527 research outputs found
The AMBRE Project: Stellar parameterisation of the ESO:FEROS archived spectra
The AMBRE Project is a collaboration between the European Southern
Observatory (ESO) and the Observatoire de la Cote d'Azur (OCA) that has been
established in order to carry out the determination of stellar atmospheric
parameters for the archived spectra of four ESO spectrographs.
The analysis of the FEROS archived spectra for their stellar parameters
(effective temperatures, surface gravities, global metallicities, alpha element
to iron ratios and radial velocities) has been completed in the first phase of
the AMBRE Project. From the complete ESO:FEROS archive dataset that was
received, a total of 21551 scientific spectra have been identified, covering
the period 2005 to 2010. These spectra correspond to ~6285 stars.
The determination of the stellar parameters was carried out using the stellar
parameterisation algorithm, MATISSE (MATrix Inversion for Spectral SynthEsis),
which has been developed at OCA to be used in the analysis of large scale
spectroscopic studies in galactic archaeology. An analysis pipeline has been
constructed that integrates spectral reduction and radial velocity correction
procedures with MATISSE in order to automatically determine the stellar
parameters of the FEROS spectra.
Stellar atmospheric parameters (Teff, log g, [M/H] and [alpha/Fe]) were
determined for 6508 (30.2%) of the FEROS archived spectra (~3087 stars). Radial
velocities were determined for 11963 (56%) of the archived spectra. 2370 (11%)
spectra could not be analysed within the pipeline. 12673 spectra (58.8%) were
analysed in the pipeline but their parameters were discarded based on quality
criteria and error analysis determined within the automated process. The
majority of these rejected spectra were found to have broad spectral features
indicating that they may be hot and/or fast rotating stars, which are not
considered within the adopted reference synthetic spectra grid of FGKM stars.Comment: 28 pages, 28 figures, 9 table
On the correlation of elemental abundances with kinematics among galactic disk stars
We have performed the detailed analysis of 174 high-resolution spectra of FGK
dwarfs obtained with the ELODIE echelle spectrograph at the Observatoire de
Haute-Provence. Abundances of Fe, Si and Ni have been determined from
equivalent widths under LTE approximation, whereas abundances of Mg have been
determined under NLTE approximation using equivalent widths of 4 lines and
profiles of 5 lines. Spatial velocities with an accuracy better than 1 km/s, as
well as orbits, have been computed for all stars. They have been used to define
2 subsamples kinematically representative of the thin disk and the thick disk
in order to highlight their respective properties. A transition occurs at
[Fe/H]=-0.3. Stars more metal-rich than this value have a flat distribution
with Zmax<1 kpc and sigma_W<20 km/s, and a narrow distribution of [alpha/Fe].
There exist stars in this metallicity regime which cannot belong to the thin
disk because of their excentric orbits, neither to the thick disk because of
their low scale height. Several thin disk stars are identified down to
[Fe/H]=-0.80. Their Mg enrichment is lower than thick disk stars with the same
metallicity. We confirm from a larger sample the results of Feltzing et al
(2003) and Bensby et al (2003) showing a decrease of [alpha/Fe] with [Fe/H] in
the thick disk interpreted as the signature of the SNIa which have
progressively enriched the ISM with iron. However our data suggest that the
star formation in the thick disk stopped when the enrichment was [Fe/H]=-0.30,
[Mg/Fe]=+0.20, [Si/Fe]=+0.17. A vertical gradient in [alpha/Fe] may exist in
the thick disk but should be confirmed with a larger sample. Finally we have
identified 2 new candidates of the HR1614 moving group.Comment: Accepted in A&A, 16 pages, 14 figure
Mn abundances in the stars of the Galactic disc with metallicities -1.0 < [Fe/H] < 0.3
In this work we present and discuss the observations of the Mn abundances for 247 FGK dwarfs, located in the Galactic disc with metallicity -1 < [Fe/H]< +0.3. The observed stars belong to the substructures of the Galaxy thick and thin discs, and to the Hercules stream. The observations were conducted using the 1.93 m telescope at Observatoire de Haute-Provence (OHP, France) equipped with the echelle type spectrographs ELODIE and SOPHIE. The abundances were derived under the LTE approximation, with an average error for the [Mn/Fe] ratio of 0.10 dex. For most of the stars in the sample Mn abundances are not available in the literature. We obtain an evolution of [Mn/Fe] ratio with the metallicity [Fe/H] consistent with previous data compilations. In particular, within the metallicity range covered by our stellar sample the [Mn/Fe] ratio is increasing with the increase of metallicity. This due to the contribution to the Galactic chemical evolution of Mn and Fe from thermonuclear supernovae. We confirm the baseline scenario where most of the Mn in the Galactic disc and in the Sun is made by thermonuclear supernovae. In particular, the effective contribution from core-collapse supernovae to the Mn in the Solar system is about 10-20%. However, present uncertainties affecting the production of Mn and Fe in thermonuclear supernovae are limiting the constraining power of the observed [Mn/Fe] trend in the Galactic discs on, e.g., the frequency of different thermonuclear supernovae populations. The different production of these two elements in different types of thermonuclear supernovae needs to be disentangled by the dependence of their relative production on the metallicity of the supernova progenitor
Superflare G and K Stars and the Lithium abundance
We analyzed here the connection of superflares and the lithium abundance in G
and K stars based on Li abundance determinations conducted with the echelle
spectra of a full set of 280 stars obtained with the ELODIE spectrograph. For
