Spiral arm amplitude variations and pattern speeds in the grand design galaxies M51, M81, and M100

1989 ◽  
Vol 343 ◽  
pp. 602 ◽  
Author(s):  
Bruce G. Elmegreen ◽  
Philip E. Seiden ◽  
Debra Meloy Elmegreen
Keyword(s):  
Grand Design ◽  
Pattern Speeds ◽  
Spiral Arm

scholarly journals How do different spiral arm models impact the ISM and GMC population?

2020 ◽  
Vol 498 (1) ◽  
pp. 1159-1174
Author(s):  
Alex R Pettitt ◽  
Clare L Dobbs ◽  
Junichi Baba ◽  
Dario Colombo ◽  
Ana Duarte-Cabral ◽  
...  
Keyword(s):  
Radial Dependence ◽  
Spiral Arms ◽  
Star Forming ◽  
Gas Kinematics ◽  
Cloud Properties ◽  
Grand Design ◽  
Pattern Speeds ◽  
Galactic Spiral ◽  
Spiral Model ◽  
Spiral Arm

ABSTRACT The nature of galactic spiral arms in disc galaxies remains elusive. Regardless of the spiral model, arms are expected to play a role in sculpting the star-forming interstellar medium (ISM). As such, different arm models may result in differences in the structure of the ISM and molecular cloud properties. In this study, we present simulations of galactic discs subject to spiral arm perturbations of different natures. We find very little difference in how the cloud population or gas kinematics vary between the different grand design spirals, indicating that the ISM on cloud scales cares little about where spiral arms come from. We do, however, see a difference in the interarm/arm mass spectra, and minor differences in tails of the distributions of cloud properties (as well as radial variations in the stellar/gaseous velocity dispersions). These features can be attributed to differences in the radial dependence of the pattern speeds between the different spiral models, and could act as a metric of the nature of spiral structure in observational studies.

scholarly journals Birth sites of young stellar associations and recent star formation in a flocculent corrugated disc

2020 ◽  
Vol 499 (4) ◽  
pp. 5623-5640
Author(s):  
Alice C Quillen ◽  
Alex R Pettitt ◽  
Sukanya Chakrabarti ◽  
Yifan Zhang ◽  
Jonathan Gagné ◽  
...  
Keyword(s):  
Space Distribution ◽  
Solar Neighbourhood ◽  
Low Velocity ◽  
Stellar Association ◽  
Stellar Orbits ◽  
Pattern Speeds ◽  
Moving Groups ◽  
Orbit Integration ◽  
Stellar Associations ◽  
Spiral Arm

ABSTRACT With backwards orbit integration, we estimate birth locations of young stellar associations and moving groups identified in the solar neighbourhood that are younger than 70 Myr. The birth locations of most of these stellar associations are at a smaller galactocentric radius than the Sun, implying that their stars moved radially outwards after birth. Exceptions to this rule are the Argus and Octans associations, which formed outside the Sun’s galactocentric radius. Variations in birth heights of the stellar associations suggest that they were born in a filamentary and corrugated disc of molecular clouds, similar to that inferred from the current filamentary molecular cloud distribution and dust extinction maps. Multiple spiral arm features with different but near corotation pattern speeds and at different heights could account for the stellar association birth sites. We find that the young stellar associations are located in between peaks in the radial/tangential (UV) stellar velocity distribution for stars in the solar neighbourhood. This would be expected if they were born in a spiral arm, which perturbs stellar orbits that cross it. In contrast, stellar associations seem to be located near peaks in the vertical phase-space distribution, suggesting that the gas in which stellar associations are born moves vertically together with the low-velocity dispersion disc stars.

scholarly journals Gravitational Bar and Spiral Arm Torques fromKs-band Observations and Implications for the Pattern Speeds

2004 ◽  
Vol 128 (1) ◽  
pp. 183-201 ◽  
Author(s):  
D. L. Block ◽  
R. Buta ◽  
J. H. Knapen ◽  
D. M. Elmegreen ◽  
B. G. Elmegreen ◽  
...  
Keyword(s):  
Pattern Speeds ◽  
Spiral Arm

scholarly journals Galactic spiral structure

2009 ◽  
Vol 465 (2111) ◽  
pp. 3425-3446 ◽  
Author(s):  
Charles Francis ◽  
Erik Anderson
Keyword(s):  
Pitch Angle ◽  
Milky Way ◽  
Spiral Galaxies ◽  
Stellar Orbits ◽  
Grand Design ◽  
Galactic Spiral Structure ◽  
Pattern Speed ◽  
Galactic Spiral ◽  
Almost All ◽  
Spiral Arm

