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Aims. We aim to detect and interpret photometric and spectroscopic variability of the bright CoRoT B-type supergiant target HD46769 (V = 5.79). We also attempt to detect a magnetic field in the target. Methods. We analyse a 23-day oversampled CoRoT light curve after detrending and spectroscopic follow-up data using standard Fourier analysis and phase dispersion minimization methods. We determine the fundamental parameters of the star, as well as its abundances from the most prominent spectral lines. We perform a Monte Carlo analysis of spectropolarimetric data to obtain an upper limit of the polar magnetic field, assuming a dipole field. Results. In the CoRoT data, we detect a dominant period of 4.84 d with an amplitude of 87 ppm and some of its (sub-)multiples. Given the shape of the phase-folded light curve and the absence of binary motion, we interpret the dominant variability in terms of rotational modulation, with a rotation period of 9.69 d. Subtraction of the rotational modulation signal does not reveal any sign of pulsations. Our results are consistent with the absence of variability in the Hipparcos light curve. The spectroscopy leads to a projected rotational velocity of 72 ± 2 kms-1 and does not reveal periodic variability or the need to invoke macroturbulent line broadening. No signature of a magnetic field is detected in our data. A field stronger than ~500 G at the poles can be excluded, unless the possible non-detected field were more complex than dipolar. Conclusions. The absence of pulsations and macroturbulence of this evolved B-type supergiant is placed into the context of instability computations and of observed variability of evolved B-type stars. [ABSTRACT FROM AUTHOR]

Context. The internal structure of pre-main-sequence (PMS) stars is poorly constrained at present. This could change significantly through high-quality asteroseismological observations of a sample of such stars. Aims. We concentrate on an asteroseismological study of HD261711, a rather hot δ Scuti-type pulsating member of the young open cluster NGC 2264 located at the blue border of the instability region. HD261711 was discovered to be a PMS δ Scuti star using the time series photometry obtained by the MOST satellite in 2006. Methods. High-precision, time-series photometry of HD261711 was obtained by the MOST and CoRoT satellites in four separate new observing runs that are put into context with the star's fundamental atmospheric parameters obtained from spectroscopy. Frequency Analysis was performed using Period04. The spectral analysis was performed using equivalent widths and spectral synthesis. Results. With the new MOST data set from 2011/12 and the two CoRoT light curves from 2008 and 2011/12, the δ Scuti variability was confirmed and regular groups of frequencies were discovered. The two pulsation frequencies identified in the data from the first MOST observing run in 2006 are confirmed and 23 new δ Scuti-type frequencies were discovered using the CoRoT data. Weighted average frequencies for each group were determined and are related to l = 0 and l = 1 p-modes. Evidence for amplitude modulation of the frequencies in two groups is seen. The effective temperature (Teff) was derived to be 8600 ± 200K, log g is 4.1± 0.2, and the projected rotational velocity (ν sin i) is 53±1 kms-1. Using our Teff value and the radius of 1.8 ± 0.5 R☉ derived from spectral energy distribution (SED) fitting, we get a luminosity log L/L☉ of 1.20 ± 0.14 which agrees well to the seismologically determined values of 1.65 R☉ and, hence, a log L/L☉ of 1.13. The radial velocity of 14 ±2 kms-1 we derived for HD261711, confirms the star's membership to NGC2264. Conclusions. Our asteroseismic models suggest that HD261711 is a δ Scuti-type star close to the zero-age main sequence (ZAMS) with a mass of 1.8 to 1.9 M☉. With an age of about 10 million years derived from asteroseismology, the star is either a young ZAMS star or a late PMS star just before the onset of hydrogen-core burning. The observed splittings about the l = 0 and 1 parent modes may be an artifact of the Fourier derived spectrum of frequencies with varying amplitudes. [ABSTRACT FROM AUTHOR]

Aims. We report the discovery of CoRoT-16b, a low density hot jupiter that orbits a faint G5V star (mV = 15.63) in 5.3523 ± 0.0002 days with slight eccentricity. A fit of the data with no a priori assumptions on the orbit leads to an eccentricity of 0.33 ± 0.1. We discuss this value and also derive the mass and radius of the planet. Methods. We analyse the photometric transit curve of CoRoT-16 given by the CoRoT satellite, and radial velocity data from the HARPS and HIRES spectrometers. A combined analysis using a Markov chain Monte Carlo algorithm is used to get the system parameters. Results. CoRoT-16b is a 0.535 -0.083/+0.085 MJ, 1.17 -0.14/+0.16 RJ hot Jupiter with a density of 0.44 -0.14/+0.21 g cm-3. Despite its short orbital distance (0.0618 ± 0.0015 AU) and the age of the parent star (6.73 ± 2.8 Gyr), the planet orbit exhibits significantly non-zero eccentricity. This is very uncommon for this type of objects as tidal effects tend to circularise the orbit. This value is discussed taking into account the characteristics of the star and the observation accuracy. [ABSTRACT FROM AUTHOR]

Context. The space mission CoRoT is devoted to the analysis of stellar variability and the photometric detection of extrasolar planets. Aims. We present the list of planetary transit candidates detected in the first short run observed by CoRoT that targeted SRc01, towards the Galactic center in the direction of Aquila, which lasted from April to May 2007. Methods. Among the acquired data, we analyzed those for 1269 sources in the chromatic bands and 5705 in the monochromatic band. Instrumental noise and the stellar variability were treated with several detrending tools, to which several transit-search algorithms were subsequently applied. Results. Fifty-one sources were classified as planetary transit candidates and 26 were followed up with ground-based observations. Until now, no planet has been detected in the CoRoT data from the SRc01 field. [ABSTRACT FROM AUTHOR]

