Transiting exoplanets from the CoRoT space mission XIV. CoRoT-11b: a transiting massive "hot-Jupiter" in a prograde orbit around a rapidly rotating F-type star
D. Gandolfi, G. Hébrard, R. Alonso, M. Deleuil, E. W. Guenther, M. Fridlund, M. Endl, P. Eigmüller, Sz. Csizmadia, M. Havel, S. Aigrain, M. Auvergne, A. Baglin, P. Barge, A. S. Bonomo, P. Bordé, F. Bouchy, H. Bruntt, J. Cabrera, S. Carpano, L. Carone, W. D. Cochran, H. J. Deeg, R. Dvorak, J. Eislöffel, A. Erikson, S. Ferraz-Mello, J.-C. Gazzano, N. P. Gibson, M. Gillon, P. Gondoin, T. Guillot, M. Hartmann, A. Hatzes, L. Jorda, P. Kabath, A. Léger, A. Llebaria, H. Lammer, P. J. MacQueen, M. Mayor, T. Mazeh, C. Moutou, M. Ollivier, M. Pätzold, F. Pepe, D. Queloz, H. Rauer, D. Rouan, B. Samuel, J. Schneider, B. Stecklum, B. Tingley, S. Udry, G. Wuchterl
aa r X i v : . [ a s t r o - ph . E P ] S e p Astronomy & Astrophysics manuscript no. CoRoT11b c (cid:13)
ESO 2018November 8, 2018
Transiting exoplanets from the CoRoT space mission XIV.CoRoT-11b: a transiting massive “hot-Jupiter” in aprograde orbit around a rapidly rotating F-type star ⋆ D. Gandolfi1 ,
2, G. H´ebrard3, R. Alonso4, M. Deleuil5, E.W. Guenther1, M. Fridlund2, M. Endl6,P. Eigm¨uller1, Sz. Csizmadia7, M. Havel8, S. Aigrain9, M. Auvergne10, A. Baglin10, P. Barge5,A. S. Bonomo5, P. Bord´e11, F. Bouchy3 ,
12, H. Bruntt10, J. Cabrera7 ,
13, S. Carpano2, L. Carone14,W. D. Cochran6, H. J. Deeg15, R. Dvorak16, J. Eisl¨offel1, A. Erikson7, S. Ferraz-Mello17, J.-C. Gazzano5 , ,
18, P. Gondoin2, T. Guillot8, M. Hartmann1, A. Hatzes1, L. Jorda5, P.Kabath7 ,
19, A. L´eger11, A. Llebaria5, H. Lammer20, P. J. MacQueen6, M. Mayor4, T. Mazeh21,C. Moutou5, M. Ollivier11, M. P¨atzold14, F. Pepe4, D. Queloz4, H. Rauer7 ,
22, D. Rouan10, B. Samuel11,J. Schneider13, B. Stecklum1, B. Tingley15, S. Udry4, and G. Wuchterl1 (Affiliations can be found after the references)
Received ; accepted
ABSTRACT
The
CoRoT exoplanet science team announces the discovery of CoRoT-11b, a fairly massive hot-Jupiter transiting a V =12 . ∗ = 1 . ± . M ⊙ , R ∗ = 1 . ± . R ⊙ , T eff = 6440 ±
120 K), with an orbital period of P = 2 . ± . . ± .
005 AU. The detection of part of the radial velocity anomaly caused by the Rossiter-McLaughlineffect shows that the transit-like events detected by
CoRoT are caused by a planet-sized transiting object in a prograde orbit.The relatively high projected rotational velocity of the star ( v sin i ⋆ = 40 ± M p = 2 . ± .
34 M
Jup and radius R p = 1 . ± .
03 R
Jup ,the resulting mean density of CoRoT-11b ( ρ p = 0 . ± .
15 g/cm ) can be explained with a model for an inflated hydrogen-planetwith a solar composition and a high level of energy dissipation in its interior. Key words. stars: planetary systems - techniques: photometry - techniques: radial velocities - techniques: spectroscopic
1. Introduction
Discovering and studying extrasolar planets, and in gen-eral planetary systems other than ours, aims at under-standing whether the solar system is peculiar and uniqueor usual and unremarkable. In this context, the discov-ery of a large population of Jupiter-like planets with asemi-major axis . . ⋆ The
CoRoT space mission, launched on 2006 December 27,has been developed and is operated by CNES, with the con-tribution of Austria, Belgium, Brazil, ESA (RSSD and ScienceProgramme), Germany and Spain. λ ) between the orbital angular momentumvector and the spin axis of the star (Gaudi & Winn 2007).This can be done by detecting the Rossiter-McLaughlin(RM) effect, i.e., the spectral distortion observed in theline profile of a rotating star as a second object passes infront of the stellar disc.Furthermore transit surveys have the potential to en-large the parameter space of planet host stars by detectingplanets around stars that are usually not observed in radialvelocity surveys. As is well known, Doppler surveys typi-cally focus on slowly rotating solar-like stars because highRV precision can easily be achieved. They usually discardmore massive main-sequence stars for which accurate RVmeasurements are rendered unfeasible by the rapid stellarrotation rate and the paucity of spectral lines. Indeed, a fewRV searches have been conducted up to now around A- andF-type stars (e.g., Lagrange et al. 2009; Guenther et al.2009; Bowler et al. 2010; Johnson et al. 2010). Transit de-tections are not affected by the stellar rotation and can lead to the discovery of planets around rapidly rotating F-typestars.Space missions like CoRoT (Co nvection , Ro tation,and planetary T ransits , Baglin et al. 2006; Auvergne et al.2009) and Kepler (Borucki et al. 2010; Koch et al. 2010)are crucial to increase the number of planets with well-known orbital and physical parameters, and consequentlyimprove the database that is needed to investigate all theaspects of the exoplanets population, down to the Earth-like mass-regime. The recent discoveries announced by the
CoRoT exoplanet science team fully demonstrate the ca-pability of the mission to determine the radius and themean density of the transiting extrasolar planets, fromthe “transition desert regime” between brown dwarfs andplanets (Deleuil et al. 2008), across hot and temperateJupiter-like objects (Barge et al. 2008; Alonso et al. 2008;Bouchy et al. 2008; Aigrain et al. 2008; Moutou et al. 2008;Rauer et al. 2009; Fridlund et al. 2010; Deeg et al. 2010),and down to the Earth-like radius regime (L´eger et al. 2009;Queloz et al. 2009).In the present paper the
CoRoT Exoplanet ScienceTeam announces its eleventh transiting planet, namelyCoRoT-11b, a fairly massive Jupiter-like planet in a rel-atively short-period orbit (about three days) around arapidly rotating F6 dwarf star. By combining the high-precision photometric data from
CoRoT with RV mea-surements and high signal-to-noise spectroscopy from theground, we fully characterised the planet’s orbit and de-rived the main physical parameters of the planet-star sys-tem. Thanks to time-series RV measurements acquired dur-ing the transit we observed part of the RM effect and con-firm the planetary transit event.
