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 References of "Santos, N. C"      in Complete repository Arts & humanities   Archaeology   Art & art history   Classical & oriental studies   History   Languages & linguistics   Literature   Performing arts   Philosophy & ethics   Religion & theology   Multidisciplinary, general & others Business & economic sciences   Accounting & auditing   Production, distribution & supply chain management   Finance   General management & organizational theory   Human resources management   Management information systems   Marketing   Strategy & innovation   Quantitative methods in economics & management   General economics & history of economic thought   International economics   Macroeconomics & monetary economics   Microeconomics   Economic systems & public economics   Social economics   Special economic topics (health, labor, transportation…)   Multidisciplinary, general & others Engineering, computing & technology   Aerospace & aeronautics engineering   Architecture   Chemical engineering   Civil engineering   Computer science   Electrical & electronics engineering   Energy   Geological, petroleum & mining engineering   Materials science & engineering   Mechanical engineering   Multidisciplinary, general & others Human health sciences   Alternative medicine   Anesthesia & intensive care   Cardiovascular & respiratory systems   Dentistry & oral medicine   Dermatology   Endocrinology, metabolism & nutrition   Forensic medicine   Gastroenterology & hepatology   General & internal medicine   Geriatrics   Hematology   Immunology & infectious disease   Laboratory medicine & medical technology   Neurology   Oncology   Ophthalmology   Orthopedics, rehabilitation & sports medicine   Otolaryngology   Pediatrics   Pharmacy, pharmacology & toxicology   Psychiatry   Public health, health care sciences & services   Radiology, nuclear medicine & imaging   Reproductive medicine (gynecology, andrology, obstetrics)   Rheumatology   Surgery   Urology & nephrology   Multidisciplinary, general & others Law, criminology & political science   Civil law   Criminal law & procedure   Criminology   Economic & commercial law   European & international law   Judicial law   Metalaw, Roman law, history of law & comparative law   Political science, public administration & international relations   Public law   Social law   Tax law   Multidisciplinary, general & others Life sciences   Agriculture & agronomy   Anatomy (cytology, histology, embryology...) & physiology   Animal production & animal husbandry   Aquatic sciences & oceanology   Biochemistry, biophysics & molecular biology   Biotechnology   Entomology & pest control   Environmental sciences & ecology   Food science   Genetics & genetic processes   Microbiology   Phytobiology (plant sciences, forestry, mycology...)   Veterinary medicine & animal health   Zoology   Multidisciplinary, general & others Physical, chemical, mathematical & earth Sciences   Chemistry   Earth sciences & physical geography   Mathematics   Physics   Space science, astronomy & astrophysics   Multidisciplinary, general & others Social & behavioral sciences, psychology   Animal psychology, ethology & psychobiology   Anthropology   Communication & mass media   Education & instruction   Human geography & demography   Library & information sciences   Neurosciences & behavior   Regional & inter-regional studies   Social work & social policy   Sociology & social sciences   Social, industrial & organizational psychology   Theoretical & cognitive psychology   Treatment & clinical psychology   Multidisciplinary, general & others     Showing results 1 to 20 of 20 1 2 The HARPS search for southern extra-solar planets. XXXVI. Eight HARPS multi-planet systems hosting 20 super-Earth and Neptune-mass companionsUdry, S.; Dumusque, X.; Lovis, C. et alin ArXiv e-prints (2017), 1705We present radial-velocity measurement of eight stars observed with the HARPS Echelle spectrograph mounted on the 3.6-m telescope in La Silla (ESO, Chile). Data span more than ten years and highlight the ... [more ▼]We present radial-velocity measurement of eight stars observed with the HARPS Echelle spectrograph mounted on the 3.6-m telescope in La Silla (ESO, Chile). Data span more than ten years and highlight the long-term stability of the instrument. We search for potential planets orbiting HD20003, HD20781, HD21693, HD31527, HD45184, HD51608, HD134060 and HD136352 to increase the number of known planetary systems and thus better constrain exoplanet statistics. After a preliminary phase looking for signals using generalized Lomb-Scargle periodograms, we perform a careful analysis of all signals to separate \emph{bona-fide} planets from spurious signals induced by stellar activity and instrumental systematics. We finally secure the detection of all planets using the efficient MCMC available on the Data and Analysis Center for Exoplanets (DACE web-platform), using model comparison whenever necessary. In total, we report the detection of twenty new super-Earth to Neptune-mass planets, with minimum masses ranging from 2 to 30 M$_{\rm Earth}$, and periods ranging from 3 to 1300 days. By including CORALIE and HARPS measurements of HD20782 to the already published data, we also improve the characterization of the extremely eccentric Jupiter orbiting this host. [less ▲]Detailed reference