Saint Mary's University

About: Saint Mary's University is a education organization based out in Halifax, Nova Scotia, Canada. It is known for research contribution in the topics: Population & Stars. The organization has 1931 authors who have published 4993 publications receiving 143226 citations.

Evidence for the Hierarchical Formation of the Galactic Spheroid

Abstract: The possibility that the Galactic spheroid was assembled from isolated, chemically distinct proto- Galactic fragments is investigated using a Monte Carlo technique designed to simulate the chemical evolution of the Galaxy in hierarchical formation scenarios which involve no gas dissipation. By com- paring the observed and simulated metallicity distributions of Galactic globular clusters and halo —eld stars, we estimate the level of fragmentation in the collapsing proto-Galaxy. Although the formation process is highly stochastic, the simulations frequently show good agreement with the observed metal- licity distributions, provided the luminosity function of proto-Galactic fragments had the form dN P L a dL , where a D (2. While this steep slope is strongly at odds with the presently observed lumi- nosity function of the Local Group, it is in close agreement with the predictions of semianalytic and numerical models of hierarchical galaxy formation. We discuss a number of possible explanations for this discrepancy. These simulations suggest that the Galactic halo and its globular cluster system were assembled via the accretion and disruption of D103 metal-poor, proto-Galactic fragments by the domi- nant building block: a protobulge whose own metal-rich globular clusters system has been preferentially eroded by dynamical processes. This formation scenario may provide a simple explanation for the diUer- ent shapes of the Galactic globular cluster and halo star metallicity distributions. Based on the similar properties of globular clusters belonging to spiral and giant elliptical galaxies, we argue that the same process (e.g., hierarchical growth involving little gas dissipation) is responsible for the formation of both giant elliptical galaxies and the bulge-halo components of spiral galaxies. Subject headings: galaxies: halosgalaxies: spiralGalaxy: evolutionGalaxy: halo ¨ Galaxy: structureglobular clusters: general

The political economy of natural resource extraction: a new model or extractive imperialism?

Abstract: This paper explores the conditions that gave rise to the “new extractivism”, its policy dynamics and development implications in Latin America. It focuses on the global political economy of natural resource extraction and the emergence of post-neoliberal resource nationalist regimes seeking socially inclusive national development strategies in Latin America. It is argued that a coincidence of economic interests leads these post-neoliberal regimes, even those with a populist and resource nationalist orientation, to side with capital against the local communities. Resume Cet article explore les facteurs qui encouragent la montee de « nouveau extrativisme », la dynamique de ses politiques et ainsi que ses implications sur le developpement en Amerique Latine. Celui-ci ce concentre sur l'economie politique mondiale d'extraction de ressources naturelles et sur l'emergence des regimes post-neoliberaux et nationalistes qui visent un developpement socialement inclusif en Amerique Latine. Il en ressort q...

Characterizing k2 planet discoveries: a super-earth transiting the bright k dwarf hip 116454

Abstract: We report the first planet discovery from the two-wheeled Kepler (K2) mission: HIP 116454 b. The host star HIP 116454 is a bright (V = 10.1, K = 8.0) K1 dwarf with high proper motion and a parallax-based distance of 55.2 ± 5.4 pc. Based on high-resolution optical spectroscopy, we find that the host star is metal-poor with (Fe/H) =− 0.16 ± 0.08 and has a radius R� = 0.716 ± 0.024 Rand mass M� = 0.775 ± 0.027 M� . The star was observed by the Kepler spacecraft during its Two-Wheeled Concept Engineering Test in 2014 February. During the 9 days of observations, K2 observed a single transit event. Using a new K2 photometric analysis technique, we are able to correct small telescope drifts and recover the observed transit at high confidence, corresponding to a planetary radius of Rp = 2.53 ± 0.18 R⊕. Radial velocity observations with the HARPS-N spectrograph reveal a 11.82 ± 1.33 M⊕ planet in a 9.1 day orbit, consistent with the transit depth, duration, and ephemeris. Follow-up photometric measurements from the MOST satellite confirm the transit observed in the K2 photometry and provide a refined ephemeris, making HIP 116454 b amenable for future follow-up observations of this latest addition to the growing population of transiting super-Earths around nearby, bright stars.

Testing the Constancy of the Gravitational Constant Using Helioseismology

Abstract: We compare the p-mode oscillation spectra of solar models, constructed under the assumption that the universal gravitation constant G varied monotonically over the course of the solar lifetime, to the most recent solar p-mode frequency observations from the Global Oscillation Network Group (GONG) instrument and Birmingham Solar Oscillation Network (BiSON). The GONG instrument consists of six telescopes spread over different longitude around the Earth, each recording, once every minute, Doppler shift images of the Sun's surface. BiSON also consists of a network of six telescopes specifically designed to observe low-l p-modes. We find that only those solar models constructed with (1/G)dG/dt ≤ ~1.6 × 10-12 yr-1 are consistent with the observations. This constraint not only probes G over cosmic time, it is stronger by almost one order of magnitude than constraints on the current maximum time variation coming from radar ranging and binary pulsar timing measurements.