scholarly journals Age-metallicity-velocity relation of stars as seen by RAVE

2015 ◽  
Vol 11 (S317) ◽  
pp. 367-368
Author(s):  
Jennifer Wojno ◽  
Georges Kordopatis ◽  
Matthias Steinmetz ◽  
Gal Matijevič ◽  
Paul J. McMillan ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Large Scale ◽  
Milky Way ◽  
Solar Neighborhood ◽  
The Past ◽  
Formation History ◽  
Data Release ◽  
Velocity Relation ◽  
History Of ◽  
Made In

AbstractThroughout the past decade, significant advances have been made in the size and scope of large-scale spectroscopic surveys, allowing for the opportunity to study in-depth the formation history of the Milky Way. Using the fourth data release of the RAdial Velocity Experiment (RAVE), we study the age-metallicity-velocity space of ~ 100,000 FGK stars in the extended solar neighborhood in order to explore evolutionary processes. Combining these three parameters, we better constrain our understanding of these interconnected, fundamental processes.

scholarly journals The Gaia-ESO Survey: Churning through the Milky Way

2018 ◽  
Vol 609 ◽  
pp. A79 ◽  
Author(s):  
M. R. Hayden ◽  
A. Recio-Blanco ◽  
P. de Laverny ◽  
S. Mikolaitis ◽  
G. Guiglion ◽  
...  
Keyword(s):  
Milky Way ◽  
Past History ◽  
Stellar Populations ◽  
Solar Neighborhood ◽  
The Sun ◽  
Radial Migration ◽  
Orbital Parameters ◽  
The Past ◽  
Major Merger ◽  
History Of

Context. There have been conflicting results with respect to the extent that radial migration has played in the evolution of the Galaxy. Additionally, observations of the solar neighborhood have shown evidence of a merger in the past history of the Milky Way that drives enhanced radial migration. Aims. We attempt to determine the relative fraction of stars that have undergone significant radial migration by studying the orbital properties of metal-rich ([Fe/H] > 0.1) stars within 2 kpc of the Sun. We also aim to investigate the kinematic properties, such as velocity dispersion and orbital parameters, of stellar populations near the Sun as a function of [Mg/Fe] and [Fe/H], which could show evidence of a major merger in the past history of the Milky Way. Methods. We used a sample of more than 3000 stars selected from the fourth internal data release of the Gaia-ESO Survey. We used the stellar parameters from the Gaia-ESO Survey along with proper motions from PPMXL to determine distances, kinematics, and orbital properties for these stars to analyze the chemodynamic properties of stellar populations near the Sun. Results. Analyzing the kinematics of the most metal-rich stars ([Fe/H] > 0.1), we find that more than half have small eccentricities (e< 0.2) or are on nearly circular orbits. Slightly more than 20% of the metal-rich stars have perigalacticons Rp> 7 kpc. We find that the highest [Mg/Fe], metal-poor populations have lower vertical and radial velocity dispersions compared to lower [Mg/Fe] populations of similar metallicity by ~10 km s-1. The median eccentricity increases linearly with [Mg/Fe] across all metallicities, while the perigalacticon decreases with increasing [Mg/Fe] for all metallicities. Finally, the most [Mg/Fe]-rich stars are found to have significant asymmetric drift and rotate more than 40 km s-1 slower than stars with lower [Mg/Fe] ratios. Conclusions. While our results cannot constrain how far stars have migrated, we propose that migration processes are likely to have played an important role in the evolution of the Milky Way, with metal-rich stars migrating from the inner disk toward to solar neighborhood and past mergers potentially driving enhanced migration of older stellar populations in the disk.

scholarly journals A Survey on Edge Performance Benchmarking

2021 ◽  
Vol 54 (3) ◽  
pp. 1-33
Author(s):  
Blesson Varghese ◽  
Nan Wang ◽  
David Bermbach ◽  
Cheol-Ho Hong ◽  
Eyal De Lara ◽  
...  
Keyword(s):  
Large Scale ◽  
Future Internet ◽  
Coupled Systems ◽  
Operational Conditions ◽  
Loosely Coupled ◽  
Performance Benchmarking ◽  
The Past ◽  
Geographically Dispersed ◽  
Tightly Coupled ◽  
History Of