viewed: 18 (1 ULiège) The HARPS search for southern extra-solar planets. XXXVI. Planetary systems and stellar activity of the M dwarfs GJ 3293, GJ 3341, and GJ 3543Astudillo-Defru, N.; Bonfils, X.; Delfosse, X. et alin Astronomy and Astrophysics (2015), 575Context. Planetary companions of a fixed mass induce reflex motions with a larger amplitude around lower-mass stars, which adds to making M dwarfs excellent targets for extra-solar planet searches. The ... [more ▼]Context. Planetary companions of a fixed mass induce reflex motions with a larger amplitude around lower-mass stars, which adds to making M dwarfs excellent targets for extra-solar planet searches. The most recent velocimeters with a stability of ~1 m s[SUP]-1[/SUP] can detect very low-mass planets out to the habitable zone of these stars. Low-mass small planets are abundant around M dwarfs, and most of the known potentially habitable planets orbit one of these cool stars.
Aims: Our M-dwarf radial velocity monitoring with HARPS on the ESO 3.6 m telescope at La Silla observatory makes a major contribution to this sample.
Methods: We present here dense radial velocity (RV) time series for three M dwarfs observed over ~five years: GJ 3293 (0.42 M[SUB]⊙[/SUB]), GJ 3341 (0.47 M[SUB]⊙[/SUB]), and GJ 3543 (0.45 M[SUB]⊙[/SUB]). We extracted these RVs through minimum χ[SUP]2[/SUP]-matching of each spectrum against a stack of all observed spectra for the same star that has a high signal-to-noise ratio. We then compared potential orbital signals against several stellar activity indicators to distinguish the Keplerian variations induced by planets from the spurious signals that result from rotational modulation of stellar surface inhomogeneities and from activity cycles.
Results: Two Neptune-mass planets - msin(i) = 1.4 ± 0.1 and 1.3 ± 0.1M[SUB]nept[/SUB] - orbit GJ 3293 with periods P = 30.60 ± 0.02 d and P = 123.98 ± 0.38 d, possibly together with a super-Earth - msin(i) ~ 7.9 ± 1.4 M[SUB]⊕[/SUB] - with period P = 48.14 ± 0.12d. A super-Earth - msin(i) ~ 6.1 M[SUB]⊕[/SUB] - orbits GJ 3341 with P = 14.207 ± 0.007d. The RV variations of GJ 3543, on the other hand, reflect its stellar activity rather than planetary signals. Based on observations made with the HARPS instrument on the ESO 3.6 m telescope under the program IDs 072.C-0488, 082.C-0718 and 183.C-0437 at Cerro La Silla (Chile).Tables A.1-A.3 (radial velocity data) are available in electronic form at http://www.aanda.org and at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/575/A119 [less ▲]Detailed reference viewed: 36 (0 ULiège) The Gaia-ESO Survey: The analysis of high-resolution UVES spectra of FGK-type starsSmiljanic, R.; Korn, A. J.; Bergemann, M. et alin Astronomy and Astrophysics (2014), 570Context. The ongoing Gaia-ESO Public Spectroscopic Survey is using FLAMES at the VLT to obtain high-quality medium-resolution Giraffe spectra for about 10[SUP]5[/SUP] stars and high-resolution UVES ... [more ▼]Context. The ongoing Gaia-ESO Public Spectroscopic Survey is using FLAMES at the VLT to obtain high-quality medium-resolution Giraffe spectra for about 10[SUP]5[/SUP] stars and high-resolution UVES spectra for about 5000 stars. With UVES, the Survey has already observed 1447 FGK-type stars.
Aims: These UVES spectra are analyzed in parallel by several state-of-the-art methodologies. Our aim is to present how these analyses were implemented, to discuss their results, and to describe how a final recommended parameter scale is defined. We also discuss the precision (method-to-method dispersion) and accuracy (biases with respect to the reference values) of the final parameters. These results are part of the Gaia-ESO second internal release and will be part of its first public release of advanced data products. Methods: The final parameter scale is tied to the scale defined by the Gaia benchmark stars, a set of stars with fundamental atmospheric parameters. In addition, a set of open and globular clusters is used to evaluate the physical soundness of the results. Each of the implemented methodologies is judged against the benchmark stars to define weights in three different regions of the parameter space. The final recommended results are the weighted medians of those from the individual methods. Results: The recommended results successfully reproduce the atmospheric parameters of the benchmark stars and the expected T[SUB]eff[/SUB]-log g relation of the calibrating clusters. Atmospheric parameters and abundances have been determined for 1301 FGK-type stars observed with UVES. The median of the method-to-method dispersion of the atmospheric parameters is 55 K for T[SUB]eff[/SUB], 0.13 dex for log g and 0.07 dex for [Fe/H]. Systematic biases are estimated to be between 50-100 K for T[SUB]eff[/SUB], 0.10-0.25 dex for log g and 0.05-0.10 dex for [Fe/H]. Abundances for 24 elements were derived: C, N, O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Mo, Ba, Nd, and Eu. The typical method-to-method dispersion of the abundances varies between 0.10 and 0.20 dex. Conclusions: The Gaia-ESO sample of high-resolution spectra of FGK-type stars will be among the largest of its kind analyzed in a homogeneous way. The extensive list of elemental abundances derived in these stars will enable significant advances in the areas of stellar evolution and Milky Way formation and