We present three newly discovered sub-Jupiter mass planets from the SuperWASP survey: WASP-54b is a heavily bloated planet of mass 0.636\(^{+0.025}_{-0.024}\) \mj and radius ...1.653\(^{+0.090}_{-0.083}\) \rj. It orbits a F9 star, evolving off the main sequence, every 3.69 days. Our MCMC fit of the system yields a slightly eccentric orbit (\(e=0.067^{+0.033}_{-0.025}\)) for WASP-54b. We investigated further the veracity of our detection of the eccentric orbit for WASP-54b, and we find that it could be real. However, given the brightness of WASP-54 V=10.42 magnitudes, we encourage observations of a secondary eclipse to draw robust conclusions on both the orbital eccentricity and the thermal structure of the planet. WASP-56b and WASP-57b have masses of 0.571\(^{+0.034}_{-0.035}\) \mj and \(0.672^{+0.049}_{-0.046}\) \mj, respectively; and radii of \(1.092^{+0.035}_{-0.033}\) \rj for WASP-56b and \(0.916^{+0.017}_{-0.014}\) \rj for WASP-57b. They orbit main sequence stars of spectral type G6 every 4.67 and 2.84 days, respectively. WASP-56b and WASP-57b show no radius anomaly and a high density possibly implying a large core of heavy elements; possibly as high as \(\sim\)50 M\(_{\oplus}\) in the case of WASP-57b. However, the composition of the deep interior of exoplanets remain still undetermined. Thus, more exoplanet discoveries such as the ones presented in this paper, are needed to understand and constrain giant planets' physical properties.
We report the discovery of WASP-43b, a hot Jupiter transiting a K7V star every 0.81 d. At 0.6-Msun the host star has the lowest mass of any star hosting a hot Jupiter. It also shows a 15.6-d rotation ...period. The planet has a mass of 1.8 Mjup, a radius of 0.9 Rjup, and with a semi-major axis of only 0.014 AU has the smallest orbital distance of any known hot Jupiter. The discovery of such a planet around a K7V star shows that planets with apparently short remaining lifetimes owing to tidal decay of the orbit are also found around stars with deep convection zones.
It is unclear whether chemically peculiar stars of the upper main sequence
represent a class completely distinct from normal A-type stars, or whether
there exists a continuous transition from the ...normal to the most peculiar late
F- to early B-type stars. A systematic abundance analysis of open cluster
early-type stars would help to relate the observed differences of the chemical
abundances of the photospheres to other stellar characteristics, without being
concerned by possible different original chemical composition. Furthermore, if
a continuous transition region from the very peculiar to the so called normal
A-F stars exists, it should be possible to detect objects with mild
peculiarities. As a first step of a larger project, an abundance analysis of 5
F-A type stars in the young cluster IC2391 was performed using high resolution
spectra obtained with the UVES instrument of the ESO VLT. Our targets seem to
follow a general abundance pattern: close to solar abundance of the light
elements and iron peak elements, heavy elements are slightly overabundant with
respect to the sun, similar to what was found in previous studies of normal
field A-type stars of the galactic plane. We detected a weakly chemically
peculiar star, HD74044. Its element pattern contains characteristics of CP1 as
well as CP2 stars, enhanced abundances of iron peak elements and also higher
abundances of Sc, Y, Ba and Ce. We did not detect a magnetic field in this star
(detection limit was 2kG). We also studied the star SHJM2, proposed as a
pre-main sequence object in previous works. Using spectroscopy we found a high
surface gravity, which suggests that the star is very close to the ZAMS.
Observations of transiting extrasolar planets are of key importance to our understanding of planets because their mass, radius, and mass density can be determined. The CoRoT space mission allows us ...to achieve a very high photometric accuracy. By combining CoRoT data with high-precision radial velocity measurements, we derive precise planetary radii and masses. We report the discovery of CoRoT-19b, a gas-giant planet transiting an old, inactive F9V-type star with a period of four days. After excluding alternative physical configurations mimicking a planetary transit signal, we determine the radius and mass of the planet by combining CoRoT photometry with high-resolution spectroscopy obtained with the echelle spectrographs SOPHIE, HARPS, FIES, and SANDIFORD. To improve the precision of its ephemeris and the epoch, we observed additional transits with the TRAPPIST and Euler telescopes. Using HARPS spectra obtained during the transit, we then determine the projected angle between the spin of the star and the orbit of the planet. We find that the host star of CoRoT-19b is an inactive F9V-type star close to the end of its main-sequence life. The host star has a mass M*=1.21+/-0.05 Msun and radius R*=1.65+/-0.04 Rsun. The planet has a mass of Mp=1.11+/-0.06 Mjup and radius of Rp=1.29+/-0.03 Rjup. The resulting bulk density is only rho=0.71+/-0.06 gcm-3, which is much lower than that for Jupiter. The exoplanet CoRoT-19b is an example of a giant planet of almost the same mass as Jupiter but a 30% larger radius.
