Occultation by (136199) Eris

in International Astronomical Union Circulars [=IAUCs] (2010), 9184

E. Jehin, J. Manfroid, M. Gillon, D. Hutsemekers, and P. Magain report that they observed an occultation of a star of magnitude I about 15.2 by the dwarf planet Eris (then at V about 18.7) on Nov. 6 using ... [more ▼]

E. Jehin, J. Manfroid, M. Gillon, D. Hutsemekers, and P. Magain report that they observed an occultation of a star of magnitude I about 15.2 by the dwarf planet Eris (then at V about 18.7) on Nov. 6 using the new telescope TRAPPIST at the European Southern Observatory (La Silla). A series of 3-s exposures of a field of size 3' x 3' (1".3/pixel) were secured in fast-readout mode (with a deadtime of 1.5 s), starting at 01h50m UT for one hour. Seven frames centered at 02h19m34s UT allowed them to derive the start of the occultation as 02h19m16s.75 +/- 0s.75 and the end as 02h19m47s.6 +/- 0s.2, for a total occultation time of 30.4 +/- 1.0 seconds. The predictions (see above) made by the Rio de Janeiro group (Assafin et al., Nov. 5) and by J. L. Ortiz estimated the time of the occultation around 02h18m UT for Chile, in good agreement with the observations. During the occultation, a point source is detected with a magnitude corresponding to that of Eris. A small flux increase was also seen at the middle of the occultation, which might result from refraction in Eris' atmosphere (Elliot and Olkin 1996, Ann. Rev. Earth Planet. Sci. 24, 89). Eris is by far the most-remote solar-system object observed to date via stellar occultation, with a geocentric distance of about 96 AU. TRAPPIST is a project driven by the University of Liege, in close collaboration with the Observatory of Geneva, supported by the Belgian Fund for Scientific Research and the Swiss National Science Foundation. [less ▲]

The 3/4 July 2010 Pluto Stellar-Occultation Observations

in Bulletin of the American Astronomical Society (2010, October 01), 42

Continuing our monitoring of Pluto's atmospheric temperature and pressure, previously shown by us to be increasing (Elliot et al., Nature 424, 165, 2003; Pasachoff et al., AJ 129, 1718, 2005) and ... [more ▼]

Continuing our monitoring of Pluto's atmospheric temperature and pressure, previously shown by us to be increasing (Elliot et al., Nature 424, 165, 2003; Pasachoff et al., AJ 129, 1718, 2005) and subsequently found by us to be leveling off (Elliot et al., AJ 134, 1, 2007), we report on a stellar occultation by Pluto of UCAC2 mag=15.3, observed from South America and Africa on 4 July 2010 UT. Success was achieved with a 0.45 m at Cerro Calan using one of our POETS (Portable Occultation, Eclipse, and Transit System; Souza et al. PASP 118, 1550, 2006), a 1.0 SMARTS (Small and Medium Aperture Research Telescope System) at Cerro Tololo, four 0.6 m telescopes of PROMPT (Panchromatic Robotic Optical Monitoring and Polarimetry Telescopes) on Cerro Tololo, and TRAPPIST's (TRansiting Planets and Planetesimals Small Telescope) 0.6-m telescope on La Silla in Chile; the 0.35 m telescope of U. Ponta Grossa, Brazil; and the 0.75-m ATOM (Automatic Telescope for Optical Monitoring), Namibia, using POETS. Winds prevented opening the 6.5 m Magellan/Clay telescope on Las Campanas, Chile, with its own frame-transfer camera, and clouds obscured the 1.9 m telescope at Sutherland, South Africa, which had POETS. With shadow velocity 23.6 km/s, it was a rapid event: maximum occultation <2 minutes. The observations were supported in part by grants NNX08AO50G to Williams College and NNX10AB27G to MIT from NASA's Planetary Astronomy Division, and NNH08AI17I to USNO for astrometry. Student participation was supported in part by NASA's Massachusetts Space Grant and NSF's REU. Japan's government donated U. Chile's Cerro Calan Goto telescope. PROMPT observations were made possible by the Robert Martin Ayers Science Fund. TRAPPIST is a project driven by the University of Liège, in close collaboration with the Observatory of Geneva, supported by the Belgian Fund for Scientific Research and the Swiss National Science Foundation. [less ▲]

The Spitzer search for the transits of HARPS low-mass planets - I. No transit for the super-Earth HD 40307b

in Astronomy and Astrophysics (2010), 518(A25),

We used Spitzer and its IRAC camera to search for the transit of the super-Earth HD 40307b. The hypothesis that the planet transits could not be firmly discarded from our first photometric monitoring of a ... [more ▼]