We report the discovery by the CoRoT space mission of a new giant planet, CoRoT-20b. The planet has a mass of 4.24 ± 0.23 MJup and a radius of 0.84 ± 0.04 RJup. With a mean density of 8.87 ± 1.10 g cm-3, it is among the most compact planets known so far. Evolutionary models for the planet suggest a mass of heavy elements of the order of 800 M⊗ if embedded in a central core, requiring a revision either of the planet formation models or both planet evolution and structure models. We note however that smaller amounts of heavy elements are expected by more realistic models in which they are mixed throughout the envelope. The planet orbits a G-type star with an orbital period of 9.24 days and an eccentricity of 0.56. The star's projected rotational velocity is v sin i = 4.5 ± 1.0 kms-1, corresponding to a spin period of 11.5 ± 3.1 days if its axis of rotation is perpendicular to the orbital plane. In the framework of Darwinian theories and neglecting stellar magnetic breaking, we calculate the tidal evolution of the system and show that CoRoT-20b is presently one of the very few Darwin-stable planets that is evolving toward a triple synchronous state with equality of the orbital, planetary and stellar spin periods. [ABSTRACT FROM AUTHOR]

Context. CoRoT is a pioneering space mission whose primary goals are stellar seismology and extrasolar planets search. Its surveys of large stellar fields generate numerous planetary candidates whose lightcurves have transit-like features. An extensive analytical and observational follow-up effort is undertaken to classify these candidates. Aims. We present the list of planetary transit candidates from the CoRoT LRa01 star field in the Monoceros constellation toward the Galactic anti-center direction. The CoRoT observations of LRa01 lasted from 24 October 2007 to 3 March 2008. Methods. We acquired and analyzed 7470 chromatic and 3938 monochromatic lightcurves. Instrumental noise and stellar variability were treated with several filtering tools by different teams from the CoRoT community. Different transit search algorithms were applied to the lightcurves. Results. Fifty-one stars were classified as planetary transit candidates in LRa01. Thirty-seven (i.e., 73% of all candidates) are "good" planetary candidates based on photometric analysis only. Thirty-two (i.e., 87% of the "good" candidates) have been followed-up. At the time of writing twenty-two cases were solved and five planets were discovered: three transiting hot-Jupiters (CoRoT-5b, CoRoT-12b, and CoRoT-21b), the first terrestrial transiting planet (CoRoT-7b), and another planet in the same system (CoRoT-7c, detected by radial velocity survey only). Evidence of another non-transiting planet in the CoRoT-7 system, namely CoRoT-7d, was recently found as well. [ABSTRACT FROM AUTHOR]

Context. Observations of transiting extrasolar planets are of key importance to our understanding of planets because their mass, radius, and mass density can be determined. These measurements indicate that planets of similar mass can have very different radii. For low-density planets, it is generally assumed that they are inflated owing to their proximity to the host-star. To determine the causes of this inflation, it is necessary to obtain a statistically significant sample of planets with precisely measured masses and radii. Aims. 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. Methods. 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. Results. 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 M☉ and radius R" = 1.65 ±0.04 R☉. 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 ρ = 0.71 ±0.06 g cm-3, which is much lower than that for Jupiter. Conclusions. The exoplanet CoRoT-19b is an example of a giant planet of almost the same mass as Jupiter but a ≈30% larger radius. [ABSTRACT FROM AUTHOR]

We report the detection of CoRoT-23b, a hot Jupiter transiting in front of its host star with a period of 3.6314 ± 0.0001 days. This planet was discovered thanks to photometric data secured with the CoRoT satellite, combined with spectroscopic radial velocity (RV) measurements. A photometric search for possible background eclipsing binaries conducted at CFHT and OGS concluded with a very low risk of false positives. The usual techniques of combining RV and transit data simultaneously were used to derive stellar and planetary parameters. The planet has a mass of Mp = 2.8±0.3 MJup, a radius of Rpl= 1.05 ± 0.13 RJup, a density of ≈3 gcm-3. RV data also clearly reveal a nonzero eccentricity of e = 0.16 ± 0.02. The planet orbits a mature G0 main sequence star of V = 15.5 mag, with a mass M⋆ = 1.14 ± 0.08 M☉, a radius R⋆ = 1. 61 ± 0.18 R☉ and quasi-solar abundances. The age of the system is evaluated to be 7 Gyr, not far from the transition to subgiant, in agreement with the rather large stellar radius. The two features of a significant eccentricity of the orbit and of a fairly high density are fairly uncommon for a hot Jupiter. The high density is, however, consistent with a model of contraction of a planet at this mass, given the age of the system. On the other hand, at such an age, circularization is expected to be completed. In fact, we show that for this planetary mass and orbital distance, any initial eccentricity should not totally vanish after 7 Gyr, as long as the tidal quality factor Qp is more than a few 105, a value that is the lower bound of the usually expected range. Even if CoRoT-23b features a density and an eccentricity that are atypical of a hot Jupiter, it is thus not an enigmatic object. [ABSTRACT FROM AUTHOR]