137 research outputs found
Precise radial velocities of giant stars. X. Bayesian stellar parameters and evolutionary stages for 372 giant stars from the Lick planet search
The determination of accurate stellar parameters of giant stars is essential
for our understanding of such stars in general and as exoplanet host stars in
particular. Precise stellar masses are vital for determining the lower mass
limit of potential substellar companions with the radial velocity method. Our
goal is to determine stellar parameters, including mass, radius, age, surface
gravity, effective temperature and luminosity, for the sample of giants
observed by the Lick planet search. Furthermore, we want to derive the
probability of these stars being on the horizontal branch (HB) or red giant
branch (RGB), respectively. We compare spectroscopic, photometric and
astrometric observables to grids of stellar evolutionary models using Bayesian
inference. We provide tables of stellar parameters, probabilities for the
current post-main sequence evolutionary stage, and probability density
functions for 372 giants from the Lick planet search. We find that of
the stars in our sample are more probably on the HB. In particular, this is the
case for 15 of the 16 planet host stars in the sample. We tested the
reliability of our methodology by comparing our stellar parameters to
literature values and find very good agreement. Furthermore, we created a small
test sample of 26 giants with available asteroseismic masses and evolutionary
stages and compared these to our estimates. The mean difference of the stellar
masses for the 24 stars with the same evolutionary stages by both methods is
only . We do not find any
evidence for large systematic differences between our results and estimates of
stellar parameters based on other methods. In particular we find no significant
systematic offset between stellar masses provided by asteroseismology to our
Bayesian estimates based on evolutionary models.Comment: 15 pages, 7 figures, accepted for publication in A&
Bose-Einstein condensates in fast rotation
In this short review we present our recent results concerning the rotation of
atomic Bose-Einstein condensates confined in quadratic or quartic potentials,
and give an overview of the field. We first describe the procedure used to set
an atomic gas in rotation and briefly discuss the physics of condensates
containing a single vortex line. We then address the regime of fast rotation in
harmonic traps, where the rotation frequency is close to the trapping
frequency. In this limit the Landau Level formalism is well suited to describe
the system. The problem of the condensation temperature of a fast rotating gas
is discussed, as well as the equilibrium shape of the cloud and the structure
of the vortex lattice. Finally we review results obtained with a quadratic +
quartic potential, which allows to study a regime where the rotation frequency
is equal to or larger than the harmonic trapping frequency.Comment: Laser Physics Letters 2, 275 (2005
Observation of Phase Defects in Quasi-2D Bose-Einstein Condensates
We have observed phase defects in quasi-2D Bose-Einstein condensates close to
the condensation temperature. Either a single or several equally spaced
condensates are produced by selectively evaporating the sites of a 1D optical
lattice. When several clouds are released from the lattice and allowed to
overlap, dislocation lines in the interference patterns reveal nontrivial phase
defects
Precise radial velocities of giant stars. XI. Two brown dwarfs in 6:1 mean motion resonance around the K giant star Ophiuchi
We present radial-velocity (RV) measurements for the K giant Oph (=
HIP88048, HD163917, HR6698), which reveal two brown dwarf companions with a
period ratio close to 6:1. For our orbital analysis we use 150 precise RV
measurements taken at Lick Observatory between 2000 and 2011, and we combine
them with RV data for this star available in the literature. Using a stellar
mass of for Oph and applying a self-consistent N-body
model we estimate the minimum dynamical companion masses to be and ,
with orbital periods d and d. We study a
large set of potential orbital configurations for this system, employing a
bootstrap analysis and a systematic grid-search coupled with our
dynamical fitting model, and we examine their long-term stability. We find that
the system is indeed locked in a 6:1 mean motion resonance (MMR), with and all six resonance angles librating
around 0. We also test a large set of coplanar inclined configurations,
and we find that the system will remain in a stable resonance for most of these
configurations. The Oph system is important for probing planetary
formation and evolution scenarios. It seems very likely that the two brown
dwarf companions of Oph formed like planets in a circumstellar disk
around the star and have been trapped in a MMR by smooth migration capture.Comment: 17 pages, 9 figures. New version with corrected number in title. No
other change
Interference of an array of independent Bose-Einstein condensates
We have observed high-contrast matter wave interference between 30
Bose-Einstein condensates with uncorrelated phases. Interference patterns were
observed after independent condensates were released from a one-dimensional
optical lattice and allowed to expand and overlap. This initially surprising
phenomenon is explained with a simple theoretical model which generalizes the
analysis of the interference of two independent condensates
Seeing zeros of random polynomials: quantized vortices in the ideal Bose gas
We propose a physical system allowing one to experimentally observe the
distribution of the complex zeros of a random polynomial. We consider a
degenerate, rotating, quasi-ideal atomic Bose gas prepared in the lowest Landau
level. Thermal fluctuations provide the randomness of the bosonic field and of
the locations of the vortex cores. These vortices can be mapped to zeros of
random polynomials, and observed in the density profile of the gas.Comment: 4 page
Personalized medicine: consequences for drug research and therapy
In drug research, a serious transformation has taken place. With increasing knowledge gained from molecular medicine, it became possible to refine and develop new therapies based on the molecular mechanisms of diseases. Medicine and drug development have seen a paradigm shift which can be characterized with the catchword “personalized medicine”, also called “stratified medicine” or “precision medicine”. Personalized medicine is based on defined tandems of therapeutic agents and diagnostic tests. With this addition to the regular medical examination of the patient, specific patient characteristics are determined. The results of such diagnostic tests are then decisive for the choice of therapy or control of the effectiveness of the chosen treatment. The benefit of personalized medicine for the patient is the higher probability of treatment success as well as improved effectiveness and reduced / avoided side effects. Health insurance systems and the public may have the advantage that the health funds can be used more efficiently on this basis. This new paradigm requires also a new debate on the remuneration in health care. In order to bring personalized therapies to patients as quickly as possible, all players in health care should work together to address the challenges associated with personalized medicine
ВЛИЯНИЕ ТРАНСПОРТНыХ ЗАДЕРЖЕК ШЛАМОВыХ ПОТОКОВ НА ПРОДОЛЖИТЕЛЬНОСТЬ НЕСТАЦИОНАРНОГО РЕЖИМА РАБОТы ВОДНО-ШЛАМОВыХ СИСТЕМ
Проблема и ее связь с научными и практическими задачами. Все подре-шетные воды гравитационного отделения аккумулируются в зумпфах большой емкости и далее перекачиваются на операцию предварительной регенерации в гидроциклоны, классификаторы или сгустители. При этом необходимо обеспе-чить подачу на самую верхнюю отметку для дальнейшего распределения шла-мовых потоков самотеком. Как правило, такие потоки характеризуются высо-кими транспортными задержками. Магистрали для шламовых потоков перед узлами вывода имеют меньшие геометрические размеры, переносят незначи-тельное количество пульпы по сравнению с вводными коммуникациями
New HARPS and FEROS observations of GJ1046
In this paper we present new precise Doppler data of GJ1046 taken between
November 2005 and July 2018 with the HARPS and the FEROS high-resolution
spectographs. In addition, we provide a new stellar mass estimate of GJ1046 and
we update the orbital parameters of the GJ1046 system. These new data and
analysis could be used together with the GAIA epoch astrometry, when available,
for braking the degeneracy and revealing the true mass of the GJ1046
system.Comment: 2 pages, 1 figure, 1 table with RV data (available only in the
Astro-PH version of the paper), Accepted by RNAA
- …