Relevant bibliographies by topics / Globular clusters

Academic literature on the topic 'Globular clusters'

Author: Grafiati
Published: 4 June 2021
Last updated: 30 July 2024

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Contents

Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Globular clusters.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Journal articles on the topic "Globular clusters"

1

Grebel, Eva K. "Globular Clusters in the Local Group." Proceedings of the International Astronomical Union 10, S312 (August 2014): 157–70. http://dx.doi.org/10.1017/s1743921315008078.

Full text
Abstract:
AbstractOnly twelve of the > 76 Local Group galaxies contain globular clusters, showing a broad range of specific frequencies. Here we summarize the properties of these globular cluster systems. Many host galaxies contain very old globulars, but in some globular cluster formation may have been delayed. An age range of several Gyr is common. Except for the inner regions of the spirals, old globular clusters tend to be metal-poor. Increasingly, light element variations and hints of multiple stellar populations are being found also in extragalactic globulars. There is ample evidence for globular cluster accretion from dwarfs onto massive galaxies, but its magnitude has yet to be quantified. Caution is needed to avoid overinterpreting indirect evidence.
APA, Harvard, Vancouver, ISO, and other styles
2

Zepf, Stephen E. "Formation Scenarios for Globular Clusters and Their Host Galaxies." Symposium - International Astronomical Union 207 (2002): 653–63. http://dx.doi.org/10.1017/s0074180900224492.

Full text
Abstract:
This review focuses on how galaxies and their globular cluster systems form. I first discuss the now fairly convincing evidence that some globular clusters form in galaxy starbursts/mergers. One way these observations are valuable is they place important constraints on the physics of the formation of globular clusters. Moreover, it is natural to associate the typically metal-rich clusters forming in mergers with the substantial metal-rich population of globulars around ellipticals, thereby implying an important role for galaxy mergers in the evolution of elliptical galaxies. I also highlight some new observational efforts aimed at constraining how and when elliptical galaxies and their globular cluster systems formed. These include systematic studies of the number of globular clusters around galaxies as a function of morphological type, studies of the kinematics of globular cluster populations in elliptical galaxies, and a variety of observational programs aimed at constraining the relative ages of globular clusters within galaxies as a function of cluster metallicity. The understanding of the formation of globular cluster systems and their host galaxies has grown dramatically in recent years, and the future looks equally promising.
APA, Harvard, Vancouver, ISO, and other styles
3

Usher, Christopher, Jean P. Brodie, Duncan A. Forbes, Aaron J. Romanowsky, Jay Strader, Joel Pfeffer, and Nate Bastian. "The SLUGGS survey: measuring globular cluster ages using both photometry and spectroscopy." Monthly Notices of the Royal Astronomical Society 490, no. 1 (September 25, 2019): 491–501. http://dx.doi.org/10.1093/mnras/stz2596.

Full text
Abstract:
ABSTRACT Globular cluster ages provide both an important test of models of globular cluster formation and a powerful method to constrain the assembly history of galaxies. Unfortunately, measuring the ages of unresolved old stellar populations has proven challenging. Here, we present a novel technique that combines optical photometry with metallicity constraints from near-infrared spectroscopy in order to measure ages. After testing the method on globular clusters in the Milky Way and its satellite galaxies, we apply our technique to three massive early-type galaxies using data from the SAGES Legacy Unifying Globulars and GalaxieS (SLUGGS) survey. The three SLUGGS galaxies and the Milky Way show dramatically different globular cluster age and metallicity distributions, with NGC 1407 and the Milky Way showing mostly old globular clusters, while NGC 3115 and NGC 3377 show a range of globular ages. This diversity implies different galaxy formation histories and that the globular cluster optical colour–metallicity relation is not universal as is commonly assumed in globular cluster studies. We find a correlation between the median age of the metal-rich globular cluster populations and the age of the field star populations, in line with models where globular cluster formation is a natural outcome of high-intensity star formation.
APA, Harvard, Vancouver, ISO, and other styles
4

Elmegreen, Bruce G. "The nature and nurture of star clusters." Proceedings of the International Astronomical Union 5, S266 (August 2009): 3–13. http://dx.doi.org/10.1017/s1743921309990809.

Full text
Abstract:
AbstractStar clusters have hierarchical patterns in space and time, suggesting formation processes in the densest regions of a turbulent interstellar medium. Clusters also have hierarchical substructure when they are young, which makes them all look like the inner mixed parts of a pervasive stellar hierarchy. Young field stars share this distribution, presumably because some of them came from dissolved clusters and others formed in a dispersed fashion in the same gas. The fraction of star formation that ends up in clusters is apparently not constant, but may increase with interstellar pressure. Hierarchical structure explains why stars form in clusters and why many of these clusters are self-bound. It also explains the cluster mass function. Halo globular clusters share many properties of disk clusters, including what appears to be an upper cluster cutoff mass. However, halo globulars are self-enriched and often connected with dwarf galaxy streams. The mass function of halo globulars could have initially been like the power-law mass function of disk clusters, but the halo globulars have lost their low-mass members. The reasons for this loss are not understood. It could have happened slowly over time as a result of cluster evaporation, or it could have happened early after cluster formation as a result of gas loss. The latter model explains best the observation that the globular cluster mass function has no radial gradient in galaxies.
APA, Harvard, Vancouver, ISO, and other styles
5

Forbes, Duncan A. "Globular Clusters in Elliptical Galaxies: Constraints on Mergers." Symposium - International Astronomical Union 186 (1999): 181–84. http://dx.doi.org/10.1017/s0074180900112495.

