fourth quadrants, which can be used for kinematic distances interior to the Solar circle. From our data we place new limits on the peak to peak variation of streaming motions in the fourth quadrant to be ~10 km/s. We show that the shape of the average HI profile beyond the terminal velocity is consistent with gas of three velocity dispersions, a cold component with Δv=6.3\Delta v=6.3 km/s, a warmer component with Δv=12.3\Delta v=12.3 km/s and a fast component with Δv=25.9\Delta v=25.9 km/s. Examining the widths with Galactic radius we find that the narrowest two components show little variation with radius and their small scale fluctuations track each other very well, suggesting that they share the same cloud-to-cloud motions. The width of the widest component is constant until R<4 kpc, where it increases sharply.Comment: 36 pages, 10 figures, accepted to ApJ. Full electronic version of table 1 available at ftp://ftp.atnf.csiro.au/pub/people/nmcclure/papers/velocity_tab1.te

    A Study to Determine Desired Life/Work Skills Not Acquired by Adults during Formal School Training

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    This problem was answered by focusing on the following questions: 1. Which topics or subjects do adults feel that they are lacking to improve either their personal or professional lives? 2. Which topics or subjects were not available to them during their formal school training

    Comment on the paper "Calorimetric Dark Matter Detection with Galactic Center Gas Clouds"

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    The paper "Calorimetric Dark Matter Detection with Galactic Center Gas Clouds" (Bhoonah et al. 2018) aims to derive limits on dark matter interactions by demanding that heat transfer due to DM interactions is less than that by astrophysical cooling, using clouds in the hot, high-velocity nuclear outflow wind of the Milky Way (Twind∼106−7T_{wind} \sim 10^{6-7} K, Vwind∼V_{wind} \sim 330 km/s). We argue that clouds in such an extreme environment cannot be assumed to be stable over the long timescales associated with their radiative cooling rates. Furthermore, Bhoonah et al. (2018) uses incorrect parameters for their clouds.Comment: 2 pages, 1 figure. Version appearing in Phys. Rev. Let
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