scholarly journals Objective Classification of Spiral Galaxies Having Extended Rotation Curves Beyond the Optical Radius

2006 ◽  
Vol 131 (5) ◽  
pp. 2452-2468 ◽  
Author(s):  
Tanuka Chattopadhyay ◽  
Asis Kumar Chattopadhyay
Keyword(s):  
Spiral Galaxies ◽  
Rotation Curves ◽  
Objective Classification ◽  
Optical Radius

scholarly journals Rotation curves and scaling relations of extremely massive spiral galaxies

2021 ◽  
Author(s):  
Enrico M Di Teodoro ◽  
Lorenzo Posti ◽  
Patrick M Ogle ◽  
S Michael Fall ◽  
Thomas Jarrett
Keyword(s):  
Spiral Galaxies ◽  
High Mass ◽  
Scaling Relations ◽  
Rotation Curves ◽  
Kinematic Models ◽  
Optical Discs ◽  
Fisher Relation ◽  
Stellar Masses ◽  
Baryonic Mass ◽  
Optical Radius

Abstract We study the kinematics and scaling relations of a sample of 43 giant spiral galaxies that have stellar masses exceeding 1011 M⊙ and optical discs up to 80 kpc in radius. We use a hybrid 3D-1D approach to fit 3D kinematic models to long-slit observations of the Hα-$\rm{[N\, \small {II}]}$ emission lines and we obtain robust rotation curves of these massive systems. We find that all galaxies in our sample seem to reach a flat part of the rotation curve within the outermost optical radius. We use the derived kinematics to study the high-mass end of the two most important scaling relations for spiral galaxies: the stellar/baryonic mass Tully-Fisher relation and the Fall (mass-angular momentum) relation. All galaxies in our sample, with the possible exception of the two fastest rotators, lie comfortably on both these scaling relations determined at lower masses, without any evident break or bend at the high-mass regime. When we combine our high-mass sample with lower-mass data from the Spitzer Photometry & Accurate Rotation Curves catalog, we find a slope of α = 4.25 ± 0.19 for the stellar Tully-Fisher relation and a slope of γ = 0.64 ± 0.11 for the Fall relation. Our results indicate that most, if not all, of these rare, giant spiral galaxies are scaled up versions of less massive discs and that spiral galaxies are a self-similar population of objects up to the very high-mass end.

Objective classification of motion- and direction-sensitive neurons in primary somatosensory cortex of awake monkeys

1987 ◽  
Vol 57 (6) ◽  
pp. 1-1 ◽  
Author(s):  
S. Warren ◽  
H. A. Hamalainen ◽  
E. P. Gardner
Keyword(s):  
Somatosensory Cortex ◽  
Cortical Neurons ◽  
Weighted Average ◽  
Direction Selectivity ◽  
Primary Somatosensory Cortex ◽  
Objective Classification

S. Warren, H. A. Hamalainen, and E. P. Gardner, “Objective classification of motion- and direction-sensitive neurons in primary somatosensory cortex of awake monkeys.” It was incorrectly stated that Orban and co-workers(J. Neurophysiol. 45: 1059–1073, 1981) attributed direction selectivity to cortical neurons having a direction index (DI) ge 20. Orban et al. actually used a weighted average of DIs and defined cells with a mean DI (MDI) above 50 as direction selective. Their criterion for direction selectivity was stricter and not less stringent, as stated in the paper. This error does not alter any of the data or conclusions of Warren et al.

scholarly journals Rotation Curves in the Outer Parts of Galaxies from HI Observations

1978 ◽  
Vol 77 ◽  
pp. 23-31 ◽  
Author(s):  
Edwin E. Salpeter
Keyword(s):  
Spiral Galaxies ◽  
Rotation Curves ◽  
Flat Rotation Curves ◽  
Arecibo Observatory

21cm observations at the Arecibo Observatory for 9 edge-on spiral galaxies are described. Flat rotation curves are found in most cases.

scholarly journals The Massive Dark Corona Of Our Galaxy

1996 ◽  
Vol 173 ◽  
pp. 175-176
Author(s):  
K.C. Freeman
Keyword(s):  
Rotation Curve ◽  
Spiral Galaxies ◽  
Galactic Center ◽  
Galactic Disk ◽  
Galactic Rotation ◽  
Rotation Curves ◽  
Stellar Component ◽  
The Galaxy ◽  
Galactic Rotation Curve

From their rotation curves, most spiral galaxies appear to have massive dark coronas. The inferred masses of these dark coronas are typically 5 to 10 times the mass of the underlying stellar component. I will review the evidence that our Galaxy also has a dark corona. Our position in the galactic disk makes it difficult to measure the galactic rotation curve beyond about 20 kpc from the galactic center. However it does allow several other indicators of the total galactic mass out to very large distances. It seems clear that the Galaxy does indeed have a massive dark corona. The data indicate that the enclosed mass within radius R increases like M(R) ≈ R(kpc) × 1010M⊙, out to a radius of more than 100 kpc. The total galactic mass is at least 12 × 1011M⊙.

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