Full text
Abstract:
There exists a relationship between globular cluster mean metallicity and parent galaxy luminosity (e.g. Brodie & Huchra 1991; Forbes et al. 1996), which appears to be similar to that between stellar metallicity and galaxy luminosity. The globular cluster relation has a similar slope but is offset by about 0.5 dex to lower metallicity. The similarity of these relations suggests that both the globular cluster system and their parent galaxy have shared a common chemical enrichment history. If we can understand the formation and evolution of the globulars, we will also learn something about galaxy formation. With this aim in mind we have created the SAGES (Study of the Astrophysics of Globular clusters in Extragalactic Systems) project. Project members include Brodie, Elson, Forbes, Freeman, Grillmair, Huchra, Kissler–Patig and Schroder. We are using HST Imaging and Keck spectroscopy to study extragalactic globular cluster systems. Further details are given at http://www.ucolick.org/~mkissler/Sages/sages.html.
APA, Harvard, Vancouver, ISO, and other styles
6

Grindlay, Jonathan E. "On the Origin of Neutron Stars in Globular Clusters." Symposium - International Astronomical Union 125 (1987): 173–85. http://dx.doi.org/10.1017/s007418090016070x.

Full text
Abstract:
The formation of neutron stars in globular clusters is discussed in light of a number of recent results and, in particular, studies of the origin and evolution of the high luminosity x-ray binaries found in globular clusters. We argue that the neutron stars most probably arise from the accretion-induced collapse of white dwarfs in compact binary systems, themselves detectable as low luminosity cluster x-ray sources. The white dwarfs which can collapse are probably the remnants of relatively more massive stars than those presently found in globulars. This can account for the predominant occurrence of the high luminosity cluster sources in clusters of relatively high metallicity, since those clusters have recently been found to probably have flatter mass functions of their component stars.
APA, Harvard, Vancouver, ISO, and other styles
7

Lee, Myung Gyoon, Sang Chul Kim, Ho Seong Hwang, Hong Soo Park, Doug Geisler, Ata Sarajedini, and William E. Harris. "A new era for the globular cluster system in M31." Proceedings of the International Astronomical Union 5, S266 (August 2009): 117–22. http://dx.doi.org/10.1017/s1743921309990950.

Full text
Abstract:
AbstractThe globular cluster system in M31 is an ideal laboratory for studying the formation and evolution of M31 as well as the globular clusters themselves. There have been numerous surveys and studies of the globular clusters in M31. However, only recently has the entire body of M31 been searched for globular clusters using wide-field CCD images by our group. A new era for the M31 globular cluster system has begun with the advent of wide-field CCD surveys of M31. We have discovered more than 100 new globular clusters in M31. Our catalog currently includes more than 500 globular clusters confirmed either based on spectra or HST images, many more than in the Milky Way. We present the structure, kinematics and chemical abundance of the M31 globular cluster system based on this large sample, and the implications for the formation and evolution of M31.
APA, Harvard, Vancouver, ISO, and other styles
8

Morrison, Heather, Paul Harding, Denise Hurley-Keller, and Kathy Perrett. "M31’s Disk System of Globular Clusters." Highlights of Astronomy 13 (2005): 165–66. http://dx.doi.org/10.1017/s153929960001546x.

Full text
Abstract:
AbstractGlobular cluster systems are often thought to be associated with violent formation events such as galaxy mergers or the formation of large bulges. However, formation in relatively ordered regions such as thin disks may also be an important process which has been overlooked.Recent high-quality spectroscopic studies of the M31 globulars show that a significant number of the clusters projected on its disk belong to a rapidly rotating thin disk. This contrasts strongly with the Milky Way system, which is composed of a halo and thick disk system and has no known thin disk globulars. It is also likely that M31 has experienced no minor mergers since the globular cluster formation epoch, as such a merger would have heated the globulars into a thick disk system. The metallicity distributions of the disk and non-disk clusters are quite similar.
APA, Harvard, Vancouver, ISO, and other styles
9

Ishchenko, Maryna, Peter Berczik, and Margarita Sobolenko. "Milky Way globular clusters on cosmological timescales." Astronomy & Astrophysics 683 (March 2024): A146. http://dx.doi.org/10.1051/0004-6361/202347990.

