scholarly journals The Structure and Kinematics of the Galaxy Thin Gaseous Disk Outside the Solar Orbit

2015 ◽  
Vol 127 (948) ◽  
pp. 126-142 ◽  
Author(s):  
G. Galazutdinov ◽  
A. Strobel ◽  
F. A. Musaev ◽  
A. Bondar ◽  
J. Krełowski
Keyword(s):  
Gaseous Disk ◽  
The Galaxy ◽  
Solar Orbit

scholarly journals A Gaseous Group with Unusual Remote Star Formation

2011 ◽  
Vol 28 (3) ◽  
pp. 271-279 ◽  
Author(s):  
N. Santiago-Figueroa ◽  
M. E. Putman ◽  
J. Werk ◽  
G. R. Meurer ◽  
E. Ryan-Weber
Keyword(s):  
Star Formation ◽  
Spiral Galaxy ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Spiral Arms ◽  
Gaseous Disk ◽  
Ram Pressure ◽  
The Galaxy ◽  
Galaxy Center ◽  
Region 10

AbstractWe present VLA 21-cm observations of the spiral galaxy ESO 481-G017 to determine the nature of remote star formation traced by an Hii region found 43 kpc and ∼800 km s−1 from the galaxy center (in projection). ESO 481-G017 is found to have a 120 kpc Hi disk with a mass of 1.2 × 1010M⊙ and UV GALEX images reveal spiral arms extending into the gaseous disk. Two dwarf galaxies with Hi masses close to 108M⊙ are detected at distances of ∼200 kpc from ESO 481-G017 and a Hi cloud with a mass of 6 × 107M⊙ is found near the position and velocity of the remote Hii region. The Hii region is somewhat offset from the Hi cloud spatially and there is no link to ESO 481-G017 or the dwarf galaxies. We consider several scenarios for the origin of the cloud and Hii region and find the most likely is a dwarf galaxy that is undergoing ram pressure stripping. The Hi mass of the cloud and Hi luminosity of the Hii region (1038.1 erg s−1) are consistent with dwarf galaxy properties, and the stripping can trigger the star formation as well as push the gas away from the stars.

scholarly journals The Magnetic Field of the Sun: An Object Lesson

1990 ◽  
Vol 140 ◽  
pp. 1-12
Author(s):  
E. N. Parker
Keyword(s):  
Magnetic Field ◽  
Small Scale ◽  
The Sun ◽  
Gaseous Disk ◽  
Galactic Field ◽  
The Galaxy ◽  
Object Lesson ◽  
Mass Ejection ◽  
Solar Field ◽  
The Magnetic Field

The magnetic field of the sun is created by a magnetohydrodynamic dynamo under conditions bearing some qualitative similarities to the apparent generation of the galactic field in the gaseous disk of the galaxy. There is a similarity, too, in the extension of bipolar lobes of the solar field above the surface of the sun and the extension of bipolar lobes of the galactic field outward from both sides of the disk. Hence one can learn a lot about the expected origin and activity of the galactic field by studying the behavior of the magnetic field of the sun. In particular, the mysteries associated with the “simple” circumstances of the origin of the solar magnetic field far below the surface are no less than the mysteries in the theoretical origin of the galactic field, where there is so little direct observation of the small scale motions and magnetic fields. There is reason to think that the activity of the magnetic field of the sun, producing prominences, flares and X-ray corona, a solar wind, and coronal mass ejection may all have counter parts in the activity of the galactic field above the surface of the gaseous disk.

scholarly journals Mass extinction and the structure of the milky way

2013 ◽  
pp. 43-52 ◽  
Author(s):  
M.D. Filipovic ◽  
J. Horner ◽  
E.J. Crawford ◽  
N.F.H. Tothill ◽  
G.L. White
Keyword(s):  
Mass Extinction ◽  
Milky Way ◽  
The Sun ◽  
Spiral Arms ◽  
New Model ◽  
The Galaxy ◽  
The Times ◽  
Extinction Events ◽  
Mass Extinction Events ◽  
Solar Orbit

We use the most up-to-date Milky Way model and solar orbit data in order to test the hypothesis that the Sun's galactic spiral arm crossings cause mass extinction events on Earth. To do this, we created a new model of the Milky Way's spiral arms by combining a large quantity of data from several surveys. We then combined this model with a recently derived solution for the solar orbit to determine the timing of the Sun's historical passages through the Galaxy's spiral arms. Our new model was designed with a symmetrical appearance, with the major alteration being the addition of a spur at the far side of the Galaxy. A correlation was found between the times at which the Sun crosses the spiral arms and six known mass extinction events. Furthermore, we identify five additional historical mass extinction events that might be explained by the motion of the Sun around our Galaxy. These five additional significant drops in marine genera that we find include significant reductions in diversity at 415, 322, 300, 145 and 33 Myr ago. Our simulations indicate that the Sun has spent ~60% of its time passing through our Galaxy's various spiral arms. Also, we briefly discuss and combine previous work on the Galactic Habitable Zone with the new Milky Way model.