We used Spitzer and its IRAC camera to search for the transit of the super-Earth HD 40307b. The hypothesis that the planet transits could not be firmly discarded from our first photometric monitoring of a transit window because of the uncertainty coming from the modeling of the photometric baseline. To obtain a firm result, two more transit windows were observed and a global Bayesian analysis of the three IRAC time series and the HARPS radial velocities was performed. Unfortunately, the hypothesis that the planet transited during the observed phase window is firmly rejected, while the probability that the planet does transit but that the eclipse was missed by our observations is nearly negligible (0.26%). [less ▲]

The Power of Deconvolution for Study of QSO Host Galaxies

in Proceedings of the International Astronomical Union, IAU Symposium (2010, May 01), Vol 267

The major challenge in studying QSO host galaxies is to remove the QSO contribution, which often outshines the whole system. Our group has acquired the technical ability to handle such data, for images ... [more ▼]

The major challenge in studying QSO host galaxies is to remove the QSO contribution, which often outshines the whole system. Our group has acquired the technical ability to handle such data, for images and slit spectroscopy, as well as integral field spectroscopy. We review here the major techniques developed by our team, and their latest applications. We are open for collaboration with other teams to spread the use of these powerful techniques. [less ▲]

The thermal emission of the young and massive planet CoRoT-2b at 4.5 and 8 μm

in Astronomy and Astrophysics (2010), 511

We report measurements of the thermal emission of the young and massive planet CoRoT-2b at 4.5 and 8 microns with the Spitzer Infrared Array Camera (IRAC). Our measured occultation depths are 0.510 +- 0 ... [more ▼]

We report measurements of the thermal emission of the young and massive planet CoRoT-2b at 4.5 and 8 microns with the Spitzer Infrared Array Camera (IRAC). Our measured occultation depths are 0.510 +- 0.042 % and 0.41 +- 0.11 % at 4.5 and 8 microns, respectively. In addition to the CoRoT optical measurements, these planet/star flux ratios indicate a poor heat distribution to the night side of the planet and are in better agreement with an atmosphere free of temperature inversion layer. Still, the presence of such an inversion is not definitely ruled out by the observations and a larger wavelength coverage is required to remove the current ambiguity. Our global analysis of CoRoT, Spitzer and ground-based data confirms the large mass and size of the planet with slightly revised values (Mp = 3.47 +- 0.22 Mjup, Rp = 1.466 +- 0.044 Rjup). We find a small but significant offset in the timing of the occultation when compared to a purely circular orbital solution, leading to e cos(omega) = -0.00291 +- 0.00063 where e is the orbital eccentricity and omega is the argument of periastron. Constraining the age of the system to be at most of a few hundreds of Myr and assuming that the non-zero orbital eccentricity is not due to a third undetected body, we model the coupled orbital-tidal evolution of the system with various tidal Q values, core sizes and initial orbital parameters. For log(Q_s') = 5 - 6, our modelling is able to explain the large radius of CoRoT-2b if log(Q_p') <= 5.5 through a transient tidal circularization and corresponding planet tidal heating event. Under this model, the planet will reach its Roche limit within 20 Myr at most. [less ▲]

Transiting exoplanets from the CoRoT space mission IX. CoRoT-6b: a transiting `hot Jupiter' planet in an 8.9d orbit around a low-metallicity star

in Astronomy and Astrophysics (2010), 512

The CoRoT satellite exoplanetary team announces its sixth transiting planet in this paper. We describe and discuss the satellite observations as well as the complementary ground-based observations ... [more ▼]

The CoRoT satellite exoplanetary team announces its sixth transiting planet in this paper. We describe and discuss the satellite observations as well as the complementary ground-based observations - photometric and spectroscopic - carried out to assess the planetary nature of the object and determine its specific physical parameters. The discovery reported here is a `hot Jupiter' planet in an 8.9d orbit, 18 stellar radii, or 0.08 AU, away from its primary star, which is a solar-type star (F9V) with an estimated age of 3.0 Gyr. The planet mass is close to 3 times that of Jupiter. The star has a metallicity of 0.2 dex lower than the Sun, and a relatively high $^7$Li abundance. While thelightcurveindicatesamuchhigherlevelof activity than, e.g., the Sun, there is no sign of activity spectroscopically in e.g., the [Ca ] H&K lines. [less ▲]

Planetary transit candidates in Corot-IRa01 field

in Astronomy and Astrophysics (2009), 506

Context: CoRoT is a pioneering space mission devoted to the analysis of stellar variability and the photometric detection of extrasolar planets. <BR />Aims: We present the list of planetary transit ... [more ▼]