evolution. Based on observations made with the ESO/VLT, at Paranal Observatory, under program 188.B-3002 (The Gaia-ESO Public Spectroscopic Survey, PIs Gilmore and Randich). Appendices are available in electronic form at http://www.aanda.org [less ▲]Detailed reference viewed: 14 (0 ULiège) The PLATO 2.0 MissionRauer, H.; Catala, C.; Aerts, C. et alin Experimental Astronomy (2014)PLATO 2.0 has recently been selected for ESA’s M3 launch opportunity (2022/24). Providing accurate key planet parameters (radius, mass, density and age) in statistical numbers, it addresses fundamental ... [more ▼]PLATO 2.0 has recently been selected for ESA’s M3 launch opportunity (2022/24). Providing accurate key planet parameters (radius, mass, density and age) in statistical numbers, it addresses fundamental questions such as: How do planetary systems form and evolve? Are there other systems with planets like ours, including potentially habitable planets? The PLATO 2.0 instrument consists of 34 small aperture telescopes (32 with 25 s readout cadence and 2 with 2.5 s candence) providing a wide field-of-view (2232 deg 2) and a large photometric magnitude range (4–16 mag). It focusses on bright (4–11 mag) stars in wide fields to detect and characterize planets down to Earth-size by photometric transits, whose masses can then be determined by ground-based radial-velocity follow-up measurements. Asteroseismology will be performed for these bright stars to obtain highly accurate stellar parameters, including masses and ages. The combination of bright targets and asteroseismology results in high accuracy for the bulk planet parameters: 2 %, 4–10 % and 10 % for planet radii, masses and ages, respectively. The planned baseline observing strategy includes two long pointings (2–3 years) to detect and bulk characterize planets reaching into the habitable zone (HZ) of solar-like stars and an additional step-and-stare phase to cover in total about 50 % of the sky. PLATO 2.0 will observe up to 1,000,000 stars and detect and characterize hundreds of small planets, and thousands of planets in the Neptune to gas giant regime out to the HZ. It will therefore provide the first large-scale catalogue of bulk characterized planets with accurate radii, masses, mean densities and ages. This catalogue will include terrestrial planets at intermediate orbital distances, where surface temperatures are moderate. Coverage of this parameter range with statistical numbers of bulk characterized planets is unique to PLATO 2.0. The PLATO 2.0 catalogue allows us to e.g.: - complete our knowledge of planet diversity for low-mass objects, - correlate the planet mean density-orbital distance distribution with predictions from planet formation theories,- constrain the influence of planet migration and scattering on the architecture of multiple systems, and - specify how planet and system parameters change with host star characteristics, such as type, metallicity and age. The catalogue will allow us to study planets and planetary systems at different evolutionary phases. It will further provide a census for small, low-mass planets. This will serve to identify objects which retained their primordial hydrogen atmosphere and in general the typical characteristics of planets in such low-mass, low-density range. Planets detected by PLATO 2.0 will orbit bright stars and many of them will be targets for future atmosphere spectroscopy exploring their atmosphere. Furthermore, the mission has the potential to detect exomoons, planetary rings, binary and Trojan planets. The planetary science possible with PLATO 2.0 is complemented by its impact on stellar and galactic science via asteroseismology as well as light curves of all kinds of variable stars, together with observations of stellar clusters of different ages. This will allow us to improve stellar models and study stellar activity. A large number of well-known ages from red giant stars will probe the structure and evolution of our Galaxy. Asteroseismic ages of bright stars for different phases of stellar evolution allow calibrating stellar age-rotation relationships. Together with the results of ESA’s Gaia mission, the results of PLATO 2.0 will provide a huge legacy to planetary, stellar and galactic science. [less ▲]Detailed reference viewed: 39 (13 ULiège) The HARPS search for southern extra-solar planets. XXXIV. A planetary system around the nearby M dwarf GJ163, with a super-Earth possibly in the habitable zoneBonfils, X.; Lo Curto, G.; Correia, A. C. M. et alE-print/Working paper (2013)The meter-per-second precision achieved by today velocimeters enables the search for 1-10 M_Earth planets in the habitable zone of cool stars. This paper reports on the detection of 3 planets orbiting ... [more ▼]The meter-per-second precision achieved by today velocimeters enables the search for 1-10 M_Earth planets in the habitable zone of cool stars. This paper reports on the detection of 3 planets orbiting GJ163 (HIP19394), a M3 dwarf monitored by our ESO/HARPS search for planets. We made use of the HARPS spectrograph to collect 150 radial velocities of GJ163 over a period of 8 years. We searched the RV time series for coherent signals and found 5 distinct periodic variabilities. We investigated the stellar activity and casted doubts on the planetary interpretation for 2 signals. Before more data can be acquired we