Showing papers by "François Bouchy published in 2009"
TL;DR: In this paper, the authors reported the discovery of very shallow (ΔF/F ≈ 3.4× 10 −4 ) periodic dips in the light curve of an active V = 11.7 G9V star observed by the CoRoT satellite, which they interpret as caused by a transiting companion.
Abstract: Aims. We report the discovery of very shallow (ΔF/F ≈ 3.4× 10 −4 ), periodic dips in the light curve of an active V = 11.7 G9V star observed by the CoRoT satellite, which we interpret as caused by a transiting companion. We describe the 3-colour CoRoT data and complementary ground-based observations that support the planetary nature of the companion. Methods. We used CoRoT colours information, good angular resolution ground-based photometric observations in- and out- of transit, adaptive optics imaging, near-infrared spectroscopy, and preliminary results from radial velocity measurements, to test the diluted eclipsing binary scenarios. The parameters of the host star were derived from optical spectra, which were then combined with the CoRoT light curve to derive parameters of the companion. Results. We examined all conceivable cases of false positives carefully, and all the tests support the planetary hypothesis. Blends with separation >0.40 �� or triple systems are almost excluded with a 8 × 10 −4 risk left. We conclude that, inasmuch we have been exhaustive, we have discovered a planetary companion, named CoRoT-7b, for which we derive a period of 0.853 59 ± 3 × 10 −5 day and a radius of Rp = 1.68 ± 0.09 REarth .A nalysis of preliminary radial velocity data yields an upper limit of 21 MEarth for the companion mass, supporting the finding. Conclusions. CoRoT-7b is very likely the first Super-Earth with a measured radius. This object illustrates what will probably become a common situation with missions such as Kepler, namely the need to establish the planetary origin of transits in the absence of a firm radial velocity detection and mass measurement. The composition of CoRoT-7b remains loosely constrained without a precise mass. A very high surface temperature on its irradiated face, ≈1800–2600 K at the substellar point, and a very low one, ≈50 K, on its dark face assuming no atmosphere, have been derived.
665 citations
TL;DR: In this paper, the authors reported the discovery of very shallow (DF/F = 3.4 10-4), periodic dips in the light curve of an active V = 11.7 G9V star observed by the CoRoT satellite, which they interpret as due to the presence of a transiting companion.
Abstract: We report the discovery of very shallow (DF/F = 3.4 10-4), periodic dips in the light curve of an active V = 11.7 G9V star observed by the CoRoT satellite, which we interpret as due to the presence of a transiting companion. We describe the 3-colour CoRoT data and complementary ground-based observations that support the planetary nature of the companion. Methods. We use CoRoT color information, good angular resolution ground-based photometric observations in- and out- of transit, adaptive optics imaging, near-infrared spectroscopy and preliminary results from Radial Velocity measurements, to test the diluted eclipsing binary scenarios. The parameters of the host star are derived from optical spectra, which were then combined with the CoRoT light curve to derive parameters of the companion. We examine carefully all conceivable cases of false positives, and all tests performed support the planetary hypothesis. Blends with separation larger than 0.40 arcsec or triple systems are almost excluded with a 8 10-4 risk left. We conclude that, as far as we have been exhaustive, we have discovered a planetary companion, named CoRoT-7b, for which we derive a period of 0.853 59 +/- 3 10-5 day and a radius of Rp = 1.68 +/- 0.09 REarth. Analysis of preliminary radial velocity data yields an upper limit of 21 MEarth for the companion mass, supporting the finding.
CoRoT-7b is very likely the first Super-Earth with a measured radius.
570 citations
TL;DR: In this article, the authors reported the detection of two new multiple planet systems orbiting solar-like stars HD 47 186 and HD 181 433, which increased to 20 the number of close-in low-mass exoplanets (below 0.1 M JUP) and strengthen the fact that 80% of these planets are in multiple planetary systems.
Abstract: We report on the detection of two new multiple planet systems orbiting solar-like stars HD 47 186 and HD 181 433. The first system contains a hot Neptune of 22.78 M ⊕ with a 4.08-day period and a Saturn of 0.35 M JUP with a 3.7-year period. The second system contains a Super-Earth of 7.5 M ⊕ with a 9.4-day period, a 0.64 M JUP with a 2.6-year period, and a third companion of 0.54 M JUP with a period of about 6 years. These detections increase to 20 the number of close-in low-mass exoplanets (below 0.1 M JUP) and strengthen the fact that 80% of these planets are in multiple planetary systems.
500 citations
University of Geneva1, Institut d'Astrophysique de Paris2, Centre national de la recherche scientifique3, Janssen Pharmaceutica4, University of Bern5, University of Paris-Sud6, Spanish National Research Council7, University of Vienna8, University of São Paulo9, European Space Agency10, University of Liège11, Austrian Academy of Sciences12, Tel Aviv University13, University of Cologne14, Technical University of Berlin15
TL;DR: In this article, an intensive observational campaign carried out with HARPS at the 3.6 m telescope at La Silla on the star CoRoT-7 was reported, where several approaches were used to extract the radial velocity signal of the planet(s) from the stellar activity signal.