2. CoRoT observations, data reduction, andanalysis
CoRoT-11b was discovered during the
CoRoT ’s secondlong run towards the Galactic centre direction, i.e., the
CoRoT
LRc02 run. The observations lasted 145 days,from 2008 April 15 to September 7. The
LRc02 field iscentred at α ≈ h m and δ ≈ ◦ ′ (J2000), be-tween the Ophiuchus and the
Serpens Cauda constella-tions. The planet was detected transiting the
CoRoT star with ID=0105833549. The main designations of the planethost star CoRoT-11 along with its equatorial coordi-nates and optical and near-infrared photometry, are re-ported in Table 1 as retrieved from the ExoDat database(Deleuil et al. 2009) and catalogue (Cutri et al.2003).The transiting planet was detected after 51 daysof observations in the so-called
CoRoT alarm-mode (Quentin et al. 2006; Surace et al. 2008). This observingstrategy consists in processing and analysing a first set ofphotometric data in order to single out planetary transitswhile the
CoRoT run is still on-going. This enabled us to The ‘ LR ’ prefix means that the field is a long-run field (typ-ically 150 days of observations). The letter ‘ c ’ refers to theGalactic centre direction. The last two digits ’ ’ indicate thatthe observed field is the second CoRoT long-run towards theGalaxy centre. See Carpano et al. (2009) for a full description of the
CoRoT target nomenclature.
Table 1.
CoRoT, GSC2.3, USNO-A2, and 2MASS identi-fiers of the planet host star CoRoT-11. Equatorial coordi-nates, optical, and near infrared photometry are from the
ExoDat catalogue (Deleuil et al. 2009) and cata-logue (Cutri et al. 2003).
Main identifiers
CoRoT
ID 0105833549GSC2.3 ID N1RO000587USNO-A2 ID 0900-134999742MASS ID 18424494+0556156CoordinatesRA (J2000) 18 h m . s ◦ ′ . ′′ r ′ i ′ switch the time sampling of the light curve from 512 to32 seconds and trigger the ground-based follow-up observa-tions (see Sect. 3). Thanks to an objective prism in the opti-cal path of the CoRoT exoplanet channel (Auvergne et al.2009), CoRoT-11 was observed in three broad-band colours(red, green, and blue), according to the specific photomet-ric mask selected at the beginning of the run. This usuallyallows us to remove false positives that mimick planetarytransit events, such as stellar activity or eclipsing binaries.A total of 261 917 photometric data-points were collectedfor each colour channel, 8 349 of those were obtained witha time sampling of 512 sec, and 253 568 with 32 sec. Thetransit signal was detected in all three colour channels withthe similar depth and the same duration and ephemeris asexpected for a bona-fide planetary transit.At the end of the
LRc02 observing run, the wholephotometric data-set of CoRoT-11 was processed usingthe
CoRoT reduction and calibration package described inAuvergne et al. (2009). The pipeline also flags bad pho-tometric data-points collected during the entrance intoand exit from the Earth’s shadow or data-points that arestrongly affected by hits of high-energy particles resultingfrom the crossing of the South Atlantic Anomaly (SAA).
In order to increase the signal-to-noise (S/N) ratio, theanalysis of the photometric data was performed using thewhite light curve, as derived by adding together the sig-nal from the three colour channels. CoRoT-11 has a closeneighbour star at about 2 ′′ northwest, falling well insidethe CoRoT photometric aperture, as well as a handful offaint nearby stars that are spatially located around the
CoRoT mask (see also Sect. 3.1 and Fig. 3). According tothe
ExoDat database, the closest neighbour star is 2.1 mag-nitudes fainter than CoRoT-11 in the r ′ -band. Following Fig. 1.
Whole (145 days) cleaned light curve of CoRoT-11, sampled at 512 seconds from the first ∼
50 days, and at 32seconds until the end of the run. For the sake of clarity, the blue dots represent 1-hour binned points. The inset plot is azoom of the light curve showing two transits of CoRoT-11b. The “jumps” observed in the plot are caused by the impactsof high-energy particles onto the CCD’s lattice. The light curve has been arbitrarily normalised to the median value ofthe flux. See the online edition of the Journal for a colour version of this figure.the method described in previous
CoRoT papers (e.g.,Alonso et al. 2008), we estimated that it contributes about12 . . ± . CoRoT data was performedapplying an iterative sigma-clipping algorithm. Most ofthe photometric points rejected according to this criterion(about 7.8 %) resulted from the crossing of the SAA andmatched the photometric data previously flagged as outlierby the
CoRoT automatic pipeline (Auvergne et al. 2009).The cleaned white light curve is plotted in Fig. 1. It shows49 transits with a depth of ∼ CoRoT
CCDs (Pinheiro da Silva et al. 2008). The high-frequency scatter of the light curve (Fig. 1) is compati-ble with other sources of similar brightness observed by
CoRoT
Aigrain et al. (2009).The
CoRoT light curves are affected by a modulationof the satellite orbital period, which changes its shape andamplitude during a long run observation. Following the pre-scription of Alonso et al. (2008), the orbital signal of each j th orbit was corrected with the signals from the previousand the following 30 orbits. The data points acquired dur-ing the transits were not considered in the estimate of themean orbital signal of the j th orbit.In order to determine the period P and transit epoch T tr , we first used an approximate ephemeris to build aphase-folded curve of the transit. A simple trapezoidalmodel was fitted to this curve to get the parametersof the average transit, i.e., depth, duration, centre, and Fig. 2.
Binned and phase-folded curve of the transit ofCoRoT-11b, with the best-fit model over-plotted and theresiduals of the fit. The standard deviation of the pointsoutside transit is of 230 ppm (with a phase sampling of5 × − , corresponding to about 129 seconds). The meanerror bar of the bins is of 239 ppm, revealing an insignificantamount of red noise in the phase-folded light curve after thecorrections described in the text have been performed.ingress/egress time. This model was then fitted to each in-dividual transit, leaving only the centre as free parameter.A linear fit to the final observed-calculated ( O − C ) dia-gram of the transit centres served to refine the ephemeris,and we iterated the process until the fitted line had no sig-nificant slope. Once the orbital period and transit epochwere derived (Table 4), we constructed a combined phase-folded transit curve to this ephemeris by successively nor- malising each transit to the regions surrounding it. In thiscase, because the star is not very active (see Fig. 1), weused simple line fits to the phases between [ − . , − .
02 ],and [ 0 . , .
06 ], using the ephemeris of Table 4, and ap-plied this normalisation to the whole section from phases[ − . , .