Full text
Abstract:
Context. The present epoch of the Gaia success gives us a possibility to predict the dynamical evolution of our Solar System in the global Galactic framework with high precision. Aims. We statistically investigated the total interaction of globular clusters with the Solar System during six billion years of look-back time. We estimated the gravitational influence of globular clusters’ flyby onto the Oort cloud system. Methods. To perform the realistic orbital dynamical evolution for each individual cluster, we used our own high-order parallel dynamical N-body φ-GPU code that we developed. To reconstruct the orbital trajectories of clusters, we used five external dynamical time variable galactic potentials selected from the IllustrisTNG-100 cosmological database and one static potential. To detect a cluster’s close passages near the Solar System, we adopted a simple distance criteria of below 200 pc. To take into account a cluster’s measurement errors (based on Gaia DR3), we generated 1000 initial positions and velocity randomisations for each cluster in each potential. Results. We found 35 globular clusters that have had close passages near the Sun in all the six potentials during the whole lifetime of the Solar System. We can conclude that at a relative distance of 50 pc between a GC and the SolS, we obtain on average ∼15% of the close passage probability over all six billion years, and at dR = 100 pc, we get on average ∼35% of the close passage probability over all six billion years. The globular clusters BH 140, UKS 1, and Djorg 1 have a mean minimum relative distance to the Sun of 9, 19, and 17 pc, respectively. We analysed the gravitational energetic influence on the whole Oort cloud system from the closest selected globular cluster flyby. We generally found that a globular cluster with a typical mass above a few times 105 M⊙ and with deep close passages in a 1–2 pc immediately results in the ejection more than ∼30% of particles from the Oort cloud system. Conclusions. We can assume that a globular cluster with close passages near the Sun is not a frequent occurrence but also not an exceptional event in the Solar System’s lifetime.
APA, Harvard, Vancouver, ISO, and other styles
10

P. Bassino, Lilia, Sergio A. Cellone, and Juan C. Forte. "A Search for Globular Clusters in the Surroundings of Dwarf Galaxies in Fornax: Intracluster Globulars?" Symposium - International Astronomical Union 207 (2002): 345–47. http://dx.doi.org/10.1017/s0074180900224030.

Full text
Abstract:
We present the results of a search for globular clusters in the surroundings of 15 low surface brightness dwarf galaxies in the Fornax cluster, on CCD images in the C and T1 bands. Globular cluster candidates show a clear bimodal color distribution. Their surface density distribution shows no concentration towards the respective dwarf galaxies but it does show concentration towards the center of the Fornax cluster. We suggest that the potential globular clusters might not be bound to the dwarf galaxies, but might instead belong to the intra-cluster medium.
APA, Harvard, Vancouver, ISO, and other styles
More sources

Dissertations / Theses on the topic "Globular clusters"

1

Varri, A. L. "DYNAMICS OF GLOBULAR CLUSTERS." Doctoral thesis, Università degli Studi di Milano, 2012. http://hdl.handle.net/2434/203358.

Full text
Abstract:
Context and motivation: Globular star clusters have long been considered the ideal astrophysical systems for the study of stellar dynamics. For such stellar systems, the relevant two-body relaxation times are typically shorter than their age, so that it can be argued that they are close to a thermodynamically relaxed state. Indeed, as a zeroth-order dynamical description, the class of models defined as a truncated Maxwellian distribution function (King models), supplemented by the assumption of spherical symmetry, have had remarkable success in the application to observed globular clusters. In fact, the great progress recently made in the acquisition of detailed photometric and kinematic information on the structure of globular clusters as well as the improvements in computational speed of the codes for performing N-body simulations and the availability of accelerator hardware call for a renewed effort in theoretical modeling. Main results: Driven by these motivations, the present Thesis is devoted to the study of such quasi-relaxed stellar systems, with the aim of providing a more realistic dynamical paradigm in which fundamental physical ingredients such as the external tidal field, internal rotation, and weak anisotropy in the velocity space are properly taken into account. The main results can be summarized as follows: (i) Self-consistent triaxial tidal models: As a generalization of the above mentioned spherical King models, we constructed a family of triaxial models in which the deviations from sphericity are induced by the presence of an external tidal field, taken into account self-consistently. By considering the simple case of a cluster in circular orbit within a host galaxy, the equilibrium distribution function is obtained from the one describing the spherical models by replacing the energy integral with the relevant Jacobi integral in the presence of the stationary tidal field. The construction of the models requires the solution of a singular perturbation problem for the relevant Poisson equation. A full characterization of the resulting configurations in terms of the relevant intrinsic and projected properties has been given and the range of the predicted flattening is consistent with that observed in most Galactic globular clusters. (ii) Self-consistent axisymmetric rotating models: By following general statistical mechanics considerations, we constructed a family of rigidly rotating models defined as an extension of the King models to the case of axisymmetric equilibria, flattened by solid-body rotation. The relevant distribution function depends only on the Jacobi integral associated to the internal rotation; the structure of the models is determined by solving the relevant Poisson equation with the same perturbation method discussed for the tidal models, since the corresponding singular perturbation problem is formally equivalent. In addition, we also considered a second family of models characterized by differential rotation, designed to be rigid in the central regions and to vanish in the outer parts. In this case the relevant Poisson equation is solved by a spectral iteration method, based on the Legendre expansion of the density and the potential. A full description of the photometric and kinematic observables has been provided and the models in the moderate rotation regime seem particularly suited to the description of the observed rotating star clusters. For general interest in stellar dynamics, we also studied the models in the strong rotation regime, which tend to show a central toroidal structure. (iii) Dynamical stability of rotating stellar systems: By means of specifically designed N-body simulations with a direct numerical code (Starlab), a full stability analysis of the family of differentially rotating models has been performed. Configurations in the rigid and moderate differential rotation regime are found to be dynamically stable; curiously, there also exists an intermediate rotation regime in which the systems exhibit a central toroidal structure and are dynamically stable. In turn, a new dynamical instability, characterized by a variety of unstable Fourier modes of the density distribution, is observed in models with strong rotation and high degree of shear, in striking analogy with recent stability analyses of differentially rotating fluids with polytropic equations of state. The excitation of an unstable mode seems to be triggered by the presence of the relevant corotation point inside the rotating configuration. This result may help to clarify the physical motivation of the ``empirical'' Ostriker & Peebles stability criterion for rotating stellar systems. (iv) Long-term evolution of rotating stellar systems: The long-term dynamical evolution of the differentially rotating models, studied as isolated systems, has been investigated by means of a comprehensive survey of N-body simulations. This study clarifies how the presence of global angular momentum affects the evolution of stellar systems with respect to the traditional paradigm for the dynamical evolution of nonrotating models and enriches the results obtained in the context of Fokker-Planck evolutionary models with rotation. In particular, by comparing the evolution of several rotating models with selected nonrotating models, characterized by the same initial structural properties, we found that rotating configurations reach core collapse more rapidly. Following early investigations, we also interpreted the evolution of a rotating system by distinguishing between a (short) initial phase, in which the gravo-gyro instability takes place and subsequently levels off, and a second phase in which the residual rotation no longer affects the dynamical evolution of the system, which experiences the gravothermal catastrophe and reaches core collapse, as it happens for nonrotating configurations. (v) Observational signatures of internal rotation in Galactic globular clusters: We successfully applied the family of differentially rotating models to the interpretation of the structure and kinematics of three Galactic globular clusters, characterized by the presence of internal rotation, namely omega Cen, 47 Tuc, and M15. The selection of the relevant models has been performed by a method which combines a number of physically-based kinematic criteria with a statistically rigorous best-fit procedure for the determination of the relevant dimensionless parameters and physical scales of the configuration, respectively. (vi) Pressure anisotropy as signature of partial relaxation in Galactic globular clusters: We have carried out a photometric and kinematic study of sample of Galactic globular clusters in different relaxation conditions, by means of King and f_nu models. The latter is a family of radially-biased spherical models, explicitly constructed for violently relaxed elliptical galaxies. The study suggests that less relaxed clusters tend to conform to the picture of formation via incomplete ``violent relaxation'', that is, the process associated to the rapid fluctuations of the gravitational potential during the early collapse phase of a self-gravitating system.
APA, Harvard, Vancouver, ISO, and other styles
2