We describe the structure and composition of six major stellar streams in a population of 20 574 local stars in the New Hipparcos Reduction with known radial velocities. We find that, once fast moving stars are excluded, almost all stars belong to one of these streams. The results of our investigation have led us to re-examine the hydrogen maps of the Milky Way, from which we identify the possibility of a symmetric two-armed spiral with half the conventionally accepted pitch angle. We describe a model of spiral arm motions that matches the observed velocities and compositions of the six major streams, as well as the observed velocities of the Hyades and Praesepe clusters at the extreme of the Hyades stream. We model stellar orbits as perturbed ellipses aligned at a focus in coordinates rotating at the rate of precession of apocentre. Stars join a spiral arm just before apocentre, follow the arm for more than half an orbit, and leave the arm soon after pericentre. Spiral pattern speed equals the mean rate of precession of apocentre. Spiral arms are shown to be stable configurations of stellar orbits, up to the formation of a bar and/or ring. Pitch angle is directly related to the distribution of orbital eccentricities in a given spiral galaxy. We show how spiral galaxies can evolve to form bars and rings. We show that orbits of gas clouds are stable only in bisymmetric spirals. We conclude that spiral galaxies evolve toward grand design two-armed spirals. We infer from the velocity distributions that the Milky Way evolved into this form about 9 billion years ago (Ga).

scholarly journals The sequence of spiral arm classes: Observational signatures of persistent spiral density waves in grand-design galaxies

2019 ◽  
Vol 14 (S353) ◽  
pp. 140-143
Author(s):  
A. Bittner ◽  
D. A. Gadotti ◽  
B. G. Elmegreen ◽  
E. Athanassoula ◽  
D. M. Elmegreen ◽  
...  
Keyword(s):  
Surface Density ◽  
Spiral Wave ◽  
Stellar Structure ◽  
Necessary Condition ◽  
Fundamental Parameters ◽  
Spiral Density Waves ◽  
Total Luminosity ◽  
Grand Design ◽  
Total Ratio ◽  
Spiral Arm

AbstractWe investigate how the properties of spiral arms relate to other fundamental galaxy properties. To this end, we use previously published measurements of those properties, and our own measurements of arm-interarm luminosity contrasts for a large sample of galaxies, using 3.6μm images from the Spitzer Survey of Stellar Structure in Galaxies. Flocculent galaxies are clearly distinguished from other spiral arm classes, especially by their lower stellar mass and surface density. Multi-armed and grand-design galaxies are similar in most of their fundamental parameters, excluding some bar properties and the bulge-to-total luminosity ratio. Based on these results, we discuss dense, classical bulges as a necessary condition for standing spiral wave modes in grand-design galaxies. We further find a strong correlation between bulge-to-total ratio and bar contrast, and a weaker correlation between arm and bar contrasts.

scholarly journals A multiwavelength study of spiral structure in galaxies. I. General characteristics in the optical

2020 ◽  
Vol 493 (1) ◽  
pp. 390-409
Author(s):  
Sergey Savchenko ◽  
Alexander Marchuk ◽  
Aleksandr Mosenkov ◽  
Konstantin Grishunin
Keyword(s):  
Pitch Angle ◽  
Spiral Structure ◽  
Wavelength Dependence ◽  
Sloan Digital Sky Survey ◽  
Galactocentric Distance ◽  
Distinctive Features ◽  
Sky Survey ◽  
Grand Design ◽  
Generation Mechanisms ◽  
Spiral Arm

