3,427 research outputs found
Substellar-mass companions to the K-dwarf BD +14 4559 and the K-giants HD 240210 and BD +20 2457
We present the discovery of substellar-mass companions to three stars by the
ongoing Penn State - Toru\' n Planet Search (PTPS) conducted with the 9.2-m
Hobby-Eberly Telescope. The K2-dwarf, BD +14 4559, has a 1.5 M companion
with the orbital period of 269 days and shows a non-linear, long-term radial
velocity trend, which indicates a possible presence of another planet-mass body
in the system. The K3-giant, HD 240210, exhibits radial velocity variations
that require modeling with multiple orbits, but the available data are not yet
sufficient to do it unambiguously. A tentative, one-planet model calls for a
6.9 M planet in a 502-day orbit around the star. The most massive of the
three stars, the K2-giant, BD +20 2457, whose estimated mass is 2.81.5
M, has two companions with the respective minimum masses of 21.4 M
and 12.5 M and orbital periods of 380 and 622 days. Depending on the
unknown inclinations of the orbits, the currently very uncertain mass of the
star, and the dynamical properties of the system, it may represent the first
detection of two brown dwarf-mass companions orbiting a giant. The existence of
such objects will have consequences for the interpretation of the so-called
brown dwarf desert known to exist in the case of solar-mass stars.Comment: 28 pages, 4 tables, 10 figures. Submitted to Ap
A Planet in a 0.6-AU Orbit Around the K0 Giant HD 102272
We report the discovery of one or more planet-mass companions to the K0-giant
HD 102272 with the Hobby-Eberly Telescope. In the absence of any correlation of
the observed periodicities with the standard indicators of stellar activity,
the observed radial velocity variations are most plausibly explained in terms
of a Keplerian motion of at least one planet-mass body around the star. With
the estimated stellar mass of 1.9M, the minimum mass of the confirmed
planet is 5.9M. The planet's orbit is characterized by a small but nonzero
eccentricity of =0.05 and the semi-major axis of 0.61 AU, which makes it the
most compact one discovered so far around GK-giants. This detection adds to the
existing evidence that, as predicted by theory, the minimum size of planetary
orbits around intermediate-mass giants is affected by both planet formation
processes and stellar evolution. The currently available evidence for another
planet around HD 102272 is insufficient to obtain an unambiguous two-orbit
solution.Comment: 10 pages, 5 figure
Planetary companions around the K giant stars 11 UMi and HD 32518
11 UMi and HD 32518 belong to a sample of 62 K giant stars that has been
observed since February 2004 using the 2m Alfred Jensch telescope of the
Th\"uringer Landessternwarte (TLS) to measure precise radial velocities (RVs).
The aim of this survey is to investigate the dependence of planet formation on
the mass of the host star by searching for planetary companions around
intermediate-mass giants. An iodine absorption cell was used to obtain accurate
RVs for this study. Our measurements reveal that the RVs of 11 UMi show a
periodic variation of 516.22 days. The RV curve of HD 32518 shows sinusoidal
variations with a period of 157.54 days. The HIPPARCOS photometry as well as
our H\alpha core flux measurements reveal no variability with the RV period.
Thus, Keplerian motion is the most likely explanation for the observed RV
variations for both giant stars. An exoplanet with a minimum mass of 10.5
Jupiter masses orbits the K giant 11 UMi. The K1 III giant HD 32518 hosts a
planetary companion with a minimum mass of 3.0 Jupiter masses in a nearly
circular orbit. These are the 4th and 5th planets published from this TLS
survey.Comment: 11 pages, 16 figure
Transmission properties of double-gap asymmetric split ring resonators in terahertz region
We investigated the electromagnetic properties of the metamaterials that consist of double-gap split ring resonators (SRRs) in the terahertz region. We found that varying the position of one gap with respect to the other causes the resonant frequency of the SRRs to shift over a broad range. This frequency shift is attributed to the change in the combined capacitance that consists of two capacitances of gaps connected in series and an additional capacitance connected in parallel to the others. Our findings are also verified by obtaining good agreement between experiments and simulations
Ultra-high energy cosmic rays threshold in Randers-Finsler space
Kinematics in Finsler space is used to study the propagation of ultra high
energy cosmic rays particles through the cosmic microwave background radiation.
We find that the GZK threshold is lifted dramatically in Randers-Finsler space.
A tiny deformation of spacetime from Minkowskian to Finslerian allows more
ultra-high energy cosmic rays particles arrive at the earth. It is suggested
that the lower bound of particle mass is related with the negative second
invariant speed in Randers-Finsler space
Superconducting phase diagram of the filled skuterrudite PrOs4Sb12
We present new measurements of the specific heat of the heavy fermion
superconductor PrOs4Sb12, on a sample which exhibits two sharp distinct
anomalies at Tc1= 1.89K and Tc2= 1.72K. They are used to draw a precise
magnetic field-temperature superconducting phase diagram of PrOs4Sb12 down to
350 mK.
We discuss the superconducting phase diagram of PrOs4Sb12 and its possible
relation with an unconventional superconducting order parameter. We give a
detailed analysis of Hc2(T), which shows paramagnetic limitation (a support for
even parity pairing) and multiband effects
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