Masters, Craig Eugene Ashman Keith M. "The low metallicity globular clusters." Diss., UMK access, 2005.

Find full text
Abstract:
Thesis (M.S.)--Dept. of Physics. University of Missouri--Kansas City, 2005.
"A thesis in physics." Typescript. Advisor: K. M. Ashman Vita. Title from "catalog record" of the print edition Description based on contents viewed June 26, 2006. Includes bibliographical references (leaves 54-56). Online version of the print edition.
APA, Harvard, Vancouver, ISO, and other styles
3

Hopwood, Madelaine E. L. "Interstellar matter in globular clusters." Thesis, Keele University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323681.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Goldsbury, Ryan. "White dwarf populations in globular clusters." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/57366.

Full text
Abstract:
This thesis details three distinct projects that explore stellar populations in Milky Way globular clusters. In the first, a method of modelling mass segregation in clusters is presented. The model is fit to 54 clusters and the best fit parameters are presented in tabular form. The newly derived parameter that indicates the amount of mass segregation correlates strongly with other dynamical cluster parameters. In the second study, white dwarf data in the cluster 47 Tucanae are used to construct an empirical relation between temperature and time for these stars. The modified data are compared to theoretical cooling models from four different research groups. We find disagreement between all of the models and the data. The models are also inconsistent with each other. In the third investigation, new UV white dwarf data in 47 Tuc is used to constrain the hydrogen mass fraction and neutrino production rates in cooling white dwarfs. A much different approach from the second project is used. The data are left untouched and the model is transformed to the space in which the data exist. Using the unbinned maximum likelihood statistic, the model’s parameter space is explored with MCMC sampling. A constraint on the rate of neutrino production in white dwarfs comes from this analysis.
Science, Faculty of
Physics and Astronomy, Department of
Graduate
APA, Harvard, Vancouver, ISO, and other styles
5

Dixon, Richard Igor John Dmitri Asoka Thomas. "Infra-red observations of globular clusters." Thesis, University of Edinburgh, 1992. http://hdl.handle.net/1842/27915.

