Knowledge Base

A

B

C

Literature Review

Goals•Determine if there is mass segregation in open clusters•To look for a correlation between mass segregation and age

in star clusters.

3

4

5

Globular star clusters are dense bunches of hundreds of thousands of stars of about the same age and have some of the oldest surviving stars in the universe as compared to open clusters which are much less dense and younger. . The

heavier members will thus tend to sink into lower (closer to the center) orbits, while the lighter members will tend to rise to higher orbits. When mass segregation is complete, the cluster will enter a “relaxed” state, in which several

distinct layers of stars of different masses are present.

The prim algorithm (left) enables us to create the minimum spanning tree. Prim’s algorithm requires one to connect stars in a cluster from point to point in the shortest manner possible. The average massive to massive star MST and normal MST weights will allow us to put these numbers into the mass segregation ratio.

Although energy can exchange in either direction, there is a statistical tendency for the kinetic energy of the two members to equalize during an encounter; this statistical phenomenon is called equipartition.

Mass segregation ratio developed by Richard J. Allison used in combination with the prim algorithm to determine the mass

segregation ratio .

Age difference between clusters correlates to the separation of the clusters suggesting that mass

segregation is present.

Age increases left to right

During two–body encounters all stars exchange their energies and try to find a thermodynamic equilibrium.

MethodologyStar Clusters n=30

Images RGB composed and sharpened using ImageJ

MST calculated using Prim algorithm by excel programmed spreadsheet

Mass Segregation Ratio using Allison formulaMetalicity/Age taken from L. Chen’s Catalog of Star Clusters/ Calculated

using Turning point theorem

Images obtained from 2mass Images obtained from Faulke’s Telescope

Stars separated into massive and less massive using APT

Comparison of Mass Segregation to Age

Images obtained from Leopard

-0.5-0.4-0.3-0.2-0.100.10.20.30.40.50

0.5

1

1.5

2

2.5

Metallicity of Star Cluster

Mas

s Seg

rega

tion

Ratio

0 0.5 1 1.5 2 2.5 3 3.5 4 4.50

0.5

1

1.5

2

2.5

MSRLinear (MSR)

AGE (MYR)

MSR

Shows MSR vs. Age( as calculated by turn-off method). A .7 correlation coefficient as well as a general trend indicate some relationship between mass segregation and age.

Shows MSR vs. Metalicity ( from spectroscopic measurement). Graph ‘s X axis is logarithmic and goes from positive to negative Fe/h values. Fe/h values decrease from left to right.

Discussion

Conclusion

Bibliography

• Raboud and Allison’s results were similar

• As the clusters changed over time, an essential part stage in their transformation may have been equipartition

•Cluster formation was more rapid then expected

• Star clusters formed highly hierarchical structure over time

• In the youngest star clusters, intermediate sized stars often were surrounded by clusters of smaller stars, suggesting some type of interaction- equipartition

The Columbia Encyclopedia, Sixth Edition Copyright ©2004, Columbia University Press. Licensed from Lernout & Hauspie Speech Products N.V. All Rights Reserved. http://www.questia.com/library/encyclopedia/star_cluster.jsp Eugenio Carretta “Abundances in Red Giant Stars of NGC 2808 and Correlations between Chemical Anomalies and Global Parameters in Globular Clusters.” Osservatorio Astronomico di Bologna. The Astronomical Journal, 2006 March.

http://adsabs.harvard.edu/abs/2006AJ....131.1766C Lee, H.; Kim, S.-L.; Kim, H.-J. ; Jeon, Y.-B.; Park, H,-S. “New Variable Stars in the Open Cluster M103.” Konkoly Observatory, Budapest, 26 October 2005, Dept. of Earth Science Education, Korea National University of Education, Korea Astronomy and Space Science Institute. http://adsabs.harvard.edu/abs/2005IBVS.5656....1L Gonzalo Alcaino and William Liller “Ages of Globular Clusters Derived from BVRI CCD photometry.” Instituto Isaac Newton, Ministerio de Educación de Chile, Santiago, Chile. Societá Astronomica Italiana, Vol 57 No. 3. http://adsabs.harvard.edu/abs/1986MmSAI..57..321A Prof. Fabrizio Mazzucconi, Enrico Albisetti and Bernardo Mannucci. “Atlas of The Skies: Journeying between the stars and planets in the discovery of the universe.”TAJ Books 2003Mike Lynch. “The Essential guide to Our Night Sky: New York Starwatch.” Voyageur Press 2005 p.46 and 47Elmegreen, Bruce G., Yuri Efremov, Ralph E. Pudritz, and Hans Zinnercker. “Observations and Theory of Star Cluster Formation.” http://www.uapress.arizona.edu/onlinebks/ppiv/chap07.pdfChandra X-ray Observatory (2008, April 29). Oldest Known Celestial Objects are Surprisingly Immature. Science Daily. Retrieved April 28, 2009, from http://www.sciencedaily.com/releases/2008/04/080428140351.htm ESA Hubble Information Centre (2008, August 6). Thousands of Globular Clusters Identified in Virgo Cluster of Galaxies. Science Daily. Retrieved April 28, 2009, from http://www.sciencedaily.com/releases/2008/08/080805234054.htm L. Chen “On the Galactic Disk Metallicity Distribution from Open Clusters. I. New Catalogs and Abundance Gradient “ Retrieved January 20th from http://www.iop.org/EJ/article/-search=67323939.1/1538-3881/125/3/1397/datafile1.txt?request-id=03792360-92e6-4fea-9709-ade8349a14a5