We present the discovery and characterization of WASP-148, a new extrasolar system that includes at least two giant planets. The host star is a slowly rotating inactive late-G dwarf with a V = 12 ...magnitude. The planet WASP-148b is a hot Jupiter of 0.72 RJup and 0.29 MJup that transits its host with an orbital period of 8.80 days. We found the planetary candidate with the SuperWASP photometric survey, then characterized it with the SOPHIE spectrograph. Our radial velocity measurements subsequently revealed a second planet in the system, WASP-148c, with an orbital period of 34.5 days and a minimum mass of 0.40 MJup. No transits of this outer planet were detected. The orbits of both planets are eccentric and fall near the 4:1 mean-motion resonances. This configuration is stable on long timescales, but induces dynamical interactions so that the orbits differ slightly from purely Keplerian orbits. In particular, WASP-148b shows transit-timing variations of typically 15 min, making it the first interacting system with transit-timing variations that is detected on ground-based light curves. We establish that the mutual inclination of the orbital plane of the two planets cannot be higher than 35°, and the true mass of WASP-148c is below 0.60 MJup. We present photometric and spectroscopic observations of this system that cover a time span of ten years. We also provide their Keplerian and Newtonian analyses; these analyses should be significantly improved through future TESS observations.
In the course of a project to study eclipsing binary stars in vinicity of the Sun, we found that the cooler component of LL Aqr is a solar twin candidate. This is the first known star with properties ...of a solar twin existing in a non-interacting eclipsing binary, offering an excellent opportunity to fully characterise its physical properties with very high precision. We used extensive multi-band, archival photometry and the Super-WASP project and high-resolution spectroscopy obtained from the HARPS and CORALIE spectrographs. The spectra of both components were decomposed and a detailed LTE abundance analysis was performed. The light and radial velocity curves were simultanously analysed with the Wilson-Devinney code. The resulting highly precise stellar parameters were used for a detailed comparison with PARSEC, MESA, and GARSTEC stellar evolution models. LL Aqr consists of two main-sequence stars (F9 V + G3 V) with masses of M1 = 1.1949\(\pm\)0.0007 and M2=1.0337\(\pm\)0.0007 \(M_\odot\), radii R1 = 1.321\(\pm\)0.006 and R2 = 1.002\(\pm\)0.005 \(R_\odot\), temperatures T1=6080\(\pm\)45 K and T2=5703\(\pm\)50 K and solar chemical composition M/H=0.02\(\pm\)0.05 dex. The absolute dimensions, radiative and photometric properties, and atmospheric abundances of the secondary are all fully consistent with being a solar twin. Both stars are cooler by about 3.5 \(\sigma\) or less metal abundant by 5\(\sigma\) than predicted by standard sets of stellar evolution models. When advanced modelling was performed, we found that full agreement with observations can only be obtained for values of the mixing length and envelope overshooting parameters that are hard to accept. The most reasonable and physically justified model fits found with MESA and GARSTEC codes still have discrepancies with observations but only at the level of 1\(\sigma\).
We report the discovery of the transiting exoplanets WASP-69b, WASP-70Ab and WASP-84b, each of which orbits a bright star (\(V\sim10)\). WASP-69b is a bloated Saturn-mass planet (0.26 \(M_{\rm ...Jup}\), 1.06 \(R_{\rm Jup}\)) in a 3.868-d period around an active, \(\sim\)1-Gyr, mid-K dwarf. ROSAT detected X-rays \(60 \pm 27"\) from WASP-69. If the star is the source then the planet could be undergoing mass-loss at a rate of \(\sim\)10\(^{12}\) g s\(^{-1}\). This is 1 to 2 orders of magnitude higher than the evaporation rate estimated for HD 209458b and HD 189733b, both of which have exhibited anomalously-large Lyman-\(\alpha\) absorption during transit. WASP-70Ab is a sub-Jupiter-mass planet (0.59 \(M_{\rm Jup}\), 1.16 \(R_{\rm Jup}\)) in a 3.713-d orbit around the primary of a spatially-resolved, 9-to-10-Gyr, G4+K3 binary, with a separation of 3.3\('\) (\(\geq\)800 AU). WASP-84b is a sub-Jupiter-mass planet (0.69 \(M_{\rm Jup}\), 0.94 \(R_{\rm Jup)}\) in an 8.523-d orbit around an active, \(\sim\)1-Gyr, early-K dwarf. Of the transiting planets discovered from the ground to date, WASP-84b has the third-longest period. For the active stars WASP-69 and WASP-84, we pre-whitened the radial velocities using a low-order harmonic series. We found this reduced the residual scatter more than did the oft-used method of pre-whitening with a fit between residual radial velocity and bisector span. The system parameters were essentially unaffected by pre-whitening.