Full text
Abstract:
Near-infra-red imaging observations of the two highly reddened globular clusters M4 and M71 are presented. These data represent the deepest K observations yet published for any cluster. The photometric accuracy and repeatability of the infra-red camera IRCAM is investigated. Observations made at wavelengths of 1.25 μm (J) and 2.2 μm (K) show clearly that the camera-array combination is capable of a photometric accuracy of better than 1% on bright stars, with no evidence of residual non-linearity of > 2% over 6 magnitudes. The reduction procedure is discussed in detail. The profile fitting package DAOPHOT produces accurate and repeatable results from these small frames with large pixels. Zero-point calibrations are examined, and the data are combined with optical data. M71: Fitting new (V-K)-V and (V-K)-K isochrones finds for the four free parameters: E(B-V)=0.26 ± 0.03; (m-M)o=12.85 ± 0.15; age=13 ± 1 Gyr and [Fe/H]=-0.78 ± 0.3, which agree very well with the adopted values from the literature. Combining these with the unified literature results gives the best yet estimates of the cluster parameters: E(B-V)=0.266 ± 0.015; (m-M)o=12.87 ± 0.07; age=14.5 ± 2 Gyr and [Fe/H]=-0.7 ± 0.4. No significant binary fraction is detected on the main sequence. M4: An extensive re-assessment of the literature concludes that a value of R to 4.0 ± 0.2 is appropriate and that the 'best' literature parameters are: E(B-V)=0.37 ± 0.01; (m-M)o=11.22 ± 0.11 ; age=16 ± 2 Gyr and [Fe/H]=-1.1 ± 0.25. The Alcaino and Liller (1984) V magnitudes are found to contain a zero-point error. Allowing for this, isochrone fitting finds an age of 16 ± 3 Gyr and [Fe/H]=-1.0 ± 0.4.
APA, Harvard, Vancouver, ISO, and other styles
6

Pierce, Michael John, and n/a. "Spectroscopy of extra-galactic globular clusters." Swinburne University of Technology, 2006. http://adt.lib.swin.edu.au./public/adt-VSWT20070731.104253.

Full text
Abstract:
The focus of this thesis is the study of stellar populations of extra-galactic glob- ular clusters (GCs) by measuring spectral indices and comparing them to simple stellar population models. We present the study of GCs in the context of tracing elliptical galaxy star formation, chemical enrichment and mass assembly. In this thesis we set out to test how can be determined about a galaxy's formation history by studying the spectra of a small sample of GCs. Are the stellar population parameters of the GCs strongly linked with the formation history of the host galaxy? We present spectra and Lick index measurements for GCs associated with 3 el- liptical galaxies, NGC 1052, NGC 3379 and NGC 4649. We derive ages, metallicities and a-element abundance ratios for these GCs using the x2 minimisation approach of Proctor & Sansom (2002). The metallicities we derive are quite consistent, for old GCs, with those derived by empirical calibrations such as Brodie & Huchra (1990) and Strader & Brodie (2004). For each galaxy the GCs observed span a large range in metallicity from approximately [Z/H]=�2 to solar. We find that the majority of GCs are more than 10 Gyrs old and that we can- not distinguish any finer, age details amongst the old GC populations. However, amongst our three samples we find two age distributions contrary to our expecta- tions. From our sample of 16 GCs associated with the 1-2 Gyr old merger remnant NGC 1052, we find no young GCs. If a significant population of GCs formed during this merger we would expect those GCs to have low mass-to-light ratios and be included in our sample of bright GCs. We find 4 young GCs in our sample of 38 around NGC 4649, an old massive cluster elliptical. There are no signs of recent star formation and therefore we do not expect any GCs to have formed within the galaxy. These results seem to indicate that the GC systems of elliptical galaxies are not strongly associated with recent field star formation. We find a correlation between the α-element abundance ratio and the metallicity for all three samples. Using Thomas, Maraston & Korn (2004) models, we measure much higher α abundance ratios for low metallicity GCs than high metallicity GCs. With current data and models we are limited in both the accuracy and the detail with which we can probe this relationship. We suggest that there are some difficulties reconciling measured GC parameters with our expectations and propose some future work which could help to resolve these and other issues.
APA, Harvard, Vancouver, ISO, and other styles
7

Pierce, Michael John. "Spectroscopy of extra-galactic globular clusters." Australasian Digital Thesis Program, 2006. http://adt.lib.swin.edu.au/public/adt-VSWT20070731.104253/index.html.

Full text
Abstract:
Thesis (Ph.D) - Swinburne University of Technology, Faculty of Information & Communication Technologies, 2006.
A dissertation presented in fulfilment of the requirements of for the degree of Doctor of Philosophy, Faculty of ICT, Swinburne University of Technology, 2006. Typescript. Bibliography p. 90-99.
APA, Harvard, Vancouver, ISO, and other styles
8

McDonald, Iain. "Stellar mass loss in globular clusters." Thesis, Keele University, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.505654.

Full text
Abstract:
This work investigates stellar mass loss in globular clusters. It comprises of optical and infra-red photometric imaging and spectroscopy, plus radio interferometry observations. I present mid-infrared spectroscopic observations of stars in the globular clusters 47 Tucanae and u Centauri, finding 47 Tuc VI (and possibly V18) and ω Cen V6 surrounded by circumstellar silicate dust. ω Cen V42 may also be surrounded by carbon-rich dust. Much of this work is devoted to finding the threshold for dust production and the mass-loss rates from cluster stars with both chromospherically- and dust- or pulsation driven winds. Using very-high-resolution optical photometry, I have identified the transition between the two driving regimes as being at earlier spectral types than in solar-metallicity stars, suggesting that pulsation and continuum-driving become the dominant wind drivers at around K5~M3, or ~1500 L.
APA, Harvard, Vancouver, ISO, and other styles
9

Noble, Richard Gareth. "Precision CCD photometry of globular clusters." Thesis, University of Leeds, 1987. http://etheses.whiterose.ac.uk/980/.

