scholarly journals The Dark Massive Halo in the Elliptical Galaxy NGC 5266

1995 ◽  
Vol 164 ◽  
pp. 446-446
Author(s):  
A. Pizzella ◽  
R. Morganti ◽  
M.E. Sadler ◽  
F. Bertola
Keyword(s):  
Spiral Galaxies ◽  
Elliptical Galaxy ◽  
Neutral Hydrogen ◽  
Major Axis ◽  
Minor Axis ◽  
Representative Point ◽  
Dust Lane ◽  
The Galaxy ◽  
Central Regions ◽  
Parallel Behaviour

Recent observations with the Australia Telescope reveal that the elliptical galaxy NGC 5266 has a disk like structure of neutral hydrogen extending as far as almost 10 Re which approximatively lies along the galaxy's major axis, at 65° apart from the inner minor–axis dust lane (Varnas et al 1987). From the present data is not clear whether the HI structure and the dust lane are two distinct disks or a single warped structure. The regularity of the velocity field of the HI structure allow us to use it as a probe of the potential of NGC 5266. The velocity curve along the major axis is flat till the last measured point (rmax ~ 10′) at Vrot = 200km/s. Assuming that the gas in moving in circular orbits, we can derive the mass of the galaxy inside to this radius. The mass–to–light ratio M/LB rises from about 3 in the central regions to 12 at 9 Re (D = 57.6 Mpc), thus indicating that NGC 5266 is embedded in a dark massive halo. Moreover the representative point (cumulative M/LB within the last measured point) of NGC 5266 in the diagram log(M/LB) – log(Re) falls well within the region characteristic of spiral galaxies (Figure 2, Bertola et al. 1993), as do ellipticals previously studied in HI, thus reinforcing the suggestion (Bertola et al. 1993) of a parallel behaviour of the dark matter in elliptical and spiral galaxies.

HI in the Dusty Elliptical Galaxy NGC 5266

1995 ◽  
Vol 12 (2) ◽  
pp. 143-145 ◽  
Author(s):  
R. Morganti ◽  
A. Pizzella ◽  
E. M. Sadler ◽  
F. Bertola
Keyword(s):  
Mass Distribution ◽  
Elliptical Galaxy ◽  
Neutral Hydrogen ◽  
Major Axis ◽  
Minor Axis ◽  
Dust Lane ◽  
Central Regions ◽  
Intrinsic Shape ◽  
Geometry And Kinematics ◽  
Compact Array

AbstractRecent observations with the Australia Telescope Compact Array show that the elliptical galaxy NGC 5266 has a disk of neutral hydrogen extending to almost 10Re. This HI disk lies along the galaxy’s major axis, at right angles to the inner minor-axis dust lane. The geometry and kinematics of the gas will allow us to determine both the intrinsic shape of the stellar galaxy and the mass distribution. The mass-to-light ratio M/LB rises from about 2 in the central regions to ~12 at 9Re (H0 = 50km s−1 Mpc−1).

scholarly journals Probing the Halo of Centaurus A: A Merger Dynamical Model for the PN Population

1996 ◽  
Vol 171 ◽  
pp. 411-411
Author(s):  
A. Mathieu ◽  
H. Dejonghe ◽  
X. Hui
Keyword(s):  
Elliptical Galaxy ◽  
Major Axis ◽  
Minor Axis ◽  
Programming Technique ◽  
Data Set ◽  
The Galaxy ◽  
Axis Rotation ◽  
Spherical Potential ◽  
Kinematical Data ◽  
Centaurus A

We use planetary nebulae observations (Hui et al. 1995) to build dynamical models of the dust-lane elliptical galaxy NGC 5128 (Centaurus A). The PN photometric and kinematical data extend out to 20 kpc (∼ 4re) along the major axis and 10 kpc along the minor axis. Our models are built using a Quadratic Programming technique (Dejonghe 1989). The method produces fits to the data set, which consists of the photometry field (E2, well fitted by a r1/4-law) together with the major- and minor- axis rotation curves and velocity dispersion profiles. Assuming the merger hypothesis for Cen A, we describe its kinematics in a spherical potential by two sub-systems, one rotating about the intrinsic short axis and the other about the intrinsic long axis of the galaxy.

scholarly journals The HI-rich Elliptical Galaxy NGC 5266: An Old Merger Remnant?