concluded that at least 3 planets are orbiting GJ163. They have orbital periods of P_b=8.632+-0.002, P_c=25.63+-0.03 and P_d=604+-8 days and minimum masses msini = 10.6+-0.6, 6.8+-0.9, and 29+-3 M_Earth, respectively. We hold our interpretations for the 2 additional signals with periods P_(e)=19.4 and P_(f)=108 days. The inner pair presents an orbital period ratio of 2.97, but a dynamical analysis of the system shows that it lays outside the 3:1 mean motion resonance. GJ163c, in particular, is a super-Earth with an equilibrium temperature of T_eq = (302+-10) (1-A)^(1/4) K and may lie in the so called habitable zone for albedo values (A=0.34-0.89) moderately higher than that of Earth (A_Earth=0.2-0.3). [less ▲]Detailed reference viewed: 15 (0 ULiège) The CORALIE survey for southern extrasolar planets XVII. New and updated long period and massive planetsMarmier, M.; Ségransan, D.; Udry, S. et alin Astronomy and Astrophysics (2013), 551Context. Since 1998, a planet-search program around main sequence stars within 50 pc in the southern hemisphere has been carried out with the CORALIE echelle spectrograph at La Silla Observatory. Aims ... [more ▼]Context. Since 1998, a planet-search program around main sequence stars within 50 pc in the southern hemisphere has been carried out with the CORALIE echelle spectrograph at La Silla Observatory. Aims: With an observing time span of more than 14 years, the CORALIE survey is now able to unveil Jovian planets on Jupiter's period domain. This growing period-interval coverage is important for building formation and migration models since observational constraints are still weak for periods beyond the ice line. Methods: Long-term precise Doppler measurements with the CORALIE echelle spectrograph, together with a few additional observations made with the HARPS spectrograph on the ESO 3.6 m telescope, reveal radial velocity signatures of massive planetary companions on long-period orbits. Results: In this paper we present seven new planets orbiting HD 27631, HD 98649, HD 106515A, HD 166724, HD 196067, HD 219077, and HD 220689, together with the CORALIE orbital parameters for three already known planets around HD 10647, HD 30562, and HD 86226. The period range of the new planetary companions goes from 2200 to 5500 days and covers a mass domain between 1 and 10.5 MJup. Surprisingly, five of them present very high eccentricities above e > 0.57. A pumping scenario by Kozai mechanism may be invoked for HD 106515Ab and HD 196067b, which are both orbiting stars in multiple systems. Since the presence of a third massive body cannot be inferred from the data of HD 98649b, HD 166724b, and HD 219077b, the origin of the eccentricity of these systems remains unknown. Except for HD 10647b, no constraint on the upper mass of the planets is provided by Hipparcos astrometric data. Finally, the hosts of these long period planets show no metallicity excess. [less ▲]Detailed reference viewed: 16 (3 ULiège) The HARPS search for southern extra-solar planets: XXXI. The M-dwarf sampleBonfils, X.; Delfosse, X.; Udry, S. et alin Astronomy and Astrophysics (2013), 549(Abridged) Searching for planets around stars with different masses probes the outcome of planetary formation for different initial conditions. This drives observations of a sample of 102 southern nearby ... [more ▼](Abridged) Searching for planets around stars with different masses probes the outcome of planetary formation for different initial conditions. This drives observations of a sample of 102 southern nearby M dwarfs, using a fraction of our guaranteed time on the ESO/HARPS spectrograph (Feb. 11th, 2003 to Apr. 1st 2009). This paper makes available the sample's time series, presents their precision and variability. We apply systematic searches and diagnostics to discriminate whether the observed Doppler shifts are caused by stellar surface inhomogeneities or by the radial pull of orbiting planets. We recover the planetary signals corresponding to 9 planets already announced by our group (Gl176b, Gl581b, c, d & e, Gl674b, Gl433b, Gl 667Cb and c). We present radial velocities that confirm GJ 849 hosts a Jupiter-mass planet, plus a long-term radial-velocity variation. We also present RVs that precise the planetary mass and period of Gl 832b. We detect long-term RV changes for Gl 367, Gl 680 and Gl 880 betraying yet unknown long-period companions. We identify candidate signals in the radial-velocity time series and demonstrate they are most probably caused by stellar surface inhomogeneities. Finally, we derive a first estimate of the occurrence of M-dwarf planets as a function of their minimum mass and orbital period. In particular, we find that giant planets (m sin i = 100-1,000 Mearth) have a low frequency (e.g. f<1% for P=1-10 d and f=0.02^{+0.03}_{-0.01} for P=10-100 d), whereas super-Earths (m sin i = 1-10 Mearth) are likely very abundant (f=0.36^{+0.25}_{-0.10} for P=1-10 d and f=0.35^{+0.45}_{-0.11} for P=10-100 d). We also obtained eta_earth=0.41^{+0.54}_{-0.13}, the frequency of habitable planets orbiting M dwarfs (1http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/546/A27 [less ▲]Detailed reference viewed: 31 (1 ULiège) The HARPS search for southern extra-solar planets XXXV. Super-Earths around the M-dwarf neighbors Gl433 and Gl667CDelfosse, X.; Bonfils, X.; Forveille, T. et alin Astronomy