scholarly journals JD1-The Planetary Nebulae and the Dynamics of NGC 1399

2009 ◽  
Vol 5 (H15) ◽  
pp. 66-66
Author(s):  
Emily McNeil ◽  
Magda Arnaboldi ◽  
Ortwin Gerhard ◽  
Kenneth Freeman ◽  
Payel Das ◽  
...  
Keyword(s):  
Planetary Nebula ◽  
Globular Clusters ◽  
Planetary Nebulae ◽  
Spectroscopy Technique ◽  
Dynamical Models ◽  
Kinematic Data

Dynamical models of galaxies are limited by the paucity of kinematic data at large radii. Beyond the feasible limit of integrated-light spectroscopy, we rely on discrete tracers such as planetary nebulae and globular clusters. We describe a large (~200) sample of planetary nebula (PN) velocities in the outer regions of the cD elliptical NGC 1399. These data were obtained with a counter-dispersed slitless-spectroscopy technique which traces the kinematics to about 60 kpc (McNeil et al., 2009).

scholarly journals Low dark matter content of the nearby early-type galaxy NGC 821

2014 ◽  
pp. 29-36 ◽  
Author(s):  
S. Samurovic ◽  
A. Vudragovic ◽  
M. Jovanovic ◽  
M.M. Cirkovic
Keyword(s):  
Dark Matter ◽  
Globular Clusters ◽  
Planetary Nebulae ◽  
Matter Content ◽  
Kinematics And Dynamics ◽  
Constant Mass ◽  
Early Type ◽  
Kinematic Data ◽  
Early Type Galaxy ◽  
Dynamical Modelling

In this paper we analyze the kinematics and dynamics of the nearby early-type galaxy NGC 821 based on its globular clusters (GCs) and planetary nebulae (PNe). We use PNe and GCs to extract the kinematics of NGC 821 which is then used for the dynamical modelling based on the Jeans equation. We apply the Jeans equation using the Newtonian mass-follows-light approach assuming constant mass-to-light ratio and find that using such an approach we can successfully fit the kinematic data. The inferred constant mass-to-light ratio, 4:2 < M=LB < 12:4 present throughout the whole galaxy, implies the lack of significant amount of dark matter. We also used three different MOND approaches and found that we can fit the kinematic data without the need for additional, dark, component.

scholarly journals Nonparametric Statistical Models of Globular Cluster Dynamics

1999 ◽  
Vol 172 ◽  
pp. 401-402
Author(s):  
William D. Heacox
Keyword(s):  
Dark Matter ◽  
Statistical Models ◽  
Globular Clusters ◽  
Sole Source ◽  
Dynamical Models ◽  
Kinematic Data ◽  
Angular Momenta ◽  
Orbital Phase ◽  
Per Se ◽  
Nonparametric Statistical

Observations only partially constrain dynamical models of globular clusters and similar systems, in large part because distances and velocities are seen only in projection, and only at a single (unknown) orbital phase. As a result, some dynamical assumptions are necessary if the cluster dynamics and mass distribution are to be inferred from kinematic data — typically that mass follows light, or that the stars observed are the sole source of the gravitational field in which they move, or that orbital energies are completely thermalized, or that orbital angular momenta are exponentially distributed — most often some combination of these is invoked. Such assumptions, reasonable as they may seem, are almost never justified by the data per se for the cluster in question, and thus diminish the credibility of resulting estimates of cluster dynamics and, especially, of the presence and extent of dark matter.

scholarly journals Dynamics of the M31 Planetary Nebula System

1995 ◽  
Vol 10 ◽  
pp. 473-474
Author(s):  
Xiaohui Hui
Keyword(s):  
Planetary Nebula ◽  
Globular Clusters ◽  
Planetary Nebulae ◽  
Radial Velocities ◽  
Stellar Disk ◽  
Dynamical Transition ◽  
Projected Area ◽  
Large Dataset ◽  
Dynamical Study ◽  
M 31

AbstractWe made a spatially complete and kinematically unbiased survey of M 31 for planetary nebulae (PNs). The survey covers a projected area of 20 by 40 kpc centered on M 31. Subsequently, we measured the radial velocities of over 800 PNs using the Hydra multi-object spectrograph on the KPNO 4-m telescope. With this large dataset, a detailed dynamical study of the stellar disk, bulge and halo populations in M 31 is currently underway. We are focusing on the dynamical transition between the disk, bulge and halo, and a comparison between the kinematics of the PNs and globular clusters.

scholarly journals Planetary nebula populations and kinematics

2011 ◽  
Vol 7 (S283) ◽  
pp. 243-250
Author(s):  
Michael G. Richer
Keyword(s):  
Planetary Nebula ◽  
Planetary Nebulae ◽  
Small Range ◽  
Evolutionary Stage ◽  
Kinematic Data