Abstract: We report on an intensive observational campaign carried out with HARPS at the 3.6 m telescope at La Silla on the star CoRoT-7. Additional simultaneous photometric measurements carried out with the Euler Swiss telescope have demonstrated that the observed radial velocity variations are dominated by rotational modulation from cool spots on the stellar surface. Several approaches were used to extract the radial velocity signal of the planet(s) from the stellar activity signal. First, a simple pre-whitening procedure was employed to find and subsequently remove periodic signals from the complex frequency structure of the radial velocity data. The dominant frequency in the power spectrum was found at 23 days, which corresponds to the rotation period of CoRoT-7. The 0.8535 day period of CoRoT-7b planetary candidate was detected with an amplitude of 3.3 m s −1 . Most other frequencies, some with amplitudes larger than the CoRoT-7b signal, are most likely associated with activity. A second approach used harmonic decomposition of the rotational period and up to the first three harmonics to filter out the activity signal from radial velocity variations caused by orbiting planets. After correcting the radial velocity data for activity, two periodic signals are detected: the CoRoT-7b transit period and a second one with a period of 3.69 days and an amplitude of 4 m s −1 . This second signal was also found in the pre-whitening analysis. We attribute the second signal to a second, more remote planet CoRoT-7c . The orbital solution of both planets is compatible with circular orbits. The mass of CoRoT-7b is 4.8 ± 0. 8( M⊕) and that of CoRoT-7c is 8.4 ± 0. 9( M⊕), assuming both planets are on coplanar orbits. We also investigated the false positive scenario of a blend by a faint stellar binary, and this may be rejected by the stability of the bisector on a nightly scale. According to their masses both planets belong to the super-Earth planet category. The average density of CoRoT-7b is ρ = 5.6 ± 1. 3gc m −3 , similar to the Earth. The CoRoT-7 planetary system provides us with the first insight into the physical nature of short period super-Earth planets recently detected by radial velocity surveys. These planets may be denser than Neptune and therefore likely made of rocks like the Earth, or a mix of water ice and rocks.
437 citations
TL;DR: The planet has an equilibrium temperature of T eq = 2516 K caused by its very short period orbit around the hot, twelfth magnitude host star and has the largest radius of any transiting planet yet detected.
Abstract: We report on the discovery of WASP-12b, a new transiting extrasolar planet with R pl = 1.79+0.09 –0.09 RJ and M pl = 1.41+0.10 –0.10 M J. The planet and host star properties were derived from a Monte Carlo Markov Chain analysis of the transit photometry and radial velocity data. Furthermore, by comparing the stellar spectrum with theoretical spectra and stellar evolution models, we determined that the host star is a supersolar metallicity ([M/H] = 0.3+0.05 –0.15), late-F (T eff = 6300+200 –100 K) star which is evolving off the zero-age main sequence. The planet has an equilibrium temperature of T eq = 2516 K caused by its very short period orbit (P = 1.09 days) around the hot, twelfth magnitude host star. WASP-12b has the largest radius of any transiting planet yet detected. It is also the most heavily irradiated and the shortest period planet in the literature.
373 citations
TL;DR: In this article, a planetary system with three super-Earths orbiting a K2 V metal-deficient star at a distance of only 13 parsec was detected by the HARPS GTO high-precision planet search.
Abstract: Received ; accepted To be inserted later Abstract. This paper reports on the detection of a planetary system with three Super-Earths orbiting HD 40307. HD 40307 is a K2 V metal-deficient star at a distance of only 13 parsec, part of the HARPS GTO high-precision planet-search programme. The three planets on circular orbits have very low minimum masses of respectively 4.2, 6.9 and 9.2 Earth masses and periods of 4.3, 9.6 and 20.5 days. The planet with the shortest period is the lightest planet detected to-date orbiting a main sequence star. The detection of the correspondingly low amplitudes of the induced radial-velocity variations is completely secured by the 135 very high-quality HARPS observations illustrated by the radial-velocity residuals around the 3-Keplerian solution of only 0.85 ms 1 . Activity and bisector indicators exclude any significant perturbations of stellar intrinsic origin, which supports the planetary interpretation. Contrary to most planet-host stars, HD 40307 has a marked sub-solar metallicity ((Fe/H) = 0.31), further supporting the already raised possibility that the occurrence of very light planets might show a di erent dependence on host star's metallicity compared to the population of gas giant planets. In addition to the 3 planets close to the central star, a small drift of the radial-velocity residuals reveals the presence of another companion in the system the nature of which is still unknown.
338 citations
TL;DR: In this paper, a substellar companion or a massive Jupiter was discovered orbiting the G5V star HD 16760 using the spectrograph SOPHIE installed on the OHP 1.93m telescope.
