168 research outputs found
Rotational and intrinsic levels in Tm169 and Lu175
Nuclear levels in Tm169 excited by electron capture of Yb169, and levels in Lu175 excited by both beta decay of Yb175 and electron capture of Hf175 have been studied by using the curved-crystal gamma-ray spectrometer and the ring-focusing beta-ray spectrometer, as well as a semicircular beta-ray spectrometer for low energies. From the precision energies and the multipolarity determinations, the levels in Tm169 have the following energies in kev, and spin and parity assignments: A (ground state) (½+), B 8.42 (3/2+), C 118.20 (5/2+), D 138.95 (7/2+), E 316.19 (7/2+), F 379.31 (7/2-), G 472.91 (9/2-). Levels A, B, C, and D are members of a rotational band whose characteristic constants are given. Levels E and F are interpreted as particle excitations and level G as a rotational level based on the state F. The Lu175 excited states have the following energies in kev, spins, and parities: A (ground state) (7/2+), B 113.81 (9/2+), C 251.46 (11/2+), D 343.40 (5/2+), E 396.31 (9/2-), F 432.76 (7/2+), G 504.7 (1/2+). A, B, and C form a rotational band for which the characteristic constants are given. Some features of the levels and transition probabilities are discussed and compared with the unified model. A brief survey of second-order rotational energy constants and of intrinsic excitation levels is given
The CORALIE survey for southern extrasolar planets. XVI. Discovery of a planetary system around HD 147018 and of two long period and massive planets orbiting HD 171238 and HD 204313
We report the detection of a double planetary system around HD 140718 as well
as the discovery of two long period and massive planets orbiting HD 171238 and
HD 204313. Those discoveries were made with the CORALIE Echelle spectrograph
mounted on the 1.2-m Euler Swiss telescope located at La Silla Observatory,
Chile. The planetary system orbiting the nearby G9 dwarf HD 147018 is composed
of an eccentric inner planet (e=0.47) with twice the mass of Jupiter (2.1 MJup
) and with an orbital period of 44.24 days. The outer planet is even more
massive (6.6 MJup) with a slightly eccentric orbit (e=0.13) and a period of
1008 days. The planet orbiting HD 171238 has a minimum mass of 2.6 MJup, a
period of 1523 days and an eccentricity of 0.40. It orbits a G8 dwarfs at 2.5
AU. The last planet, HD 204313 b, is a 4.0 MJup -planet with a period of 5.3
years and has a low eccentricity (e = 0.13). It orbits a G5 dwarfs at 3.1 AU.
The three parent stars are metal rich, which further strengthened the case that
massive planets tend to form around metal rich stars.Comment: 6 pages, 6 figures, accepted for publication in A&
Comparing HARPS and Kepler surveys: The alignment of multiple-planet systems
Aims. We study a subset of the planetary population characterized both by
HARPS and Kepler surveys. We compare the statistical properties of planets in
systems with m.sin i >5-10 M_Earth and R>2 R_Earth. If we assume that the
underlying population has the same characteristics, the different detection
sensitivity to the orbital inclination relative to the line of sight allows us
to probe the planets' mutual inclination.
Methods. We considered the frequency of systems with one, two and three
planets as dictated by HARPS data. We used Kepler's planetary period and host
mass and radii distributions (corrected from detection bias) to model planetary
systems in a simple yet physically plausible way. We then varied the mutual
inclination between planets in a system according to different prescriptions
(completely aligned, Rayleigh distributions and isotropic) and compared the
transit frequencies with one, two or three planets with those measured by
Kepler.
Results. The results show that the two datasets are compatible, a remarkable
result especially because there are no tunable knobs other than the assumed
inclination distribution. For m.sin i cutoffs of 7-10 M_Earth, which are those
expected to correspond to the radius cutoff of 2 R_Earth, we conclude that the
results are better described by a Rayleigh distribution with mode of 1 deg or
smaller. We show that the best-fit scenario only becomes a Rayleigh
distribution with mode of 5 deg if we assume a rather extreme mass-radius
relationship for the planetary population.
