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 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 The Ring of HI in LEO: Probing the Mass Distribution in a Galaxy Group

1987 ◽  
Vol 117 ◽  
pp. 116-116
Author(s):  
Stephen E. Schneider ◽  
Edwin E. Salpeter ◽  
Yervant Terzian
Keyword(s):  
Mass Distribution ◽  
Elliptical Galaxy ◽  
Neutral Hydrogen ◽  
Ring Structure ◽  
Intergalactic Gas ◽  
Large Ring ◽  
Eccentric Ring

The intergalactic neutral hydrogen in the M96 group (Schneider et al. 1983) provides an unusual probe of the detailed mass distribution in a group of galaxies. Previous observations (Schneider 1985) tentatively suggested the existence of a large ring structure to the gas. Sensitive new observations made at Arecibo confirm that the intergalactic gas forms a 200 kpc diameter eccentric ring around the two central galaxies in the group, the giant elliptical galaxy NGC 3379 (M105) and the lenticular NGC 3384.

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.

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 Arecibo Galaxy Environments Survey–Description of the Survey and Early Results

2006 ◽  
Vol 2 (S235) ◽  
pp. 227-229
Author(s):  
R. F. Minchin ◽  
R. Auld ◽  
J. I. Davies ◽  
B. Catinella ◽  
L. Cortese ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Neutral Hydrogen ◽  
Virgo Cluster ◽  
Early Results ◽  
L Band ◽  
Arecibo Observatory ◽  
Higher Sensitivity

AbstractThe Arecibo Galaxy Environments Survey (AGES) is a 2000-hour neutral hydrogen (H I) survey using the new Arecibo L-band Feed Array (ALFA) multibeam instrument at Arecibo Observatory. It will cover 200 square degrees of sky, sampling a range of environments from the Local Void through to the Virgo Cluster with higher sensitivity, spatial resolution and velocity resolution than previous neutral hydrogen surveys.

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.

scholarly journals A Neutral Hydrogen Cloud in the Vicinity of the Elliptical Galaxy NGC 4318

1987 ◽  
Vol 115 ◽  
pp. 634-635
Author(s):  
L. Bottinelli ◽  
D. Fraix-Burnet ◽  
L. Gouguenheim
Keyword(s):  
Optical Properties ◽  
Radial Velocity ◽  
Elliptical Galaxy ◽  
Neutral Hydrogen ◽  
Morphological Type ◽  
Virgo Cluster ◽  
List Type ◽  
Type Number

NGC 4318, in the Virgo Cluster, has the following optical properties: —morphological type: E (Nilson, 1973)—BoT magnitude : 13.8 (Nilson, 1973)—photometric axis : 0.8′ × 0.6′ (Nilson, 1973)—heliocentric radial velocity: −300 km s−1 (Arakelian et al., 1975)1247± 15 km s (Tonry, 1981)1215 km s−1 (Huchra et al., 1983)

scholarly journals A motion picture film of galactic 21-cm line emission

1970 ◽  
Vol 38 ◽  
pp. 122-125 ◽  
Author(s):  
G. Westerhout
Keyword(s):  
Galactic Plane ◽  
Line Emission ◽  
Neutral Hydrogen ◽  
Hydrogen Distribution ◽  
Motion Picture Film ◽  
Contour Maps ◽  
Latitude Range ◽  
The Galaxy ◽  
Line Survey ◽  
Line Work

Since 1964 we have been observing 21-cm line profiles in a new survey of the neutral hydrogen distribution in the neighborhood of the galactic plane with the 300-foot radio telescope of the National Radio Astronomy Observatory in Green Bank, W.Va. This is the largest telescope available for 21-cm line work; it has a beamwidth of 10 min of arc and is equipped with an excellent line receiver. Since it seems unlikely that an extensive hydrogen-line survey will be made with any larger telescope, we felt that for reference purposes a concerted effort should be made to obtain as many 21-cm data as possible pertaining to the structure of the Galaxy with this telescope. The data have been presented in the form of contour maps giving the intensity of the 21-cm line radiation as a function of right-ascension and velocity at constant declination. A series of contour maps was distributed to the astronomical community in 1966 as the first edition of the Maryland–Green Bank Galactic 21-cm Line Survey. The second edition, containing 1200 pages and approximately 1800 maps, was distributed in the summer and fall of 1969. It is expected that additional contour maps, completing the survey as originally planned, covering a latitude range from bII = +1° to −1°, lII = 11° to 235° (bII = +3° to −3° between lII = 100° and 145°), will be finished by the summer of 1970. Scans were made across the galactic equator with a stationary telescope, so that the declination is constant through each scan; the declination intervals varied from 4 to 6 min of arc. Eventually, we plan to cover a strip from bII = +5° to −5° between lII = 11° and 235°, containing 225000 independent points at intervals of 6 min of arc, with an effective beamwidth of 12.5 min of arc, a velocity resolution of 2 km s-1, and a total of 1.2 × 108 individual intensities.

scholarly journals Hoag's object: the quintessential ring galaxy

2012 ◽  
Vol 10 (H16) ◽  
pp. 368-368
Author(s):  
Noah Brosch ◽  
Ido Finkelman ◽  
Alexei Moiseev
Keyword(s):  
Star Formation ◽  
Elliptical Galaxy ◽  
Neutral Hydrogen ◽  
Perfect Ring ◽  
Large Disk ◽  
Low Level ◽  
The Core ◽  
Event Triggered

AbstractWe present new observations of Hoag's Object, known as “the most perfect ring galaxy,“ that show that a preferred explanation for this object is (a) the formation of a triaxial elliptical galaxy some 10 Gyr ago, (b) the accretion of a large disk of neutral hydrogen at about the same time, (c) low-level star formation in the HI disk for all the time since that event triggered by the triaxial potential of the core.

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