Abstract: We report on the discovery of a substellar companion or a massive Jupiter orbiting the G5V star HD 16760 using the spectrograph SOPHIE installed on the OHP 1.93-m telescope. Characteristics and performances of the spectrograph are presented, as well as the SOPHIE exoplanet consortium program. With a minimum mass of 14.3 MJup, an orbital period of 465 days and an eccentricity of 0.067, HD 16760b seems to be located just at the end of the mass distribution of giant planets, close to the planet/brown-dwarf transition. Its quite circular orbit supports a formation in a gaseous protoplanetary disk.
232 citations
TL;DR: In this article, the authors used the high-resolution spectograph SOPHIE mounted on the 1.93m telescope at the Observatoire de Haute-Provence to obtain 55 spectra of HD 189733 over nearly two months, and compared the variability in spectroscopic activity indices with the evolution in the radial-velocity residuals and the shape of spectral lines.
Abstract: Aims. Extra-solar planet search programs require high-precision velocity measurements. They need to determine how to differentiate between radial-velocity variations due to Doppler motion and the noise induced by stellar activity. Methods. We monitored the active K2V star HD 189733 and its transiting planetary companion, which has a 2.2-day orbital period. We used the high-resolution spectograph SOPHIE mounted on the 1.93-m telescope at the Observatoire de Haute-Provence to obtain 55 spectra of HD 189733 over nearly two months. We refined the HD 189733b orbit parameters and placed limits on both the eccentricity and long-term velocity gradient. After subtracting the orbital motion of the planet, we compared the variability in spectroscopic activity indices with the evolution in the radial-velocity residuals and the shape of spectral lines. Results. The radial velocity, the spectral-line profile, and the acti vity indices measured in He I (5875.62 A), Hα (6562.81 A), and both of the Ca II H&K lines (3968.47 A and 3933.66 A, respectively) exhibit a periodicity close to the stellar-rotation pe riod and the correlations between them are consistent with a spotted stellar surface in rotation. We used these correlations to corr ect for the radialvelocity jitter due to stellar activity. This results in ach ieving high precision in measuring the orbital parameters, with a semi-amplitude ◦ .
230 citations
TL;DR: In this article, a combined Markov-chain Monte-Carlo analysis of spectroscopic and photometric data on these stars was applied to determine a full set of system parameters including the projected spin-orbit misalignment angle of HD 189733b to an unprecedented precision via the Rossiter-McLaughlin effect.
Abstract: We present radial-velocity sequences acquired during three transits of the exoplanet HD 189733b and one transit of CoRoT-3b. We applied a combined Markov-chain Monte-Carlo analysis of spectroscopic and photometric data on these stars, to determine a full set of system parameters including the projected spin-orbit misalignment angle of HD 189733b to an unprecedented precision via the Rossiter-McLaughlin effect: β = 0.85 ◦ +0.32 −0.28 . This small but non-zero inclination of the planetary orbit is important to understand the origin of the system. On CoRoT-3b, results seem to point towards a non-zero inclination as well with β = 37.6 ◦ +10.0 −22.3 , but this remains marginal. Systematic effects due to non-Gaussian cross-correlation functions appear to be the main cause of significant residuals that prevent an accurate determination of the projected stellar rotation velocity V sin(I) for both stars.
191 citations
TL;DR: In this article, a combined Markov-Chain Monte Carlo analysis of spectroscopic and photometric data on these stars was applied to determine a full set of system parameters including the project spin-orbit misalignement angle of HD 189733b to an unprecedented precision via the Rossiter-McLaughlin effect.
Abstract: We present radial-velocity sequences acquired during three transits of the exoplanet HD 189733b and one transit of the CoRoT-3b. We applied a combined Markov-Chain Monte Carlo analysis of spectroscopic and photometric data on these stars, to determine a full set of system parameters including the project spin-orbit misalignement angle of HD 189733b to an unprecedented precision via the Rossiter-McLaughlin effect: beta = 0.85 degrees (+0.32 -0.28) . This small but non-zero inclination of the planetary orbit is important to understand the origin of the system. On CoRoT-3b, results seem to point towards a non-zero inclination as well with beta = 37.6 degrees (+10.0 -22.3), but this remains marginal. Systematic effects due to non-gaussian cross-correlation functions appear to be the main cause of significant residuals that prevent an accurate determination of the projected stellar rotation velocity V sin(I) for both stars.
179 citations
TL;DR: In this paper, the authors reported the detection of the primary transit of the extra-solar planet HD(80 606 b, thanks to photometric and spectroscopic observations performed at the Observatoire de Haute-Provence, simultaneously with the CCD camera at the 120-cm telescope and the SOPHIE ǫ-spectrograph on the 193cm telescope.