Full text
Abstract:
The first part of this thesis presents a review of colour-magnitude photometry of Galactic globular clusters. A survey has been made of recently-published colourmagnitude photometry of globular clusters, and a self-consistent distance scale established for these data, using the method of subdwarf matching to the observed main sequences. The distances thus derived have been combined with other published colour-magnitude data to infer cluster ages and horizontal branch magnitudes. The relationship between cluster horizontal branch magnitude and metallicity is dicussed. In Chapter 2, a review is made of the photometric applications of charge coupled devices, giving particular attention to the aquisition and analysis of crowded field CCD images within globular clusters. Digital photometric techniques are discussed, including analytic profile fitting to stellar images. The major experimental part of this thesis concerns observations of the globular cluster w Centauri. These observations, their subsequent reduction, and photometric analysis, are discussed in Chapter 3. This chapter also contains a discussion of previous work on this cluster, and highlights its extremely unusual nature. The significant discovery of geometrically varying stellar profiles in the programme CCD images, and the techniques for their analysis, are discussed. The colour-magnitude data from these observations are discussed in Chapter 4. The distance to the cluster is determined, and it is shown that there exists an intrinsic spread in colour upon the cluster main sequence. Theoretical isochrones are employed to show that this spread in colour is consistent with a main sequence metallicity distribution similar to that seen in more highly-evolved stars within the cluster. The age of the cluster is determined as 16 +3 Gyr, by comparison with theoretical isochrones. This result is consistent with recent determinations for other clusters, and supports the theory that the Galactic globular cluster system is essentially coeval. The cluster main sequence luminosity function has been constructed, and is compared with recent observations and theory. In Chapter 5, a preliminary colour-magnitude study of the SMC cluster Lindsay 11 is presented.
APA, Harvard, Vancouver, ISO, and other styles
10

Milone, Antonino. "Multiple stellar populations in globular clusters." Doctoral thesis, Università degli studi di Padova, 2009. http://hdl.handle.net/11577/3426620.

