85540506
Oscillations in Procyon A First results from a multi-site campaign
Procyon A is a bright F5IV star in a binary system. Although the distance, mass and angular diameter of this star are all known with high precision, the exact evolutionary state is still unclear. Evolutionary tracks with different ages and different mass fractions of hydrogen in the core pass, within the errors, through the observed position of Procyon A in the Hertzsprung-Russell diagram. For more than15 years several different groups have studied the solar-like oscillations in Procyon A to determine its evolutionary state. Although several studies independently detected power excess in the periodogram, there is no agreement on the actual oscillation frequencies yet. This is probably due to either insufficient high-quality data (i.e., aliasing) or due to intrinsic properties of the star (i.e., short mode lifetimes). Now a spectroscopic multi-site campaign using 10 telescopes world-wide (minimizing aliasing effects) with a total time span of nearly 4 weeks (increase the frequency resolution) is performed to identify frequencies in this star and finally determine its properties and evolutionary state.
55685116
A substellar component orbiting the F-star 30 Arietis B
Context. Most current radial velocity planet search programs have concentrated on stars of one solar mass. Our knowledge on the frequency of giant planets and brown dwarf companions to more massive stars is thus rather limited. In the case of solar-like stars, the frequency of short-period brown dwarf companions and very massive planets seems to be low. Aims. Here we present evidence for a substellar companion to 30 Ari B, an F-star of 1.16 ± 0.04 $M_\odot$ that is a member of a hierarchical triple system. Methods. The companion was detected by means of precise radial velocity measurements using the 2-m Alfred-Jensch telescope and its echelle spectrograph. An iodine absorption cell provided the wavelength reference for precise stellar radial velocity measurements. Results. We analyzed our radial velocity measurements and derived an orbit to the companion with period, P = 335.1 ± 2.5 days, eccentricity e = 0.289 ± 0.092, and mass function $f(m)$ = (6.1 ± 1.7)$\times$10 -7 $M_\odot$. Conclusions. We conclude that the radial velocity variations of 30 Ari B are due to a companion with m  sin  i of 9.88 ± 0.94 $M_{\mathrm{Jup}}$ that is either a massive planet or a brown dwarf. The object thus belongs to the rare class of massive planets and brown dwarfs orbiting main- sequence stars.
11578943
Planets of young stars: the TLS radial velocity survey
We report on the search for planets orbiting 46 nearby young stars performed at the State Observatory of Turingia (TLS) by means of a radial velocity survey. The aim of this program is to test the theories of formation/evolution of planetary systems. For 19(8) stars we can exclude planets with Msini > 1 MJ (5 MJ) and P < 10 days; we find 1 short period binary and 5 stars with long period RV-trend. One good young exo-planet candidate is presented.
14319327
Confirmation of the Planet Hypothesis for the Long-period Radial Velocity Variations of Beta Geminorum
Aims. Our aim is to confirm the nature of the long period radial velocity measurements for β Gem first found by Hatzes & Cochran (1993). Methods. We present precise stellar radial velocity measurements for the K giant star β Gem spanning over 25 years. An examination of the Ca II K emission, spectral line shapes from high resolution data ($R = 210\,000$), and Hipparcos photometry was also made to discern the true nature of the long period radial velocity variations. Results. The radial velocity data show that the long period, low amplitude radial velocity variations found by Hatzes & Cochran (1993) are long-lived and coherent. Furthermore, the Ca II K emission, spectral line bisectors, and Hipparcos photometry show no significant variations of these quantities with the radial velocity period. An orbital solution assuming a stellar mass of 1.7 $M_\odot$ yields a period, $P = 589.6$ days, a minimum mass of 2.3 M Jupiter , and a semi-major axis, $a = 1.6$ AU. The orbit is nearly circular ($e = 0.02$). Conclusions. The data presented here confirm the planetary companion hypothesis suggested by Hatzes & Cochran (1993). β Gem is one of six intermediate mass stars known to host a sub-stellar companion and suggests that planet-formation around stars much more massive than the sun may common.
119282381
Exoplanets around G-K Giants
G and K giants are a class of radial velocity (RV) variables. One reason for this variability are planetary companions which are indicated in time series of stellar spectra. Since 2004 these spectra in the visual range were obtained with the high resolution coud\'e \'echelle spectrograph mounted on the 2m telescope of the Th\"uringer Landessternwarte Tautenburg (TLS) for a northern sample of 62 very bright K giants. In the South around 300 G and K giants were observed with HARPS mounted on the 3.6m telescope on La Silla. The TLS sample contains at least 11 stars (18 %) which show low-amplitude, long-period RV variations most likely due to planets. This percentage of planet frequency is confirmed by preliminary results of the HARPS study. Moreover the TLS survey seems to indicate that giant planets do not favour metal-rich stars, are more massive, and have longer periods than those found around solar-type host stars.