AbstractThe brightest planetary nebulae achieve similar maximum luminosities, have similar ratios of chemcial abundances, and apparently share similar kinematics in all galaxies. These similarities, however, are not necessarily expected theoretically and appear to hide important evolutionary differences. As predicted theoretically, metallicity appears to affect nebular kinematics, if subtly, and there is a clear variation with evolutionary stage. To the extent that it can be investigated, the internal kinematics for galactic and extragalactic planetary nebulae are similar. The extragalactic planetary nebulae for which kinematic data exist, though, probably pertain to a small range of progenitor masses, so there may still be much left to learn, particularly concerning the kinematics of planetary nebulae that descend from the more massive progenitors.

scholarly journals Planetary Nebulae in M31: Abundances, and comparison with bright Planetary Nebulae in the LMC

1997 ◽  
Vol 180 ◽  
pp. 475-476
Author(s):  
M. G. Richer ◽  
G. Stasińska ◽  
M. L. McCall
Keyword(s):  
Planetary Nebula ◽  
Luminosity Function ◽  
Large Population ◽  
Wavelength Region ◽  
Planetary Nebulae ◽  
Surprising Result ◽  
Population Synthesis ◽  
Abundance Distribution ◽  
Wide Range ◽  
The Mean

We have obtained spectra of 28 planetary nebulae in the bulge of M31 using the MOS spectrograph at the Canada-France-Hawaii Telescope. Typically, we observed the [O II] λ3727 to He I λ5876 wavelength region at a resolution of approximately 1.6 å/pixel. For 19 of the 21 planetary nebulae whose [OIII]λ5007 luminosities are within 1 mag of the peak of the planetary nebula luminosity function, our oxygen abundances are based upon a measured [OIII]λ4363 intensity, so they are based upon a measured electron temperature. The oxygen abundances cover a wide range, 7.85 dex < 12 + log(O/H) < 9.09 dex, but the mean abundance is surprisingly low, 12 + log(O/H)–8.64 ± 0.32 dex, i.e., roughly half the solar value (Anders & Grevesse 1989). The distribution of oxygen abundances is shown in Figure 1, where the ordinate indicates the number of planetary nebulae with abundances within ±0.1 dex of any point on the x-axis. The dashed line indicates the mean abundance, and the dotted lines indicate the ±1 σ points. The shape of this abundance distribution seems to indicate that the bulge of M31 does not contain a large population of bright, oxygen-rich planetary nebulae. This is a surprising result, for various population synthesis studies (e.g., Bica et al. 1990) have found a mean stellar metallicity approximately 0.2 dex above solar. This 0.5 dex discrepancy leads one to question whether the mean stellar metallicity is as high as the population synthesis results indicate or if such metal-rich stars produce bright planetary nebulae at all. This could be a clue concerning the mechanism responsible for the variation in the number of bright planetary nebulae observed per unit luminosity in different galaxies (e.g., Hui et al. 1993).

scholarly journals Planetary Nebula Evolution Traced by Distance-Independent Parameters

1993 ◽  
Vol 155 ◽  
pp. 480-480
Author(s):  
C.Y. Zhang ◽  
S. Kwok
Keyword(s):  
Physical Properties ◽  
Mass Distribution ◽  
Planetary Nebula ◽  
Strong Support ◽  
Planetary Nebulae ◽  
Central Star ◽  
Evolution Model ◽  
The Core ◽  
Independent Parameters ◽  
Central Stars

Making use of the results from recent infrared and radio surveys of planetary nebulae, we have selected 431 nebulae to form a sample where a number of distance-independent parameters (e.g., Tb, Td, I60μm and IRE) can be constructed. In addition, we also made use of other distance-independent parameters ne and T∗ where recent measurements are available. We have investigated the relationships among these parameters in the context of a coupled evolution model of the nebula and the central star. We find that most of the observed data in fact lie within the area covered by the model tracks, therefore lending strong support to the correctness of the model. Most interestingly, we find that the evolutionary tracks for nebulae with central stars of different core masses can be separated in a Tb-T∗ plane. This implies that the core masses and ages of the central stars can be determined completely independent of distance assumptions. The core masses and ages have been obtained for 302 central stars with previously determined central-star temperatures. We find that the mass distribution of the central stars strongly peaks at 0.6 M⊙, with 66% of the sample having masses <0.64 MM⊙. The luminosities of the central stars are then derived from their positions in the HR diagram according to their core masses and central star temperatures. If this method of mass (and luminosity) determination turns out to be accurate, we can bypass the extremely unreliable estimates for distances, and will be able to derive other physical properties of planetary nebulae.

scholarly journals The Remarkable Evolution of the Post-Agb Star FG SGE

1998 ◽  
Vol 11 (1) ◽  
pp. 363-363
Author(s):  
Johanna Jurcsik ◽  
Benjamin Montesinos
Keyword(s):  
Time Scales ◽  
Effective Temperature ◽  
Planetary Nebula ◽  
Planetary Nebulae ◽  
Central Star ◽  
Evolutionary Models ◽  
Single Star ◽  
Line Intensities ◽  
Evolutionary Changes ◽  
Evolutionary Studies