06 ]. We used a Savitzky-Golay filter to recognizea few remaining outliers before binning in phase. Takinginto account the photometry rejected according to the firstsigma-clipping algorithm, this process removed about 1 . ∼
90 %.Finally, the data-points were binned in blocks of 0.0005in phase, and the error bars were estimated as the standarddeviation of the data points inside each bin divided by thesquare root of the number of points inside the bin. Thephase-folded curve of the transit is shown in Fig. 2.The transit was fitted to a model using the formalism ofGim´enez (2006). To find the solution that best matches ourdata, we minimized the χ using the algorithm AMOEBA(Press et al. 1992). The fitted parameters were the centre ofthe transit, the phase of start of the transit θ , the planet-to-star radius ratio k = R p /R ∗ , the orbital inclination i andthe two non-linear limb darkening coefficients u + = u a + u b and u − = u a − u b . We used a quadratic law for the limbdarkening, given by I ( µ ) = I (1)[1 − u a (1 − µ ) − u b (1 − µ ) ],where I is the distribution of brightness over the star and µ is the cosine of the angle between the normal to the localstellar surface and the line of sight. The use of u + and u − isa better choice to avoid correlations between the two limbdarkening coefficients u a and u b , as described in Gim´enez(2006). To estimate the errors in each of the parameters weperformed the χ minimization to five hundred different setsof data. These data-sets were constructed with different val-ues for the contamination factor (estimated at 13 . ± . σ of the fitted Gaussian distribution. The parame-ters and associated errors are listed in Table 4, along withthe scaled semi-major axis a/R ∗ , as derived using Eq. 12in Gim´enez (2006). Assuming a circular orbit (i.e., e = 0)and combining the scaled semi-major axis a/R ∗ with theorbital period P via the Kepler’s laws, we derived the pa-rameter M / ∗ /R ∗ = 0 . ± .
010 in solar units, whichleads to a mean stellar density ρ ∗ = 0 . ± .
02 g/cm (see Seager & Mall´en-Ornelas 2003; Winn 2010, for the rel-evant formulas). The transit fit yielded the limb darken-ing coefficients u + = 0 . ± .
06 and u − = 0 . ± . u + = 0 . ± .
01 and u − = 0 . ± .
01 predicted by Sing(2010) for a star with the same fundamental parameters asCoRoT-11 (Sect. 3.4).Note that the standard deviation of the residuals out-side the transit phase is 230 ppm, which is within the uncer- tainties identical to the mean error bar of each of the bins(239 ppm), thus revealing the small low-frequency noisein the phase-folded light curve after the analysis describedabove.
We searched for the eclipse of the planet in the
CoRoT lightcurve with the same techniques as described in Alonso et al.(2009a,b) and Fridlund et al. (2010). To account for a pos-sible eccentric orbit, we mapped the χ levels of a fit to atrapezoid (with the shape parameters estimated from thetransit) for different orbital phases. We did not obtain anysignificant detection above 100 ppm in depth. We can thusset an upper 3 σ limit for the planetary eclipse depth of100 ppm, which we translated into an upper limit to thebrightness temperature of 2650 K (Alonso et al. 2009b).
3. Ground-based observations, data reduction, andanalysis
As already described in previous
CoRoT discovery papers,intensive ground-based observations are mandatory to es-tablish the planetary nature of the transiting candidatesdetected by
CoRoT . These follow-ups are crucial to ruleout possible false positives, i.e., physical configurations thatmimick planetary transits, which cannot be excluded onthe basis of meticulous light curve analyses only. Out ofabout 50 promising candidates detected per
CoRoT longrun field (see Carpano et al. 2009; Moutou et al. 2009b;Cabrera et al. 2009; Carone et al. 2010), usually only ahandful turns out to be bona fide planetary objects.Furthermore, ground-based observations are needed to as-sess the planetary nature of the transiting object, derive thetrue mass of the planet, and measure the stellar parametersof the host star needed to accurately compute the planetradius .Follow-up campaigns of the planetary transit candidatesdetected by the alarm-mode in the LRc02 field started inearly Summer 2008. In the following subsection we will de-scribe the complementary photometric and spectroscopicground-based observations of CoRoT-11.
The objective prism placed along the optical path of the
CoRoT exoplanet channel spreads the light of the observedtargets over about 50 pixels on the CCDs, correspond-ing to a projected sky area of about 20 ′′ × ′′ . The to-tal flux of each CoRoT target is then computed by in-tegrating the pixel signal over a preselected photometricmask elongated along the dispersion direction and cover-ing most of the point spread function (PSF). As alreadydescribed in Sect. 2.2, this increases the possibility thatthe light of neighbour stars could contaminate the flux ofthe
CoRoT target. Furthermore, what is believed to be a“good” planetary transit might actually turn out to be theeclipse of a faint nearby binary system, whose light is di-luted by the
CoRoT target star.To reproduce the observed ∼ . ∼ We remind the reader that transits provide the direct mea-surement of only the planet-to-star radius ratio.4andolfi et al.: The transiting exoplanet CoRoT-11b
Fig. 3.
Sky area around CoRoT-11.
Left : r ′ -filter imageas retrieved from the ExoDat database. CoRoT-11 is thebrightest source in the centre of the image. The nearbycontaminant star, about 2 ′′ northwest from the main target,is clearly visible. Right : image acquired by
CoRoT , at thesame scale and orientation. The thick line around the targetdelimits the photometric mask used to integrate the signalof CoRoT-11. Note how the target and the contaminant arecompletely blurred and blended. The crosses in the imagemark the position of the stars in the field.fainter than CoRoT-11. As already mentioned above,CoRoT-11 has a close, 2.1 mag fainter neighbour starthat might thus actually be the potential source of falsealarm (Fig. 3). In order to exclude this scenario, we tookadvantage of the
CoRoT ephemeris to perform the so-called “on-off” photometry. In this procedure, candidatesare photometrically observed with ground-based facilitiesat higher spatial resolution than
CoRoT during the transit(on-observation) and out of the transit (off-observation).The brightness of the candidates, as well as that of anynearby stars, is then monitored to unveil any potentialbackground eclipsing binary. Full details of this method aredescribed in Deeg et al. (2009).According to this observing strategy, R -band photome-try was carried out on 2008 July 4, using the CCD cameramounted on the Swiss Leonard Euler 1.2 m telescope atLa Silla Observatory (Chile), under photometric sky con-dition. Four sets of five consecutive exposures of 45 sec-onds each were acquired. The first set was obtained duringthe predicted transit (on-observation), whereas the remain-ing three were taken out of transit (off-observations). Thedata were reduced with standard IRAF routines ; aperturephotometry was performed with the DAOPHOT packageunder the IRAF environment. Differential photometry wasobtained for CoRoT-11, as well as for the nearby contam-inants, using a set of nearby comparison stars. The on-off Euler observations clearly show that CoRoT-11 is thesource of the transit events detected by CoRoT (Fig. 4).The first photometric data-set shows a dimming of the lightof CoRoT-11 at the expected time and with roughly the IRAF is distributed by the National Optical AstronomyObservatory, which is operated by the Association ofUniversities for Research in Astronomy (AURA), inc., undercooperative agreement with the National Science Foundation.
Fig. 4. r -band light curve of CoRoT-11 as seen with theCCD camera mounted on the Swiss Leonard Euler 1.2 mtelescope at La Silla Observatory (Chile). The black circlesmark each single exposure. The transit fit is over-plottedas derived from the CoRoT light curve analysis.same depth at mid-transit. The 2.1 mag fainter star lo-cated at about 2 ′′ northwest of the target should undergoeclipses with depths of about 0 . R ≈ . . ′′ from CoRoT-11.More Johnson R -band photometric observations ofCoRoT-11 were carried out using the 30 cm TEST telescopeat the Th¨uringer Landessternwarte (TLS), Tautenburg(Germany), on 2008 September 7. Full details of the instru-ment, observing strategy, and data reduction can be foundin Eisl¨offel et al. (2007) and Eigm¨uller & Eisl¨offel (2009).Although these observations were performed at higher time-sampling than those at Euler, they were affected by poorweather conditions, especially in the second half of thenight. Nevertheless, we succeeded to observe the transitingress of CoRoT-11b at the expected CoRoT ephemerisand exclude significant photometric variations in the nearbycontaminant stars.