Full text
Abstract:
Over the last few years HST observations have resulted in one of the most exciting and unexpected developments in stellar population studies: the photometric discovery of multiple generations of stars in several globular clusters (GC). It began with the discovery that the main sequence (MS) of Omega Centauri splits for several magnitudes into two distinct branches (Anderson 1997, Bedin et al.2004) . Since, surprisingly the blue branch was found to have higher metallicity (Piotto et al. 2005), the only isochrones that are able to fit this combination of color and metallicity are highly enriched in helium (Y 0.38), relative to the dominant population that is presumed to have near primordial helium. During my PhD, I contributed to a series of discoveries, mainly based on HST data of unparalleled photometric accuracy, that demonstrated that Omega Centauri is far to be unique among globular clusters. Many other GCs were found to have features in their colour-magnitude diagram indicating the presence of multiple stellar populations. The first of this series of globulars was NGC-2808 that manifests the presence of different populations of stars with a split of the MS into three well defined sequences, even thought its sub-giant branch (SGB) is very narrow, with no dispersion in the abundance of iron-peak elements (Chapter 2, Piotto et al.2007). Evidence of multiple populations has been found also in NGC-1851 (Milone et al.2008), this time in the form of a split in the SGB region. Moreover, the presence of a group of RGB stars with enhanced Sr and Ba and strong CN bands (Yong/Grundahl 2008), and the presence of a bimodal horizontal branch, agrees with the hypothesisof two stellar generations inferred by the observed SGB split. In addition, several other massive globulars have splitted SGB: NGC-6388, NGC-6715 (M54), NGC-6656 (M22), NGC-5286, NGC-7089 and NGC-362. Notably, each of these clusters has a different color magnitude diagram and chemical properties. Interestingly enough, in M22, two groups of stars, characterized by different -element and slightly different iron content (Marino et al. in preparation), were found along the RGB, in the same percentage of the two groups observed in the SGB. The high accuracy ACS photometry has also revealed that the multiple stellar population phenomenon is not confined only to Galactic GCs. Mackey/Broby Nielsen (2007) suggest the presence of two populations in Large Magellanic Cloud (LMC) globular NGC-1846. Moreover, by studying a large number of intermediate-age clusters in the LMC, we found that 70% of the entire analized sample hosts multiple stellar populations. All these findings are introducing the intriguing idea that the multiple stellar populations are a common feature among Gcs, challenging the paradigm of globulars hosting a unique population of stars. In this Thesis I will discuss our observational findings in the context of multiple populations in GCs found during my PhD and their implications in the theoretical modelson the formation and evolution of these objects.
Le recenti osservazioni condotte da HST negli ultimi anni hanno portato a uno dei piu' eccitanti e sorprendenti sviluppi negli studi sulle popolazioni stellari: la scoperta di generazioni multiple di stelle in molti ammassi globulari. La prima di queste scoperte fu la sequenza principale di Omega Centauri che si divide in due distinti rami al livello di varie magnitudini. Poiche', inaspettatamente e' stato trovato che il ramo blu ha metallicita' maggiore (Piotto et al.2005), le sole isocrone in grado di riprodurre questa combinazione di colore e metallicita' , sono arricchite in elio (Y0.38) rispetto alla popolazione dominante che si suppone avere elio primordiale. Durante la mia tesi di dottorato, ho contribuito a una serie di queste scoperte, principalmente basate su dati HST di incomparabile precisione fotometrica, che hanno mostrato che Omega Centauri non e' cosi' peculiare tra gli ammassi globulari. Sono stati trovati molti altri ammassi globulari che mostrano evidenze, nel loro diagramma colore magnitudine, della presenza di diverse popolazioni di stelle. Il primo di questa serie di globulari e' stato NGC-2808 che manifesta la presenza di diverse popolazioni stellari con una separazione della sequenza principale in tre sequenze ben definite, anche se il ramo delle sub giganti e' molto stretto, e non ci sono evidenze per una dispersione nell'abbondanza degli elementi pesanti. Evidenze di popolazioni multiple sono state trovate anche in NGC -1851 (Milone et al.2008), questa volta nella forma di una separazione nella regione del ramo delle sub giganti. Inoltre, la presenza di un gruppo di giganti rosse sovrabbondanti in Sr e Ba e caratterizzate da bande del CN forti, e la presenza di un ramo orizzontale bimodale, sono in accordo con l'ipotesi di due generazioni stellari come indicato dalla bimodalita' del ramo delle sub-giganti. L'elevata precisione della fotometria ACS ha inoltre rivelato che il fenomeno delle popolazioni multiple non e' confinato solo agli ammassi globulari della nostra Galassia. Mackey /Broby Nielsen (2007) suggeriscono la presenza di due popolazioni nell'ammasso NGC-1846 nella Grande Nube di Magellano. Inoltre, dallo studio di un elevato numero di ammassi ad eta' intermedia nella Grande Nube, abbiamo trovato che il 70% del campione analizzato ospita popolazioni multiple. Tutte queste scoperte stanno affermando l'affascinante idea per cui la presenza di diverse popolazioni stellari sia una caratteristica comune tra gli ammassi globulari, abbattendo il paradigma per cui questi oggetti ospiterebbero un'unica popolazione di stelle. In questa Tesi discutera' le nostre scoperte osservative, nel contesto delle popolazioni multiple in ammassi globulari, trovate durante il mio dottorato e le loro implicazioni sui modelli teorici di formazione e l'evoluzione di questi oggetti.
APA, Harvard, Vancouver, ISO, and other styles
More sources

Books on the topic "Globular clusters"

1

Hotka, Michael A. Globular Clusters Observing Club: A guide to observing globular clusters, objects selected by Leroy W.L. Guatney, an avid globular cluster observer. Kansas City, MO: Astronomical League, 2004.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
2

Richtler, Tom, and Søren Larsen, eds. Globular Clusters - Guides to Galaxies. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-76961-3.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

United States. National Aeronautics and Space Administration., ed. Voyager observations of globular clusters. [Washington, DC: National Aeronautics and Space Administration, 1994.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
4

Castellani, V. Globular clusters in the UV. Madrid: IUE Observatory, 1986.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
5

United States. National Aeronautics and Space Administration., ed. Voyager observations of globular clusters. [Washington, DC: National Aeronautics and Space Administration, 1994.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
6

United States. National Aeronautics and Space Administration., ed. UV-bright stars in globular clusters. [Washington, D.C.?: National Aeronautics and Space Administration, 1994.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
7

United States. National Aeronautics and Space Administration., ed. UV-bright stars in globular clusters. [Washington, D.C.?: National Aeronautics and Space Administration, 1994.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
8

Space Telescope Science Institute (U. Theory For the Origin of Globular Clusters. S.l: s.n, 1985.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
9

B, Oke J., Nemec James Mitchell 1953-, and United States. National Aeronautics and Space Administration., eds. Spectroscopy of the globular clusters in M87. [Washington, DC: National Aeronautics and Space Administration, 1986.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
10

Workshop on Extragalactic Globular Cluster Systems (2002 Garching bei München, Germany). Extragalactic globular cluster systems: Proceedings of the ESO workshop held in Garching, Germany, 27-30 August 2002. Berlin: Springer, 2003.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
More sources

Book chapters on the topic "Globular clusters"