high-active stars we show a definite correlation between and the
chromosphere activity. We show that sets of stars with high Li abundance and
having superflares possess common properties. It relates, firstly, to stars
with activity saturation. We consider the X-ray data for G, K, and M stars
separately, and show that transition from a saturation mode to solar-type
activity takes place at values of rotation periods 1.1, 3.3, and 7.2 days for
G2, K4 and M3 spectral types, respectively. We discuss bimodal distribution of
a number of G and K main-sequence stars versus an axial rotation and location
of superflare stars with respect to other Kepler stars. We conclude that
superflare G and K stars are mainly fast rotating young objects, but some of
them belong to stars with solar-type activity. At the same time, we found a
group of G stars with high Li content , but being
slower rotators with rotation periods > 10 days, which are characterized by low
chromospheric activity. This agrees with a large spread in Li abundances in
superflare stars. A mechanism leading to this effect is discussed.Comment: 6 pages, 8 figures. The 19th Cambridge Workshop on Cool Stars,
Stellar Systems, and the Su
Barium and Yttrium abundance in intermediate-age and old open clusters
Barium is a neutron capture element, that, in open clusters, is frequently
over-abundant with respect to the Iron. A clear explanation for this is still
missing. Additionally, its gradient across the Galactic disk is poorly
constrained. We measure the abundance of yttrium and barium using the synthetic
spectrum method from UVES high-resolution spectra of eight distant open
clusters, namely Ruprecht 4, Ruprecht 7, Berkeley 25, Berkeley 73, Berkeley 75,
NGC 6192, NGC 6404, and NGC 6583. The barium abundance was estimated using NLTE
approximation. We confirm that Barium is indeed over-abundant in most clusters,
especially young clusters. Finally, we investigated the trend of yttrium and
barium abundances as a function of distance in the Galaxy and ages. Several
scenarios for the barium over-abundance are then discussed.Comment: 9 pages, 10 figure
On the subject of the Ba overabundance in the open clusters stars
For eight distant open clusters, namely Ruprecht 4, Ruprecht 7, Berkeley 25, Berkeley 73, Berkeley 75, NGC 6192, NGC 6404, and NGC 6583, we determined the yttrium and barium abundances using the UVES, VLT spectra (ESO, Chile). The stars of one young cluster (Ruprecht 7) demonstrate significant barium overabundance( 3c0.55 dex) that can not be due to the determination error. We have considered the Ba abundance determination errors due to LTE approach, saturation of the lines, synthetic and observed barium line fitting, and the causes of the Ba overabundance associated with the Galactic disc enrichment or the origin of open clusters. Possible explanation for this overabundance can be the origin of n-capture elements enrichment of the clusters (galactic or extragalactic) or additional sources of the Ba production
Mechanism of the environmental management implementation on the forestry enterprises
The article presents scientific and methodical approaches to the implementation and operation of environmentally oriented forest management, on the basis of a common ecomangement methodology and the main provisions of ISO 14001, which take into account sectoral characteristics and principles of environmentally sustainable forest management, and application of ecological-economic management technologies. Essentially-content basis of environmentally oriented forest management and its specific typical forms (such as ecosystem and environmental management) have been outlined. Principles and functions of environmental management of forestry enterprises and the basic stages of its implementation and functioning have been considered
Petrostructural typification of the kanskiy greenstone belt ultramafites
Two types of ultramafites have been distinguished in the Kanskiy greenstone belt (NW of the Eastern Sayan): magmatic of the dunite-wehrlite-picrite composition and restitic of the dunite-harzburgite composition. They are united into Kingashskiy and Idarskiy complexes, correspondingl
Напрями державного регулювання та підтримки інноваційної діяльності в сфері природокористування та охорони навколишнього середовища
Найважливіша особливість природоохоронного управління, ефективного в сучасних умовах, полягає в орієнтації на активізацію інноваційної діяльності у сфері раціонального природокористування та охорони навколишнього середовища відповідно до принципів сталого розвитку країни та регіонів. Основним завданням стає створення привабливих умов для діяльності інноваційних організацій та розвитку екологічно орієнтованого підприємництва. Для цього необхідна система заходів державного регулювання та підтримки, оскільки без створення платоспроможного і зацікавленого ринку збуту екологічних товарів і послуг пряме бюджетне фінансування буде малоефективним.
При цитуванні документа, використовуйте посилання http://essuir.sumdu.edu.ua/handle/123456789/1732
Розвиток співробітництва бізнесу та громадських некомерційних організацій в Україні
Проблеми забезпечення сталого розвитку, підвищення економічної стабільності та конкурентоспроможності вітчизняних підприємств особливо актуальні для сучасної української економіки. Виішення частини цих проблем лежить у площині співробітництва бізнесу та громадських некомерційних організацій (НКО). Однак, в Україні, на відміну від практики багатьох країн, таке співробітництво супроводжується багатьма складностями та умовностями. Насамперед, відсутність стратегічного партнерства в цій сфері пов'язане з незрілістю громадських організацій в Україні. Некомерційні організації ще досить молоді, що спричиняє проблеми, як у відношенні НКО до бізнесу, так і ставлення бізнесу до НКО.
При цитуванні документа, використовуйте посилання http://essuir.sumdu.edu.ua/handle/123456789/3686
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