Abstract: We report the detection of the primary transit of the extra-solar planet HD 80 606 b, thanks to photometric and spectroscopic observations performed at the Observatoire de Haute-Provence, simultaneously with the CCD camera at the 120-cm telescope and the SOPHIE spectrograph on the 193-cm telescope. We observed the whole egress of the transit and partially its central part, in both datasets with the same timings. The ingress occurred before sunset so was not observed. The full duration of the transit was between 9.5 and 17.2 h. The data allows the planetary radius to be measured ($R_{\mathrm{p}} = 0.9 \pm 0.10\,{R}_{\rm Jup}$) and other parameters of the system to be refined. Radial velocity measurements show the detection of a prograde Rossiter-McLaughlin effect, and provide a hint of a spin-orbit misalignment. If confirmed, this misalignment would corroborate the hypothesis that HD 80 606 b owes its unusual orbital configuration to Kozai migration. HD 80 606 b is by far the transiting planet on the longest period detected today. Its unusually small radius reinforces the observed relationship between the planet radius and the incident flux received from the star and opens new questions for theory. Orbiting a bright star ($V=9$), it opens opportunities for numerous follow-up studies.
TL;DR: In this paper, the authors reported measurements of the thermal emission of the young and massive planet CoRoT-2b at 4.5 and 8 microns with the Spitzer Infrared Array Camera (IRAC).
Abstract: We report measurements of the thermal emission of the young and massive planet CoRoT-2b at 4.5 and 8 microns with the Spitzer Infrared Array Camera (IRAC). Our measured occultation depths are 0.510 +- 0.042 % and 0.41 +- 0.11 % at 4.5 and 8 microns, respectively. In addition to the CoRoT optical measurements, these planet/star flux ratios indicate a poor heat distribution to the night side of the planet and are in better agreement with an atmosphere free of temperature inversion layer. Still, the presence of such an inversion is not definitely ruled out by the observations and a larger wavelength coverage is required to remove the current ambiguity. Our global analysis of CoRoT, Spitzer and ground-based data confirms the large mass and size of the planet with slightly revised values (Mp = 3.47 +- 0.22 Mjup, Rp = 1.466 +- 0.044 Rjup). We find a small but significant offset in the timing of the occultation when compared to a purely circular orbital solution, leading to e cos(omega) = -0.00291 +- 0.00063 where e is the orbital eccentricity and omega is the argument of periastron. Constraining the age of the system to be at most of a few hundreds of Myr and assuming that the non-zero orbital eccentricity is not due to a third undetected body, we model the coupled orbital-tidal evolution of the system with various tidal Q values, core sizes and initial orbital parameters. For log(Q_s') = 5 - 6, our modelling is able to explain the large radius of CoRoT-2b if log(Q_p') <= 5.5 through a transient tidal circularization and corresponding planet tidal heating event. Under this model, the planet will reach its Roche limit within 20 Myr at most.
TL;DR: In this paper, the authors reported the detection of the primary transit of the extra-solar planet HD 80606 b, thanks to photometric and spectroscopic observations performed at Observatoire de Haute-Provence, simultaneously with the CCD camera at the 120 cm telescope and the SOPHIE spectrograph at the 193 cm telescope.
Abstract: We report the detection of the primary transit of the extra-solar planet HD 80606 b, thanks to photometric and spectroscopic observations performed at Observatoire de Haute-Provence, simultaneously with the CCD camera at the 120-cm telescope and the SOPHIE spectrograph at the 193-cm telescope. We observed the whole egress of the transit and partially its central part, in both data sets with the same timings. The ingress occurred before sunset and was not observed. The full duration of the transit was between 9.5 and 17.2 hours. The data allows the planetary radius to be measured (Rp = 0.9 +- 0.1 RJup) and other parameters of the system to be refined. Radial velocity measurements show the detection of a prograde Rossiter-McLaughlin effect, and provide a hint for a spin-orbit misalignment. If confirmed, this misalignment would corroborate the hypothesis that HD 80606 b owes its unusual orbital configuration to Kozai migration. HD 80606 b is by far the transiting planet on the longest period detected today. Its unusually small radius reinforces the observed relationship between the planet radius and the incident flux received from the star and opens new questions for theory. Orbiting a quite bright star (V=9), it opens opportunities to numerous follow-up studies.
TL;DR: In this paper, the authors reported the photometric and spectroscopic detection of the primary transit of the 111-day-period, eccentric extra-solar planet HD 80606b, at Observatoire de Haute-Provence, France.