Low-resolution reconnaissance spectroscopy of the planethost star was performed with the long-slit spectrographmounted at the Nasmyth focus of the 2 m Alfred Jenschtelescope of the TLS observatory, Tautenburg, Germany.These observations were part of an intensive programmedevoted to the spectroscopic “snap-shot” of the plane-tary candidates detected by the alarm-mode in the
LRc02
CoRoT field. They were useful to quickly classify the starsand derive a first estimate of their photospheric parame-ters. Furthermore, they allowed us to identify and removegiant stars, for which the transiting object would result in alow-mass stellar companion, as well as B-type objects andrapidly rotating early-type stars, for which high-precisionradial velocity measurements cannot be achieved.CoRoT-11 was observed on 2008 August 8, under clearand stable weather conditions. Three consecutive exposuresof 20 minutes each were acquired and subsequently com-bined to remove cosmic ray hits and improve the S/Nratio. The data reduction was performed with a semi-
Fig. 5.
Section of the TLS low-resolution spectrum ofCoRoT-11 (thin black line). Overplotted with a thick redline is the best-fitting F6 V template. The spectra havebeen arbitrarily normalised to the flux at 5160 ˚A. See theonline edition of the Journal for a colour version of thisfigure.automatic pipeline developed under the IDL environ-ment. Relative flux calibration was performed observingtwo spectro-photometric standard stars. The final extractedand co-added spectrum covers the wavelength range 4950–7320 ˚A, with a resolving power R ≈ S/N ≈
60. The spectral type and the luminosity class ofCoRoT-11 was derived by fitting the observed spectrumwith a grid of suitable template spectra, as described inFrasca et al. (2003) and Gandolfi et al. (2008) and shownin Fig. 5. We found that CoRoT-11 is an F6 V star, withan accuracy of about ± The RV follow-up of the host star CoRoT-11 was startedin summer 2008 by acquiring two high-resolution spec-tra with the SOPHIE spectrograph (Bouchy et al. 2009)attached to the 1.93 m telescope of the Haute-ProvenceObservatory (France). The instrument was set in its highefficiency (HE), leading to a resolving power of R ≈
40 000.These observations revealed a rapidly rotating star with rel-atively broad spectral lines, corresponding to a projectedrotational velocity ( v sin i ⋆ ) of ∼
40 km/s. According tothe
CoRoT ephemeris, the SOPHIE spectra were securedaround the extreme orbital phases (i.e., phase 0.25 and0.75), and showed a RV variation of ∼
450 m/s in phasewith the
CoRoT ephemeris. Because the F6 V spectral typeof the host star translates into a stellar mass of about1.3 M ⊙ , the measured RV variation is compatible with a ∼ Jup
Jupiter planet. Twelve additional RV measure-ments were obtained in summer 2008 and 2009 using theHARPS spectrograph (Mayor et al. 2003) mounted at the3.6 m ESO telescope on La Silla (Chile). The spectra wereacquired at different orbital phases, under good weatherconditions and without strong moonlight contamination.The data were acquired setting the spectrograph both in IDL is distributed by ITT Visual Information Solutions,Boulder, Colorado. the EGGS and HARPS standard modes, yielding a resolv-ing power of R ≈
70 000 and R ≈
115 000, respectively.The extraction of both the SOPHIE and HARPS spec-tra was performed using the respective pipelines. Followingthe techniques described by Baranne at al. (1996) andPepe at al. (2002), the radial velocities were measured froma weighted cross-correlation of the spectra with a numericalmask. We used a standard G2 mask that includes more than3500 lines. Cross-correlations with F0 and K5 masks gavesimilar results. One SOPHIE spectrum and three HARPSspectra were corrected for small moonlight contaminationfollowing the method described in Pollacco et al. (2008)and H´ebrard et al. (2008), which uses a reference back-ground sky spectrum obtained through a second fiber spa-tially located near the target. This led to a radial velocitycorrection of 700 ±
80 m/s and below 450 ±
50 m/s for theSOPHIE and HARPS spectra, respectively.Two complementary RV measurements were acquiredusing the echelle spectrograph mounted on the 2 m AlfredJensch telescope of the TLS observatory, Tautenburg(Germany), in July and August 2009. For each observingnight, two consecutive exposures of 30 minutes each wererecorded to increase the S/N ratio and remove cosmic rayhits. The adopted instrument set-up yielded a spectral res-olution of about R ≈
30 000. The data were reduced us-ing standard IRAF routines. The wavelength solution wasimproved acquiring ThAr spectra immediately before andafter each stellar observation. After accounting for instru-mental shifts with telluric lines, the radial velocities weremeasured cross-correlating the target spectra with a spec-trum of the RV standard star HR 5777 observed with thesame instrument set-up.As part of NASA’s key science programme in support ofthe
CoRoT mission, more RV measurements were obtainedwith the HIRES spectrograph (Vogt et al. 1994) mountedon the Keck I 10 m telescope, at the Keck Observatory(Mauna Kea, Hawai’i). With the aim of detecting theRossiter-McLaughlin effect, 13 RV measurements were se-cured during the expected transit on 2009 July 1 (UT). Theobservations were performed with the red cross-disperserand the I absorption cell to correct for instrumental shiftsof the spectrograph. The 0 . ′′
861 wide slit together with the14 ′′ tall decker was employed to allow proper backgroundsubtraction, yielding a resolving power of R ≈
50 000. Inorder to adequately sample the RM anomaly, the exposuretime was set to 900 seconds. Two extra spectra of 1200 sec-onds each were also acquired out of transit, on 2009 June 30(UT). The spectra were reduced with IRAF standard rou-tines. The HIRES RV measurements were derived with theiodine data modelling code “Austral” (Endl et al. 2000).The final RV measurements of CoRoT-11 are reportedin Table 2, along with error bars, exposure times, andS/N ratio. In spite of the good RV stability of the spec-trographs used in the present work, the relatively high v sin i ⋆ of CoRoT-11 strongly affected the RV precision ofour measurements and led to an accuracy in the range ∼ −
200 m/s, with a typical error bar of about 100 m/seven for the HARPS and HIRES data. The five data-sets,i.e., the SOPHIE, HIRES, and TLS data, and the twoHARPS modes, were simultaneously fitted with a Keplerianmodel, assuming a circular orbit. The HIRES RV measure-ments acquired during the transit were not used in the fit.Both period and transit central time were fixed according
Table 2.
Radial velocities of the planet host star CoRoT-11 obtained with the SOPHIE, HARPS (EGGS and standardHARPS mode), COUD´E@TLS, and HIRES spectrographs. The systemic velocities for each instrument, as derived fromthe circular Keplerian fit to the data, are reported on the right of the listed spectrographs. The footnote indicates theRV measurements that have been corrected for moonlight contamination.
