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.
In a previous work, we explored the possibility that the beta Pictoris moving group (BPMG), consisting of low-mass post-T Tauri stars, was formed near the Scorpius-Centaurus OB association. The cause ...of the formation could be a Typ IIE supernova exploding either in Lower Centaurus Crux (LCC) or the Upper Centaurus Lupus (UCL), the two older subgroups of that association. Here we present new results for BPMG. A more detailed analysis of the orbit confinement in this group leads to a star distribution pattern at birth that can be considered as a representation of the density distribution in the natal cloud. We also propose a plausible origin for the supernova that could have triggered the star formation in BPMG by finding the past position of the runaway star HIP 46950. We find that this scenario is capable of explaining the origin of all the members of BPMG proposed by Zuckerman and coworkers and by Song and coworkers, with the exception of HIP 79881, which is probably an old main-sequence interloper.
Context. The CoRoT satellite searches for planets by applying the transit method, monitoring up to 12 000 stars in the galactic plane for 150 days in each observing run. This search is contaminated ...by a large fraction of false positives, caused by different eclipsing binary configurations that might be confused with a transiting planet. Aims. We evaluate the rates and nature of false positives in the CoRoT exoplanets search and compare our results with semiempirical predictions. Methods. We consider the detected binary and planet candidates in the first three extended CoRoT runs, and classify the results of the follow-up observations completed to verify their planetary nature. We group the follow-up results into undiluted binaries, diluted binaries, and planets and compare their abundances with predictions from the literature. Results. 83% of the initial detections are classified as false positives using only the CoRoT light-curves, the remaining 17% require follow-up observations. Finally, 12% of the candidates in the follow-up program are planets. The shape of the overall distribution of the false positive rate follows previous predictions, except for candidates with transit depths below about 0.4%. For candidates with transit depths in the range from 0.1–0.4%, CoRoT detections are nearly complete, and this difference from predictions is probably real and dominated by a lower than expected abundance of diluted eclipsing binaries.
Context. The pioneer space mission for photometric planet searches, CoRoT, steadily monitors about 12 000 stars in each of its fields of view. Transit candidates can be detected early in the ...processing of the data and before the end of a run of observation. Aims. We report the detection of the first planet discovered by CoRoT and characterizing it with the help of follow-up observations. Methods. Raw data were filtered from outliers and residuals at the orbital period of the satellite. The orbital parameters and the radius of the planet were estimated by best fitting the phase folded light curve with 34 successive transits. Doppler measurements with the SOPHIE spectrograph permitted us to secure the detection against binaries and to estimate the mass of the planet. Results. The accuracy of the data is very high with a dispersion in the 2.17 min binned phase-folded light curve that does not exceed similar to 3.\times10 super(-4) in flux unit. The planet orbits a mildly metal-poor G0V star of magnitude V =13.6 in 1.5 days. The estimated mass and radius of the star are 0.95\pm0.15 M_{\odot} and 1.11\pm0.05 R_{\odot}. We find the planet has a radius of 1.49\pm0.08 R_{\rm Jup}, a mass of 1.03\pm0.12 M_{\rm Jup}, and a particularly low mean density of 0.38\pm0.05 g cm super(-3).
The dynamical evolution of the recently detected stellar group Mamajek 2 is studied by means of its past three-dimensional orbit. The past orbits of the open clusters NGC 2516 and alpha Persei, ...belonging to the so-called 'Local Association,' were also computed in order to check for a possible common past dynamical evolution of these systems. To complete the data of the Mamajek 2 small group, we have obtained high-resolution FEROS spectra to measure the radial and also the projected rotational velocities of its members; an estimate of its metallicity was obtained as well. Two exceptionally low-rotating A-type stars turned out to be a strong magnetic Ap star in one case, and a normal A0 star with near-solar metallicity in the other. The dynamical results showed that NGC 2516 and Mamajek 2 may have had a common origin at the age of 135 ± 5 Myr. This dynamical age confirms the individual ages of 140 Myr for NGC 2516 and 120 ± 25 Myr for Mamajek 2 obtained independently by photometric methods. Both these groups appear to have the same solar metallicity giving support to a common birth scenario. The dynamical approach is showing that some bound open clusters can form in a coeval fashion with unbound stellar groups or with associations.
Aims. We present here the list of planetary transit candidates detected in the first long run observed by CoRoT: LRc01, towards the galactic center in the direction of Aquila, which lasted from May ...to October 2007. Methods. we analyzed 3719 (33%) sources in the chromatic bands and 7689 in the monochromatic band. Instrumental noise and the stellar variability were treated with several detrending tools, on which subsequently several transit search algorithms were applied. Results. Forty two sources were classified as planetary transit candidates and up to now 26 cases have been solved. One planet (CoRoT-2b) and one brown-dwarf (CoRoT-3b) have been the subjects of detailed publications.
Context. CoRoT is a pioneering space mission 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 field observed by CoRoT, IRa01, the initial run toward the Galactic anticenter, which lasted for 60 days. Methods. We analysed 3898 sources in the coloured bands and 5974 in the monochromatic band. Instrumental noise and stellar variability were taken into account using detrending tools before applying various transit search algorithms. Results. Fifty sources were classified as planetary transit candidates and the most reliable 40 detections were declared targets for follow-up ground-based observations. Two of these targets have so far been confirmed as planets, CoRoT-1b and CoRoT-4b, for which a complete characterization and specific studies were performed.
In the present study, considering the physical conditions that are relevant in interactions between supernova remnants (SNRs) and dense molecular clouds for triggering star formation we have built a ...diagram of SNR radius versus cloud density in which the constraints above delineate a shaded zone where star formation is allowed. We have also performed fully 3D radiatively cooling numerical simulations of the impact between SNRs and clouds under different initial conditions in order to follow the initial steps of these interactions. We determine the conditions that may lead either to cloud collapse and star formation or to complete cloud destruction and find that the numerical results are consistent with those of the SNR-cloud density diagram. Finally, we have applied the results above to the beta Pictoris stellar association which is composed of low-mass post-T Tauri stars with an age of 11 Myr. It has been recently suggested that its formation could have been triggered by the shock wave produced by an SN explosion localized at a distance of about 62 pc that may have occurred either in the Lower Centaurus Crux or in the Upper Centaurus Lupus which are both nearby older subgroups of that association (Ortega and co-workers). Using the results of the analysis above we have shown that the suggested origin for the young association at the proposed distance is plausible only for a very restricted range of initial conditions for the parent molecular cloud, that is, a cloud with a radius of the order of 10 pc and density of the order of 20 cm-3 and a temperature of the order of 50-100 K.PUBLICATION ABSTRACT
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