Results 31 to 40 of about 25,712 (75)
The Structure of Spiral Shocks Excited by Planetary-mass Companions [PDF]
, 2015 Direct imaging observations have revealed spiral structures in protoplanetary disks. Previous studies have suggested that planet-induced spiral arms cannot explain some of these spiral patterns, due to the large pitch angle and high contrast of the spiral arms in observations.
arxiv +1 more source
Giant Molecular Clouds are More Concentrated to Spiral Arms than Smaller Clouds [PDF]
Astrophys.J.641:L113-L116,2006, 2005 From our catalog of Milky Way molecular clouds, created using a temperature thresholding algorithm on the Bell Laboratories 13CO Survey, we have extracted two subsets:(1) Giant Molecular Clouds (GMCs), clouds that are definitely larger than 10^5 solar masses, even if they are at their `near distance', and (2) clouds that are definitely smaller than 10 ...
arxiv +1 more source
Characteristics of Spiral Arms in Late-type Galaxies [PDF]
, 2014 We have measured the positions of large numbers of H II regions in four nearly face-on, late-type, spiral galaxies: NGC 628 (M 74), NGC 1232, NGC 3184 and NGC 5194 (M 51). Fitting log-periodic spiral models to segments of each arm yields local estimates of spiral pitch angle and arm width.
arxiv +1 more source
The formation of molecular clouds in spiral galaxies [PDF]
Mon.Not.Roy.Astron.Soc.371:1663-1674,2006, 2006 We present Smoothed Particle Hydrodynamics (SPH) simulations of molecular cloud formation in spiral galaxies. These simulations model the response of a non-self-gravitating gaseous disk to a galactic potential. The spiral shock induces high densities in the gas, and considerable structure in the spiral arms, which we identify as molecular clouds.
arxiv +1 more source
Simulations of spiral galaxies with an active potential: molecular cloud formation and gas dynamics [PDF]
, 2008 We describe simulations of the response of a gaseous disc to an active spiral potential. The potential is derived from an N-body calculation and leads to a multi-armed time-evolving pattern. The gas forms long spiral arms typical of grand design galaxies, although the spiral pattern is asymmetric.
arxiv +1 more source
Spiral Structure and Galaxy Environment [PDF]
, 2002 Among 330 normal spirals of types Sa-Sc the fraction of objects exhibiting ``ring'', ``intermediate'' and ``spiral'' arm varieties does not correlated with environment. A similar conclusion appears to apply to the arm varieties of 123 barred spirals of types SBa-SBc.
arxiv +1 more source
Stellar spiral arms in smooth-armed galaxies
The Astrophysical Journal, 1986 Deep multicolor surface photometry has been obtained for three extreme examples of smooth-armed spirals, galaxies with a global spiral pattern but with little or no interstellar gas, dust, or recent star formation: NGC 7743, NGC 495 and NGC 718. The results suggest that smooth-armed spirals may be transient bar-driven density waves (with a lifetime of ...
R.C. Kennicutt, B.K. Edgar
openaire +2 more sources
Arm Structure in Anemic Spiral Galaxies [PDF]
The Astronomical Journal, 2002 Anemic galaxies have less prominent star formation than normal galaxies of the same Hubble type. Previous studies showed they are deficient in total atomic hydrogen but not in molecular hydrogen. Here we compare the combined surface densities of HI and H2 at mid-disk radii with the Kennicutt threshold for star formation.
Debra Meloy Elmegreen +8 more
openaire +3 more sources
Offset between stellar spiral arms and gas arms of the Milky Way [PDF]
, 2015 Spiral arms shown by different components may not be spatially coincident, which can constrain formation mechanisms of spiral structure in a galaxy. We reassess the spiral arm tangency directions in the Milky Way through identifying the bump features in the longitude plots of survey data for infrared stars, radio recombination lines (RRLs), star ...
arxiv +1 more source