FG Sagittae is one of the most important key objects of post-AGB stellar evolutionary studies. As a consequence of a final helium shell flash, this unique variable has shown real evolutionary changes on human time scales during this century. The observational history was reviewed in comparison with predictions from evolutionary models. The central star of the old planetary nebula (Hel-5) evolved from left to right in the HR diagram, going in just hundred years from the hot region of exciting sources of planetary nebulae to the cool red supergiant domain just before our eyes becoming a newly-born post-AGB star. The effective temperature of the star was around 50,000 K at the beginning of this century, and the last estimates in the late 1980s give 5,000-6,500 K. Recent spectroscopic observations obtained by Ingemar Lundström show definite changes in the nebular line intensities. This fact undoubtedly rules out the possibility that, instead of FG Sge, a hidden hot object would be the true central star of the nebula. Consequently, the observed evolutionary changes are connected with the evolution of a single star.

scholarly journals Anisotropy in ω Centauri and 47 Tucanae

1988 ◽  
Vol 126 ◽  
pp. 663-664
Author(s):  
G. Meylan
Keyword(s):  
Globular Clusters ◽  
Velocity Dispersion ◽  
Dynamical Models ◽  
Comprehensive Description ◽  
Great Opportunity ◽  
The Galaxy

The southern sky gives us the great opportunity to observe two among the brightest and nearest globular clusters of the Galaxy: ω Cen and 47 Tuc. For these giant clusters, we present the comparison between observations and King-Michie multi-mass dynamical models with anisotropy in the velocity dispersion. A more comprehensive description of this work is to be published (Meylan 1986a,b).

scholarly journals What to expect when using globular clusters as tracers of the total mass distribution in Milky Way-mass galaxies

2021 ◽  
Vol 502 (2) ◽  
pp. 2828-2844
Author(s):  
Meghan E Hughes ◽  
Prashin Jethwa ◽  
Michael Hilker ◽  
Glenn van de Ven ◽  
Marie Martig ◽  
...  
Keyword(s):  
Dark Matter ◽  
Radial Distribution ◽  
Globular Clusters ◽  
Dominant Factor ◽  
Quality Uncertainty ◽  
Dynamical Models ◽  
Accuracy And Precision ◽  
The Galaxy ◽  
Dark Matter Distribution ◽  
Ideal Tracer

ABSTRACT Dynamical models allow us to connect the motion of a set of tracers to the underlying gravitational potential, and thus to the total (luminous and dark) matter distribution. They are particularly useful for understanding the mass and spatial distribution of dark matter (DM) in a galaxy. Globular clusters (GCs) are an ideal tracer population in dynamical models, since they are bright and can be found far out into the halo of galaxies. We aim to test how well Jeans-Anisotropic-MGE (JAM) models using GCs (positions and line-of-sight velocities) as tracers can constrain the mass and radial distribution of DM haloes. For this, we use the E-MOSAICS suite of 25 zoom-in simulations of L* galaxies. We find that the DM halo properties are reasonably well recovered by the JAM models. There is, however, a strong correlation between how well we recover the mass and the radial distribution of the DM and the number of GCs in the galaxy: the constraints get exponentially worse with fewer GCs, and at least 150 GCs are needed in order to guarantee that the JAM model will perform well. We find that while the data quality (uncertainty on the radial velocities) can be important, the number of GCs is the dominant factor in terms of the accuracy and precision of the measurements. This work shows promising results for these models to be used in extragalactic systems with a sample of more than 150 GCs.

scholarly journals Central Dynamics of Globular Clusters: the Case for a Black Hole in ω Centauri

2007 ◽  
Vol 3 (S246) ◽  
pp. 341-345
Author(s):  
Eva Noyola ◽  
Karl Gebhardt ◽  
Marcel Bergmann
Keyword(s):  
Black Hole ◽  
Relaxation Time ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Dwarf Galaxy ◽  
Kinematic Data ◽  
The Core ◽  
Galactic System ◽  
Interesting Candidate ◽  
Radial Anisotropy

AbstractThe globular cluster ω Centauri is one of the largest and most massive members of the Galactic system. Its classification as a globular cluster has been challenged making it a candidate for being the stripped core of an accreted dwarf galaxy; this and the fact that it has one of the largest velocity dispersions for star clusters in our galaxy makes it an interesting candidate for harboring an intermediate mass black hole. We measure the surface brightness profile from integrated light on an HST/ACS image, and find a central power-law cusp of logarithmic slope -0.08. We also analyze Gemini GMOS-IFU kinematic data for a 5”x5” field centered on the nucleus of the cluster, as well as for a field 14″ away. We detect a clear rise in the velocity dispersion from 18.6 kms−1 at 14″ to 23 kms−1 in the center. Given the very large core in ω Cen (2.58'), an increase in the dispersion in the central 10″ is difficult to attribute to stellar remnants, since it requires too many dark remnants and the implied configuration would dissolve quickly given the relaxation time in the core. However, the increase could be consistent with the existence of a central black hole. Assuming a constant M/L for the stars within the core, the dispersion profile from these data and data at larger radii implies a black hole mass of 4.0+0.75−1.0×104M⊙. We have also run flattened, orbit-based models and find a similar mass. In addition, the no black hole case for the orbit model requires an extreme amount of radial anisotropy, which is difficult to preserve given the short relaxation time of the cluster.

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