HJD RV σ RV Bisector Texp S/N per resolution(days) (km/s) (km/s) (km/s) (sec) element at 5500 ˚ASOPHIE - HE Mode V r = − . ± .
160 km/s2454643.60252 a -1.164 0.218 1402 422454683.42036 -0.714 0.206 1607 50HARPS - EGGS Mode V r = − . ± .
041 km/s2454731.52836 -0.932 0.067 -0.531 2700 882454742.51115 -1.364 0.104 -0.149 2700 542454745.51100 -1.370 0.087 -0.476 2700 662454746.51455 -0.986 0.071 -0.583 2700 812454747.51953 -1.509 0.115 -0.892 1800 48HARPS - Standard Mode V r = − . ± .
044 km/s2455023.66206 a -1.663 0.149 -0.286 3600 342455024.63997 a -1.405 0.111 -0.705 3600 482455045.69605 a -1.013 0.114 -0.747 3600 522455064.60739 -1.166 0.083 -0.408 3300 642455067.51277 -1.085 0.092 -0.204 3300 592455068.49041 -1.547 0.130 0.472 3300 422455069.51299 -1.384 0.110 -0.497 3300 48COUD´E@TLS V r = − . ± .
130 km/s2455035.46055 -0.951 0.174 2 × × V r = − . ± .
040 km/s2455012.80417 -0.033 0.050 1200 612455013.06216 0.181 0.086 1200 712455013.78975 -0.165 0.089 900 542455013.80073 -0.083 0.090 900 562455013.81181 -0.170 0.135 900 562455013.82275 0.173 0.111 900 572455013.83360 -0.012 0.142 900 572455013.84473 0.099 0.073 900 562455013.85572 0.037 0.119 900 562455013.86677 0.274 0.108 900 552455013.87785 0.240 0.078 900 552455013.88881 0.017 0.100 900 562455013.89978 0.089 0.080 900 562455013.91097 -0.263 0.086 900 542455014.05389 -0.386 0.119 900 58
Notes. ( a ) Corrected for moonlight contamination. to the
CoRoT ephemeris. An RV shift was let free to varyin the fit between the five data sets.The RV measurements are plotted in Fig. 6 togetherwith the best-fitting circular orbit. The derived orbital pa-rameters are reported in Table 4, along with error bars thatwere computed from χ variations and Monte Carlo ex-periments. The RV measurements led to a semi-amplitude K = 280 ±
40 m/s. The standard deviation of the resid-uals to the fit is σ O − C = 88 m/s, in agreement with theexpected accuracy of the RV measurements. The reduced χ is 1.1 for the 22 RV measurements used in the fit. We explored the possibility that the observed RV vari-ations of CoRoT-11 do not result from the planet’s orbitalmotion, but are instead caused by a periodic distortions inthe spectral lines caused by either stellar magnetic activ-ity or the presence of a hypothetical unresolved eclipsingbinary, whose light is diluted by CoRoT-11. In order to ex-clude these scenarios, we performed an analysis of the cross-correlation function (CCF) profile. Using the highest res-olution spectra in our data-set (i.e., the HARPS measure-ments) and following the line-bisector technique describedin Queloz et al. (2001), we derived the difference in veloc-ity space between the lower and upper part of the HARPS Fig. 6.
Top:
Radial velocity measurements of CoRoT-11 with 1- σ error bars as a function of time and the Keplerian fitto the data. The data are from SOPHIE (green squares), HARPS (blue downward and upward triangles for EGGS andHARPS modes, respectively), HIRES (red circles), and COUD´E@TLS (red diamonds). The left and right panels showthe two observational seasons in 2008 and 2009. The systemic radial velocity of V r = − . ± .
041 km/s, as derivedfrom the HARPS/EGGS data-set only, is plotted with a horizontal dotted line.
Bottom:
Residuals of the fit.CCFs (i.e., bisector span). The value of the bisector spanvelocities are listed in Table 2. The uncertainty was setto twice that of the corresponding HARPS radial velocitymeasurements. We found that the CCFs show a system-atic asymmetric profile, translating into a negative valueof the bisector span velocities (Table 2 and Fig. 7), whichis usually observed in rapidly rotating F-type stars (Gray1986, 1989). Nevertheless, the CCF bisector spans showneither significant variations nor any trend as a function ofboth RV measurements and orbital phases (Fig. 7). The lin-ear Pearson correlation coefficient between the HARPS RVmeasurements and the corresponding CCF bisector spansis − .
25. Removing the only outlier point with positive bi-sector span (i.e., 0 .
472 km/s), the correlation coefficientapproaches zero, being − .
03. Thus the observed RV vari-ations seem not to be caused by spectral line profile vari-ations to any significant degree, but are mainly due to theDoppler shift induced by the orbital motion of CoRoT-11b. The RV observations and the transit-signal detectedby
CoRoT point to a hot-Jupiter-sized planet that orbitsthe star.The phase-folded RV measurements are plotted inFig. 8. As already described, the orbit was assumed to becircular, which is a reasonable assumption for close-in hot-Jupiters. The radial velocities are not accurate enough toconstrain the eccentricity with the orbital fit only. Indeed,a Keplerian fit with an eccentricity of about 0.6 providesa solution that agrees with the
CoRoT ephemeris, with aRV semi-amplitude K which is 15 % larger than the oneobtained for a circular orbit. The standard deviation of theresiduals to this eccentric fit ( σ O − C = 95 m/s) is marginallyhigher than the circular fit. Only extremely eccentric or-bits with e > . Fig. 7.
Bisector spans versus radial velocity measurements(top panel) and orbital phases (bottom panel) as derivedfrom the HARPS data (blue downward and upward tri-angles for EGGS and HARPS modes, respectively). Thehorizontal dotted line marks the average negative value ofthe CCF bisector span, i.e. − .
417 km/s.vantage of the transit fit parameter M / ∗ /R ∗ , from whichthe mean stellar density can be inferred (Sect. 2.2). The ob- Fig. 8.
Phase-folded radial velocity measurements ofCoRoT-11, and Keplerian fit to the data. The horizon-tal dotted line marks the systemic radial velocity V r = − . ± .
041 km/s, as derived from the HARPS/EGGSdata-set only.tained value of M / ∗ /R ∗ depends on the eccentricity of theorbit. We found that for e & . alarm-mode dataonly. Nevertheless, although the HIRES measurementscover only the first half of the transit, they clearly show thatthe Rossiter-McLaughlin (RM) anomaly has been detected,which also confirms the occurrence of the transit events.The RM amplitude is large ( ∼
400 m/s), because of the faststellar rotation. This also proves that the transiting objecthas a planetary size. The first part of the spectroscopic tran-sit shows radial velocities that are blue-shifted compared tothe Keplerian fit, which clearly indicates that the orbit isprograde. In addition, systematics seem to be present in thedata at a level above the expected uncertainties for somemeasurements. It is thus difficult to constrain the spin-orbitangle with the current data. In Fig. 9 we show a modelwith λ = 0 ◦ and v sin i ⋆ = 40 km/s, using the analyticalapproach developed by Ohta et al. (2005). The fit is notsatisfying, suggesting in particular a v sin i ⋆ value higherthan the one we derived from the SOPHIE RV data andthe spectral analysis (Sect. 3.4), in order to have a largeramplitude for the anomaly. It is known that a discrepancycould be found between the v sin i ⋆ values measured fromthe RM effect and from the spectral modelling of line broad-ening, especially for fast rotators (see e.g., Simpson et al.2010). Concerning the spin-orbit angle, the data are com-patible with λ = 0 ◦ . However, as for v sin i ⋆ , the moderatequality of the data-set prohibits accurate measurements.Additional RM observations of CoRoT-11 should be per-formed, with a full coverage of the event. To derive the fundamental atmospheric parameters of theplanet host star, we observed CoRoT-11 with the high-
Fig. 9.