and Astrophysics (2012), 553Context. M dwarfs have often been found to have super-Earth planets with short orbital periods. These stars are thus preferential targets in searches for rocky or ocean planets in the solar neighborhood ... [more ▼]Context. M dwarfs have often been found to have super-Earth planets with short orbital periods. These stars are thus preferential targets in searches for rocky or ocean planets in the solar neighborhood. Aims: Our research group recently announced the discovery of one and two low-mass planets around the M1.5V stars Gl 433 and Gl 667C, respectively. We found these planets with the HARPS spectrograph on the ESO 3.6-m telescope at La Silla Observatory, from observations obtained during the guaranteed time observing program of that instrument. Methods: We obtained additional HARPS observations of those two stars, for a total of 67 and 179 radial velocity measurements for Gl 433 and Gl 667C, respectively, and present here an orbital analysis of these extended data sets and our main conclusions about both planetary systems. Results: One of the three planets, Gl 667Cc, has a mass of only M2sini ~ 4.25 M⊕ and orbits in the central habitable zone of its host star. It receives only 10% less stellar energy from Gl 667C than the Earth receives from the Sun. However, planet evolution in the habitable zone can be very different if the host star is a M dwarf or a solar-like star, without necessarily questioning the presence of water. The two other planets, Gl 433b and Gl 667Cb, both have M2sini of ~5.5 M⊕ and periods of ~7 days. The radial velocity measurements of both stars contain longer timescale signals, which we fit with longer period Keplerians. For Gl 433, the signal probably originates in a magnetic cycle, while data of longer time span will be needed before conclusive results can be obtained for Gl 667C. The metallicity of Gl 433 is close to solar, while Gl 667C is metal poor with [Fe/H] ~ -0.6. This reinforces the recent conclusion that the occurrence of super-Earth planets does not strongly correlate with the stellar metallicity. [less ▲]Detailed reference viewed: 40 (1 ULiège) The HARPS search for southern extra-solar planets XXXII. Only 4 planets in the Gl~581 systemForveille, T.; Bonfils, X.; Delfosse, X. et alE-print/Working paper (2011)The Gl 581 planetary system has generated wide interest, because its 4 planets include both the lowest mass planet known around a main sequence star other than the Sun and the first super-Earth planet in ... [more ▼]The Gl 581 planetary system has generated wide interest, because its 4 planets include both the lowest mass planet known around a main sequence star other than the Sun and the first super-Earth planet in the habitable zone of its star. A recent paper announced the possible discovery of two additional super-Earth planets in that system, one of which would be in the middle of the habitable zone of Gl 581. The statistical significance of those two discoveries has, however, been questioned. We have obtained 121 new radial velocity measurements of Gl 581 with the HARPS spectrograph on the ESO 3.6 m telescope, and analyse those together with our previous 119 measurements of that star to examine these potential additional planets. We find that neither is likely to exist with their proposed parameters. We also obtained photometric observations with the 2.5 m Isaac Newton Telescope during a potential transit of the inner planet, Gl 581e, which had a 5% geometric transit probability. Those observations exclude transits for planet densities under 4 times the Earth density within -0.2 sigma to +2.7 sigma of the predicted transit center. [less ▲]Detailed reference viewed: 37 (1 ULiège) A short-period super-Earth orbiting the M2.5 dwarf GJ 3634. Detection with HARPS velocimetry and transit search with Spitzer photometryBonfils, X.; Gillon, Michaël ; Forveille, T. et alin Astronomy and Astrophysics (2011), 528We report on the detection of GJ 3634b, a super-Earth of mass m sin i = 7.0[SUB]-0.8[SUP]+0.9[/SUP]~M_⊕[/SUB] and period P = 2.64561 ± 0.00066 day. Its host star is a M2.5 dwarf, has a mass of 0.45 ± 0.05 ... [more ▼]We report on the detection of GJ 3634b, a super-Earth of mass m sin i = 7.0[SUB]-0.8[SUP]+0.9[/SUP]~M_⊕[/SUB] and period P = 2.64561 ± 0.00066 day. Its host star is a M2.5 dwarf, has a mass of 0.45 ± 0.05 M[SUB]ȯ[/SUB], a radius of 0.43 ± 0.03 R[SUB]ȯ[/SUB] and lies 19.8 ± 0.6 pc away from our Sun. The planet is detected after a radial-velocity campaign using the ESO/Harps spectrograph. GJ 3634b had an a priori geometric probability to undergo transit of ~7% and, if telluric in composition, a non-grazing transit would produce a photometric dip of ≲0.1%. We therefore followed-up upon the RV detection with photometric observations using the 4.5-μm band of the IRAC imager onboard Spitzer. Our six-hour long light curve excludes that a transit occurs for 2σ of the probable transit window, decreasing the probability that GJ 3634b undergoes transit to ~0.5%. Based on observations made with the Harps instrument on the ESO 3.6-m telescope at La Silla Observatory under program IDs 082.C-0718(B) and183.C-0437(A), and observations made with Warm Spitzer under program 60027.Radial-velocity and photometric tables (Tables 2 and 3) are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/528/A111 [less ▲]Detailed