Cataclysmic binaries in star clusters. 1: A search for erupting dwarf novae in the globular cluster M92

1994 ◽  
Vol 429 ◽  
pp. 767 ◽  
Author(s):  
Michael M. Shara ◽  
Louis E. Bergeron ◽  
Anthony F. J. Moffat
Keyword(s):  
Globular Cluster ◽  
Star Clusters ◽  
Dwarf Novae ◽  
Cataclysmic Binaries

scholarly journals A Search for Cataclysmic Binaries in the Globular Cluster M3

1985 ◽  
Vol 113 ◽  
pp. 103-104
Author(s):  
M. M. Shara ◽  
A. F. J. Moffat ◽  
D. A. Hanes
Keyword(s):  
Emission Line ◽  
Globular Cluster ◽  
Equivalent Width ◽  
Dwarf Novae ◽  
X Ray ◽  
Cataclysmic Binaries ◽  
Line Equivalent Width

Deep Hβ narrowband and broadband images of M3 have been electronically blinked to search for cataclysmic binaries. Tests of the method on a known, faint cataclysmic enable us to set limits on the sensitivity of the technique. No bright (MB < 6) emission-line (equivalent width > 12 Å) cataclysmic binaries exist in M3 between 4 and 30 core radii from the center. Low luminosity globular X-ray sources could still be weak-lined (E.W. < 12 Å) and bright (MB ≃ +5 like some old novae) or strong-lined (E.W. ≃ 60 Å) and faint (MB > 7 like dwarf novae).

scholarly journals The Globular Cluster System of M31

2002 ◽  
Vol 207 ◽  
pp. 38-45
Author(s):  
P. Jablonka
Keyword(s):  
Globular Cluster ◽  
Star Clusters ◽  
Cluster System ◽  
The Other ◽  
Current Status ◽  
The Subject ◽  
Globular Cluster System

This review presents the current status of our knowledge of M31 star clusters. Given the broadness of the subject, I chose to focus on some of its aspects which are not covered by the other participants in this conference.

scholarly journals Constraints for Cataclysmic Binary Evolution as Derived from Space Distributions

1984 ◽  
Vol 80 ◽  
pp. 363-385
Author(s):  
H. W. Duerbeck
Keyword(s):  
Stellar Populations ◽  
Recurrence Time ◽  
Type I ◽  
Symbiotic Stars ◽  
Late Type ◽  
Dwarf Novae ◽  
Space Density ◽  
Long Period ◽  
Mira Variables ◽  
Cataclysmic Binaries

AbstractSpace densities and galactic z-distributions of novae, recurrent novae, dwarf novae and symbiotic stars are newly determined and discussed in the context of earlier determinations. The data are then compared with the distributions of single and binary stars of possibly related types (late type giants, Mira variables, Algol systems, W UMa systems).Novae and dwarf novae have similar distributions, those of fairly young stellar populations. The observed space density of potential novae (novalike objects) indicates that the mean recurrence time of novae might be as small as a few hundred years, which leads, with given nova shell masses and mass transfer rates in the minimum stage, to a secular decrease of the masses of the components undergoing nova outbursts.Recurrent novae and symbiotic stars have distributions of older stellar populations, similar to those of late type giants and Mira variables.On the basis of galactic distribution, novae and dwarf novae are closely related and may be final stages of W UMa systems, as well as progenitors of supernovae of type I. A small fraction of W UMa systems seems to belong to an older population. If evolutionary transitions between these types of stars can be substantiated, the presence of a minority of novae and dwarf novae in globular clusters and of supernovae I in elliptical galaxies can be explained.Due to the lack of sufficiently well determined space distributions of Algol binaries, the suggestion that long-period Algol systems might be the progenitors of cataclysmic binaries can as yet neither be substantiated nor refuted. A very high space density of long-period Algol systems in the solar neighbourhood is derived. The observed space density of cataclysmic binaries could be explained by the transformation of a small percentage of the long-period Algol systems by common envelope evolution.

