1,549 research outputs found
Mass Segregation and Equipartition of Energy in Two Globular Clusters with Central Density Cusps
We begin by presenting the analysis of a set of deep B- and V-band images of
the central density cusp of the globular cluster M30 (NGC 7099), taken with the
Faint Object Camera aboard the Hubble Space Telescope. These images are the
first to resolve lower-mass main-sequence stars in the cluster's central 10''.
From the positions of individual stars, we measure an improved position for the
cluster center; this new position is 2.6'' from the previously known position.
We find no evidence of a ``flat'', constant-surface-density core; however, the
data do not rule out the presence of a core of radius up to 1.9'' (95%
confidence level). We measure a logarithmic cusp slope (d \log \sigma / d \log
r$) of -0.76 +- 0.07 (1-sigma) for stars with masses between 0.69 and 0.76
\Msun, and -0.82 +- 0.11 for stars with masses between 0.57 and 0.69 \Msun. We
also compare the overall mass function (MF) of the cluster cusp with the MF of
a field at r = 4.6' (near the cluster half-mass radius). The observed degree of
mass segregation is well matched by the predictions of an isotropic, multimass
King model. We then use the Jeans equation to compare the structure of M30 with
that of M15, another cusped cluster, using data from this and a previous paper.
We find that M30 is very close to achieving equipartition of energy between
stellar species, at least over the observed range in mass and radius, while M15
is not. This difference may be a result of the longer relaxation time in the
observed field in M15. The data also suggest that the degree of mass
segregation within the two cluster cusps is smaller than one would expect from
the measurements at larger radius. If so, this phenomenon might be the result
of gravothermal oscillations, of centrally-concentrated populations of
binaries, or of a ~10^3 \Msun black hole in one or more clusters
Radiation kinetics in electronic materials Semiannual report
Degradation and recovery of minority carriers in solar cells including lithiu
The Price of Killing a Child: Is the Fair Labor Standards Act Strong Enough to Protect Children in Today\u27s Workplace?
Counselor Leadership Development and Mentoring: A Proposed Training Model with Graduate Counseling Students
A change of mesospheric ozone content under electron precipitation influence
The simulation model of a change of O, O2 and O3 oxygen component content at the heights 50 to 140 km under electron precipitation influence is presented. Parameters of the air mass vertical transfer are introduced into the model. Calculation results showed that after the intense precipitation in approx. 3 days the ozone content increased at heights approx. 80 km. These results agree with the experimentally found effects of the content change under precipitation conditions
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