scholarly journals Cobalt and copper abundances in 56 Galactic bulge red giants

2020 ◽  
Vol 640 ◽  
pp. A89
Author(s):  
H. Ernandes ◽  
B. Barbuy ◽  
A. C. S. Friaça ◽  
V. Hill ◽  
M. Zoccali ◽  
...  
Keyword(s):  
High Resolution ◽  
Red Giants ◽  
High Resolution Data ◽  
Mean Values ◽  
Chemical Enrichment ◽  
Very Large Telescope ◽  
The Galaxy ◽  
Observed Behaviour ◽  
Red Clump ◽  
Secondary Element

Context. The Milky Way bulge is an important tracer of the early formation and chemical enrichment of the Galaxy. The abundances of different iron-peak elements in field bulge stars can give information on the nucleosynthesis processes that took place in the earliest supernovae. Cobalt (Z = 27) and copper (Z = 29) are particularly interesting. Aims. We aim to identify the nucleosynthesis processes responsible for the formation of the iron-peak elements Co and Cu. Methods. We derived abundances of the iron-peak elements cobalt and copper in 56 bulge giants, 13 of which were red clump stars. High-resolution spectra were obtained using FLAMES-UVES at the ESO Very Large Telescope by our group in 2000–2002, which appears to be the highest quality sample of optical high-resolution data on bulge red giants obtained in the literature to date. Over the years we have derived the abundances of C, N, O, Na, Al, Mg; the iron-group elements Mn and Zn; and neutron-capture elements. In the present work we derive abundances of the iron-peak elements cobalt and copper. We also compute chemodynamical evolution models to interpret the observed behaviour of these elements as a function of iron. Results. The sample stars show mean values of [Co/Fe] ~ 0.0 at all metallicities, and [Cu/Fe] ~ 0.0 for [Fe/H] ≥−0.8 and decreasing towards lower metallicities with a behaviour of a secondary element. Conclusions. We conclude that [Co/Fe] varies in lockstep with [Fe/H], which indicates that it should be produced in the alpha-rich freezeout mechanism in massive stars. Instead [Cu/Fe] follows the behaviour of a secondary element towards lower metallicities, indicating its production in the weak s-process nucleosynthesis in He-burning and later stages. The chemodynamical models presented here confirm the behaviour of these two elements (i.e. [Co/Fe] vs. [Fe/H] ~constant and [Cu/Fe] decreasing with decreasing metallicities).

scholarly journals High-Resolution B-Photometry of the Milky Way and Results on Galactic Structure

1990 ◽  
Vol 139 ◽  
pp. 205-206
Author(s):  
S. Kimeswenger ◽  
W. Schlosser ◽  
K. J. Seidensticker ◽  
B. Hoffmann ◽  
Th. Schmidt-Kaler
Keyword(s):  
High Resolution ◽  
Milky Way ◽  
Galactic Structure ◽  
Surface Photometry ◽  
High Resolution Data ◽  
V Band ◽  
The Galaxy ◽  
Global Parameters ◽  
Pioneer 10 ◽  
Resolution Data

During the last two decades, many attempts were made to determine the global parameters of the Galaxy and to compare the Galaxy to other galaxies (Schmidt-Kaler and Schlosser 1973; de Vaucouleurs and Pence 1978; Gilmore 1984; van der Kruit 1986). While most of these investigations are based on star counts, a detailed overall study by surface photometry, because of the lack of homogeneous high-resolution data, is rare. The last attempt by van der Kruit (1986), based on Pioneer 10 data, suffered from low resolution. The great number of individual structures at low and even intermediate latitudes could not be recognized. Our work (B-band, Hoffmann et al. 1989, this volume; V-band, Schlosser, Schmidt-Kaler, and Schneider 1989; U-Band and R-band photometry, in preparation) provides this homogeneous high-resolution data.