We report the discovery by the WASP transit survey of a giant planet in a close orbit (0.0295+-0.0009 AU) around a moderately bright (V=11.6, K=10) G9 dwarf (0.89+-0.08 M_sun, 0.84+-0.03 R_sun) in ...the Southern constellation Eridanus. Thanks to high-precision follow-up photometry and spectroscopy obtained by the telescopes TRAPPIST and Euler, the mass and size of this planet, WASP-50b, are well constrained to 1.47+-0.09 M_jup and 1.15+-0.05 R_jup, respectively. The transit ephemeris is 2455558.6120 (+-0.0002) + N x 1.955096 (+-0.000005) HJD_UTC. The size of the planet is consistent with basic models of irradiated giant planets. The chromospheric activity (log R'_HK = -4.67) and rotational period (P_rot = 16.3+-0.5 days) of the host star suggest an age of 0.8+-0.4 Gy that is discrepant with a stellar-evolution estimate based on the measured stellar parameters (rho_star = 1.48+-0.10 rho_sun, Teff = 5400+-100 K, Fe/H= -0.12+-0.08) which favours an age of 7+-3.5 Gy. This discrepancy could be explained by the tidal and magnetic influence of the planet on the star, in good agreement with the observations that stars hosting hot Jupiters tend to show faster rotation and magnetic activity (Pont 2009; Hartman 2010). We measure a stellar inclination of 84 (-31,+6) deg, disfavouring a high stellar obliquity. Thanks to its large irradiation and the relatively small size of its host star, WASP-50b is a good target for occultation spectrophotometry, making it able to constrain the relationship between hot Jupiters' atmospheric thermal profiles and the chromospheric activity of their host stars proposed by Knutson et al. (2010).
Mon.Not.Roy.Astron.Soc. 367 (2006) 1478-1514 We present an analysis of interstellar Na I (lambda=3302.37\AA, 3302.98\AA),
Ti II (lambda=3383.76\AA) and Ca II K (lambda=3933.66\AA) absorption features
...for 74 sightlines towards O- and B-type stars in the Galactic disc. The data
were obtained from the UVES Paranal Observatory Project, at a spectral
resolution of 3.75km/s and with mean signal to noise ratios per pixel of 260,
300 and 430 for the Na I, Ti II and Ca II observations, respectively.
Interstellar features were detected in all but one of the Ti II sightlines and
all of the Ca II sightlines. The dependence of the column density of these
three species with distance, height relative to the Galactic plane, H I column
density, reddening and depletion relative to the solar abundance has been
investigated. We also examine the accuracy of using the Na I column density as
an indicator of that for H I. In general we find similar strong correlations
for both Ti and Ca, and weaker correlations for Na. Our results confirm the
general belief that Ti and Ca occur in the same regions of the interstellar
medium and also that the Ti II/Ca II ratio is constant over all parameters. We
hence conclude that the absorption properties of Ti and Ca are essentially
constant under the general interstellar medium conditions of the Galactic disc.
We report on the discovery of a hot Jupiter-type exoplanet, CoRoT-17b, detected by the CoRoT satellite. It has a mass of \(2.43\pm0.30\)\Mjup and a radius of \(1.02\pm0.07\)\Rjup, while its mean ...density is \(2.82\pm0.38\) g/cm\(^3\). CoRoT-17b is in a circular orbit with a period of \(3.7681\pm0.0003\) days. The host star is an old (\(10.7\pm1.0\) Gyr) main-sequence star, which makes it an intriguing object for planetary evolution studies. The planet's internal composition is not well constrained and can range from pure H/He to one that can contain \(\sim\)380 earth masses of heavier elements.
Based on a model of globular cluster self-enrichment published in a previous
paper, we present an explanation for the metallicity gradient observed
throughout the galactic Old Halo. Our ...self-enrichment model is based on the
ability of globular cluster progenitor clouds to retain the ejecta of a first
generation of Type II Supernovae. The key point is that this ability depends on
the pressure exerted on the progenitor cloud by the surrounding protogalactic
medium and therefore on the location of the cloud in the protoGalaxy. Since
there is no significant (if any) metallicity gradient in the whole halo, we
also present a review in favour of a galactic halo partly build via accretions
and mergers of satellite systems. Some of them bear their own globular clusters
and therefore ``contaminate'' the system of globular clusters formed ``in
situ'', namely within the original potential well of the Galaxy. Therefore, the
comparison between our self-enrichment model and the observational data should
be limited to the genuine galactic globular clusters, the so-called Old Halo
group.
The 12C14N/12C15N and 12C14N/13C14N isotopic ratios are determined for the
first time in a Jupiter-family comet, 88P/1981 Q1 Howell, and in the chemically
peculiar Oort Cloud comet C/1999 S4 ...(LINEAR). By comparing these measurements
to previous ones derived for six other Oort Cloud comets (including one of
Halley-type), we find that both the carbon and nitrogen isotopic ratios are
constant within the uncertainties. The mean values are 12C/13C ~ 90 and 14N/15N
\~ 145 for the eight comets. These results strengthen the view that CN radicals
originate from refractory organics formed in the protosolar molecular cloud and
subsequently incorporated in comets.
We have obtained the first continuous disk averaged spectrum of Mars from 450 to 1550 Ghz using the Herschel-SPIRE Fourier Transform Spectrometer. The spectrum was obtained at a constant resolution ...of 1.4 GHz across the whole band. The flux from the planet is such that the instrument was operated in "bright source" mode to prevent saturation of the detectors. This was the first successful use of this mode and in this work we describe the method used for observing Mars together with a detailed discussion of the data reduction techniques required to calibrate the spectrum. We discuss the calibration accuracy obtained and describe the first comparison with surface and atmospheric models. In addition to a direct photometric measurement of the planet the spectrum contains the characteristic transitions of 12CO from J 5-4 to J 13-12 as well as numerous H2O transitions. Together these allow the comparison to global atmospheric models allowing the mean mixing ratios of water and 12CO to be investigated. We find that it is possible to match the observed depth of the absorption features in the spectrum with a fixed water mixing ratio of 1 x 10-4 and a 12CO mixing ratio of 9 x 10-4