Abstract: We recently reported the photometric and spectroscopic detection of the primary transit of the 111-day-period, eccentric extra-solar planet HD 80606b, at Observatoire de Haute-Provence, France. The whole egress of the primary transit and a section of its central part were observed, allowing the measurement of the planetary radius, and evidence for a spin-orbit misalignment through the observation of the Rossiter-McLaughlin anomaly. The ingress not having been observed for this long-duration transit, uncertainties remained in the parameters of the system. We present here a refined, combined analysis of our photometric and spectroscopic data, together with further published radial velocities, ground-based photometry, and Spitzer photometry around the secondary eclipse, as well as new photometric measurements of HD 80606 acquired at Mount Hopkins, Arizona, just before the beginning of the primary transit. Although the transit is not detected in those new data, they provide an upper limit for the transit duration, which narrows down the possible behaviour of the Rossiter-McLaughlin anomaly in the unobserved part of the transit. We analyse the whole data with a Bayesian approach using a Markov-chain Monte Carlo integration on all available information. We find Rp = 0.98 ± 0.03RJup for the planetary radius, and a total primary transit duration of 11.9 ± 1.3 h from first to fourth contact. Our analysis reinforces the hypothesis of spin-orbit misalignment in this system (alignment excluded at >95% level), with a positive projected angle between the planetary orbital axis and the stellar rotation (median solution λ ∼ 50 ◦ ). As HD 80606 is a component of a binary system, the peculiar orbit of its planet could result from a Kozai mechanism.
TL;DR: The ground-based photometric follow-up of transit detections by the CoRoT space mission has been studied in this paper, where the authors present the motivation, techniques and performance of the ground-to-ground photometrically followup of transits.
Abstract: The motivation, techniques and performance of the ground-based photometric follow-up of transit detections by the CoRoT space mission are presented. Its principal raison d’etre arises from the much higher spatial resolution of common ground-based telescopes in comparison to CoRoT’s cameras. This allows the identification of many transit candidates as arising from eclipsing binaries that are contaminating CoRoT’s lightcurves, even in low-amplitude transit events that cannot be detected with ground-based obervations. For the ground observations, “on” – “off” photometry is now largely employed, in which only a short timeseries during a transit and a section outside a transit is observed and compared photometrically. CoRoTplanet candidates’ transits are being observed by a dedicated team with access to telescopes with sizes ranging from 0.2 to 2 m. As an example, the process that led to the rejection of contaminating eclipsing binaries near the host star of the Super-Earth planet CoRoT-7b is shown. Experiences and techniques from this work may also be useful for other transit-detection experiments, when the discovery instrument obtains data with a relatively low angular resolution.
TL;DR: Moutou et al. as mentioned in this paper reported the photometric and spectroscopic detection of the primary transit of the 111-day-period, eccentric extra-solar planet HD80606 b, at Observatoire de Haute-Provence, France.
Abstract: We recently reported the photometric and spectroscopic detection of the primary transit of the 111-day-period, eccentric extra-solar planet HD80606 b, at Observatoire de Haute-Provence, France (Moutou et al. 2009). The whole egress of the primary transit and a section of its central part were observed, allowing the measurement of the planetary radius, and evidence for a spin-orbit misalignment through the observation of the Rossiter-McLaughlin anomaly. The ingress having not been observed for this long-duration transit, uncertainties remained in the parameters of the system. We present here a refined, combined analysis of our photometric and spectroscopic data, together with further published radial velocities, ground-based photometry, and Spitzer photometry around the secondary eclipse, as well as new photometric measurements of HD 80606 acquired at Mount Hopkins, Arizona, just before the beginning of the primary transit. Although the transit is not detected in those new data, they provide an upper limit for the transit duration, which narrows down the possible behaviour of the Rossiter-McLaughlin anomaly in the unobserved part of the transit. We analyse the whole data with a Bayesian approach using a Markov-chain Monte Carlo integration on all available information. We find R_p = 0.98 +- 0.03 R_Jup for the planetary radius, and a total primary transit duration of 11.9 +- 1.3 hours from first to fourth contact. Our analysis reinforces the hypothesis of spin-orbit misalignment in this system (alignment excluded at >95 % level), with a positive projected angle between the planetary orbital axis and the stellar rotation (median solution lambda ~ 50 degrees). As HD80606 is a component of a binary system, the peculiar orbit of its planet could result from a Kozai mechanism.
TL;DR: In this article, the HARPS spectrograph revealed the presence of two extra-solar planets orbiting the star HD 45364, and a dynamical analysis of the system further showed a 3:2 mean motion resonance between the two planets.
Abstract: Precise radial-velocity measurements with the HARPS spectrograph reveal the presence of two planets orbiting the solar-type star HD 45364. The companion masses are M sini = 0.187 MJup and 0.658 MJup, with semi-major axes of a = 0.681 AU and 0.897 AU, and eccentricities of e = 0.168 and 0.097, respectively. A dynamical analysis of the system further shows a 3:2 mean motion resonance between the two planets, which prevents close encounters and ensures the stability of the system over 5 Gyr. This is the first time that such a resonant configuration has been observed for extra-solar planets, although there is an analogue in our Solar System formed by Neptune and Pluto. This singular planetary system may provide important constraints on planetary formation and migration scenarios.
Queen's University1, California State University, Northridge2, Las Cumbres Observatory Global Telescope Network3, University of St Andrews4, Open University5, Keele University6, Institut d'Astrophysique de Paris7, Harvard University8, California Institute of Technology9, University of Geneva10, University of Exeter11, University of Leicester12, University of Warwick13
TL;DR: In this paper, the authors reported the discovery of WASP-10b, a new transiting extrasolar planet (ESP) discovered by the WASP Consortium and confirmed using Not FIES and SOPHIE radial velocity data.