Radial velocities of CoRoT-11 measured with theHIRES spectrograph around the transit that occurred onJuly 1 st , 2010. The left panel shows all the RV data andthe right panel shows a magnification on the transit. Thedashed line shows the Keplerian fit without transit. Thesolid line shows the Rossiter-McLaughlin anomaly fit for λ = 0 ◦ . The vertical dotted lines show the transit firstcontact, mid-time, and fourth contact. The data have beenarbitrarily shifted to the systemic radial velocity of V r = − . ± .
041 km/s (horizontal dotted line), as derivedfrom the HARPS/EGGS data-set only.resolution spectrograph UVES mounted at the 8.2 m VeryLarge Telescope (ESO-VLT; Paranal Observatory, Chile).Two consecutive spectra of 2380 seconds each were acquiredin service mode on 2008 September 17, under the ESO pro-gramme 081.C-0413(C). The star was observed through a0 . ′′ λ ≈ − T eff ), surface gravity (log g ),metallicity ([Fe / H]), and projected rotational velocity( v sin i ⋆ ) of CoRoT-11 were derived following the pro-cedure already adopted for other CoRoT host stars(e.g., Deleuil et al. 2008; Fridlund et al. 2010; Bruntt et al.2010). We took advantage of different spectral analy-sis packages applied independently by different teamswithin the
CoRoT community, e.g., the SME 2.1(Valenti & Piskunov 1996; Valenti & Fischer 2005), theVWA (Bruntt et al. 2004, 2008, 2010) software. We foundthat the estimated values of the above mentioned physicalparameters agree within the error bars. The final adoptedvalues are T eff = 6440 ±
120 K, log g = 4 . ± . / H] = − . ± .
08, and v sin i ⋆ = 40 ± v sin i ⋆ of the star, only 71 Fig. 10.
Small section of the observed UVES spectrum(thin black line) together with the best-fitting synthetictemplate (dashed line). The spectral lines used for theabundance analysis and the neighbouring lines are shownwith black and red colours, respectively. See the online edi-tion of the Journal for a colour version of this figure.lines turned out to be sufficiently isolated and thus suitablefor spectral analysis. A small section of the observed andfitted synthetic spectra is shown in Fig. 10. Abundanceswere computed relative to the Sun to correct the oscillatorstrengths (see Bruntt et al. 2008; Bruntt 2009). We deter-mined the atmospheric parameters by adjusting them tominimise the correlation of iron (Fe) with equivalent width(EW) and excitation potential (EP). Furthermore, we re-quired that Fe i and Fe ii have the same mean abundancewithin the uncertainty. To evaluate the uncertainty on theatmospheric parameters, we perturbed them to determinewhen the correlations of Fe i with EW or EP become sig-nificant or the Fe i and Fe ii abundances deviate by morethan 1 σ (see Bruntt et al. 2008, for details). In Table 3 welist the abundances relative to the Sun for the five elementsNa, Si, Ca, Fe, and Ni.
4. Results
To determine the mass and radius of the CoRoT-11host star we took advantage of the stellar parameter( M / ∗ /R ∗ ) as derived from the CoRoT light curve analysis(Sect. 2.2), and of the effective temperature and metallic-ity ( T eff and [Fe / H]) as obtained from the spectral analysis(Sect. 3.4). We thus compare the location of the star on a log ( M / ∗ /R ∗ ) vs. log ( T eff ) H-R diagram with evolutionarytracks computed with the CESAM code (Morel & Lebreton2008). According to these theoretical models we obtaineda stellar mass of M ⋆ = 1 . ± . M ⊙ and a stellar radiusof R ⋆ = 1 . ± . R ⊙ , with an age of about 2 . ± . g = 4 . ± .
06, in good agreement with the spec-troscopically determined value of log g = 4 . ± .
23. Wealso checked whether the high rotation rate of the star canaccount for a significant flattening at the poles. Accordingto the equation by Claret (2000) and assuming that thestar is seen almost edge-on, the equatorial and polar radiishould differ by only ∼ . Table 3.
Abundances relative to the Sun for five elementsin CoRoT-11. The number of spectral lines used in theVWA abundance analysis are given in the last column.
Element [
A/H ] N Na i − . ± .
15 2Si i . ± .
09 5Si ii . ± .
18 2Ca i . ± .
12 4Fe i − . ± .
08 44Fe ii − . ± .
08 6Ni i − . ± .
11 8 (2008). The seven
BV r ′ i ′ JHKs broad-band magnitudesas retrieved from the
ExoDat database enabled us to con-struct the spectral energy distribution (SED) of CoRoT-11, covering a wide spectral range, from optical to near-infrared wavelengths (see Table 1). Simultaneously usingall the photospheric colours encompassed by the SED, wederived the interstellar extinction to the star ( A V ) by fit-ting the observed SED with a theoretical one progressivelyreddened with an increasing value of A V . The theoreti-cal SEDs were computed with the NextGen stellar atmo-sphere model (Hauschildt et al. 1999) with the same T eff ,log g , and [Fe / H] as the star, the response curve of the
ExoDat photometric system, and the extinction law byCardelli et al. (1989). Assuming a total-to-selective extinc-tion R V = A V /E B − V = 3 . A V = 0 . ± .
10 mag and a distance to thestar d = 560 ±
30 pc (Table 4).We attempted to derive the rotation period of thestar from the
CoRoT light curve. The Lomb-Scargle peri-odogram (Scargle 1982) applied to the out-of transit data-points shows only one significant broad peak at about8 . ± ∼ .
25 %.This period is not compatible with the maximum rotationperiod of 1 . ± .
22 days derived from the projected ro-tational velocity and radius of the planet host star. Thedetected signal at 8 . ± .
02 magperiodic variation of the nearby contaminant star locatedat about 2 ′′ from CoRoT-11 (see Sect. 2.2 and 3.1). On theother hand, a low-level of magnetic activity of CoRoT-11might account for no significant signals at . . ii H & K and Balmer lines.
Based on the stellar mass and radius (Sect. 4.1), the RVcurve semi-amplitude (Sect. 3.3), the planet-to-star radiusratio, and the planet orbit inclination (Sect. 2.2), we de-rived a mass for CoRoT-11b of M p = 2 . ± .
34 M
Jup anda radius of R p = 1 . ± .
03 R
Jup , yielding a mean plan-etary density ρ p = 0 . ± .
15 g/cm . The planet orbitsits host star at a distance of a = 0 . ± .
005 AU in2 . ± . e = 0. According to theresults presented in Sect. 3.3, we cannot exclude a slightlyeccentric orbit, with 0 . e . .