reference viewed: 46 (0 ULiège) The CORALIE survey for southern extrasolar planets. XVI. Discovery of a planetary system around HD 147018 and of two long period and massive planets orbiting HD 171238 and HD 204313Segransan, D.; Udry, S.; Mayor, M. et alin Astronomy and Astrophysics (2010), 511We report the detection of a double planetary system around HD 140718 as well as the discovery of two long period and massive planets orbiting HD 171238 and HD 204313. Those discoveries were made with the ... [more ▼]We report the detection of a double planetary system around HD 140718 as well as the discovery of two long period and massive planets orbiting HD 171238 and HD 204313. Those discoveries were made with the CORALIE Echelle spectrograph mounted on the 1.2-m Euler Swiss telescope located at La Silla Observatory, Chile. The planetary system orbiting the nearby G9 dwarf HD 147018 is composed of an eccentric inner planet (e = 0.47) with twice the mass of Jupiter (2.1 MJup) and with an orbital period of 44.24 days. The outer planet is even more massive (6.6 MJup) with a slightly eccentric orbit (e = 0.13) and a period of 1008 days. The planet orbiting HD 171238 has a minimum mass of 2.6 MJup, a period of 1523 days and an eccentricity of 0.40. It orbits a G8 dwarfs at 2.5 AU. The last planet, HD 204313 b, is a 4.0 M[SUB]Jup[/SUB]-planet with a period of 5.3 years and has a low eccentricity (e = 0.13). It orbits a G5 dwarfs at 3.1 AU. The three parent stars are metal rich, which further strengthens the case that massive planets tend to form around metal rich stars. [less ▲]Detailed reference viewed: 43 (2 ULiège) Darwin-A Mission to Detect and Search for Life on Extrasolar PlanetsCockell, C. S.; Léger, A.; Fridlund, M. et alin Astrobiology (2009), 9(1)The discovery of extrasolar planets is one of the greatest achievements of modern astronomy. The detection of planets that vary widely in mass demonstrates that extrasolar planets of low mass exist. In ... [more ▼]The discovery of extrasolar planets is one of the greatest achievements of modern astronomy. The detection of planets that vary widely in mass demonstrates that extrasolar planets of low mass exist. In this paper, we describe a mission, called Darwin, whose primary goal is the search for, and characterization of, terrestrial extrasolar planets and the search for life. Accomplishing the mission objectives will require collaborative science across disciplines, including astrophysics, planetary sciences, chemistry, and microbiology. Darwin is designed to detect rocky planets similar to Earth and perform spectroscopic analysis at mid-infrared wavelengths (6-20 mum), where an advantageous contrast ratio between star and planet occurs. The baseline mission is projected to last 5 years and consists of approximately 200 individual target stars. Among these, 25-50 planetary systems can be studied spectroscopically, which will include the search for gases such as CO[SUB]2[/SUB], H[SUB]2[/SUB]O, CH[SUB]4[/SUB], and O[SUB]3[/SUB]. Many of the key technologies required for the construction of Darwin have already been demonstrated, and the remainder are estimated to be mature in the near future. Darwin is a mission that will ignite intense interest in both the research community and the wider public. [less ▲]Detailed reference viewed: 201 (19 ULiège) TW ;Hydrae: evidence of stellar spots instead of a Hot JupiterHuélamo, N.; Figueira, P.; Bonfils, X. et alin Astronomy and Astrophysics (2008), 489Context: TW Hya is a classical T Tauri star that shows significant radial-velocity variations in the optical regime. These variations have been attributed to a 10 M_Jup planet orbiting the star at 0.04 AU ... [more ▼]Context: TW Hya is a classical T Tauri star that shows significant radial-velocity variations in the optical regime. These variations have been attributed to a 10 M_Jup planet orbiting the star at 0.04 AU. Aims: The aim of this letter is to confirm the presence of the giant planet around TW Hya by (i) testing whether the observed RV variations can be caused by stellar spots and (ii) analyzing new optical and infrared data to detect the signal of the planet companion. Methods: We fitted the RV variations of TW Hya using a cool spot model. In addition, we obtained new high-resolution optical & infrared spectra, together with optical photometry of TW Hya and compared them with previous data. Results: Our model shows that a cold spot covering 7% of the stellar surface and located at a latitude of 54° can reproduce the reported RV variations. The model also predicts a bisector semi-amplitude variation <10 m s[SUP]-1[/SUP], which is less than the errors of the RV measurements discussed in Setiawan et al. (2008, Nature, 451, 38). The analysis of our new optical RV data, with typical errors of 10 m s[SUP]-1[/SUP], shows a larger RV amplitude that varies depending on the correlation mask used. A slight correlation between the RV variation and the bisector is also observed although not at a very significant level. The infrared H-band RV curve is almost flat, showing a small variation (<35 m s[SUP]-1[/SUP]) that is not consistent with the published optical orbit. All these results support the spot scenario rather than the presence of a hot Jupiter. Finally, the photometric data shows a 20% (peak to peak) variability, which is much larger than the 