Edge computing is the next Internet frontier that will leverage computing resources located near users, sensors, and data stores to provide more responsive services. Therefore, it is envisioned that a large-scale, geographically dispersed, and resource-rich distributed system will emerge and play a key role in the future Internet. However, given the loosely coupled nature of such complex systems, their operational conditions are expected to change significantly over time. In this context, the performance characteristics of such systems will need to be captured rapidly, which is referred to as performance benchmarking, for application deployment, resource orchestration, and adaptive decision-making. Edge performance benchmarking is a nascent research avenue that has started gaining momentum over the past five years. This article first reviews articles published over the past three decades to trace the history of performance benchmarking from tightly coupled to loosely coupled systems. It then systematically classifies previous research to identify the system under test, techniques analyzed, and benchmark runtime in edge performance benchmarking.

scholarly journals The Luminosity Function of White Dwarfs in the Local Disk and Halo

1989 ◽  
Vol 114 ◽  
pp. 15-23 ◽  
Author(s):  
James Liebert ◽  
Conard C. Dahn ◽  
David G. Monet
Keyword(s):  
White Dwarfs ◽  
Luminosity Function ◽  
Solar Neighborhood ◽  
Star Formation History ◽  
Empirical Estimates ◽  
Formation History ◽  
History Of ◽  
Cool White Dwarfs ◽  
Local Disk

The luminosity function (LF) and total space density of white dwarfs in the solar neighborhood contain important information about the star formation history of the stellar population, and provide an independent method of measuring its age. The first empirical estimates of the LF for degenerate stars were those of Weidemann (1967), Kovetz and Shaviv (1976) and Sion and Liebert (1977). The follow-up investigations made possible by the huge Luyten Palomar proper motion surveys, however, added many more faint white dwarfs to the known sample. While the number of known cool white dwarfs grew to nearly one hundred, these did not include any that were much fainter intrinsically than the coolest degenerates found from the early Luyten, van Biesbroeck and Eggen-Greenstein lists.

scholarly journals PEREDARAN OPIUM DI MINANGKABAU ABAD KE-19

2020 ◽  
Vol 10 (2) ◽  
Author(s):  
Muhammad Nasir
Keyword(s):  
19Th Century ◽  
Large Scale ◽  
Reform Movement ◽  
Religious Groups ◽  
Opium Trade ◽  
Islamic Reform ◽  
History Of ◽  
The 19Th Century ◽  
Made In

This article discusses the history of Minangkabau in the 19th century AD. One of the themes of 19th century Minangkabau history is the Islamic reform movement promoted by religious groups commonly called the Padri movement. One of the central issues of the Padri movement was eradicating the habit of drinking alcoholism that occurred in Minangkabau society. The habit of smoking the drug that comes from boiling opium certainly indicates the existence of the drug on a large scale. Therefore, this article will present a picture of the opium trade in Minangkabau in the 19th century from upstream (providers) to downstream (dealers). It is hoped that this article will be useful as an explanation for the habit of smoking made in the Minangkabau community at that time.

scholarly journals Evolution of word meanings through metaphorical mapping: Systematicity over the past millennium.

2018 ◽  
Author(s):  
Yang Xu ◽  
Barbara Claire Malt ◽  
Mahesh Srinivasan
Keyword(s):  
Large Scale ◽  
Computational Models ◽  
Compact Set ◽  
Large Set ◽  
Word Meanings ◽  
The Past ◽  
History Of ◽  
Cognitive Principles ◽  
Metaphorical Mapping ◽  
Past Millennium