2. Nevertheless, for e = 0 . Fig. 11. v sin i ⋆ distribution of the known extrasolar plan-ets. The position of CoRoT-11b is highlighted with an ar-row.within the error bar of our estimation. A summary of theplanetary parameters derived in the present work is re-ported in Table 4.
5. Discussion
Together with 30 Ari Bb (Guenther et al. 2009),OGLE2-TR-L9b (Snellen et al. 2009), and WASP-33b (Collier Cameron et al. 2010) orbiting a F6 V( v sin i ⋆ = 39 km/s), F3 V ( v sin i ⋆ = 39 . v sin i ⋆ = 90 ±
10 km/s), respectively, CoRoT-11b isthe fourth extrasolar planet discovered around a rapidlyrotating main sequence star ( v sin i ⋆ = 40 ± T eff = 6440 ±
120 K, isone of the hottest stars known to harbour an extrasolarplanet.Most of the bulk of known extrasolar planets have beendetected with the RV method. Although this technique hasdramatically increased the number of discoveries in the lastfifteen years, it suffers from a strong selection bias, becauseit is mostly restricted to planets around slowly rotatingstars ( v sin i ⋆ .
10 km/s). This observational bias limits ourknowledge of extrasolar planets to mainly late-type solar-like stars. One of the big advantages of the transit methodis that it is insensitive to the stellar rotation, enabling usto single out planets even around intermediate-mass stars(Collier Cameron et al. 2010). This allows us to enlarge theparameter space of planet host stars and gives us a chanceto study the planet formation around A and F stars. Evenif CoRoT-11b has been confirmed and studied thanks to acomplementary and intensive RV campaign, it would havelikely been rejected from any RV search sample because ofthe fast rotation of its parent star. Indeed, about 20 RVmeasurements were needed to assess the planetary natureof CoRoT-11b and constrain its mass within ∼
15 %. Butthe RV signature of CoRoT-11b has been detected becauseof its high mass. Taking into account the accuracy of our RVmeasurements (100 −
200 m/s), if the mass of CoRoT-11bhad been M p . . Jup , it would not have been detectedby the RV survey.
Fig. 12.
Semi-major axis versus planetary mass for theknown extrasolar planets detected in radial velocity (trian-gles) and transit surveys (circles). The position of CoRoT-11b is highlighted with an arrow.According to our planetary mass determinations ( M p =2 . ± . Jup . As already noticed by Torres et al.(2010), there seems to be a lack of transiting hot-Jupiterswith masses larger than about 2 M
Jup . Based on the listof currently known transiting planets , hot-Jupiters withmasses in the range 0 . . M p . . Jup seem to be ∼ . . M p . . Jup . This trend is also confirmed by the number ofplanets discovered with the RV method. In Fig. 12 the semi-major axis of the planets detected in radial velocity andtransit surveys is plotted as a function of the planetarymass. Let us consider only the objects with a . . M p & . Jup , i.e., hot-Saturn and Jupiter planets.There is a clear clump of hot-giant planets with massesbetween the mass of Saturn ( ∼ .
30 M
Jup ) and Jupiter, or-biting their parent star at about 0 . − .
06 AU. Startingfrom ∼ . Jup , the number of hot-Jupiters seems todrop off, whereas the spread in the semi-major axis in-creases. For M p & Jup the number of hot-Jupiters fallsoff significantly. The same trend is not seen for planets with1 . a . M p > Jup are significantly less commonthan “normal” hot-Saturn and Jupiter planets.By assuming that CoRoT-11b is a hydrogen-rich gas gi-ant we estimated the planet’s thermal mass loss by apply-ing the method outlined in detail in Lammer et al. (2009).Because the planet orbits a F6-type star with an age be-tween 1.0 and 3.0 Gyr, we used the soft X-rays and EUVflux scaling law of Eq. 12 of Lammer et al. (2009) and in-tegrated the thermal mass loss during the planet’s history We refer the reader to the Extra Solar Planets Encyclopediafor a constantly updated list of known extra solar planets(http://exoplanet.eu/). 11andolfi et al.: The transiting exoplanet CoRoT-11b up to the two age values given above. By using the stel-lar and planetary parameters and a heating efficiency η forhydrogen-rich thermospheres, which can be considered be-tween 10 - 25 % (Lammer et al. 2009; Murray-Clay et al.2009), we obtained a present time mass loss rate for CoRoT-11b of about 2 . × g/s or an integrated loss of 0.07 %of its present mass ( η = 10 %), and about 5 . × g/s,or 0.18 % ( η = 25 %) if the host star and planet are1.0 Gyr old. If the the star/planet system is 3.0 Gyr old,we estimated a mass loss rate of about 3 . × g/s, or0 . η = 10 %) and about 7 . × g/s, or 0.25 %( η = 25 %) during the planet lifetime. These loss ratesagree well with hydrodynamic escape model results for typ-ical hot Jupiters (Yelle et al. 2008). Although the planetradius is 1 . ± .
03 R
Jup , the main reason why the ther-mal mass loss of CoRoT-11b is not significant is related tothe large mass of the planet of 2 . ± .
34 M
Jup . Accordingto Lammer et al. (2009), only hot gas giant planets with ρ p << should experience large thermal mass loss.In order to investigate whether a standard model for anirradiated planet can account for the density of CoRoT-11b, we computed stellar and planetary evolution mod-els using CESAM (Morel & Lebreton 2008) and CEPAM(Guillot & Morel 1995), as described in Bord´e et al. (2010)and Guillot & Havel (2010). The results are shown inFig. 13 where the evolution of the size of CoRoT-11b isplotted as a function of the system age. The colours indicatethe distance in standard deviations from the inferred effec-tive temperature and mean stellar density, i.e., less than1 σ (red), 2 σ (blue) or 3 σ (green). These constraints arecompared to planetary evolution models for a homogeneoussolar-composition hydrogen-planet, with different hypothe-ses: (1) using a “standard model”, i.e., without additionalsources of heat; (2) by increasing interior opacities by afactor 30; (3) by adding a fraction ( ∼ × and 5 × erg/s at the centre of theplanet. The first three cases correspond to standard recipesused to explain the inflated giant exoplanets (Guillot 2008).The last two cases correspond to higher dissipation levelsthat are required to explain the planet size for the oldestages.Interestingly, as for CoRoT-2b (Guillot & Havel 2010),two classes of solutions are found: (i) the standard solu-tion for which the host star is on the main sequence (withan age of about 2 . ± . ± i λ T eff = 6440 ±
120 K), CoRoT-11would belong to the narrow class of F-stars, which havesuffered strong surface lithium depletion during the firstbillion years of their life. Indeed, studies of the lithium con-tent in the photosphere of F-type stars in galactic clustersand field stars have revealed the presence of a narrow dipin the lithium abundance for effective temperature between6500 and 6800 K (Mallik et al. 2003; B¨ohm-Vitense 2004).While the so-called “lithium-dip” is absent in the Pleiades(Pilachowski et al. 1987) and in general in all the young
Fig. 13.
