scholarly journals A Complete Sample of Globular Clusters in NGC 5128

1988 ◽  
Vol 126 ◽  
pp. 545-546
Author(s):  
Ray Sharples
Keyword(s):  
Power Law ◽  
Density Profile ◽  
Globular Clusters ◽  
Elliptical Galaxy ◽  
Major Axis ◽  
Cluster System ◽  
Radial Velocities ◽  
Complete Sample ◽  
The Core ◽  
The Galaxy

We present the results of an unbiased survey to search for globular clusters around the nearby elliptical galaxy NGC 5128. A total of 44 clusters has been identified on the basis of radial velocities alone. The cluster system appears to be flattened towards the major axis of the galaxy but does not show any dynamically significant rotation. There is a deficit of clusters in the core when compared with the power law density profile seen at large radii.

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.

scholarly journals An Overview of the Globular Cluster System of the Galaxy

1988 ◽  
Vol 126 ◽  
pp. 37-48
Author(s):  
Robert Zinn
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Milky Way ◽  
Galactic Center ◽  
Galactic Plane ◽  
Cluster System ◽  
Open Clusters ◽  
The Galaxy ◽  
Globular Cluster System ◽  
Harlow Shapley

Harlow Shapley (1918) used the positions of globular clusters in space to determine the dimensions of our Galaxy. His conclusion that the Sun does not lie near the center of the Galaxy is widely recognized as one of the most important astronomical discoveries of this century. Nearly as important, but much less publicized, was his realization that, unlike stars, open clusters, HII regions and planetary nebulae, globular clusters are not concentrated near the plane of the Milky Way. His data showed that the globular clusters are distributed over very large distances from the galactic plane and the galactic center. Ever since this discovery that the Galaxy has a vast halo containing globular clusters, it has been clear that these clusters are key objects for probing the evolution of the Galaxy. Later work, which showed that globular clusters are very old and, on average, very metal poor, underscored their importance. In the spirit of this research, which started with Shapley's, this review discusses the characteristics of the globular cluster system that have the most bearing on the evolution of the Galaxy.

Globular cluster system of NGC 3613, a massive elliptical galaxy in a poor environment

2019 ◽  
Vol 14 (S351) ◽  
pp. 84-88
Author(s):  
Bruno J. De Bórtoli ◽  
Lilia P. Bassino ◽  
Juan P. Caso ◽  
Ana I. Ennis
Keyword(s):  
Globular Cluster ◽  
Elliptical Galaxy ◽  
Cluster System ◽  
Host Galaxy ◽  
Low Density ◽  
Stellar Component ◽  
Magnitude Diagram ◽  
The Galaxy ◽  
Colour Distribution ◽  
Globular Cluster System

AbstractWe present an analysis of the globular cluster system (GCS) of the galaxy NGC 3613, an intrinsically bright elliptical galaxy (MV = −21.5) in a low density environment (it is the central galaxy of a group of a dozen galaxies). Based on Gemini/GMOS photometry of NGC 3613 we obtained the following properties for this GCS. A ‘blue tilt’ is detected in the colour-magnitude diagram. The colour distribution is bimodal, presenting the two classical globular cluster (GC) sub-populations. The spatial and azimuthal projected distributions show that red sub-population correlates with the stellar component of the host galaxy.

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 Radial Velocities of Globular Clusters in the Giant Elliptical Galaxy NGC 1399

1998 ◽  
Vol 115 (1) ◽  
pp. 121-129 ◽  
Author(s):  
Dante Minniti ◽  
Markus Kissler-Patig ◽  
Paul Goudfrooij ◽  
Georges Meylan
Keyword(s):  
Globular Clusters ◽  
Elliptical Galaxy ◽  
Radial Velocities

scholarly journals The halo of M 105 and its group environment as traced by planetary nebula populations

2020 ◽  
Vol 642 ◽  
pp. A46
Author(s):  
J. Hartke ◽  
M. Arnaboldi ◽  
O. Gerhard ◽  
L. Coccato ◽  
C. Pulsoni ◽  
...  
Keyword(s):  
Lower Limit ◽  
Density Profile ◽  
Surface Brightness ◽  
Broad Band ◽  
Major Axis ◽  
Asymptotic Giant Branch ◽  
Number Density ◽  
Detection Techniques ◽  
The Galaxy ◽  
Low Mass