1997 ◽  
Vol 14 (1) ◽  
pp. 89-91 ◽  
Author(s):  
R. Morganti ◽  
E. M. Sadler ◽  
T. A. Oosterloo ◽  
A. Pizzella ◽  
F. Bertola
Keyword(s):  
Dark Matter ◽  
Spiral Galaxies ◽  
Elliptical Galaxy ◽  
Neutral Hydrogen ◽  
Dark Matter Halo ◽  
Dust Lane ◽  
Neutral Gas

AbstractWe present HI images for the dust-lane elliptical galaxy NGC 5266. This galaxy contains more than 1010M☉ of HI and our data show that the neutral hydrogen extends to ∼8 arcmin each side of the nucleus, or eight times the optical half-light radius Re. Surprisingly, the outer HI gas extends almost orthogonally to the optical dust lane. The overall HI kinematics can be successfully modelled by assuming that the gas hes in two orthogonal planes—in the plane of the dust lane in the central parts and perpendicular to this in the outer regions. The large amount of neutral gas observed and the HI morphology suggest that this object may have formed from the merger of two gas rich spiral galaxies. If so, it probably represents a relatively old merger remnant since most of the HI appears settled. The mass-to-light ratio has also been derived, with evidence for a dark matter halo around this galaxy.

scholarly journals A Spiral-Like Disk of Ionized Gas in IC 1459: Signature of a Merging Collision?

1990 ◽  
Vol 124 ◽  
pp. 215-219
Author(s):  
Paul Goudfrooij ◽  
H.U. Nørgaard-Nielsen ◽  
H.E. Jørgensen ◽  
L. Hansen ◽  
T. de Jong
Keyword(s):  
Spiral Structure ◽  
Elliptical Galaxy ◽  
Broad Band ◽  
Major Axis ◽  
Colour Index ◽  
Line Flux ◽  
Ionized Gas ◽  
The Galaxy ◽  
Merger Event ◽  
Stellar Body

AbstractWe report the discovery of a large (15 kpc diameter) Hα+[NII] emission-line disk in the elliptical galaxy IC 1459, showing weak spiral structure. The line flux peaks strongly at the nucleus and is more concentrated than the stellar continuum. The major axis of the disk of ionized gas coincides with that of the stellar body of the galaxy. The mass of the ionized gas is estimated to be ~ 1 105 M⊙, less than 1% of the total mass of gas present in IC 1459. The total gas mass of 4 107 M⊙ has been estimated from the dust mass derived from a broad-band colour index image and the IRAS data. We speculate that the presence of dust and gas in IC 1459 is a signature of a merger event.

A Centaurus A : Spectra of the Optical Filament

1975 ◽  
Vol 2 (6) ◽  
pp. 366-367 ◽  
Author(s):  
B.A. Peterson ◽  
R.J. Dickens ◽  
R.D. Cannon
Keyword(s):  
Radio Source ◽  
Elliptical Galaxy ◽  
Brightness Distribution ◽  
Radio Brightness ◽  
Dust Lane ◽  
X Ray ◽  
The Galaxy ◽  
Centaurus A

The radio source, Cen A, is large and complex with many peaks in the brightness distribution over an area about 4 x 10 degrees. The peculiar elliptical galaxy NGC 5128 lies between the two strong inner radio brightness peaks and is centred on a weaker central radio source. This radio source is in the centre of the dust lane which divides the galaxy and may be related to the infrared, X-ray and γ-ray sources.

The Hi Neighborhoods Around STARBIRDS

2018 ◽  
Vol 14 (S344) ◽  
pp. 280-282
Author(s):  
Megan C. Johnson ◽  
Kristen B. W. McQuinn ◽  
John Cannon ◽  
Charlotte Martinkus ◽  
Evan Skillman ◽  
...  
Keyword(s):  
Star Formation ◽  
Surface Brightness ◽  
Spiral Galaxies ◽  
Dwarf Galaxies ◽  
Neutral Hydrogen ◽  
Tidal Interactions ◽  
Low Surface Brightness ◽  
The Galaxy ◽  
Green Bank Telescope ◽  
Intense Star Formation