Evolution of the size of CoRoT-11b (in Jupiterunits, 1 R
Jup = 71 492 km) as a function of the age ofthe system (in Ga=10 years). The coloured areas corre-spond to constraints derived from stellar evolutionary mod-els matching the mean stellar density and effective temper-ature within a certain number of standard deviations: lessthan 1 σ (red), 2 σ (blue) or 3 σ (green). The curves are evo-lutionary tracks for CoRoT-11b computed assuming a plan-etary mass of M = 2 .
33 M
Jup and equilibrium temperature T eq = 1657 K), and using different models as labelled (seetext for more details and the online edition of the Journalfor a colour version of this figure).cluster ( .
100 Myr), this dip is well observed in older clus-ter like the Hyades (700 Myr; Boesgaard & Tripicco 1986a),NGC 752 (1 . . ± . Acknowledgements.
We thank the anonymous referee for his/hercareful reading, useful comments, and suggestions, which helped toimprove the manuscript.This paper is based on observations carried out at the EuropeanSouthern Observatory (ESO), La Silla and Paranal (Chile), under ob-serving programs numbers 081.C-0388, 081.C-0413, and 083.C-0186.The authors are grateful to the staff at ESO La Silla and ESO ParanalObservatories for their support and contribution to the success of theHARPS and UVES observing runs.This paper is also based on observations performed with SOPHIEat the Observatoire de Haute-Provence, France, under observing pro-gram PNP.08A.MOUT.Part of the data presented herein were obtained at the W.M.Keck Observatory from telescope time allocated to the NationalAeronautics and Space Administration through the agency’s scien-tific partnership with the California Institute of Technology and theUniversity of California. The Observatory was made possible by thegenerous financial support of the W.M. Keck Foundation. The authorswish to recognize and acknowledge the very significant cultural roleand reverence that the summit of Mauna Kea has always had withinthe indigenous Hawaiian community. We are most fortunate to havethe opportunity to conduct observations from this mountain.The team at IAC acknowledges support by grant ESP2007-65480-C02-02 of the Spanish Ministerio de Ciencia e Innovacion. TheGerman
CoRoT
Team (TLS and the University of Cologne) acknowl-edges DLR grants 50OW0204, 50OW0603, and 50QP07011.This research has made use of the SIMBAD database, operatedat CDS, Strasbourg, France.
Table 4.
CoRoT-11b - Planet and star parameters.
Ephemeris
Planet orbital period P [days] 2 . ± . T tr [HJD-2 400 000] 54597 . ± . d tr [h] 2 . ± . Results from radial velocity observations
Orbital eccentricity e K [m/s] 280 . ± . Fitted transit parameters
Planet-to-star radius ratio k = R p /R ∗ . ± . u + . ± . u − . ± . θ ) − . ± . Deduced transit parameters
Scaled semi-major axis a/R ∗ . ± . M / ∗ /R ∗ [solar units] 0 . ± . ρ ∗ [g/cm ] 0 . ± . i [deg] 83 . ± . a b . ± . Spectroscopic parameters
Effective temperature T eff [K] 6440 ± g b [dex] 4 . ± . g c [dex] 4 . ± . / H] [dex] − . ± . v sin i ⋆ [km/s] 40 . ± . d Stellar physical parameters from combined analysis
Star mass M ⋆ [ M ⊙ ] 1 . ± . R ⋆ [ R ⊙ ] 1 . ± . t [Gyr] 2 . ± . A V [mag] 0 . ± . d [pc] 560 ± Planetary physical parameters from combined analysis
Planet mass M p [M J ] e . ± . R p [R J ] e . ± . ρ p [g/cm ] 0 . ± . a [AU] 0 . ± . f T eq [K] 1657 ± Notes. ( a ) The impact parameter is defined as b = a · cos iR ∗ ( b ) Derived from the spectroscopic analysis. ( c ) Derived using the light curve parameter M / ∗ /R ∗ and the stellar mass as inferred from stellar evolutionary models. ( d ) With an accuracy of ± ( e ) Radius and mass of Jupiter taken as 71492 km and 1.8986 × g, respectively. ( f ) Zero albedo equilibrium temperature for an isotropic planetary emission.
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Rev., 139, 437 List of Objects ‘CoRoT-11b’ on page 2‘CoRoT-11’ on page 2‘HR 5777’ on page 6‘30 Ari Bb’ on page 11‘OGLE2-TR-L9b’ on page 11‘WASP-33b’ on page 11‘Pleiades’ on page 12‘Hyades’ on page 12‘NGC 752’ on page 12 Th¨uringer Landessternwarte, Sternwarte 5, Tautenburg, D-07778 Tautenburg, Germany Research and Scientific Support Department, ESTEC/ESA,PO Box 299, 2200 AG Noordwijk, The Netherlands Institut d’Astrophysique de Paris, UMR7095 CNRS,Universit´e Pierre & Marie Curie, 98bis boulevard Arago,75014 Paris, France Observatoire de l’Universit´e de Gen`eve, 51 chemin desMaillettes, 1290 Sauverny, Switzerland Laboratoire d’Astrophysique de Marseille, 38 rue Fr´ed´ericJoliot-Curie, 13388 Marseille cedex 13, France McDonald Observatory, University of Texas at Austin,Austin, TX 78712, USA Institute of Planetary Research, German Aerospace Center,Rutherfordstrasse 2, 12489 Berlin, Germany Universit´e de Nice-Sophia Antipolis, CNRS UMR 6202,Observatoire de la Cˆote d’Azur, BP 4229, 06304 Nice Cedex4, France Oxford Astrophyiscs, Denys Wilkinson Building, KebleRoad, Oxford OX1 3RH LESIA, Observatoire de Paris, Place Jules Janssen, 92195Meudon cedex, France Institut d’Astrophysique Spatiale, Universit´e Paris XI, F-91405 Orsay, France Observatoire de Haute Provence, 04670 Saint Michell’Observatoire, France LUTH, Observatoire de Paris, CNRS, Universit´e ParisDiderot; 5 place Jules Janssen, 92195 Meudon, France Rheinisches Institut f¨ur Umweltforschung an der Universit¨atzu K¨oln, Aachener Strasse 209, 50931, Germany Instituto de Astrof´ısica de Canarias, E-38205 La Laguna,Tenerife, Spain University of Vienna, Institute of Astronomy,T¨urkenschanzstr. 17, A-1180 Vienna, Austria IAG, University of S˜ao Paulo, Brasil University of Li`ege, All´ee du 6 aoˆut 17, Sart Tilman, Li`ege1, Belgium European Southern Observatory, Alonso de Crdova 3107,Casilla 19001, Santiago de Chile, Chile Space Research Institute, Austrian Academy of Science,Schmiedlstr. 6, A-8042 Graz, Austria School of Physics and Astronomy, Raymond and BeverlySackler Faculty of Exact Sciences, Tel Aviv University, TelAviv, Israel Center for Astronomy and Astrophysics, TU Berlin,Hardenbergstr. 36, 10623 Berlin, Germany Dpto. de Astrof´ısica, Universidad de La Laguna, 38206 LaLaguna, Tenerife, Spain Laboratoire d’Astronomie de Lille, Universit´e de Lille 1, 1impasse de l’Observatoire, 59000 Lille, France25