Towards a revised climatology of summertime dimethylsulfide concentrations and sea–air fluxes in the Southern Ocean

2016 ◽  
Vol 13 (2) ◽  
pp. 364 ◽  
Author(s):  
Tereza Jarníková ◽  
Philippe D. Tortell
Keyword(s):  
High Resolution ◽  
Southern Ocean ◽  
Chlorophyll A ◽  
Mixed Layer ◽  
Mixed Layer Depth ◽  
Cloud Formation ◽  
Layer Depth ◽  
High Resolution Data ◽  
Mean Values ◽  
Data Coverage

Environmental context The trace gas dimethylsulfide (DMS) is emitted from surface ocean waters to the overlying atmosphere, where it forms aerosols that promote cloud formation and influence Earth’s climate. We present an updated climatology of DMS emissions from the vast Southern Ocean, demonstrating how the inclusion of new data yields higher regional sources compared with previously derived values. Our work provides an important step towards better quantifying the oceanic emissions of an important climate-active gas. Abstract The Southern Ocean is a dominant source of the climate-active gas dimethylsulfide (DMS) to the atmosphere. Despite significant improvements in data coverage over the past decade, the most recent global DMS climatology does not include a growing number of high-resolution surface measurements in Southern Ocean waters. Here, we incorporate these high resolution data (~700000 measurements) into an updated Southern Ocean climatology of summertime DMS concentrations and sea–air fluxes. Owing to sparse monthly data coverage, we derive a single summertime climatology based on December through February means. DMS frequency distributions and oceanographic properties (mixed-layer depth and chlorophyll-a) show good general coherence across these months, providing justification for the use of summertime mean values. The revised climatology shows notable differences with the existing global climatology. In particular, we find increased DMS concentrations and sea–air fluxes south of the Polar Frontal zone (between ~60 and 70°S), and increased sea–air fluxes in mid-latitude waters (40–50°S). These changes are attributable to both the inclusion of new data and the use of region-specific parameters (e.g. data cut-off thresholds and interpolation radius) in our objective analysis. DMS concentrations in the Southern Ocean exhibit weak though statistically significant correlations with several oceanographic variables, including ice cover, mixed-layer depth and chlorophyll-a, but no apparent relationship with satellite-derived measures of phytoplankton photophysiology or taxonomic group abundance. Our analysis highlights the importance of using regional parameters in constructing climatological DMS fields, and identifies regions where additional observations are most needed.

scholarly journals High-resolution spectroscopic study of red clump stars in the Galaxy: iron-group elements

2010 ◽  
Vol 408 (2) ◽  
pp. 1225-1232 ◽  
Author(s):  
E. Puzeras ◽  
G. Tautvaišienė ◽  
J. G. Cohen ◽  
D. F. Gray ◽  
S. J. Adelman ◽  
...  
Keyword(s):  
High Resolution ◽  
Spectroscopic Study ◽  
Iron Group ◽  
The Galaxy ◽  
Red Clump

scholarly journals Optical and Ultraviolet Spectral Morphology of Luminous OB Stars in the Galaxy and the Magellanic Clouds

1986 ◽  
Vol 116 ◽  
pp. 185-198 ◽  
Author(s):  
Nolan R. Walborn
Keyword(s):  
High Resolution ◽  
Hubble Space Telescope ◽  
Optical Data ◽  
High Resolution Data ◽  
Ob Stars ◽  
Central Cluster ◽  
Distant Galaxies ◽  
The Galaxy ◽  
H Ii Region ◽  
30 Doradus

Three areas of current progress relevant to the theme of this Symposium will be discussed. (1) New spectroscopic observations of the 30 Doradus central cluster, obtained independently by the author and by J. Melnick, confirm the presence of numerous very early O-type members, including several of type O3. In combination with sophisticated new direct imagery of the luminous central object R136 by A. Walker and by G. Weigelt, these results have evident implications for understanding the ionization of the supergiant H II region, as well as for the interpretation of R136 itself and of the apparently similar regions seen in more distant galaxies. In particular, no evidence remains for a supermassive object in 30 Doradus, but its central cluster is revealed as a spectacular grouping of very massive hot stars. (2) A further member of the Ofpe/WN9 category in the LMC has been identified, bringing their number to seven, with no exact spectroscopic counterparts yet known in the Galaxy. One of these objects is currently in a state of outburst and has been interpreted by O. Stahl et al. as the hottest known Hubble-Sandage variable. (3) An extensive survey of IUE high-resolution data has revealed a strong correlation between the ultraviolet stellar wind features and the optical spectral classifications for the majority of normal O stars. These results are relevant to future studies with the High Resolution Spectrograph on the Hubble Space Telescope, which may observe restricted UV wavelength ranges in faint extragalactic OB stars lacking optical data of comparable quality.

scholarly journals Concerning the Li-rich status of KIC 9821622: a Kepler field RGB star reported as a Li-rich giant

