3,216 research outputs found
On algebraic construction of certain integrable and super-integrable systems
We propose a new construction of two-dimensional natural bi-Hamiltonian
systems associated with a very simple Lie algebra. The presented construction
allows us to distinguish three families of super-integrable monomial potentials
for which one additional first integral is quadratic, and the second one can be
of arbitrarily high degree with respect to the momenta. Many integrable systems
with additional integrals of degree greater than two in momenta are given.
Moreover, an example of a super-integrable system with first integrals of
degree two, four and six in the momenta is found.Comment: 37 page
Potential of thermal analysis in preparation and characterization of solid catalysis
Supported catalysts contain often only small amounts of active component(s) which renders their characterization difficult, particularly because they usually contain a substantial amount of water. Thermal analysis (TA) coupled with mass spectrometry (MS) offers an interesting potential for characterizing such material, various steps of catalyst preparation as well as crucial properties of fresh and used catalysts can be investigated. Some examples illustrating the versatility of TA-MS in catalysis research, such as solid-state reactions occurring upon exposure of the precursors or catalysts to reducing, oxidizing or inert atmosphere, are presented in this study. The combined use of TA and MS allows in many cases a much more detailed interpretation of the observed phenomena than could be achieved by one of these methods alon
Role and distribution of different Ba-containing phases in supported Pt-Ba NSR catalysts
Pt-Ba/MeO (where MeO=Al2O3, CeO2, SiO2 and ZrO2) NO x storage-reduction catalysts with Ba-loading varying from 0wt.% to 28wt.% were investigated concerning stability of Ba phases and NO x storage-reduction efficiency. For Pt-Ba/Al2O3 three different Ba-containing phases with different thermal stability are distinguished based on their interaction with the support. The relative concentration of these phases varies with the Ba-loading and NO x storage tests indicated that the BaCO3 phase decomposing between 400°C and 800°C (LT-BaCO3) is the most efficient Ba containing phase for NO x storage. Similar investigations of Pt-Ba catalysts supported on CeO2, SiO2 and ZrO2 showed that the relative amount of LT-BaCO3 phase depends also on the support material. NO x storage measurements confirmed a correlation between the concentration of LT-BaCO3 and NO x storage efficiency. Basicity and textural properties of the support are identified as crucial parameters for efficient NO x storage catalyst
Bound and unbound substructures in Galaxy-scale Dark Matter haloes
We analyse the coarse-grained phase-space structure of the six Galaxy-scale
dark matter haloes of the Aquarius Project using a state-of-the-art 6D
substructure finder. Within r_50, we find that about 35% of the mass is in
identifiable substructures, predominantly tidal streams, but including about
14% in self-bound subhaloes. The slope of the differential substructure mass
function is close to -2, which should be compared to around -1.9 for the
population of self-bound subhaloes. Near r_50 about 60% of the mass is in
substructures, with about 30% in self-bound subhaloes. The inner 35 kpc of the
highest resolution simulation has only 0.5% of its mass in self-bound
subhaloes, but 3.3% in detected substructure, again primarily tidal streams.
The densest tidal streams near the solar position have a 3-D mass density about
1% of the local mean, and populate the high velocity tail of the velocity
distribution.Comment: Submitted to MNRAS on 12/10/2010, 11 pages, 10 figure
Three red giants with substellar-mass companions
We present three giant stars from the ongoing Penn State-Toru\'n Planet
Search with the Hobby-Eberly Telescope, which exhibit radial velocity
variations that point to a presence of planetary --mass companions around them.
BD+49 828 is a K0 giant with a = minimum mass companion in
AU (d),
orbit. HD 95127, a log/=,
, K0 giant has a = minimum mass companion in
AU (d), orbit.