Six detached white-dwarf close binaries Morales-Rueda, L.; Marsh, T. R.; Maxted, P. F. L. ...
Monthly notices of the Royal Astronomical Society,
05/2005, Letnik:
359, Številka:
2
Journal Article
Kinematic structure in the young σ Orionis association Jeffries, R. D.; Maxted, P. F. L.; Oliveira, J. M. ...
Monthly notices of the Royal Astronomical Society. Letters,
09/2006, Letnik:
371, Številka:
1
Journal Article
Planets orbiting binary systems are relatively unexplored compared to those
around single stars. Detections of circumbinary planets and planetary systems
offer a first detailed view into our ...understanding of circumbinary planet
formation and dynamical evolution. The BEBOP (Binaries Escorted by Orbiting
Planets) radial velocity survey plays a special role in this adventure as it
focuses on eclipsing single-lined binaries with an FGK dwarf primary and M
dwarf secondary allowing for the highest-radial velocity precision using the
HARPS and SOPHIE spectrographs. We obtained 4512 high-resolution spectra for
the 179 targets in the BEBOP survey which we used to derive the stellar
atmospheric parameters using both equivalent widths and spectral synthesis. We
furthermore derive stellar masses, radii, and ages for all targets. With this
work, we present the first homogeneous catalogue of precise stellar parameters
for these eclipsing single-lined binaries.
Aims. In this paper we discuss the radio continuum and X-ray properties of the so-far poorly studied Galactic supernova remnant (SNR) G5.9 + 3.1. Methods. We present the radio spectral energy ...distribution (SED) of the Galactic SNR G5.9 + 3.1 obtained with the Murchison Widefield Array (MWA). Combining these new observations with the surveys at other radio continuum frequencies, we discuss the integrated radio continuum spectrum of this particular remnant. We have also analyzed an archival XMM-Newton observation, which represents the first detection of X-ray emission from this remnant. Results. The SNR SED is very well explained by a simple power-law relation. The synchrotron radio spectral index of G5.9 + 3.1 is estimated to be 0.42 ± 0.03 and the integrated flux density at 1 GHz to be around 2.7 Jy. Furthermore, we propose that the identified point radio source, located centrally inside the SNR shell, is most probably a compact remnant of the supernova explosion. The shell-like X-ray morphology of G5.9 + 3.1 as revealed by XMM-Newton broadly matches the spatial distribution of the radio emission, where the radio-bright eastern and western rims are also readily detected in the X-ray while the radio-weak northern and southern rims are weak or absent in the X-ray. Extracted MOS1+MOS2+PN spectra from the whole SNR as well as the north, east, and west rims of the SNR are fit successfully with an optically thin thermal plasma model in collisional ionization equilibrium with a column density NH ~ 0.80 × 1022 cm−2 and fitted temperatures spanning the range kT ~ 0.14–0.23 keV for all of the regions. The derived electron number densities ne for the whole SNR and the rims are also roughly comparable (ranging from ~0.20f−1∕2 to ~0.40f−1∕2 cm−3, where f is the volume filling factor). We also estimate the swept-up mass of the X-ray emitting plasma associated with G5.9+3.1 to be ~46f−1∕2 M⊙.
We report three newly discovered exoplanets from the SuperWASP survey. WASP-127b is a heavily inflated super-Neptune of mass 0.18 +/- 0.02 M_J and radius 1.37 +/- 0.04 R_J. This is one of the least ...massive planets discovered by the WASP project. It orbits a bright host star (Vmag = 10.16) of spectral type G5 with a period of 4.17 days. WASP-127b is a low-density planet that has an extended atmosphere with a scale height of 2500 +/- 400 km, making it an ideal candidate for transmission spectroscopy. WASP-136b and WASP-138b are both hot Jupiters with mass and radii of 1.51 +/- 0.08 M_J and 1.38 +/- 0.16 R_J, and 1.22 +/- 0.08 M_J and 1.09 +/- 0.05 R_J, respectively. WASP-136b is in a 5.22-day orbit around an F9 subgiant star with a mass of 1.41 +/- 0.07 M_sun and a radius of 2.21 +/- 0.22 R_sun. The discovery of WASP-136b could help constrain the characteristics of the giant planet population around evolved stars. WASP-138b orbits an F7 star with a period of 3.63 days. Its radius agrees with theoretical values from standard models, suggesting the presence of a heavy element core with a mass of ~10 M_earth. The discovery of these new planets helps in exploring the diverse compositional range of short-period planets, and will aid our understanding of the physical characteristics of both gas giants and low-density planets.
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