1

Hodge, Paul. "Globular Clusters." In The Andromeda Galaxy, 124–44. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-015-8056-4_9.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Lang, Kenneth R. "Globular Clusters." In Astrophysical Data, 257–77. New York, NY: Springer US, 1992. http://dx.doi.org/10.1007/978-1-4684-0640-5_14.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Castellani, Vittorio, and Angelo Cassatella. "Globular Clusters." In Astrophysics and Space Science Library, 637–54. Dordrecht: Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-009-3753-6_29.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Ashman, Keith M. "Globular Clusters and Dark Clusters." In Large Scale Structures of the Universe, 590. Dordrecht: Springer Netherlands, 1988. http://dx.doi.org/10.1007/978-94-009-2995-1_141.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Sneden, C. "Abundances in Globular Clusters." In Galaxy Evolution: Connecting the Distant Universe with the Local Fossil Record, 145–52. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-011-4213-7_23.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Demarque, Pierre, Constantine P. Deliyannis, and Ata Sarajedini. "Ages of Globular Clusters." In Observational Tests of Cosmological Inflation, 111–29. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3510-8_11.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Meylan, G., and G. A. Drukier. "Structure of Globular Clusters." In Highlights of Astronomy, 609–15. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-4778-1_5.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Mcmillan, S. L. W., C. Pryor, and E. S. Phinney. "Binaries in Globular Clusters." In Highlights of Astronomy, 616–21. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-4778-1_6.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Kier, Ruben. "July: Just Globular Clusters." In The 100 Best Targets for Astrophotography, 163–69. New York, NY: Springer US, 2009. http://dx.doi.org/10.1007/978-1-4419-0603-8_7.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Brosche, P., M. Odenkirchen, H. J. Tucholke, and M. Geffert. "Motions of Globular Clusters." In Astronomical and Astrophysical Objectives of Sub-Milliarcsecond Optical Astrometry, 259–63. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-0069-4_42.

Full text
APA, Harvard, Vancouver, ISO, and other styles

Conference papers on the topic "Globular clusters"

1

Gratton, Raffaele G. "Globular Clusters." In GRADUATE SCHOOL IN ASTRONOMY: X Special Courses at the National Observatory of Rio de Janeiro (X CCE). AIP, 2006. http://dx.doi.org/10.1063/1.2219325.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Manchester, R. N. "Globular clusters and pulsars." In Back to the Galaxy. AIP, 1992. http://dx.doi.org/10.1063/1.43928.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Johnston, Helen M., Frank Verbunt, and Günther Hasinger. "ROSAT observations of globular clusters." In The evolution of X-ray binaries. AIP, 1994. http://dx.doi.org/10.1063/1.45952.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Sams III, Bruce J. "Speckle imaging of globular clusters." In Astronomy '90, Tucson AZ, 11-16 Feb 90, edited by James B. Breckinridge. SPIE, 1990. http://dx.doi.org/10.1117/12.19295.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Yong, David. "Chemical Abundances in Globular Clusters." In XII International Symposium on Nuclei in the Cosmos. Trieste, Italy: Sissa Medialab, 2013. http://dx.doi.org/10.22323/1.146.0078.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

JETZER, PHILIPPE. "MICROLENSING EVENTS FROM GALACTIC GLOBULAR CLUSTERS." In Proceedings of the MG12 Meeting on General Relativity. WORLD SCIENTIFIC, 2012. http://dx.doi.org/10.1142/9789814374552_0434.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Lynch, Ryan S., Jason R. Boyles, Duncan R. Lorimer, Robert Mnatsakanov, Philip J. Turk, Scott M. Ransom, Marta Burgay, et al. "Non-Recycled Pulsars in Globular Clusters." In RADIO PULSARS: AN ASTROPHYSICAL KEY TO UNLOCK THE SECRETS OF THE UNIVERSE. AIP, 2011. http://dx.doi.org/10.1063/1.3615117.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Rosenblatt, Edward I. "The pregalactic formation of globular clusters." In After the first three minutes. AIP, 1991. http://dx.doi.org/10.1063/1.40449.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Lloyd, Sheridan, Anthony Brown, and Paula Chadwick. "Fermi-LAT Studies of Globular Clusters." In 7th International Fermi Symposium. Trieste, Italy: Sissa Medialab, 2017. http://dx.doi.org/10.22323/1.312.0105.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

D’Amico, Nichi. "New millisecond pulsars in globular clusters." In RELATIVISTIC ASTROPHYSICS: 20th Texas Symposium. AIP, 2001. http://dx.doi.org/10.1063/1.1419604.

Full text
APA, Harvard, Vancouver, ISO, and other styles

Reports on the topic "Globular clusters"

1

Waters, Christopher Z., Stephen E. Zepf, Tod R. Lauer, Edward A. Baltz, and Joseph Silk. Luminosity Function of Faint Globular Clusters in M87. Office of Scientific and Technical Information (OSTI), July 2006. http://dx.doi.org/10.2172/886783.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Press, W. H. (Astrophysics of binary stars, Seyfert galaxies, quasars, and globular clusters. Final technical report. Office of Scientific and Technical Information (OSTI), March 1985. http://dx.doi.org/10.2172/6429223.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Meylan, G., D. Minniti, C. Pryor, C. G. Tinney, E. S. Phinney, and B. Sams. Proper motion with HST: Searching for high-velocity stars in the core of the globular cluster 47 Tucanae. Office of Scientific and Technical Information (OSTI), February 1996. http://dx.doi.org/10.2172/211576.

Full text
APA, Harvard, Vancouver, ISO, and other styles
You might also be interested in the extended bibliographies on the topic 'Globular clusters' for particular source types:
Journal articles Dissertations / Theses Books
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!

To the bibliography