4% variation expected for the modeled cool spot. The fact that the optical data are correlated with the surface of the cross-correlation function points towards hot spots as being responsible for the photometric variability. Conclusions: We conclude that the best explanation for the RV signal observed in TW Hya is the presence of a cool stellar spot and not an orbiting hot Jupiter. Based on observations taken at the VLT (Paranal), under programs 280.C-5064(A) and 075.C-0202(A), and with the CORALIE spectrograph and EulerCAM both at the Euler Swiss telescope (La Silla). [less ▲]Detailed reference viewed: 59 (0 ULiège) A transiting planet among 23 new near-threshold candidates from the OGLE survey - OGLE-TR-182Pont, F.; Tamuz, O.; Udalski, A. et alin Astronomy and Astrophysics (2008), 487By re-processing the data of the second season of the OGLE survey for planetary transits and adding new mesurements on the same fields gathered in subsequent years with the OGLE telescope, we have ... [more ▼]By re-processing the data of the second season of the OGLE survey for planetary transits and adding new mesurements on the same fields gathered in subsequent years with the OGLE telescope, we have identified 23 new transit candidates, recorded as OGLE-TR-178 to OGLE-TR-200. We studied the nature of these objects with the FLAMES/UVES multi-fiber spectrograph on the VLT. One of the candidates, OGLE-TR-182, was confirmed as a transiting gas giant planet on a 4-day orbit. We characterised it with further observations using the FORS1 camera and UVES spectrograph on the VLT. OGLE-TR-182b is a typical hot Jupiter'' with an orbital period of 3.98 days, a mass of 1.01 ± 0.15~M_Jup and a radius of 1.13[SUP]+0.24[/SUP][SUB]-0.08[/SUB]~R_Jup. Confirming this transiting planet required a large investment in telescope time with the best instruments available, and we comment on the difficulty of the confirmation process for transiting planets in the OGLE survey. We delineate the zone were confirmation is difficult or impossible, and discuss the implications for the CoRoT space mission in its quest for transiting telluric planets. Based on observations made with the FORS1 camera and the FLAMES/UVES spectrograph at the VLT, ESO, Chile (programmes 076.C-0706 and 177.C-0666) and 1.3-m Warsaw Telescope at Las Campanas Observatory, Chile. [less ▲]Detailed reference viewed: 52 (1 ULiège) OGLE-TR-211 - a new transiting inflated hot Jupiter from the OGLE survey and ESO LP666 spectroscopic follow-up programUdalski, A.; Pont, F.; Naef, D. et alin Astronomy and Astrophysics (2008), 482We present results of the photometric campaign for planetary and low-luminosity object transits conducted by the OGLE survey in the 2005 season (Campaign #5). About twenty of the most promising candidates ... [more ▼]We present results of the photometric campaign for planetary and low-luminosity object transits conducted by the OGLE survey in the 2005 season (Campaign #5). About twenty of the most promising candidates discovered in these data were subsequently verified spectroscopically with the VLT/FLAMES spectrograph. One of the candidates, OGLE-TR-211, reveals clear changes of radial velocity with a small amplitude of 82 m/s, varying in phase with photometric transit ephemeris. Further analysis confirms the planetary nature of this system. Follow-up precise photometry of OGLE-TR-211 with VLT/FORS, together with radial velocity spectroscopy, supplemented with high-resolution, high S/N VLT/UVES spectra allowed us to derive parameters of the planet and host star. OGLE-TR-211b is a hot Jupiter orbiting an F7-8 spectral type dwarf star with a period of 3.68 days. The mass of the planet is equal to 1.03±0.20 M_Jup, while its radius 1.36[SUP]+0.18[/SUP][SUB]-0.09[/SUB] R_Jup. The radius is about 20% larger than the typical radius of hot Jupiters of similar mass. OGLE-TR-211b is, then, another example of inflated hot Jupiters - a small group of seven exoplanets with large radii and unusually low densities - objects that are a challenge to the current models of exoplanets. Based on observations made with the FORS1 camera and the FLAMES/UVES spectrograph at the VLT, ESO, Chile (program 07.C-0706, 076.C-0122, and 177.C-0666) and 1.3-m Warsaw Telescope at Las Campanas Observatory, Chile. [less ▲]Detailed reference viewed: 52 (2 ULiège) The HARPS search for southern extra-solar planets. X. A m sin i = 11 M_â planet around the nearby spotted M dwarf GJ 674Bonfils, X.; Mayor, M.; Delfosse, X. et alin Astronomy and Astrophysics (2007), 474Context: How planet properties depend on stellar mass is a key diagnostic of planetary formation mechanisms. Aims: This motivates planet searches around stars that are significantly more massive or less ... [more ▼]Context: How planet properties depend on stellar mass is a key diagnostic of planetary formation mechanisms. Aims: This motivates planet searches around stars that are significantly more massive or less massive than the Sun, and in particular our radial velocity search for planets around very low-mass stars. Methods: As part of that program, we obtained measurements of GJ 674, an M 2.5 dwarf at d = 4.5 pc. These measurements have dispersion much in excess of their internal errors. An intensive observing campaign demonstrates that the excess dispersion is due to two superimposed coherent signals, with periods of 