scholarly journals Modeling globular clusters as multi-wavelength emitters

2021 ◽  
Author(s):  
Hambeleleni Davids ◽  
Christo Venter ◽  
Michael Backes
Keyword(s):  
Globular Clusters ◽  
Multi Wavelength

scholarly journals Multiple populations in the Sagittarius nuclear cluster M 54 and in other anomalous globular clusters

2015 ◽  
Vol 11 (S317) ◽  
pp. 170-175
Author(s):  
A. P. Milone
Keyword(s):  
Globular Clusters ◽  
Galactic Halo ◽  
Dwarf Galaxy ◽  
Hubble Space Telescope ◽  
Stellar System ◽  
Stellar Populations ◽  
Building Blocks ◽  
Multi Wavelength ◽  
Nuclear Cluster ◽  
Different Content

AbstractM 54 is the central cluster of the Sagittarius dwarf galaxy. This stellar system is now in process of being disrupted by the tidal interaction with the Milky Way and represents one of the building blocks of the Galactic Halo. Recent discoveries, based on the synergy of photometry and spectroscopy have revealed that the color-magnitude diagram (CMD) of some massive, anomalous, Globular Clusters (GCs) host stellar populations with different content of heavy elements. In this paper, I use multi-wavelength Hubble Space Telescope (HST) photometry to detect and characterize multiple stellar populations in M 54. I provide empirical evidence that this GC shares photometric and spectroscopic similarities with the class of anomalous GCs. These findings make it tempting to speculate that, similarly to Sagittarius nuclear cluster M 54, other anomalous GCs were born in an extra-Galactic environment.

scholarly journals The Formation and Evolution of Young Star Clusters in the Antennae

2002 ◽  
Vol 207 ◽  
pp. 367-377
Author(s):  
Bradley C. Whitmore
Keyword(s):  
Power Law ◽  
Globular Clusters ◽  
Compact Star ◽  
Star Clusters ◽  
Young Star ◽  
Power Law Distribution ◽  
Barred Galaxies ◽  
Tenfold Increase ◽  
Multi Wavelength ◽  
Formation And Evolution

Five populations of young, massive, compact star clusters have been identified in the “Antennae galaxies”, the nearest and youngest example of a prototypical merging galaxy. The brightest of these clusters have all the attributes expected of young globular clusters, hence allowing us to study the formation and evolution of globular clusters in the local universe. Comparisons between the different populations and a variety of multi-wavelength observations are providing new insights into the formation of the clusters. For example, the very red clusters originally identified by Whitmore and Schweizer (1995) appear to be the youngest population, just emerging from their dust cocoon. The cluster luminosity functions for a wide variety of galaxies (i.e., mergers, starbursts, barred galaxies, spirals) appear to follow a “universal” power law, with index ≈ −2. The primary difference between the different galaxies is the normalization, with roughly a tenfold increase in the number of clusters in merging and starbursting galaxies. Hence, the fact that the brightest clusters are in mergers may be largely a statistical result. Simulations are now showing how the initial power law distribution for the clusters will evolve toward the peaked distribution found for old globular clusters, via a combination of processes including two-body evaporation, disk shocking, and stellar mass loss.

MULTI-WAVELENGTH MODELING OF GLOBULAR CLUSTERS—THE MILLISECOND PULSAR SCENARIO

2013 ◽  
Vol 779 (2) ◽  
pp. 126 ◽  
Author(s):  
A. Kopp ◽  
C. Venter ◽  
I. Büsching ◽  
O. C. de Jager
Keyword(s):  
Globular Clusters ◽  
Millisecond Pulsar ◽  
Multi Wavelength

Recent Advances in High Dispersion Spectroscopy of Globular Cluster Stars

1988 ◽  
Vol 132 ◽  
pp. 525-530
Author(s):  
Raffaele G. Gratton
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
High Dispersion ◽  
Photographic Material ◽  
Recent Advances ◽  
Metal Abundances ◽  
Ccd Detectors ◽  
Major Progress

The use CCD detectors has allowed a major progress in abundance derivations for globular cluster stars in the last years. Abundances deduced from high dispersion spectra now correlates well with other abundance indicators. I discuss some problems concerning the derivation of accurate metal abundances for globular clusters using high dispersion spectra from both the old photographic and the most recent CCD data. The discrepant low abundances found by Cohen (1980), from photographic material for M71 giants, are found to be due to the use of too high microturbulences.