AbstractStarbursts are finite periods of intense star formation (SF) that can dramatically impact the evolutionary state of a galaxy. Recent results suggest that starbursts in dwarf galaxies last longer and are distributed over more of the galaxy than previously thought, with star formation efficiencies (SFEs) comparable to spiral galaxies, much higher than those typical of non-bursting dwarfs. This difference might be explainable if the starburst mode is externally triggered by gravitational interactions with other nearby systems. We present new, sensitive neutral hydrogen observations of 18 starburst dwarf galaxies, which are part of the STARburst IRregular Dwarf Survey (STARBIRDS) and each were mapped with the Green Bank Telescope (GBT) and/or Parkes Telescope in order to study the low surface brightness gas distributions, a common tracer for tidal interactions.

scholarly journals Anisotropic Distribution Functions for the Elliptical Galaxy NGC 1600

1996 ◽  
Vol 171 ◽  
pp. 413-413
Author(s):  
Michael Matthias ◽  
Ortwin Gerhard
Keyword(s):  
Perturbation Theory ◽  
Elliptical Galaxy ◽  
Major Axis ◽  
Distribution Functions ◽  
Minor Axis ◽  
Dynamical Models ◽  
Ccd Photometry ◽  
Radial Anisotropy ◽  
Best Fitting ◽  
Integral Distribution

Three-integral (3I) dynamical models for NGC 1600 were constructed as follows: (i) Lucy-inversion of CCD photometry and gravitational potential as in Binney, Davies, Illingworth (ApJ 361, 78, 1990), assuming axisymmetry. (ii) Third integral by perturbation theory as in Gerhard & Saha (MN 261, 311, 1991). (iii) Two- and three-integral distribution functions as in Dehnen & Gerhard (MN 261, 311, 1993), assuming various anisotropy patterns. The kinematic results from these models are presented in Fig. 1. The best-fitting 3I model (solid line, right panels) has outward-increasing radial anisotropy on the major axis and is nearly isotropic on the minor axis. The M/L of the various 3I-models varies only slightly around M/L=6.2.

The Dust Opacity of Spiral Galaxies

1991 ◽  
Vol 9 (1) ◽  
pp. 86-88
Author(s):  
Y. I. Byun ◽  
K. C. Freeman
Keyword(s):  
Radiative Transfer ◽  
Spiral Galaxies ◽  
Transfer Problem ◽  
Major Axis ◽  
Disk Galaxies ◽  
Radiative Transfer Problem ◽  
The Galaxy ◽  
The Asymmetry

AbstractIn order to find the best observable diagnostics for the amount of internal extinction within spiral galaxies, we have constructed models for disk galaxies with immersed dust layers. The radiative transfer problem, including both scattering and pure absorption, has been computed for a range of model galaxies. This reveals a set of superior diagnostics for the opacity. These include the behaviour of the radial colour and luminosity distributions, the amplitude of the asymmetry between the near and far sides of the major axis, and their dependence on the orientation of the galaxy with respect to the observer.

scholarly journals The Distribution and Kinematics of Neutral Hydrogen in NGC 807

1987 ◽  
Vol 127 ◽  
pp. 423-424
Author(s):  
L. L. Dressel
Keyword(s):  
Elliptical Galaxy ◽  
Line Emission ◽  
Neutral Hydrogen ◽  
Minor Axis ◽  
Dynamical Equilibrium ◽  
Arecibo Observatory

I have detected 21 cm line emission from neutral hydrogen in the giant elliptical galaxy NGC 807 at Arecibo Observatory, and I have mapped this emission with the VLA. Unlike the active and dwarf ellipticals that have been mapped thus far, NGC 807 has a fairly regular disk of gas rotating about the apparent optical minor axis. Combined with observations of active ellipticals, this observation suggests that two classes of HI-rich ellipticals may exist: ellipticals which have accreted gas and become active recently, and quiescent ellipticals which have either produced gas internally or accreted it so long ago that it has reached dynamical equilibrium.

scholarly journals Planetary Nebulae in elliptical galaxies: Dynamical models for Centaurus A

1997 ◽  
Vol 180 ◽  
pp. 472-472
Author(s):  
Anne Mathieu ◽  
Herwig Dejonghe
Keyword(s):  
Elliptical Galaxy ◽  
Planetary Nebulae ◽  
Elliptical Galaxies ◽  
Minor Axis ◽  
Dynamical Models ◽  
Dust Lane ◽  
Centaurus A

We use planetary nebulae major- and minor-axis kinematics (Hui et al. 1995) of the dust-lane elliptical galaxy NGC 5128 (Centaurus A) to build triaxial dynamical models.

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