2019 ◽  
Vol 491 (3) ◽  
pp. 3838-3843
Author(s):  
Raghubar Singh ◽  
Yerra Bharat Kumar ◽  
Bacham E Reddy ◽  
Wako Aoki
Keyword(s):  
High Resolution ◽  
Thermodynamic Equilibrium ◽  
Local Thermodynamic Equilibrium ◽  
Red Giants ◽  
Inert Core ◽  
Low Mass ◽  
Non Local ◽  
Red Clump ◽  
Red Giant

ABSTRACT Given the implications for the origin of Li enhancement in red giants, we have reviewed the Li-rich classification of KIC 9821622, the only bonafide red giant branch (RGB) giant with a He inert core to date, reported as a Li-rich giant by reanalysing the high-resolution spectra. We have obtained A(Li)LTE = 1.42 ± 0.05 dex. After correcting for non-local thermodynamic equilibrium (NLTE), we have A(Li)NLTE = 1.57 ± 0.05 dex, which is significantly less than the reported A(Li) = 1.80 ± 0.2 dex. We found that the subordinate line at 6103 Å is too weak or absent to measure Li abundance. The derived abundance is normal for red giants undergoing dilution during the first dredge-up. Since all known Kepler field Li-rich giants belong to the red clump region, this clarification removes the anomaly and strengthens the evidence that Li enhancement in low-mass giants may be associated only with the He-core burning phase. The origin of Li excess probably lies during the He flash at the RGB tip, a phase immediately preceding the red clump.

scholarly journals Variability of the near-infrared extinction curve towards the Galactic centre

2019 ◽  
Vol 630 ◽  
pp. L3 ◽  
Author(s):  
F. Nogueras-Lara ◽  
R. Schödel ◽  
F. Najarro ◽  
A. T. Gallego-Calvente ◽  
E. Gallego-Cano ◽  
...  
Keyword(s):  
Near Infrared ◽  
Stellar Structure ◽  
Extinction Curve ◽  
Line Of Sight ◽  
Galactic Centre ◽  
High Angular Resolution ◽  
Mean Values ◽  
The Galaxy ◽  
Red Clump ◽  
Significant Line

Context. Due to the extreme extinction towards the Galactic centre (AV ∼ 30 mag), its stellar population is mainly studied in the near-infrared (NIR) regime. Therefore, a proper analysis of the NIR extinction curve is necessary to fully characterise the stellar structure and population of the inner part of the galaxy. Aims. We studied the dependence of the extinction index (αλ) in the NIR on the line of sight, wavelength, and extinction. Methods. We used the GALACTICNUCLEUS imaging survey, a high angular resolution catalogue (0.2″) for the inner part of the Galaxy in JHKs, and studied the spatial variation in the extinction index. We also applied two independent methods based on red clump stars to compute the extinction index between different bands and its variation with wavelength. Results. We did not detect any significant line-of-sight or extinction variation in α within the studied region in the nuclear stellar disc. The extinction index between JH and HKs differs by 0.19 ± 0.05. We obtained mean values for the extinction indices αJH = 2.43 ± 0.03 and αHKs = 2.23 ± 0.03. The dependence of the extinction index on the wavelength could explain the differences obtained for αλ in the literature since it was assumed constant for the NIR regime.

scholarly journals Asteroseismology of luminous red giants with Kepler. II. Dependence of mass loss on pulsations and radiation

2020 ◽  
Author(s):  
Jie Yu ◽  
Saskia Hekker ◽  
Timothy R Bedding ◽  
Dennis Stello ◽  
Daniel Huber ◽  
...  
Keyword(s):  
Mass Loss ◽  
Mass Loss Rate ◽  
Asymptotic Giant Branch ◽  
Red Giants ◽  
Asymptotic Giant Branch Stars ◽  
Chemical Enrichment ◽  
Dust Mass ◽  
Red Giant ◽  
The Masses ◽  
Loss Rates

