584 research outputs found
Nuclear star cluster formation in energy-space
In a virialized stellar system, the mean-square velocity is a direct tracer
of the energy per unit mass of the system. Here, we exploit this to estimate
and compare root-mean-square velocities for a large sample of nuclear star
clusters and their host (late- or early-type) galaxies. Traditional
observables, such as the radial surface brightness and second-order velocity
moment profiles, are subject to short-term variations due to individual
episodes of matter infall and/or star formation. The total mass, energy and
angular momentum, on the other hand, are approximately conserved. Thus, the
total energy and angular momentum more directly probe the formation of galaxies
and their nuclear star clusters, by offering access to more fundamental
properties of the nuclear cluster-galaxy system than traditional observables.
We find that there is a strong correlation, in fact a near equality, between
the root-mean-square velocity of a nuclear star cluster and that of its host.
Thus, the energy per unit mass of a nuclear star cluster is always comparable
to that of its host galaxy. We interpret this as evidence that nuclear star
clusters do not form independently of their host galaxies, but rather that
their formation and subsequent evolution are coupled. We discuss how our
results can potentially be used to offer a clear and observationally testable
prediction to distinguish between the different nuclear star cluster formation
scenarios, and/or quantify their relative contributions.Comment: 12 pages, 3 figures, 4 tables; accepted for publication in MNRA
Learning processes of students in competence based pre-vocational secondary education
The purpose of this study was to validate a causal and hierarchical model to elaborate on the relation between goal orientations, information processing strategies and development of conceptual knowledge of pre-vocational secondary education-students. This model can be used to describe students' learning processes in competence-based education. Preferences of students (n=719) for certain types of goals and information processing strategies were examined using questionnaires. The development of conceptual knowledge was investigated by having students create concept maps before and after a learning situation (e.g. project). Results of causal and hierarchical analyses showed that students' preferences for mastery and performance goals positively affected their preferences for using deep processing strategies. Performance of surface processing strategies had a negative effect on the development of conceptual knowledge
Сучасні тенденції розвитку міжнародних торговельно-економічних відносин
У статті визначено і обґрунтовано сучасні тенденції розвитку міжнародних торгівельно-економічних відносин. Проаналізовано основні макроекономічні показники США, Японії, країн-членів ЄС, країн, що розвиваються, їх зміну в процесі глобалізації і в період економічної кризи. Ключові слова: торгівля, економічні відносини, макроекономічні показники, США, Японія, ЄС, економічна криза.В статье определены и обоснованы современные тенденции развития международных торгово-экономических отношений. Проанализированы основные макроэкономические показатели США, Японии, стран-членов ЕС, развивающихся стран, их изменения в процес се глобализации и в период экономического кризиса. Ключевые слова: торговля, экономические отношения, макроэкономические показатели, США, Япония, ЕС, экономический кризис.The article specifies and substantiates current trends of developing international trade and economic relations. Basic macroeconomic indices of the USA, Japan, members EU, developed countries, their transformations in the process of globalization, as well as in the period of economic crisis are analyzed. Key word: trade, economic relations, macroeconomic indices, USA, Japan, EU, economic crisis
Oppervlakte en urine-afvoer van de dichte vloer in relatie tot hokbevuiling bij vleesvarkens
Hokbevuiling bij vleesvarkens vormt geen probleem bij een hoeveelheid dichte vloer tot maximaal 0,3 m2 per dier. Er moet dan wel aan een aantal voorwaarden worden voldaan
Грошово-кредитна система Сполучених Штатів Америки
У статті розглядаються проблеми функціонування грошово-кредитної системи Сполучених Штатів Америки — однієї з найбільш розвинених країн світу. Ключові слова: центральний банк, комерційні банки, небанківські кредитні установи, грошова одиниця, грошово-кредитна система.В статье рассматриваются проблемы функционирования денежно-кредитной системы Соединенных Штатов Америки, одной из наиболее развитых стран мира. Ключевые слова: центральный банк, коммерческие банки, небанковские кредитные учреждения, денежная единица, денежно-кредитная система.The problems of functioning of the money-andcredit United States of America are examined in the article, one of the most prosperous countries world. Key words: Central bank, commercial banken, nonbanken of credit institution, money unit, gold-credit system
Probing the AGN Unification Model at redshift z 3 with MUSE observations of giant Ly nebulae
A prediction of the classic active galactic nuclei (AGN) unification model is
the presence of ionisation cones with different orientations depending on the
AGN type. Confirmations of this model exist for present times, but it is less
clear in the early Universe. Here, we use the morphology of giant Ly
nebulae around AGNs at redshift z3 to probe AGN emission and therefore
the validity of the AGN unification model at this redshift. We compare the
spatial morphology of 19 nebulae previously found around type I AGNs with a new
sample of 4 Ly nebulae detected around type II AGNs. Using two
independent techniques, we find that nebulae around type II AGNs are more
asymmetric than around type I, at least at radial distances ~physical kpc
(pkpc) from the ionizing source. We conclude that the type I and type II AGNs
in our sample show evidence of different surrounding ionising geometries. This
suggests that the classical AGN unification model is also valid for
high-redshift sources. Finally, we discuss how the lack of asymmetry in the
inner parts (r30 pkpc) and the associated high values of the HeII to
Ly ratios in these regions could indicate additional sources of (hard)
ionizing radiation originating within or in proximity of the AGN host galaxies.
This work demonstrates that the morphologies of giant Ly nebulae can be
used to understand and study the geometry of high redshift AGNs on
circum-nuclear scales and it lays the foundation for future studies using much
larger statistical samples.Comment: 15 pages, 13 figures, accepted for publication in MNRA
Climbing to the top of the galactic mass ladder: evidence for frequent prolate-like rotation among the most massive galaxies
We present the stellar velocity maps of 25 massive early type galaxies
located in dense environments observed with MUSE. Galaxies are selected to be
brighter than M_K=-25.7 magnitude, reside in the core of the Shapley Super
Cluster or be the brightest galaxy in clusters richer than the Virgo Cluster.
We thus targeted galaxies more massive than 10^12 Msun and larger than 10 kpc
(half-light radius). The velocity maps show a large variety of kinematic
features: oblate-like regular rotation, kinematically distinct cores and
various types of non-regular rotation. The kinematic misalignment angles show
that massive galaxies can be divided into two categories: those with small or
negligible misalignment, and those with misalignment consistent with being 90
degrees. Galaxies in this latter group, comprising just under half of our
galaxies, have prolate-like rotation (rotation around the major axis). Among
the brightest cluster galaxies the incidence of prolate-like rotation is 50 per
cent, while for a magnitude limited sub-sample of objects within the Shapley
Super Cluster (mostly satellites), 35 per cent of galaxies show prolate-like
rotation. Placing our galaxies on the mass - size diagram, we show that they
all fall on a branch extending almost an order of magnitude in mass and a
factor of 5 in size from the massive end early-type galaxies, previously
recognised as associated with major dissipation-less mergers. The presence of
galaxies with complex kinematics and, particularly, prolate-like rotators
suggests, according to current numerical simulations, that the most massive
galaxies grow predominantly through dissipation-less equal-mass mergers.Comment: 11 pages, 4 figures, accepted to MNRA
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