scholarly journals Color Profiles of Spiral Galaxies: Clues on Outer-Disk Formation Scenarios

2008 ◽  
Vol 683 (2) ◽  
pp. L103-L106 ◽  
Author(s):  
Judit Bakos ◽  
Ignacio Trujillo ◽  
Michael Pohlen
Keyword(s):  
Spiral Galaxies ◽  
Disk Formation ◽  
Outer Disk

Density waves in the outer disk of spiral galaxies

2010 ◽  
Author(s):  
G. Bertin ◽  
N. C. Amorisco ◽  
Giuseppe Bertin ◽  
Franca De Luca ◽  
Giuseppe Lodato ◽  
...  
Keyword(s):  
Spiral Galaxies ◽  
Density Waves ◽  
Outer Disk

scholarly journals Color Profiles of Disk Galaxies since z ~ 1: Probing Outer Disk Formation Scenarios

2008 ◽  
Vol 679 (2) ◽  
pp. L69-L72 ◽  
Author(s):  
R. Azzollini ◽  
I. Trujillo ◽  
J. E. Beckman
Keyword(s):  
Disk Galaxies ◽  
Disk Formation ◽  
Outer Disk

scholarly journals The Z Velocity Dispersion of Outer H I Disks

1996 ◽  
Vol 169 ◽  
pp. 489-495
Author(s):  
John M. Dickey
Keyword(s):  
Velocity Distribution ◽  
Velocity Dispersion ◽  
Spiral Galaxies ◽  
Thermal State ◽  
Stellar Disk ◽  
Interstellar Gas ◽  
Heating And Cooling ◽  
Outer Disk ◽  
Atomic Gas

The velocity dispersion of the interstellar gas measured perpendicular to the disk in face-on spiral galaxies shows a remarkable consistency. Typically the width of the velocity distribution decreases monotonically with increasing galactic radius through the luminous, stellar disk; but in the outer disk where there is gas but no stars the velocity dispersion is συ ≃ 7 km s−1 with a scatter of 2 km s–1 at most from one position to another and from one galaxy to another. Trying to understand this number raises questions about the thermal state of the H I in outer, gaseous disks. The most important issue is to understand the dominant heating and cooling processes for the atomic gas.

STAR FORMATION IN THE OUTER DISK OF SPIRAL GALAXIES

2012 ◽  
Vol 757 (1) ◽  
pp. 64 ◽  
Author(s):  
Kate L. Barnes ◽  
Liese van Zee ◽  
Stéphanie Côté ◽  
David Schade
Keyword(s):  
Star Formation ◽  
Spiral Galaxies ◽  
Outer Disk

The first 200 kyr of the Solar System: making the planetary material diversity

2018 ◽  
Vol 14 (S345) ◽  
pp. 137-140
Author(s):  
Francesco C. Pignatale ◽  
Sébastien Charnoz ◽  
Marc Chaussidon ◽  
Emmanuel Jacquet
Keyword(s):  
Refractory Material ◽  
Thermal Processing ◽  
Large Scale ◽  
Transport Processes ◽  
Heterogeneous Distribution ◽  
Disk Formation ◽  
Outer Disk ◽  
Thermal Histories ◽  
High And Low Temperatures ◽  
Compositional Diversity

AbstractChondrites are made of a mixture of solids formed at high and low temperatures. This heterogeneity was thought to be produced by large scale transport processes in the Sun’s isolated accretion disk. However, mounting evidences suggest that refractory inclusions in chondrites were produced together with the disk formation.We present numerical simulations of the formation and transport of rocky materials during the collapse of the Solar Nebula’s parent cloud and the consequent disk assembling.We find that the interplay between the cloud collapse, the dynamics of gas and dust and thermal processing of different species in the disk, results in a local mixing of solids with different thermal histories. Our simulations return an heterogeneous distribution of refractory material with higher concentration in the outer disk. This refractory material has a short formation timescales, during the first tens of kyr of the Sun (class 0-I). Our results open new frontiers into the origin of the compositional diversity of chondrites.

scholarly journals The Mass Distribution in Disk Galaxies

2015 ◽  
Vol 11 (A29B) ◽  
pp. 195-196
Author(s):  
Stéphane Courteau ◽  
Aaron A. Dutton
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Spiral Galaxies ◽  
Formation Mechanisms ◽  
Disk Galaxies ◽  
Outer Disk ◽  
Mass Fractions ◽  
Low Mass ◽  
The Mean ◽  
Inner Parts

