TY - JOUR

T1 - Further properties of the dynamical clock A+ indicator in a toy model of pure dynamical friction

AU - Pasquato, M.

N1 - Funding Information:
This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sk lodowska-Curie grant agreement No. 664931. I wish to thank Dr. Pier-francesco di Cintio, Dr. Paolo Miocchi, Dr. Alessandro Cobbe, and Dr. Stefano Pugnetti for helpful discussion on this subject.
Publisher Copyright:
© 2020 Instituto de Astronoma, Universidad Nacional Autonoma de Mexico.

PY - 2020/4

Y1 - 2020/4

N2 - The Alessandrini A+ indicator is a measure of star cluster dynamical evolu-tion based on the mass-segregation of blue straggler stars. A+ is defined as the integral of the cumulative distribution of blue stragglers over log radius, minus a term related to the reference population used. In a companion paper I introduced a model of dynamical friction and calculated the A+ indicator analytically. Here I show further properties of the time evolution of A+, focusing on the physical interpretation of its time derivative dA+=dt. I find that dA+=dt is the mean of the reciprocal dyamical friction timescale, weighted by the density of blue stragglers. I show that it is non-negative (as expected based on monotonicity) due to the den-sity of blue-stragglers being non-negative and that, for a radially non-decreasing dynamical friction timescale, dA+=dt is also non-decreasing with time, making A+ a convex function.

AB - The Alessandrini A+ indicator is a measure of star cluster dynamical evolu-tion based on the mass-segregation of blue straggler stars. A+ is defined as the integral of the cumulative distribution of blue stragglers over log radius, minus a term related to the reference population used. In a companion paper I introduced a model of dynamical friction and calculated the A+ indicator analytically. Here I show further properties of the time evolution of A+, focusing on the physical interpretation of its time derivative dA+=dt. I find that dA+=dt is the mean of the reciprocal dyamical friction timescale, weighted by the density of blue stragglers. I show that it is non-negative (as expected based on monotonicity) due to the den-sity of blue-stragglers being non-negative and that, for a radially non-decreasing dynamical friction timescale, dA+=dt is also non-decreasing with time, making A+ a convex function.

KW - Blue stragglers

KW - Globular clusters: General

KW - Methods: Analytical

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U2 - 10.22201/ia.01851101p.2020.56.01.02

DO - 10.22201/ia.01851101p.2020.56.01.02

M3 - Article

AN - SCOPUS:85088296992

SN - 0185-1101

VL - 56

SP - 7

EP - 10

JO - Revista Mexicana de Astronomia y Astrofisica

JF - Revista Mexicana de Astronomia y Astrofisica

IS - 1

ER -