One way that languages are able to communicate a potentially infinite set of ideas through a finite lexicon is by compressing emerging meanings into words, such that over time, individual words come to express multiple, related senses of meaning. We propose that overarching communicative and cognitive pressures have created systematic directionality in how new metaphorical senses have developed from existing word senses over the history of English. Given a large set of pairs of semantic domains, we used computational models to test which domains have been more commonly the starting points (source domains) and which the ending points (target domains) of metaphorical mappings over the past millennium. We found that a compact set of variables, including externality, embodiment, and valence, explain directionality in the majority of about 5000 metaphorical mappings recorded over the past 1100 years. These results provide the first large-scale historical evidence that metaphorical mapping is systematic, and driven by measurable communicative and cognitive principles.

scholarly journals Local Stellar Kinematics from RAVE data—VII. Metallicity Gradients from Red Clump Stars

2016 ◽  
Vol 33 ◽  
Author(s):  
Ö. Önal Taş ◽  
S. Bilir ◽  
G. M. Seabroke ◽  
S. Karaali ◽  
S. Ak ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Milky Way ◽  
Absolute Magnitude ◽  
Selection Effects ◽  
Stellar Kinematics ◽  
Experiment Data ◽  
Radial Gradient ◽  
Data Release ◽  
The Difference ◽  
Red Clump

AbstractWe investigate the Milky Way Galaxy’s radial and vertical metallicity gradients using a sample of 47 406 red clump stars from the RAdial Velocity Experiment Data Release 4. Distances are calculated by adopting Ks-band absolute magnitude as −1.54±0.04 mag for the sample. The metallicity gradients are calculated with their current orbital positions (Rgc and Z) and with their orbital properties (Rm and zmax): d[Fe/H]/dRgc = −0.047±0.003 dex kpc−1 for |Z| ≤ 0.5 kpc and d[Fe/H]/dRm = −0.025±0.002 dex kpc−1 for zmax ≤ 0.5 kpc. This reaffirms the radial metallicity gradient in the thin disc but highlights that gradients are sensitive to the selection effects caused by the difference between Rgc and Rm. The radial gradient is flat in the distance interval 0.5-1 kpc from the plane and then becomes positive greater than 1 kpc from the plane. The radial metallicity gradients are also eccentricity dependent. We showed that d[Fe/H]/dRm = −0.089±0.010, −0.073±0.007, −0.053±0.004 and −0.044±0.002 dex kpc−1 for ep ≤ 0.05, ep ≤ 0.07, ep ≤ 0.10 and ep ≤ 0.20 sub-samples, respectively, in the distance interval zmax ≤ 0.5 kpc. Similar trend is found for vertical metallicity gradients. Both the radial and vertical metallicity gradients are found to become shallower as the eccentricity of the sample increases. These findings can be used to constrain different formation scenarios of the thick and thin discs.

The Role of Biography in Writing the History of Archaeology (1992)

2008 ◽  
Author(s):  
Douglas R. Givens
Keyword(s):  
No Value ◽  
History Of Archaeology ◽  
History Of Anthropology ◽  
Historical Evidence ◽  
Past Work ◽  
The Past ◽  
Institutional Influences ◽  
History Of ◽  
Made In

The history of any discipline involves the explanation of its past and how the past has influenced its development through time. Its ‘objects are events which have finished happening, and conditions no longer in existence. Only when they are no longer perceptible do they become objects of historical thought’ (Collingwood 1946: 233). Writing the history of archaeology involves the analysis of past events and of the contributions that individual archaeologists have made to its development through time. The roles of individuals in archaeology are best seen in biographical accounts of their labours and in the contributions to the discipline that they have made. In general, historians of archaeological science, who are interested in explaining the roles of the individuals in its development, must focus their attention on three important items. First, the most important item is evidence that something has occurred. If individuals’ contributions have no basis in truth and cannot be justified, then they are of no value to the historian of archaeology. Second, the historical picture of individuals’ lives and work must have defined boundaries in space and time. These provide the area of focus for study and description of individuals’ activities. Third, the efforts of individual practitioners must be couched within the intellectual climate in which they are made. Individuals’ contributions are not made in an intellectual vacuum, apart from collegial or institutional influences. Biography, as a tool for writing the history of archaeology, must embrace all of these requisites. For those engaged in explaining archaeology’s past, historical evidence of event and period provide the foundation upon which we can trace our science’s development. Studying and evaluating past work can be helpful in separating useful and outdated methodologies of the field and laboratory. Moreover, the study of the history of anthropology may give the anthropologist needed ‘distance from their own theoretical and methodological preoccupations’ (Darnell 1974: 2). What we see anthropology today as being is certainly not what the ultimate science of humankind will be in the future.