Abstract Mass loss by red giants is an important process to understand the final stages of stellar evolution and the chemical enrichment of the interstellar medium. Mass-loss rates are thought to be controlled by pulsation-enhanced dust-driven outflows. Here we investigate the relationships between mass loss, pulsations, and radiation, using 3213 luminous Kepler red giants and 135000 ASAS–SN semiregulars and Miras. Mass-loss rates are traced by infrared colours using 2MASS and WISE and by observed-to-model WISE fluxes, and are also estimated using dust mass-loss rates from literature assuming a typical gas-to-dust mass ratio of 400. To specify the pulsations, we extract the period and height of the highest peak in the power spectrum of oscillation. Absolute magnitudes are obtained from the 2MASS Ks band and the Gaia DR2 parallaxes. Our results follow. (i) Substantial mass loss sets in at pulsation periods above ∼60 and ∼100 days, corresponding to Asymptotic-Giant-Branch stars at the base of the period-luminosity sequences C′ and C. (ii) The mass-loss rate starts to rapidly increase in semiregulars for which the luminosity is just above the red-giant-branch tip and gradually plateaus to a level similar to that of Miras. (iii) The mass-loss rates in Miras do not depend on luminosity, consistent with pulsation-enhanced dust-driven winds. (iv) The accumulated mass loss on the Red Giant Branch consistent with asteroseismic predictions reduces the masses of red-clump stars by 6.3%, less than the typical uncertainty on their asteroseismic masses. Thus mass loss is currently not a limitation of stellar age estimates for galactic archaeology studies.

scholarly journals High-Resolution Traffic Sensing with Probe Autonomous Vehicles: A Data-Driven Approach

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 464
Author(s):  
Wei Ma ◽  
Sean Qian
Keyword(s):  
High Resolution ◽  
Autonomous Vehicles ◽  
Penetration Rate ◽  
Data Driven ◽  
Traffic Information ◽  
Flow Density ◽  
Massive Data ◽  
Market Penetration ◽  
High Resolution Data ◽  
Data Driven Approach

Recent decades have witnessed the breakthrough of autonomous vehicles (AVs), and the sensing capabilities of AVs have been dramatically improved. Various sensors installed on AVs will be collecting massive data and perceiving the surrounding traffic continuously. In fact, a fleet of AVs can serve as floating (or probe) sensors, which can be utilized to infer traffic information while cruising around the roadway networks. Unlike conventional traffic sensing methods relying on fixed location sensors or moving sensors that acquire only the information of their carrying vehicle, this paper leverages data from AVs carrying sensors for not only the information of the AVs, but also the characteristics of the surrounding traffic. A high-resolution data-driven traffic sensing framework is proposed, which estimates the fundamental traffic state characteristics, namely, flow, density and speed in high spatio-temporal resolutions and of each lane on a general road, and it is developed under different levels of AV perception capabilities and for any AV market penetration rate. Experimental results show that the proposed method achieves high accuracy even with a low AV market penetration rate. This study would help policymakers and private sectors (e.g., Waymo) to understand the values of massive data collected by AVs in traffic operation and management.

scholarly journals Development and Application of a Novel Pluri-Residue Method to Determine Polar Pesticides in Fruits and Vegetables through Liquid Chromatography High Resolution Mass Spectrometry

Foods ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 553
Author(s):  
Lorena Manzano-Sánchez ◽  
José Antonio Martínez-Martínez ◽  
Irene Domínguez ◽  
José Luis Martínez Vidal ◽  
Antonia Garrido Frenich ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
High Resolution ◽  
High Performance ◽  
Fruits And Vegetables ◽  
High Resolution Mass Spectrometry ◽  
Stationary Phases ◽  
Mean Values ◽  
Polar Pesticides ◽  
Relative Standard ◽  
The Matrix

Nowadays, highly polar pesticides are not included in multiresidue methods due to their physico-chemical characteristics and therefore, specific analytical methodologies are required for their analysis. Laboratories are still looking for a pluri-residue method that encompasses the largest number of polar pesticides. The aim of this work was the simultaneous determination of ethephon, 2-hydroxyethylphosphonic acid (HEPA), fosetyl aluminum, glyphosate, aminomethylphosphonic acid (AMPA), N-acetyl-glyphosate and N-acetyl-AMPA in tomatoes, oranges, aubergines and grapes. For that purpose, an ultra high performance liquid chromatography (UHPLC) coupled to a high resolution single mass spectrometer Orbitrap-MS were used. Different stationary phases were evaluated for chromatographic separation, and among them, the stationary phase Torus DEA provided the best separation of the selected compounds. The QuPPe method was used for the extraction of the analytes, but slight modifications were needed depending on the matrix. The developed method was validated, observing matrix effect in all matrices. Intra- and inter-day precision were estimated, and relative standard deviation were lower than 19%. Recoveries were satisfactory, and mean values ranged from 70% to 110%. Limits of quantification were between 25 and 100 µg kg−1. Finally, the analytical method was applied to different fruits and vegetables (oranges, tomatoes, aubergines and grapes).

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