364 research outputs found
A comparison of the globular cluster luminosity functions of the inner and outer halo of the Milky Way and M31
We show that the globular cluster luminosity function (GCLF) of the inner
halo of the Milky Way is statistically different from the GCLF of the outer
halo. We also find a similar difference between the inner and outer halo
population of M31. We assert that this difference is evidence for some form of
dynamical evolution of the cluster population and/or a dependence of GCLF shape
on the environment in which the cluster population formed. We also find that
the turnover luminosity of the GCLF is unaffected by these differences and
further assert that this stability of the turnover luminosity affirms its
usefulness as an indicator of cosmic distance.Comment: 3 pages, 2 figures, submitted to MNRA
GRK6 deficiency is associated with enhanced CXCR4-mediated neutrophil chemotaxis in vitro and impaired responsiveness to G-CSF in vivo
The Canada-France Ecliptic Plane Survey - Full Data Release: The orbital structure of the Kuiper belt
We report the orbital distribution of the trans-neptunian objects (TNOs)
discovered during the Canada-France Ecliptic Plane Survey, whose discovery
phase ran from early 2003 until early 2007. The follow-up observations started
just after the first discoveries and extended until late 2009. We obtained
characterized observations of 321 sq.deg. of sky to depths in the range g ~
23.5--24.4 AB mag. We provide a database of 169 TNOs with high-precision
dynamical classification and known discovery efficiency. Using this database,
we find that the classical belt is a complex region with sub-structures that go
beyond the usual splitting of inner (interior to 3:2 mean-motion resonance
[MMR]), outer (exterior to 2:1 MMR), and main (in between). The main classical
belt (a=40--47 AU) needs to be modeled with at least three components: the
`hot' component with a wide inclination distribution and two `cold' components
(stirred and kernel) with much narrower inclination distributions. The hot
component must have a significantly shallower absolute magnitude (Hg)
distribution than the other two components. With 95% confidence, there are
8000+1800-1600 objects in the main belt with Hg <= 8.0, of which 50% are from
the hot component, 40% from the stirred component and 10% from the kernel; the
hot component's fraction drops rapidly with increasing Hg. Because of this, the
apparent population fractions depend on the depth and ecliptic latitude of a
trans-neptunian survey. The stirred and kernel components are limited to only a
portion of the main belt, while we find that the hot component is consistent
with a smooth extension throughout the inner, main and outer regions of the
classical belt; the inner and outer belts are consistent with containing only
hot-component objects. The Hg <= 8.0 TNO population estimates are 400 for the
inner belt and 10,000 for the outer belt within a factor of two.Comment: 59 pages, 9 figures, 7 table
Low CO/CO<sub>2</sub> ratios of comet 67P measured at the Abydos landing site by the <i>Ptolemy</i> mass spectrometer
Comets are generally considered to contain the best-preserved material from the beginning of our planetary system, although the mechanism of their formation and subsequent evolution are still poorly understood. Here we report the direct in situ measurement of H2O, CO, and CO2 by the Ptolemy mass spectrometer onboard the Philae lander, part of the European Space Agency’s Rosetta mission, at the Abydos site of the Jupiter-family comet 67P/Churyumov-Gerasimenko. A CO/CO2 ratio of around 0.07 ± 0.04 is found at the surface of the comet, a value substantially lower than the one measured by ROSINA in the coma. Such a major difference is a potential indication of heterogeneity of the nucleus and not of changes in the CO/CO2 ratio of the coma with radial distance
- …