Mushroom-Shaped Structures as Tracers of Buoyant Flow in the Galactic Disk
نویسنده
چکیده
Recent Hi emission observations of the Southern Galactic hemisphere have revealed a mushroom-like structure extending from z = −70 to −450 pc, composed of a stem and a cap. Similar structures occur in three-dimensional simulations of a dynamic galactic disk driven by isolated and clustered supernovae. Using these simulations, we show that hot gas in the Galactic disk that is not evacuated through chimneys expands into the cooler gas of the thick disk, forming mushroom-shaped structures. This new class of objects traces buoyant flow of hot gas into the thick disk. Subject headings: Hydrodynamics – ISM: structure – Galaxy: evolution – Galaxy: structure – Galaxy: general
منابع مشابه
A Mushroom-shaped Structure from the Impact of a Cloud with the Galactic Disk
We propose that the mushroom-shaped structure of the Galactic worm GW 123.4–1.5 is created by a cloud collision with the Galactic gas disk. A hydrodynamic simulation shows that a mushroom-shaped structure is created after the cloud crosses the Galactic midplane. The lifetime of the mushroom-shaped structure is of order the dynamical time scale of the disk, ∼ 10 years. We find that the velocitie...
متن کاملHow was the mushroom - shaped GW 123 . 4 – 1 . 5 formed in the Galactic disk ?
The unusual mushroom-shaped HI cloud, GW 123.4–1.5, is hundreds of parsecs in size but does not show any correlations to HI shells or chimney structures. To investigate the origin and velocity structure of GW 123.4–1.5, we perform three-dimensional hydrodynamical simulations of the collision of a high-velocity cloud with the Galactic disk. We also perform a parameter study of the density, radiu...
متن کاملar X iv : a st ro - p h / 00 03 08 1 v 1 6 M ar 2 00 0 Galactic Worm 123 . 4 - 1 . 5 : A Mushroom - shaped HI Cloud
The Dominion Radio Astrophysical Observatory’s Synthesis Telescope provides the highest resolution data (1 arcmin and 0.82 km s) to date of an H I worm candidate. Observed as part of the Canadian Galactic Plane Survey, mushroom-shaped GW 123.4-1.5 extends only a few hundred parsecs, contains ∼ 10 M⊙ of neutral hydrogen, and appears unrelated to a conventional shell or chimney structure. Our pre...
متن کاملThe effect of variation of stellar dispersion velocities by the galactic latitude in interpreting gravitational microlensing observations
Our galaxy is a spiral galaxy and its stars are mostly in a thin disk and rotate around the galactic center. The vertical component of the dispersion velocity of stars is a function of the galactic latitude and decreases with increasing it. In the galactic Besancon model, this dependence is ignored and they just consider the dependence of dispersion velocity on the stellar age. Becanson model i...
متن کاملRole O f High - Altitude Tracers In The Measurement O f The Galactic Disk Potential
The role of high-altitude (Z > 200~~) tracer,stars in determining the Galactic disk potential is systematically analyzed. It is shown that such tracers cannot, by themselves, be used to measure the missing mass in the disk. Up to 60% of the disk mass may be in unobserved components with only a 20% discrepancy between the measured high-altitude disk potential and what could be expected from the ...
متن کامل