scholarly journals Observations of Southern Dwarf Novae

1979 ◽  
Vol 53 ◽  
pp. 497-497
Author(s):  
N. Vogt
Keyword(s):  
Orbital Period ◽  
White Dwarf ◽  
Photometric Data ◽  
Emission Lines ◽  
List Type ◽  
Type Number ◽  
Dwarf Novae ◽  
Broad Emission ◽  
Cataclysmic Binaries ◽  
Short Period

Preliminary results of spectroscopic and photometric data for five dwarf novae are presented : 1) V 436 Cen. The orbital period of 0.0669 days was determined from radial velocity variations. The RV half amplitude of the primary, K1. = 159 km/s, implies very small masses of M1 ≲ 0.20 M⊙ and M2 = 0.18 M⊙ for the binary components.2) Z Cha. Broad emission (Hβ, Hγ, Hδ) and superimposed narrow absorption lines of Hβ-HII, HeI 4471, Cal 4427 and Call K characterize the spectrum during quiescence. Apparently, the cool, optically thin outer disc is seen on the background of a hot continuum, originating from the white dwarf or the inner disc. The RV half amplitude K1 = 87 km/s results in masses of M1 = 1.10 M⊙ and M⊙ = 0.21 M⊙.3) EX Hya. The RV half amplitude K1 = 68 km/s reveals masses of M1 = 1.4 M⊙ and M2 = 0.19 M⊙ The equivalent widths of the emission lines of H, HeI 4471 and HeII 4686 vary with the phase of the recently detected 67 minute cycle (maximal EW coincides nearly with maximal continuum intensity).4) 0Y Car is an eclipsing binary with an orbital period of 0.0631 days. The eclipses show strong variations in shape and amplitude in the course of an outburst, similar as those of Z Cha. The observations seem to confirm that the location of the eruption is the central part of the disc which increases in size and luminosity.5) EK TrA shows periodic superhumps (P = 0.0645 days) during supermaximum, and therefore belongs to the SU UMa sub-group of dwarf novae which are also characterized by a quasi-periodic occurence of super-maxima. The SU UMa sub-group comprises 70% of the ultra-short period cataclysmic binaries, and at least 18% of all dwarf novae.

scholarly journals The Formation and Evolution of Star Clusters and Galaxies

2005 ◽  
Vol 13 ◽  
pp. 347-349
Author(s):  
Stephen E. Zepf
Keyword(s):  
Galaxy Formation ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Near Infrared ◽  
Cluster Formation ◽  
Star Clusters ◽  
Elliptical Galaxies ◽  
Cluster Systems ◽  
Important Observation ◽  
Formation And Evolution

AbstractThis paper addresses the questions of what we have learned about how and when dense star clusters form, and what studies of star clusters have revealed about galaxy formation and evolution. One important observation is that globular clusters are observed to form in galaxy mergers and starbursts in the local universe, which both provides constraints on models of globular cluster formation, and suggests that similar physical conditions existed when most early-type galaxies and their globular clusters formed in the past. A second important observation is that globular cluster systems typically have bimodal color distributions. This was predicted by merger models, and indicates an episodic formation history for elliptical galaxies. A third and very recent result is the discovery of large populations of intermediate age globular clusters in several elliptical galaxies through the use of optical to near-infrared colors. These provide an important link between young cluster systems observed in starbursts and mergers and old cluster systems. This continuum of ages of the metal-rich globular cluster systems also indicates that there is no special age or epoch for the formation of the metal-rich globular clusters, which comprise about half of the cluster population. The paper concludes with a brief discussion of recent results on the globular cluster – low-mass X-ray binary connection.

scholarly journals Modeling Formation of Globular Clusters: Beacons of Galactic Star Formation

2010 ◽  
Vol 6 (S270) ◽  
pp. 381-384
Author(s):  
Oleg Y. Gnedin
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Cluster Formation ◽  
Star Clusters ◽  
Mass Function ◽  
Giant Molecular Clouds ◽  
Early Galaxies ◽  
The Masses