Abstract: We report the discovery of WASP-10b, a new transiting extrasolar planet (ESP) discovered by the WASP Consortium and confirmed using NOT FIES and SOPHIE radial velocity data. A 3.09 day period, 29 mmag transit depth, and 2.36 hour duration are derived for WASP-10b using WASP and high precision photometric observations. Simultaneous fitting to the photometric and radial velocity data using a Markov-chain Monte Carlo procedure leads to a planet radius of 1.28RJ, a mass of 2.96MJ and eccentricity of �0.06. WASP-10b is one of the more massive transiting ESPs, and we compare its characteristics to the current sample of transiting ESP, where there is currently little information for masses greater than �2MJ and non-zero eccentricities. WASP-10’s host star, GSC 2752-00114 (USNO-B1.0 1214-0586164) is among the fainter stars in the WASP sample, with V=12.7 and a spectral type of K5. This result shows promise for future late-type dwarf star surveys.
TL;DR: In this article, the HARPS spectrograph revealed the presence of two extra-solar planets orbiting the solar-type star HD45364, with semi-major axes of 0.681 AU and 0.897 AU, respectively.
Abstract: Precise radial-velocity measurements with the HARPS spectrograph reveal the presence of two planets orbiting the solar-type star HD45364. The companion masses are 0.187 Mjup and 0.658 Mjup, with semi-major axes of 0.681 AU and 0.897 AU, and eccentricities of 0.168 and 0.097, respectively. A dynamical analysis of the system further shows a 3:2 mean motion resonance between the two planets, which prevents close encounters and ensures the stability of the system over 5 Gyr. This is the first time that such a resonant configuration has been observed for extra-solar planets, although there is an analogue in our Solar System formed by Neptune and Pluto. This singular planetary system may provide important constraints on planetary formation and migration scenarios.
University of Geneva1, University of Exeter2, Janssen Pharmaceutica3, University of Paris-Sud4, Spanish National Research Council5, University of Vienna6, European Space Agency7, Centre national de la recherche scientifique8, Austrian Academy of Sciences9, University of Liège10, Tel Aviv University11, University of Cologne12, Technical University of Berlin13
TL;DR: In this article, the authors used two different filtering approaches, and several methods to evaluate the significance of a detection of the secondary eclipse in the CoRoT white channel data, whose response function goes from ∼400 to ∼1000 nm.
Abstract: The transiting planet CoRoT-1b is thought to belong to the pM-class of planets, in which the thermal emission dominates in the optical wavelengths. We present a detection of its secondary eclipse in the CoRoT white channel data, whose response function goes from ∼400 to ∼1000 nm. We used two different filtering approaches, and several methods to evaluate the significance of a detection of the secondary eclipse. We detect a secondary eclipse centered within 20 min at the expected times for a circular orbit, with a depth of 0.016 ± 0.006%. The center of the eclipse is translated in a1 -σ upper limit to the planet’s eccentricity of e cos ω< 0.014. Under the assumption of a zero Bond Albedo and blackbody emission from the planet, it corresponds to a TCoRoT = 2330 +120 −140 K. We provide the equilibrium temperatures of the planet as a function of the amount of reflected light. If the planet is in thermal equilibrium with the incident flux from the star, our results imply an inefficient transport mechanism of the flux from the day to the night sides.
Technical University of Berlin1, University of Geneva2, Centre national de la recherche scientifique3, University of Exeter4, Spanish National Research Council5, Janssen Pharmaceutica6, University of Paris7, Institut d'Astrophysique de Paris8, University of Sydney9, University of Cologne10, European Space Agency11, University of Vienna12, University of Liège13, Austrian Academy of Sciences14, Tel Aviv University15
TL;DR: In this paper, the CoRoT-5b was detected during observations of the LRa01 field, the first long-duration field in the galactic anticenter direction, and the phase folded lightcurve was used to fit the transit signal and derive the main planetary parameters.
Abstract: Aims. The CoRoT space mission continues to photometrically monitor about 12 000 stars in its field-of-view for a series of target fields to search for transiting extrasolar planets ever since 2007. Deep transit signals can be detected quickly in the “alarm-mode” in parallel to the ongoing target field monitoring. CoRoT’s first planets have been detected in this mode. Methods. The CoRoT raw lightcurves are filtered for orbital residuals, outliers, and low-frequency stellar signals. The phase folded lightcurve is used to fit the transit signal and derive the main planetary parameters. Radial velocity follow-up observations were initiated to secure the detection and to derive the planet mass. Results. We report the detection of CoRoT-5b, detected during observations of the LRa01 field, the first long-duration field in the galactic anticenter direction. CoRoT-5b is a “hot Jupiter-type” planet with a radius of 1.388 +0.046 −0.047 RJup ,am ass of 0.467
TL;DR: In this paper, the photometric precision of stellar light curves obtained by the CoRoT satellite in its planet finding channel, with a particular emphasis on the timescales characteristic of planetary transits, was studied.