Conclusions. These results have important consequences for our understanding
of the role of several proposed formation and evolution mechanisms. They
confirm that planets are likely to have been formed in a disk and show that
most planetary systems evolve quietly without strong angular momentum exchanges
(abridged).Comment: 10 pages, 6 figures, 4 tables, accepted for publication in Astronomy
& Astrophysic
The CORALIE survey for southern extra-solar planets XV. Discovery of two eccentric planets orbiting HD4113 and HD156846
We report the detection of two very eccentric planets orbiting HD4113 and
HD156846 with the CORALIE Echelle spectrograph mounted on the 1.2-m Euler Swiss
telescope at La Silla. The first planet, HD4113b, has minimum mass of
, a period of days and an
eccentricity of . It orbits a metal rich G5V star at
AU which displays an additional radial velocity drift of 28 m s/yr
observed during 8 years. The combination of the radial-velocity data and the
non-detection of any main sequence stellar companion in our high contrast
images taken at the VLT with NACO/SDI, characterizes the companion as a
probable brown dwarf or as a faint white dwarf. The second planet, \object{HD
156846 b}, has minimum mass of M, a period
of days, an eccentricity of and is located
at AU from its parent star. HD156846 is a metal rich G0 dwarf and is
also the primary of a wide binary system ( AU, years). Its
stellar companion, \object{IDS 17147-1914 B}, is a M4 dwarf. The very high
eccentricities of both planets can be explained by Kozai oscillations induced
by the presence of a third object.Comment: 4 pages, 5 figures, A&A Letter accepte
Statistical evolution of isotope composition of nuclear fragments
Calculations within the statistical multifragmentation model show that the
neutron content of intermediate mass fragments can increase in the region of
liquid-gas phase transition in finite nuclei. The model predicts also
inhomogeneous distributions of fragments and their isospin in the freeze-out
volume caused by an angular momentum and external long-range Coulomb field.
These effects can take place in peripheral nucleus-nucleus collisions at
intermediate energies and lead to neutron-rich isotopes produced in the
midrapidity kinematic region.Comment: 14 pages with 4 figures. GSI preprint, Darmstadt, 200
New salicylaldoximato-borate ligands resulting from anion hydrolysis and their respective copper and iron complexes
TESS Discovery of a Transiting Super-Earth in the Mensae System
We report the detection of a transiting planet around Mensae (HD
39091), using data from the Transiting Exoplanet Survey Satellite (TESS). The
solar-type host star is unusually bright (V=5.7) and was already known to host
a Jovian planet on a highly eccentric, 5.7-year orbit. The newly discovered
planet has a size of and an orbital period of 6.27
days. Radial-velocity data from the HARPS and AAT/UCLES archives also displays
a 6.27-day periodicity, confirming the existence of the planet and leading to a
mass determination of . The star's proximity and
brightness will facilitate further investigations, such as atmospheric
spectroscopy, asteroseismology, the Rossiter--McLaughlin effect, astrometry,
and direct imaging.Comment: Accepted for publication ApJ Letters. This letter makes use of the
TESS Alert data, which is currently in a beta test phase. The discovery light
curve is included in a table inside the arxiv submissio
TESS Discovery of an ultra-short-period planet around the nearby M dwarf LHS 3844
Data from the newly-commissioned \textit{Transiting Exoplanet Survey
Satellite} (TESS) has revealed a "hot Earth" around LHS 3844, an M dwarf
located 15 pc away. The planet has a radius of and
orbits the star every 11 hours. Although the existence of an atmosphere around
such a strongly irradiated planet is questionable, the star is bright enough
(, ) for this possibility to be investigated with transit and
occultation spectroscopy. The star's brightness and the planet's short period
will also facilitate the measurement of the planet's mass through Doppler
spectroscopy.Comment: 10 pages, 4 figures. Submitted to ApJ Letters. This letter makes use
of the TESS Alert data, which is currently in a beta test phase, using data
from the pipelines at the TESS Science Office and at the TESS Science
Processing Operations Cente
The CORALIE survey for southern extrasolar planets XIX. Brown dwarfs and stellar companions unveiled by radial velocity and astrometry
A historical planet-search on a sample of 1647 nearby southern main sequence
stars has been ongoing since 1998 with the CORALIE spectrograph at La Silla
Observatory, with a backup subprogram dedicated to the monitoring of binary
stars. We review 25 years of CORALIE measurements and search for Doppler
signals consistent with stellar or brown dwarf companions to produce an updated
catalog of both known and previously unpublished binary stars in the
planet-search sample, assessing the binarity fraction of the stellar population
and providing perspective for more precise planet-search in the binary sample.
We perform new analysis on the CORALIE planet-search sample radial velocity
measurements, searching for stellar companions and obtaining orbital solutions
for both known and new binary systems. We perform simultaneous radial velocity
and proper motion anomaly fits on the subset of these systems for which
Hipparcos and Gaia astrometry measurements are available, obtaining accurate
estimates of true mass for the companions. We find 218 stars in the CORALIE
sample to have at least one stellar companion, 130 of which are not yet
published in the literature and for which we present orbital solutions. The use
of proper motion anomaly allow us to derive true masses for the stellar
companions in 132 systems, which we additionally use to estimate stability
regions for possible planetary companions on circumprimary or circumbinary
orbits. Finally, we produce detection limit maps for each star in the sample
and obtain occurrence rates of and
for brown dwarf and stellar companions respectively
in the CORALIE sample.Comment: 34 pages, 15 figures, accepted for publication in A&
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