AbstractModern hydrodynamic simulations of galaxy formation are able to predict accurately the rates and locations of the assembly of giant molecular clouds in early galaxies. These clouds could host star clusters with the masses and sizes of real globular clusters. I describe current state-of-the-art simulations aimed at understanding the origin of the cluster mass function and metallicity distribution. Metallicity bimodality of globular cluster systems appears to be a natural outcome of hierarchical formation and gradually declining fraction of cold gas in galaxies. Globular cluster formation was most prominent at redshifts z > 3, when massive star clusters may have contributed as much as 20% of all galactic star formation.

scholarly journals A Candidate for the Recovered Nova of 1938 in the Globular Cluster M 14

1988 ◽  
Vol 126 ◽  
pp. 585-586
Author(s):  
Michael M. Shara ◽  
Michael Potter ◽  
Anthony F. J. Moffat ◽  
Helen Sawyer Hogg ◽  
Amelia Wehlau
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Dynamical Evolution ◽  
Close Binaries ◽  
Dwarf Novae ◽  
X Ray ◽  
Negative Results ◽  
Classical Nova ◽  
M 14

Although close binaries are believed to be of importance in the dynamical evolution of globular clusters, searches for such binaries have produced mostly negative results, aside from x-ray sources. Two dwarf novae which are possible cluster members are known (Margon and Downes 1983) and two classical nova candidates have been found. The crowded field around the nova observed in 1860 close to the center of M80 makes ground-based recovery of that star impossible with present techniques. Here we report on our attempt to recover the star which erupted in 1938 about 30″ (0.8 core radii) from the center of M14.

scholarly journals Isolated Binaries and Triples in N-body Systems

1995 ◽  
Vol 164 ◽  
pp. 372-372
Author(s):  
J. Anosova ◽  
L. Kiseleva
Keyword(s):  
Globular Cluster ◽  
Binary Stars ◽  
Star Clusters ◽  
Dynamical Evolution ◽  
Time Interval ◽  
Galactic Field ◽  
Multiple Stars ◽  
Binary And Multiple Stars ◽  
Marked Tendency ◽  
Triple Stars

Stars show a marked tendency to form the systems of different multiplicity starting from the smallest systems as binary and triple stars up to clusters with a significantly larger number of objects (N ~ 107 for globular cluster s). Different investigators have used different methods of binary stars identificati on but modern observations give a frequency of binary and multiple stars in the Galactic field up to 70% Binary and multiple stars are also often present within star clusters. It is therefore very important to be able to identify such systems as rather isolated substructures in which the dynamical evolution is not significantly affected by other stars (at least, during some considerab le time interval).

scholarly journals Similarities of the intermediate-age SMC star cluster NGC 152 with inner disk clusters in the Milky Way

1991 ◽  
Vol 148 ◽  
pp. 198-199
Author(s):  
T. Richtler ◽  
Klaas S. De Boer ◽  
A. Vallenari ◽  
W. Seggewiss
Keyword(s):  
Globular Cluster ◽  
Milky Way ◽  
Star Clusters ◽  
Star Cluster ◽  
Horizontal Branch ◽  
Vertical Extension ◽  
Magnitude Diagram ◽  
The Mean ◽  
Normal Feature ◽  
Selection Of

A colour-magnitude diagram (CMD) of the region containing the intermediate-age SMC globular cluster NGC 152 was published recently (Melcher & Richtler 1989). A particularly interesting feature of this CMD is the “clump” of He-core burning stars, which are predominantly field stars. A selection of stars near the cluster centre leads to the CMD shown in Figure 1. The vertical extension of the clump (explainable by the evolution of stars younger than 1 Gyr) is replaced by a “tilted horizontal branch” (we use this expression for lack of a better one). The age of NGC 152 is about 1.3 Gyr and the reddening is small; the metallicity is unknown but less than −0.6 dex, which is the mean metallicity of the young SMC population. The tilted HB can be reproduced in CMD simulations using the method developed by Vallenari et al. (1990), and thus can be considered as a normal feature of star clusters like NGC 152. It is evident also in other intermediate-age MC clusters like Kron 3 (Rich et al. 1984).

Sign in / Sign up

Export Citation Format

Share Document