58892126
Three-integral multicomponent dynamical models and simulations of the nuclear star cluster in NGC 4244
Adaptive optics observations of the flattened nuclear star cluster in the nearby edge-on spiral galaxy NGC 4244 using the Gemini near-infrared integral field spectrograph (NIFS) have revealed clear rotation. Using these kinematics plus 2MASS photometry, we construct a series of axisymmetric two-component particle dynamical models with our improved version of NMAGIC, a flexible χ2-made-to-measure code. The models consist of a nuclear cluster disc embedded within a spheroidal particle population. We find a mass for the nuclear star cluster of M = 1.6+0.5 −0.2 × 107M� within ∼42.4 pc (2 arcsec). We also explore the presence of an intermediate-mass black hole and show that models with a black hole as massive as M• = 5.0 × 105M� are consistent with the available data. Regardless of whether a black hole is present or not, the nuclear cluster is vertically anisotropic (βz < 0), as was found with earlier anisotropic Jeans models. We then use the models as initial conditions for Nbody simulations. These simulations show that the nuclear star cluster is stable against nonaxisymmetric 
perturbations. We also explore the effect of the nuclear cluster accreting star clusters at various inclinations. Accretion of a star cluster with mass 13 per cent that of the nuclear cluster is already enough to destroy the vertical anisotropy, regardless of orbital inclination.
15693672
A MULTISITE CAMPAIGN TO MEASURE SOLAR-LIKE OSCILLATIONS IN PROCYON. I. OBSERVATIONS, DATA REDUCTION, AND SLOW VARIATIONS
We have carried out a multisite campaign to measure oscillations in the F5 star Procyon A. We obtained high-precision velocity observations over more than three weeks with 11 telescopes, with almost continuous coverage for the central 10 days. This represents the most extensive campaign so far organized on any solar-type oscillator. We describe in detail the methods we used for processing and combining the data. These involved calculating weights for the velocity time series from the measurement uncertainties and adjusting them in order to minimize the noise level of the combined data. The time series of velocities for Procyon shows the clear signature of oscillations, with a plateau of excess power that is centered at 0.9 mHz and is broader than has been seen for other stars. The mean amplitude of the radial modes is -->38.1 ± 1.3 cm s−1 (2.0 times solar), which is consistent with previous detections from the ground and by the WIRE spacecraft, and also with the upper limit set by the MOST spacecraft. The variation of the amplitude during the observing campaign allows us to estimate the mode lifetime to be -->1.5+ 1.9−0.8 days. We also find a slow variation in the radial velocity of Procyon, with good agreement between different telescopes. These variations are remarkably similar to those seen in the Sun, and we interpret them as being due to rotational modulation from active regions on the stellar surface. The variations appear to have a period of about 10 days, which presumably equals the stellar rotation period or, perhaps, half of it. The amount of power in these slow variations indicates that the fractional area of Procyon covered by active regions is slightly higher than for the Sun.
59379579
Determination of deuteron beam polarizations at COSY
The vector and tensor polarizations of a deuteron beam have been measured using elastic deuteron-carbon scattering at 75.6 MeV and deuteron-proton scattering at 270 MeV. After their acceleration to 1170 MeV inside the COSY ring, the polarizations of the deuterons were checked by studying a variety of nuclear reactions using a cluster target at the ANKE magnet spectrometer placed at an internal target position of the storage ring. All these measurements were consistent with the absence of depolarization during acceleration and provide us with a number of secondary standards that can be used in subsequent experiments at the facility.
118273451
First results on strangeness production from the ANKE facility
ANKE is a second generation experimental facility at the internal beam of the accelerator COSY at the Forschungszentrum Julich (Germany). It has recently (May 1998) been installed in the ring, commissioned and immediately after this been exploited for first experiments. Using circulating beams of protons with energies between 1.0 and 2.3 GeV, sub- and near threshold production of K+ mesons in collisions with carbon-strip targets has been investigated. The detection system of ANKE used for the first measurements is capable of detecting positively charged ejectiles in the momentum range between about 100 and 600 MeV/c. In particular, it has been optimized for K+ identification in the presence of an intense background of protons and pions. The final results of the experiments (cross sections and momentum spectra) will be used to obtain more detailed information on the subthreshold production mechanism.
54509312
High precision beam momentum determination in a synchrotron using a spin resonance method
In order to measure the mass of the eta meson with high accuracy using the dp -> He-3 eta reaction, the momentum of the circulating deuteron beam in the Cooler Synchrotron COSY of the Forschungszentrum Julich has to be determined with unprecedented precision. This has been achieved by studying the spin dynamics of the polarized deuteron beam. By depolarizing the beam through the use of an artificially induced spin resonance, it was possible to evaluate its momentum p with a precision of Delta p/p < 10(-4) for a momentum of roughly 3 GeV/c.
93582438
Momentum dependence of hadronic production of the ϕ-meson and its width in nuclear matter
Information on the properties of the ϕ meson in the nuclear environment has been derived from its production in proton collisions with C, Cu, Al, and Au nuclear targets. The experiment was carried out with 2.83 GeV protons at the Cooler Synchrotron COSY, with the ϕ being detected via its K + K − decay using the ANKE magnetic spectrometer. The measured dependence of the production cross section on the nuclear mass number has been compared with calculations within three different nuclear models. These suggest a significant broadening of the width of the ϕ in medium relative to its vacuum value. The ANKE results obtained in the momentum range 0.6 < pϕ < 1.6 GeV/c are compared with data from photoproduction experiments at slightly higher momenta.