Abstract: In this short paper, we study the photometric precision of stellar light curves obtained by the CoRoT satellite in its planet finding channel, with a particular emphasis on the timescales characteristic of planetary transits Together with other articles in the same issue of this journal, it forms an attempt to provide the building blocks for a statistical interpretation of the CoRoT planet and eclipsing binary catch to date
After pre-processing the light curves so as to minimise long-term variations and outliers, we measure the scatter of the light curves in the first three CoRoT runs lasting more than 1 month, using an iterative non-linear filter to isolate signal on the timescales of interest The bevhaiour of the noise on 2h timescales is well-described a power-law with index 025 in R-magnitude, ranging from 01mmag at R=115 to 1mmag at R=16, which is close to the pre-launch specification, though still a factor 2-3 above the photon noise due to residual jitter noise and hot pixel events There is evidence for a slight degradation of the performance over time We find clear evidence for enhanced variability on hours timescales (at the level of 05 mmag) in stars identified as likely giants from their R-magnitude and B-V colour, which represent approximately 60 and 20% of the observed population in the direction of Aquila and Monoceros respectively On the other hand, median correlated noise levels over 2h for dwarf stars are extremely low, reaching 005mmag at the bright end
TL;DR: In this article, the authors used HARPS to measure oscillations in the low-mass star τ Cet. Although the data were compromised by instrumental noise, they were able to extract the main features of the oscillations.
Abstract: We used HARPS to measure oscillations in the low-mass star τ Cet. Although the data were compromised by instrumental noise, we have been able to extract the main features of the oscillations. We found τ Cet to oscillate with an amplitude that is about half that of the Sun, and with a mode lifetime that is slightly shorter than solar. The large frequency separation is 169 μHz, and we have identified modes with degrees 0, 1, 2, and 3. We used the frequencies to estimate the mean density of the star to an accuracy of 0.45% which, combined with the interferometric radius, gives a mass of 0.783 ± 0.012 M� (1.6%).
TL;DR: In this article, the discovery of six new substellar companions of main-sequence stars, detected by multiple Doppler measurements with the instrument HARPS installed on the ESO 3.6m telescope, La Silla, Chile, was reported.
Abstract: We report the discovery of six new substellar companions of main-sequence stars, detected by multiple Doppler measurements with the instrument HARPS installed on the ESO 3.6 m telescope, La Silla, Chile. These extrasolar planets orbit the stars BD -17 0063, HD 20868, HD 73267, HD 131664, HD 145377, and HD 153950. The orbital characteristics that reproduce the observed data are presented, as well as the stellar and planetary parameters. Masses of the companions range from 2 to 18 Jupiter masses, and periods range from 100 to 2000 days. The observational data are carefully analysed for activity-induced effects, and we conclude that the observed radial velocity variations are of exoplanetary origin. Of particular interest is the very massive planet (or brown-dwarf companion) orbiting the metal-rich HD 131664 with m 2 sin i = 18.15 M Jup and a 5.34-year orbital period. These new discoveries are consistent with the observed statistical properties of exoplanet samples known so far.
TL;DR: In this article, the CoRoT-5b was detected during observations of the LRa01 field, the first long-duration field in the galactic anticenter direction, and a phase folded lightcurve was used to fit the transit signal and derive the main planetary parameters.
Abstract: Aims. The CoRoT space mission continues to photometrically monitor about 12 000 stars in its field-of-view for a series of target fields to search for transiting extrasolar planets ever since 2007. Deep transit signals can be detected quickly in the "alarm-mode" in parallel to the ongoing target field monitoring. CoRoT's first planets have been detected in this mode. Methods. The CoRoT raw lightcurves are filtered for orbital residuals, outliers, and low-frequency stellar signals. The phase folded lightcurve is used to fit the transit signal and derive the main planetary parameters. Radial velocity follow-up observations were initiated to secure the detection and to derive the planet mass. Results. We report the detection of CoRoT-5b, detected during observations of the LRa01 field, the first long-duration field in the galactic anticenter direction. CoRoT-5b is a "hot Jupiter-type" planet with a radius of 1.388(+0.046, -0.047) R_Jup, a mass of 0.467(+0.047, -0.024) M_Jup, and therefore, a mean density of 0.217(+0.031, -0.025) g cm-3. The planet orbits an F9V star of 14.0 mag in 4.0378962 +/- 0.0000019 days at an orbital distance of 0.04947(+0.00026,
-0.00029) AU.
Spanish National Research Council1, University of Exeter2, Centre national de la recherche scientifique3, Paris Diderot University4, University of Paris-Sud5, University of Sydney6, Janssen Pharmaceutica7, University of Cologne8, European Space Agency9, University of Vienna10, University of Geneva11, University of Liège12, Institut d'Astrophysique de Paris13, Austrian Academy of Sciences14, Tel Aviv University15, Technical University of Berlin16, University of La Laguna17, Lille University of Science and Technology18, Institut de mécanique céleste et de calcul des éphémérides19
TL;DR: In this article, the authors evaluated the rates and nature of false positives in the CoRoT exoplanets search and compared their results with semi-empirical predictions, and classified the results of the follow-up observations completed to verify their planetary nature.