scholarly journals The dark halo in the elliptical galaxy NGC 3108

2004 ◽  
Vol 220 ◽  
pp. 177-178 ◽  
Author(s):  
Gyula I. G. Józsa ◽  
Thomas A. Oosterloo ◽  
Raffaella Morganti ◽  
Daniela Vergani
Keyword(s):  
Rotation Curve ◽  
Elliptical Galaxy ◽  
Dark Halo ◽  
Spectroscopic Measurements ◽  
Dust Lane ◽  
Gaseous Disk ◽  
The Galaxy

We investigate the properties of the dark halo of the dust-lane elliptical galaxy NGC 3108. This galaxy contains a large massive gaseous disk, which shows rapid and regular rotation. That makes NGC 3108 a target for measurements usually feasible only for spriral galaxies. Combining spectroscopic measurements of the disk in the optical- and the radio regime, we provide a reliable rotation curve of the galaxy out to 3 Reff and show that the rotation curve does not decline up to a radius of 5.5 Reff corresponding to 28 kpc.

scholarly journals The Local Galactic Escape Velocity

1987 ◽  
Vol 117 ◽  
pp. 39-50
Author(s):  
Bruce W. Carney ◽  
David W. Latham
Keyword(s):  
Proper Motion ◽  
Escape Velocity ◽  
The Galaxy ◽  
Solar Orbit ◽  
Local Value

From a new photometric and spectroscopic survey of high proper motion stars, combined with previously published work, we find that the local value of the escape velocity from the Galaxy exceeds 500 km s−1. This gives direct dynamical evidence that the total Galactic mass exceeds the mass inside the solar orbit by a factor of at least five.

scholarly journals AM2020–5050: an Elliptical Galaxy with an Outer Ring

1987 ◽  
Vol 127 ◽  
pp. 413-414
Author(s):  
Bradley Whitmore ◽  
François Schweizer
Keyword(s):  
Gravitational Potential ◽  
Velocity Dispersion ◽  
Elliptical Galaxy ◽  
Rotational Velocity ◽  
Gaseous Disk ◽  
Polar Ring ◽  
Photometric And Spectroscopic Observations ◽  
The Galaxy ◽  
Ring Galaxies ◽  
Optical Ring

Photometric and spectroscopic observations show that the inner component of AM2020—5050 is an elliptical galaxy, unlike other polar-ring galaxies which have an SO disk at the center. A comparison of the central velocity dispersion with the rotational velocity in the ring suggests the presence of a nearly spherical gravitational potential. The inner component has a rapidly rotating core with rotational velocities at 3″ substantially higher than at 8″. Although the optical ring is quite narrow, Hα emission is observed all the way through the center of the galaxy, indicating the presence of an extended gaseous disk.

scholarly journals Spontaneous Discontinuities in Galactic Magnetic Fields and the Creation of Galactic X-ray Halos

1990 ◽  
Vol 140 ◽  
pp. 169-175 ◽  
Author(s):  
E. N. Parker
Keyword(s):  
Spiral Galaxies ◽  
Magnetic Energy ◽  
Gaseous Disk ◽  
X Ray ◽  
Galactic Magnetic Fields ◽  
Current Sheets ◽  
The Galaxy ◽  
Tangential Discontinuities ◽  
Halo Gas ◽  
The Magnetic Field

The magnetic field in the gaseous disk of the galaxy is dynamically unstable to undulations with wavelengths of the order of 1 kpc. The elevated portions of the field are subject to rapid inflation (~ 50 km/sec) by the cosmic rays produced within the gaseous disk. The result is a magnetic halo of 1–3 × 10−6 gauss, composed of close packed bipolar lobes of field extending outward from the surface of the disk to distances of several kpc. The inflation is presumably irregular, producing tangential discontinuities (current sheets) throughout the extended bipolar fields. A major portion of the magnetic energy is dissipated by rapid reconnection at these current sheets, heating the tenuous halo gas to temperatures of 106 − 107 °K and producing the X-ray emission observed from the halos of many spiral galaxies.

The phenomenon of “self-focusing” in the gaseous disk of the Galaxy

2010 ◽  
Vol 54 (2) ◽  
pp. 133-138 ◽  
Author(s):  
Yu. N. Mishurov ◽  
A. A. Ponomareva
Keyword(s):  
Gaseous Disk ◽  
Self Focusing ◽  
The Galaxy
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