4.69 and 35 days. Results: These data are described well by a 2-planet Keplerian model where each planet has a ~11 M_â minimum mass. A careful analysis of the (low-level) magnetic activity of GJ 674, however, demonstrates that the 35-day period coincides with the stellar rotation period. This signal therefore originates in a spot inhomogeneity modulated by stellar rotation. The 4.69-day signal, on the other hand, is caused by a bona-fide planet, GJ 674b. Conclusions: Its detection adds to the growing number of Neptune-mass planets around M-dwarfs and reinforces the emerging conclusion that this mass domain is much more populated than the Jovian mass range. We discuss the metallicity distributions of M dwarf with and without planets and find a low 11% probability that they are drawn from the same parent distribution. Moreover, we find tentative evidence that the host star metallicity correlates with the total mass of their planetary system. Based on observations made with the HARPS instrument on the ESO 3.6 m telescope under the GTO program ID 072.C-0488 at Cerro La Silla (Chile). Radial-velocity, photometric and Ca II H+K index time series are only available in electronic format the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strabg.fr/cgi-bin/qcat?J/A+A/474/293 [less ▲]Detailed reference viewed: 35 (1 ULiège) The transiting planet OGLE-TR-132b revisited with new spectroscopy and deconvolution photometry[SUP], [/SUP]Gillon, Michaël ; Pont, F.; Moutou, C. et alin Astronomy and Astrophysics (2007), 466OGLE-TR-132b transits a very metal-rich F dwarf about 2000 pc from the Sun, in the Galactic disc towards Carina. It orbits very close to its host star (a = 0.03 AU) and has an equilibrium temperature of ... [more ▼]OGLE-TR-132b transits a very metal-rich F dwarf about 2000 pc from the Sun, in the Galactic disc towards Carina. It orbits very close to its host star (a = 0.03 AU) and has an equilibrium temperature of nearly 2000 K. Using rapid-cadence transit photometry from the FORS2 camera on the VLT and SUSI2 on the NTT, and high-resolution spectroscopy with UVES on the VLT, we refine the shape of the transit light curve and the parameters of the system. In particular, we improve the planetary radius estimate, R = 1.18 ± 0.07 R[SUB]J[/SUB] and provide very precise ephemeris, T_tr = 2 453 142.59123 ± 0.0003 BJD and P = 1.689868 ± 0.000003 days. The obtained planetary mass is 1.14 ± 0.12 M_J. Our results give a slightly smaller and lighter star, and bigger planet, than previous values. As the VLT/FORS2 light curve obtained in this analysis with the deconvolution photometry algorithm DECPHOT shows a transit depth in disagreement with the one obtained by a previous study using the same data, we analyze them with two other reduction methods (aperture and image subtraction). The light curves obtained with the three methods are in good agreement, though deconvolution-based photometry is significantly more precise. It appears from these results that the smaller transit depth obtained in the previous study was due to a normalisation problem inherent to the reduction procedure used. Based on data collected with the FORS2 imager at the VLT-UT4 telescope (Paranal Observatory, ESO, Chile) in the programme 273.C-5017A, with the SUSI2 imager at the NTT telescope (La Silla Observatory, ESO, Chile) in the programme 075.C-0462A, and with the UVES spectrograph at the VLT-UT2 telescope (Paranal Observatory, ESO, Chile) in the programme 076.C-0131. The reduced photometric data used in this work are available only in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/466/743 [less ▲]Detailed reference viewed: 19 (3 ULiège) The "666" collaboration on OGLE transits. I. Accurate radius of the planets OGLE-TR-10b and OGLE-TR-56b with VLT deconvolution photometryPont, F.; Moutou, C.; Gillon, Michaël et alin Astronomy and Astrophysics (2007), 465Transiting planets are essential to study the structure and evolution of extra-solar planets. For that purpose, it is important to measure precisely the radius of these planets. Here we report new high ... [more ▼]Transiting planets are essential to study the structure and evolution of extra-solar planets. For that purpose, it is important to measure precisely the radius of these planets. Here we report new high-accuracy photometry of the transits of OGLE-TR-10 and OGLE-TR-56 with VLT/FORS1. One transit of each object was covered in Bessel V and R filters, and treated with the deconvolution-based photometry algorithm DECPHOT, to ensure accurate millimagnitude light curves. Together with earlier spectroscopic measurements, the data imply a radius of 1.22{[SUP]+0.12[/SUP][SUB]-0.07[/SUB]} R[SUB]J[/SUB] for OGLE-TR-10b and 1.30 ± 0.05 R[SUB]J[/SUB] for OGLE-TR-56b. A re-analysis of the original OGLE photometry resolves an earlier discrepancy about the radius of OGLE-TR-10. The transit of OGLE-TR-56 is almost grazing, so that small systematics in the photometry can cause large changes in the derived radius. Our study confirms both planets as inflated hot Jupiters, with large radii comparable to that of HD 209458b and at least two other recently discovered transiting gas giants. Based on data collected with the FORS1 imager at the VLT-Kueyen telescope (Paranal Observatory, ESO, Chile) in the programme 177.C-0666E. [less ▲]Detailed reference viewed: 52 (1 ULiège) 1 2