Abstract: 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.
TL;DR: In this article, the authors used two different filtering approaches, and several methods to evaluate the significance of a detection of the secondary eclipse in the CoRoT white channel data, whose response function goes from ~400 to ~1000 nm.
Abstract: The transiting planet CoRoT-1b is thought to belong to the pM-class of planets, in which the thermal emission dominates in the optical wavelengths. We present a detection of its secondary eclipse in the CoRoT white channel data, whose response function goes from ~400 to ~1000 nm. We used two different filtering approaches, and several methods to evaluate the significance of a detection of the secondary eclipse. We detect a secondary eclipse centered within 20 min at the expected times for a circular orbit, with a depth of 0.016+/-0.006%. The center of the eclipse is translated in a 1-sigma upper limit to the planet's eccentricity of ecosomega<0.014. Under the assumption of a zero Bond Albedo and blackbody emission from the planet, it corresponds to a T_{CoRoT}=2330 +120-140 K. We provide the equilibrium temperatures of the planet as a function of the amount of reflected light. If the planet is in thermal equilibrium with the incident flux from the star, our results imply an inefficient transport mechanism of the flux from the day to the night sides.
TL;DR: In this paper, the photometric precision of stellar light curves obtained by the CoRoT satellite in its planet-finding channel, with a particular emphasis on the time scales characteristic of planetary transits, was studied.
Abstract: In this short paper, we study the photometric precision of stellar light curves obtained by the CoRoT satellite in its planet-finding channel, with a particular emphasis on the time scales characteristic of planetary transits. Together with other articles in the same issue of this journal, it forms an attempt to provide the building blocks for a statistical interpretation of the CoRoT planet and eclipsing binary catch to date. After pre-processing the light curves so as to minimise long-term variations and outliers, we measure the scatter of the light curves in the first three CoRoT runs lasting more than 1 month, using an iterative non-linear filter to isolate signal on the time scales of interest. The behaviour of the noise on 2 h time scales is described well by a power-law with index 0.25 in R-magnitude, ranging from 0.1 mmag at R = 11. 5t o 1m mag atR = 16, which is close to the pre-launch specification, though still a factor 2−3 above the photon noise due to residual jitter noise and hot pixel events. There is evidence of slight degradation in the performance over time. We find clear evidence of enhanced variability on hour time scales (at the level of 0.5 mmag) in stars identified as likely giants from their R magnitude and B − V colour, which represent approximately 60 and 20% of the observed population in the directions of Aquila and Monoceros, respectively. On the other hand, median correlated noise levels over 2 h for dwarf stars are extremely low, reaching 0.05 mmag at the bright end.
TL;DR: In this paper, the SOPHIE spectrograph installed on the 1.93m telescope of the Observatoire de Haute Provence (OHP) was used for high-precision radial velocity measurements.
Abstract: Charge Transfer Inefficiency (CTI) is a well known effect of charge-coupled devices (CCD). The charge transfer from one pixel to the next is not perfect and is quantified by the fraction of charge successfully moved (clocked) between adjacent pixels. The amplitude of this effect depends on the signal level inside the pixel. In the context of high-precision radial velocity measurements using cross-dispersed echelle spectrograph, this CTI effect on a CCD recording spectral orders may introduce associated spectral lines shifts. Indeed if the signal level recorded on the spectra is changing, the CTI amplitude will change affecting the associated centroid of all spectral lines. Such effect may introduced radial velocity shifts of several m s-1 . We describe here CTI effect which is affecting the SOPHIE spectrograph installed on the 1.93-m telescope of Observatoire de Haute Provence (OHP). We calibrated the effect thanks to the Thorium-Argon lines and we applied a software correction on the spectra in order to assess the charge lost during the readout process on all pixels.
University of Cologne1, European Space Research and Technology Centre2, Paris Diderot University3, German Aerospace Center4, University of La Laguna5, Spanish National Research Council6, Austrian Academy of Sciences7, University of Oxford8, University of Geneva9, University of Exeter10, University of Provence11, Janssen Pharmaceutica12, University of Paris13, Institut d'Astrophysique de Paris14, University of Texas at Austin15, University of Göttingen16, University of Vienna17, University of São Paulo18, University of Nice Sophia Antipolis19, University of Liège20, European Southern Observatory21, Tel Aviv University22, Pontifical Catholic University of Chile23, Technical University of Berlin24, Institut de mécanique céleste et de calcul des éphémérides25, Lille University of Science and Technology26, Las Cumbres Observatory Global Telescope Network27
TL;DR: In this paper, the authors presented 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.
Abstract: 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.