Finally, HD 216536, is a K0 giant with a minimum mass companion in
AU (d),
orbit. Both, HD 95127 b and HD 216536 b in their
compact orbits, are very close to the engulfment zone and hence prone to
ingestion in the near future. BD+49 828 b is among the longest period planets
detected with the radial velocity technique until now and it will remain
unaffected by stellar evolution up to a very late stage of its host. We discuss
general properties of planetary systems around evolved stars and planet
survivability using existing data on exoplanets in more detail.Comment: 47 pages, 11 figures. Accepted by Ap
Influenceof measuring conditions on the quantification of spectroscopic signals inTA-FTIR-MS systems
Simultaneous thermal analysis (TA) and evolved gas analysis by mass spectrometry (MS) and/or Fourier transform infrared spectroscopy (FTIR) is a powerful hyphenated technique combining direct measurement of mass loss and sensitive spectroscopic analysis. In the present study the influence of several experimental parameters which may affect the quantification of FTIR signals have been studied using a combined TA-FTIR-MS system. Parameters studied include: sample mass (1-400 mg), carrier gas flow rate (25-200 mL min-1), resolution of the FTIR spectrometer (1-32 cm-1), and location of injection of the calibrating gas. MS analysis, which was not significantly affected by the experimental conditions, was used as a reference for assessing the accuracy of quantification by FTIR. The quantification of the spectroscopic signals was verified by the decomposition (NaHCO3) or dehydration (CuSO4·5H2O) of compounds with well-known stoichiometry. The systematic study of the parametric sensitivity revealed that spectral resolution and carrier gas flow rate, which affect the acquisition time in the IR-cell, are key parameters that must be adjusted carefully for reliable quantification. The dependence of the reliability of quantification on these parameters is illustrated and conditions leading to proper quantification are discussed. As an example, for a standard spectral resolution of 4 cm-1 and a FTIR gas cell volume of 8.7 mL, the carrier gas flow must be lower than 100 mL min-1 for warranting accurate results (relative deviation <2%). The concentration range of analyzed species is limited but can be extended by proper selection of the wavenumber regions for molecules giving strong IR signal
TAPAS - Tracking Advanced Planetary Systems with HARPS-N. II. Super Li-rich giant HD 107028
Lithium rich giant stars are rare objects. For some of them, Li enrichment
exceeds abundance of this element found in solar system meteorites, suggesting
that these stars have gone through a Li enhancement process. We identified a Li
rich giant HD 107028 with A(Li) > 3.3 in a sample of evolved stars observed
within the PennState Torun Planet Search. In this work we study different
enhancement scenarios and we try to identify the one responsible for Li
enrichment for HD 107028. We collected high resolution spectra with three
different instruments, covering different spectral ranges. We determine stellar
parameters and abundances of selected elements with both equivalent width
measurements and analysis, and spectral synthesis. We also collected multi
epoch high precision radial velocities in an attempt to detect a companion.
Collected data show that HD 107028 is a star at the base of Red Giant Branch.
Except for high Li abundance, we have not identified any other anomalies in its
chemical composition, and there is no indication of a low mass or stellar
companion. We exclude Li production at the Luminosity Function Bump on RGB, as
the effective temperature and luminosity suggest that the evolutionary state is
much earlier than RGB Bump. We also cannot confirm the Li enhancement by
contamination, as we do not observe any anomalies that are associated with this
scenario. After evaluating various scenarios of Li enhancement we conclude that
the Li-overabundance of HD 107028 originates from Main Sequence evolution, and
may be caused by diffusion process.Comment: Accepted for publication in A&
Tracking Advanced Planetary Systems (TAPAS) with HARPS-N. III. HD 5583 and BD+15 2375 - two cool giants with warm companions
Evolved stars are crucial pieces to understand the dependency of the planet
formation mechanism on the stellar mass and to explore deeper the mechanism
involved in star-planet interactions. Over the past ten years, we have
monitored about 1000 evolved stars for radial velocity variations in search for
low-mass companions under the Penn State - Torun Centre for Astronomy Planet
Search program with the Hobby-Eberly Telescope. Selected prospective candidates
that required higher RV precision measurements have been followed with HARPS-N
at the 3.6 m Telescopio Nazionale Galileo under the TAPAS project.
We aim to detect planetary systems around evolved stars to be able to build
sound statistics on the frequency and intrinsic nature of these systems, and to
deliver in-depth studies of selected planetary systems with evidence of
star-planet interaction processes. For HD 5583 we obtained 14 epochs of precise
RV measurements collected over 2313 days with the Hobby-Eberly Telescope (HET),
and 22 epochs of ultra-precise HARPS-N data collected over 976 days. For BD+15
2375 we collected 24 epochs of HET data over 3286 days and 25 epochs of HARPS-S
data over 902 days.
We report the discovery of two planetary mass objects orbiting two evolved
Red Giant stars: HD~5583 has a m sin i = 5.78 M companion at 0.529~AU in
a nearly circular orbit (e=0.076), the closest companion to a giant star
detected with the RV technique, and BD+15~2735 that with a m sin i= 1.06
M holds the record of the lightest planet found so far orbiting an
evolved star (in a circular e=0.001, 0.576~AU orbit). These are the third and
fourth planets found within the TAPAS project, a HARPS-N monitoring of evolved
planetary systems identified with the Hobby-Eberly Telescope.Comment: 9 pages, 6 figures. Accepted by Astronomy and Astrophysic
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