Context. M 105 (NGC 3379) is an early-type galaxy in the Leo I group. The Leo I group is the nearest group that contains all main galaxy types and can thus be used as a benchmark to study the properties of the intra-group light (IGL) in low-mass groups. Aims. We present a photometric survey of planetary nebulae (PNe) in the extended halo of the galaxy to characterise its PN populations and investigate the presence of an extended PN population associated with the intra-group light. Methods. We use PNe as discrete stellar tracers of the diffuse light around M 105. These PNe were identified on the basis of their bright [O III]5007 Å emission and the absence of a broad-band continuum using automated detection techniques. We compare the PN number density profile with the galaxy surface-brightness profile decomposed into metallicity components using published photometry of the Hubble Space Telescope in two halo fields. Results. We identify 226 PNe candidates within a limiting magnitude of m5007, lim = 28.1 from our Subaru-SuprimeCam imaging, covering 67.6 kpc (23 effective radii) along the major axis of M 105 and the halos of NGC 3384 and NGC 3398. We find an excess of PNe at large radii compared to the stellar surface brightness profile from broad-band surveys. This excess is related to a variation in the luminosity-specific PN number α with radius. The α-parameter value of the extended halo is more than seven times higher than that of the inner halo. We also measure an increase in the slope of the PN luminosity function at fainter magnitudes with radius. Conclusions. We infer that the radial variation of the PN population properties is due to a diffuse population of metal-poor stars ([M/H] < −1.0) following an exponential profile, in addition to the M 105 halo. The spatial coincidence between the number density profile of these metal-poor stars and the increase in the α-parameter value with radius establishes the missing link between metallicity and the post-asymptotic giant branch phases of stellar evolution. We estimate that the total bolometric luminosity associated with the exponential IGL population is 2.04 × 109 L⊙ as a lower limit. The lower limit on the IGL fraction is thus 3.8%. This work sets the stage for kinematic studies of the IGL in low-mass groups.

What do globular clusters tell us about isolated ellipticals? The case of NGC 6411

2019 ◽  
Vol 14 (S351) ◽  
pp. 60-63
Author(s):  
J. P. Caso ◽  
Lilia P. Bassino ◽  
T. Richtler ◽  
R. Salinas
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Luminosity Function ◽  
Elliptical Galaxy ◽  
Cluster System ◽  
Colour Distribution ◽  
Globular Cluster System

AbstractWe summarize the results from a study of the globular cluster (GC) system of the isolated elliptical galaxy NGC 6411, based on Gemini/GMOS g', r', i’ photometry. The extent of the globular cluster system is about 70 kpc. It contains ≍700 members. The colour distribution and luminosity function are typical of old GC systems. An excess of bright GCs with intermediate colours might evidence an intermediate-age merger.

scholarly journals CCD Photometry in the Core of the Fornax Dwarf Galaxy

1988 ◽  
Vol 126 ◽  
pp. 583-584
Author(s):  
Robert M. Light ◽  
P. Seitzer
Keyword(s):  
Globular Clusters ◽  
Stellar Population ◽  
Dwarf Galaxy ◽  
Field Population ◽  
Ccd Photometry ◽  
The Core ◽  
The Galaxy ◽  
Good Determination ◽  
Giant Branch Stars

The present study is concerned with the examination of properties of stars in the core of the Fornax dwarf spheroidal galaxy. Previous studies have shown that Fornax has a very diverse stellar population. Four of the globular clusters associated with Fornax were found to have metallicities significantly lower than the mean metallicity of the field population of the galaxy (Buonanno et al. 1985); these clusters point out an older, metal-poor population. Also, there are a number of luminous carbon stars, which are indicative of a much younger population (see Mould and Aaronson 1986). Studies of the field population of Fornax (Demers, Kunkel, and Hardy, 1979; Buonanno et al., 1985) have shown a dispersion in metallicity. We have measured a large sample of giant branch stars, enabling a good determination of mean properties of the Fornax stellar population, as well as allowing a comparison of stars as a function of distance from the center of Fornax.

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.

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