Observations for the Role of Flux rope Eruption in a Geoeffective Solar Flare

2014 ◽  
Vol 4 (2) ◽  
pp. 555-564
Author(s):  
A.M Aslam
Keyword(s):  
Solar Flare ◽  
Flux Rope ◽  
Magnetic Configuration ◽  
Solar Dynamics Observatory ◽  
Multi Wavelength ◽  
Solar Dynamics ◽  
Halo Coronal Mass Ejection ◽  
Mass Ejection ◽  
The Waves

On September 24, 2011 a solar flare of M 7.1 class was released from the Sun. The flare was observed by most of the space and ground based observatories in various wavebands. We have carried out a study of this flare to understand its causes on Sun and impact on earth. The flare was released from NOAA active region AR 11302 at 12:33 UT. Although the region had already produced many M class flares and one X- class flare before this flare, the magnetic configuration was not relaxed and still continued to evolve as seen from HMI observations. From the Solar Dynamics Observatory (SDO) multi-wavelength (131 Ã…, 171 Ã…, 304 Ã… and 1600Ã…) observations we identified that a rapidly rising flux rope triggered the flare although HMI observations revealed that magnetic configuration did not undergo a much pronounced change. The flare was associated with a halo Coronal Mass Ejection (CME) as recorded by LASCO/SOHO Observations. The flare associated CME was effective in causing an intense geomagnetic storm with minimum Dst index -103 nT. A radio burst of type II was also recorded by the WAVES/WIND. In the present study attempt is made to study the nature of coupling between solar transients and geospace.

Multi-wavelength imaging and its application as a plasma torch health monitor

1997 ◽  
Author(s):  
C. Winstead ◽  
W. Wang ◽  
R. Cook ◽  
G. Miller ◽  
C. Winstead ◽  
...  
Keyword(s):  
Plasma Torch ◽  
Multi Wavelength ◽  
Health Monitor

Choice of Optimum Operational Regime for Total Stations upon Making Geodetic Surveys under Heavy Aerosol Atmosphere Pollution

2018 ◽  
Vol 938 (8) ◽  
pp. 12-19
Author(s):  
S. B. Verdiyev
Keyword(s):  
Rational Choice ◽  
Theoretical Modelling ◽  
Total Station ◽  
Visible Band ◽  
Multi Wavelength ◽  
Atmosphere Pollution ◽  
Experimental Researches ◽  
Practical Recommendations

The possibility to use multi-wavelength regime of total stations operation for making surveys under heavy aerosol atmosphere pollution is researched. The actuality of single- and multi-wavelength regimes rational choice under heavy aerosol atmosphere pollution is grounded. The task on researching the matter of operational regime choice for total stations is formulated. The method for solution of the formulated task is suggested. The theoretical modelling and experimental researches are held to formulate the criterion for choice of single- or multi-wavelength regimes. The practical recommendations for such a choice are formulated. The practical recommendations are formulated for choice of measurements regime. According to formulated recommendations if a single-wavelength total station operates in the field of longer wavelengths (R) of visible band and a three-wavelengths one operates with bias to shorter (B, G, R) wavelengths, the single-wavelength total station should be preferred. But if the single-wavelength total station operates in the field of shorter wavelengths (B) and the three-wavelengths one operates with bias to longer wavelengths (B, G, R) then the multi-wavelengths total station should be preferred. The recommendation described in this article are relevant for both the regimes of measurements with- and without reflector and can be useful for users of total stations.

The Formation and Evolution of Candidate Young Globular Clusters in NGC 3256

1999 ◽  
Vol 118 (2) ◽  
pp. 752-764 ◽  
Author(s):  
Stephen E. Zepf ◽  
Keith M. Ashman ◽  
Jayanne English ◽  
Kenneth C. Freeman ◽  
Ray M. Sharples
Keyword(s):  
Globular Clusters ◽  
Formation And Evolution
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