AbstractWe present the relative fraction of baryons and dark matter at various radii in galaxies. For spiral galaxies, this fraction measured in a galaxy's inner parts is typically baryon-dominated (maximal) and dark-matter dominated (sub-maximal) in the outskirts. The transition from maximal to sub-maximal baryons occurs within the inner parts of low-mass disk galaxies (with Vtot ≤ 200 km s−1) and in the outer disk for more massive systems. The mean mass fractions for late- and early-type galaxies vary significantly at the same fiducial radius and circular velocity, suggesting a range of galaxy formation mechanisms. A more detailed discussion, and resolution of the so-called “maximal disk problem”, is presented in Courteau & Dutton, ApJL, 801, 20.

scholarly journals Abundance Gradient in the Disk of NGC 300

2008 ◽  
Vol 4 (S254) ◽  
pp. 97-102
Author(s):  
Marija Vlajić ◽  
Joss Bland-Hawthorn ◽  
Ken C. Freeman
Keyword(s):  
Chemical Evolution ◽  
Stellar Population ◽  
Spiral Galaxies ◽  
Stellar Populations ◽  
Stellar Disk ◽  
Galactic Disks ◽  
Abundance Gradient ◽  
Outer Disk ◽  
Formation And Evolution ◽  
Metallicity Distribution

AbstractThe structure of the outer parts of galactic disks and the nature of their stellar populations are fundamental to our understanding of the formation and evolution of spiral galaxies. Ages and metallicity distributions of stars in the outermost regions of spiral disks provide important clues on how and when the disks are assembled. In our earlier work we trace the extended stellar disk of NGC 300 out to a radius of at least 10 disk scale lengths, with no sign of truncation. We now revisit the outer disk of NGC 300 in order to derive the metallicity distribution of the faint stellar population in its outskirts. We find that predominantly old stellar population in the outer disk exhibits a negative abundance gradient – as predicted by the chemical evolution models – out to about 10 kpc, followed by the metallicity plateau in the outermost disk.

scholarly journals Should the Outer Milky Way be Axisymmetric?

1996 ◽  
Vol 169 ◽  
pp. 1-10
Author(s):  
James Binney
Keyword(s):  
Galaxy Formation ◽  
Milky Way ◽  
Spiral Galaxies ◽  
Velocity Fields ◽  
Spiral Arms ◽  
Upper Limit ◽  
Outer Disk ◽  
Fisher Relation

The shape of the outer Milky Way should be heavily influenced by the shape of our heavy halo. Simulations of the formation of collisionless halos indicate that they should be highly triaxial, with a tendency to pro-lateness. If our halo were as strongly triaxial as these simulations suggest, the outer disk would have ellipticity ϵdisk ≃ 0.06.Simulations of galaxy formation which include an appropriately small fraction of gaseous matter give rise to halos of much smaller ellipticity, and predict ϵdisk ≃ 0.02. These simulations are not as reliable as purely collisionless simulations, and we should treat their results with some caution. However, it is not incredible that a small fraction of gas could radically reduce the ellipticity of a halo by making the system's potential more centrally concentrated.The distribution of the apparent ellipticities of spiral galaxies indicates that their disks have slightly eliptical disks, ϵdisk ≃ 0.05. This may merely reflect ephemeral features such as spiral arms, however. The velocity fields of disks provide a more robust probe of the ellipticity ϵΦ of galaxy potentials. The narrowness of the Tully–Fisher relation places an interesting upper limit ϵΦ < 0.1. More detailed studies of individual velocity fields will be required if we are unambiguously to demonstrate ϵΦ > 0 in some cases.

scholarly journals Magnetic Fields in the Disk-Halo Interface

1991 ◽  
Vol 144 ◽  
pp. 169-174
Author(s):  
Yoshiaki Sofue
Keyword(s):  
Magnetic Fields ◽  
Large Scale ◽  
Spiral Galaxies ◽  
Galactic Center ◽  
Interstellar Gas ◽  
Outer Disk ◽  
Vertical Field ◽  
Interstellar Gas In Galaxies ◽  
Halo Gas

A review is given of large-scale magnetic fields in disks and halos of spiral galaxies. A particular attention is given to vertical field structures, and we discuss their origin and implication on their interaction with halo gas. We point out that the disk-halo magnetic interface plays an important role in circulation of interstellar gas in galaxies, in particular a large-scale circulartion from the galactic center to outer disk regions.

Sign in / Sign up

Export Citation Format

Share Document