ABSTRACT Different spiral generation mechanisms are expected to produce different morphological and kinematic features. In this first paper in a series, we carefully study the parameters of spiral structure in 155 face-on spiral galaxies, selected from the Sloan Digital Sky Survey, in the three gri bands. We use a method for deriving a set of parameters of spiral structure, such as the width of the spiral arms, their fraction to the total galaxy luminosity, and their colour, which have not been properly studied before. Our method is based on an analysis of a set of photometric cuts perpendicular to the direction of a spiral arm. Based on the results of our study, we compare the main three classes of spirals: grand design, multi-armed, and flocculent. We conclude that: (i) for the vast majority of galaxies (86 per cent), we observe an increase of their arm width with Galactocentric distance; (ii) more luminous spirals in grand design galaxies exhibit smaller variations of the pitch angle with radius than those in less luminous grand design spirals; (iii) grand design galaxies show less difference between the pitch angles of individual arms than multi-armed galaxies. Apart from these distinctive features, all three spiral classes do not differ significantly by their pitch angle, arm width, width asymmetry, and environment. Wavelength dependence is found only for the arm fraction. Therefore, observationally we find no strong difference (except for the view and number of arms) between grand design, multi-armed, and flocculent spirals in the sample galaxies.

scholarly journals An Updated View of Giant Molecular Clouds, Gas Flows and Star Formation in M51 with PAWS

2012 ◽  
Vol 8 (S292) ◽  
pp. 139-142
Author(s):  
S. E. Meidt ◽  
E. Schinnerer ◽  
A. Hughes ◽  
D. Colombo ◽  
J. Pety ◽  
...  
Keyword(s):  
Star Formation ◽  
External Pressure ◽  
Radial Dependence ◽  
Gas Flows ◽  
Giant Molecular Clouds ◽  
Global Pattern ◽  
Grand Design ◽  
Co Emission ◽  
Spiral Arm

AbstractWe present an overview of the latest results from the PdBI Arcsecond Whirlpool Survey (PAWS, PI: E. Schinnerer), which has mapped CO(1-0) emission in the nearby grand-design spiral galaxy M51 at 40pc resolution. Our data are sensitive to GMCs above 105 M⊙, allowing the construction of the largest GMC catalog to date – containing over 1500 objects – using the CPROPS algorithm (Rosolowsky & Leroy 2006). In the inner disk of M51, the properties of the CO emission show significant variation that can be linked to the dynamical environment in which the molecular gas is located. We find that dynamically distinct regions host clouds with different properties and exhibit different GMC mass spectra, as well as distinct patterns of star formation. To understand how this sensitivity to environment emerges, we consider the role of pressure on GMC stabilization (including shear and star formation feedback-driven turbulence). We suggest that, in the presence of significant external pressure, streaming motions driven by the spiral arm can act to reduce the surface pressure on clouds. The resulting stabilization impacts the global pattern of star formation and can account for the observed non-monotonic radial dependence of the gas depletion time. Our findings have implications for the observed scatter in the standard GMC relations and extragalactic star formation laws.

scholarly journals Widths of Lindblad Resonances in Galaxies: Origin of the Hole in the Gas Disk of the Milky Way

1996 ◽  
Vol 157 ◽  
pp. 540-544
Author(s):  
Leonid Marochnik ◽  
Roald Sagdeev ◽  
Daniel Usikov
Keyword(s):  
Milky Way ◽  
Density Wave ◽  
Planetary Rings ◽  
Galactic Disks ◽  
Barred Galaxies ◽  
Hubble Sequence ◽  
Wide Range ◽  
Grand Design ◽  
Pattern Speeds

AbstractIt is shown that slopes of p(R) = Ω(R) ± κ(R)/m curves at Lindblad resonances determine the widths of resonance regions. The ability of galactic disks to respond to torques exerted at ILRs by perturbers (bar, density wave, galaxy-satellite, etc.) is determined by the widths of inner Lindblad resonances (ILRs). Widths of ILRs vary along the Hubble sequence of normal and barred galaxies. Galaxies having the bulge to disk ratio of masses and radii similar to the Milky Way could have wide ILRs if they are formed at the region of 2-4 kpc from their centers. A wide range of possible perturbers with pattern speeds 4≤ Ωp ≤ 26 km s≤1 kpc−1 could excite an ILR at this region of the Milky Way. Probably, the ILR of Milky Way’s grand design is located in the same region. The hole in the galactic H2 disk is also located in this region. The mechanism responsible for the origin of this hole could be similar to that opening gaps in planetary rings.

scholarly journals Flocculent and grand design spiral arm structure in cluster galaxies

1982 ◽  
Vol 201 (4) ◽  
pp. 1035-1039 ◽  
Author(s):  
D. M. Elmegreen ◽  
B. G. Elmegreen ◽  
A. Dressler
Keyword(s):  
Cluster Galaxies ◽  
Grand Design ◽  
Spiral Arm ◽  
Design Spiral
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