scholarly journals Recent Star Formation History of the Magellanic Clouds

1999 ◽  
Vol 190 ◽  
pp. 470-472
Author(s):  
Eva K. Grebel ◽  
Wolfgang Brandner
Keyword(s):  
Star Formation ◽  
Large Scale ◽  
New Age ◽  
Magellanic Clouds ◽  
Star Formation History ◽  
Star Forming ◽  
Formation History ◽  
History Of

A new age calibration of Cepheids and supergiants is used to study the large-scale recent star formation history of the LMC and the SMC. We find evidence for migration of star formation along the LMC bar as well as for the existence of long-lived (≈ 200 Myr) extended star-forming features.

“Big History” Old and New: Presuppositions, Limits, Alternatives

2015 ◽  
Vol 9 (2) ◽  
pp. 306-326 ◽  
Author(s):  
Allan Megill
Keyword(s):  
Nineteenth Century ◽  
Sixteenth Century ◽  
Large Scale ◽  
Innovative Approach ◽  
Human History ◽  
Comparative History ◽  
Historical Knowledge ◽  
The Past ◽  
History Of ◽  
Big History

In recent years David Christian and others have promoted “Big History” as an innovative approach to the study of the past. The present paper juxtaposes to Big History an old Big History, namely, the tradition of “universal history” that flourished in Europe from the mid-sixteenth century until well into the nineteenth century. The claim to universality of works in that tradition depended on the assumed truth of Christianity, a fact that was fully acknowledged by the tradition’s adherents. The claim of the new Big History to universality likewise depends on prior assumptions. Simply stated, in its various manifestations the “new” Big History is rooted either in a continuing theology, or in a form of materialism that is assumed to be determinative of human history, or in a somewhat contradictory amalgam of the two. The present paper suggests that “largest-scale history” as exemplified in the old and new Big Histories is less a contribution to historical knowledge than it is a narrativization of one or another worldview. Distinguishing between largest-scale history and history that is “merely” large-scale, the paper also suggests that a better approach to meeting the desire for large scale in historical writing is through more modest endeavors, such as large-scale comparative history, network and exchange history, thematic history, and history of modernization.

scholarly journals Sciences and audiences along the last century: the impact of Astronomy Education

2018 ◽  
Vol 13 (S349) ◽  
pp. 474-478
Author(s):  
Rosa M. Ros ◽  
Beatriz Garca
Keyword(s):  
Secondary Teachers ◽  
Astronomy Education ◽  
Interest In Science ◽  
The Past ◽  
The World ◽  
History Of ◽  
The Impact ◽  
Made In ◽  
Science Activities

AbstractJust as in the past, the development of the natural sciences and in particular of astronomy has changed the history of humanity. If we think about the role of our discipline into the future, it shows its enormous power in the field of education, owing to the possibility of awakening interest in science in very varied audiences. Within the framework of the enormous progress made in the technologies related to astronomy, many of them of daily use, the role of the astronomer in the era of Communications acquires fundamental importance.In this presentation, we will try to make a journey through the different ways of presenting astronomical topics for different audiences over the last 100 years. In turn, we will show some specific achievements, associated with education programmes of the discipline. We discuss the impact produced by proposals that are both rigorous in terms of content, and also appeal to the development of the human being in an integral manner, within the framework of citizen science activities.For this research, we have taken into account the uninterrupted development of the NASE programme, which has performed 112 courses in 24 countries throughout the world and in different languages. NASE has involved 4966 secondary teachers in the last eight years.

Sign in / Sign up

Export Citation Format

Share Document