Context: CoRoT is a pioneering space mission devoted to the analysis of stellar variability and the photometric detection of extrasolar planets. <BR />Aims: We present the list of planetary transit candidates detected in the first field observed by CoRoT, IRa01, the initial run toward the Galactic anticenter, which lasted for 60 days. <BR />Methods: We analysed 3898 sources in the coloured bands and 5974 in the monochromatic band. Instrumental noise and stellar variability were taken into account using detrending tools before applying various transit search algorithms. <BR />Results: Fifty sources were classified as planetary transit candidates and the most reliable 40 detections were declared targets for follow-up ground-based observations. Two of these targets have so far been confirmed as planets, CoRoT-1b and CoRoT-4b, for which a complete characterization and specific studies were performed. The CoRoTâ space mission, launched on December 27th 2006, has been developed and is operated by CNES, with contributions from Austria, Belgium, Brazil, ESA, Germany, and Spain. Four French laboratories associated with the CNRS (LESIA, LAM, IAS ,OMP) collaborate with CNES on the satellite development. First CoRoT data are available to the public from the CoRoT archive: http://idoc-corot.ias.u-psud.fr. [less ▲]

Planetary transit candidates in CoRoT-LRc01 field

in Astronomy and Astrophysics (2009), 506

Aims: We present here the list of planetary transit candidates detected in the first long run observed by CoRoT: LRc01, towards the galactic center in the direction of Aquila, which lasted from May to ... [more ▼]

Aims: We present here the list of planetary transit candidates detected in the first long run observed by CoRoT: LRc01, towards the galactic center in the direction of Aquila, which lasted from May to October 2007. <BR />Methods: we analyzed 3719 (33%) sources in the chromatic bands and 7689 in the monochromatic band. Instrumental noise and the stellar variability were treated with several detrending tools, on which subsequently several transit search algorithms were applied. <BR />Results: Forty two sources were classified as planetary transit candidates and up to now 26 cases have been solved. One planet (CoRoT-2b) and one brown-dwarf (CoRoT-3b) have been the subjects of detailed publications. The CoRoT space mission, launched on December 27 2006, was developed and is operated by CNES, with contributions from Austria, Belgium, Brazil, ESA, Germany and Spain. The first CoRoT data are available to the community from the CoRoT archive: http://idoc-corot.ias.u-psud.fr. [less ▲]

The CoRoT-7 planetary system: two orbiting super-Earths

in Astronomy and Astrophysics (2009), 506

We report on an intensive observational campaign carried out with HARPS at the 3.6 m telescope at La Silla on the star CoRoT-7. Additional simultaneous photometric measurements carried out with the Euler ... [more ▼]

We report on an intensive observational campaign carried out with HARPS at the 3.6 m telescope at La Silla on the star CoRoT-7. Additional simultaneous photometric measurements carried out with the Euler Swiss telescope have demonstrated that the observed radial velocity variations are dominated by rotational modulation from cool spots on the stellar surface. Several approaches were used to extract the radial velocity signal of the planet(s) from the stellar activity signal. First, a simple pre-whitening procedure was employed to find and subsequently remove periodic signals from the complex frequency structure of the radial velocity data. The dominant frequency in the power spectrum was found at 23 days, which corresponds to the rotation period of CoRoT-7. The 0.8535 day period of CoRoT-7b planetary candidate was detected with an amplitude of 3.3 m s[SUP]-1[/SUP]. Most other frequencies, some with amplitudes larger than the CoRoT-7b signal, are most likely associated with activity. A second approach used harmonic decomposition of the rotational period and up to the first three harmonics to filter out the activity signal from radial velocity variations caused by orbiting planets. After correcting the radial velocity data for activity, two periodic signals are detected: the CoRoT-7b transit period and a second one with a period of 3.69 days and an amplitude of 4 m s[SUP]-1[/SUP]. This second signal was also found in the pre-whitening analysis. We attribute the second signal to a second, more remote planet CoRoT-7c . The orbital solution of both planets is compatible with circular orbits. The mass of CoRoT-7b is 4.8±0.8 (M[SUB]â [/SUB]) and that of CoRoT-7c is 8.4± 0.9 (M[SUB]â [/SUB]), assuming both planets are on coplanar orbits. We also investigated the false positive scenario of a blend by a faint stellar binary, and this may be rejected by the stability of the bisector on a nightly scale. According to their masses both planets belong to the super-Earth planet category. The average density of CoRoT-7b is Ï =5.6± 1.3 g cm[SUP]-3[/SUP], similar to the Earth. The CoRoT-7 planetary system provides us with the first insight into the physical nature of short period super-Earth planets recently detected by radial velocity surveys. These planets may be denser than Neptune and therefore likely made of rocks like the Earth, or a mix of water ice and rocks. Based on observations made with HARPS spectrograph on the 3.6-m ESO telescope and the EULER Swiss telescope at La Silla Observatory, Chile. The HARPS results presented in this paper (Appendix A) are available in electronic form at http://www.aanda.org and 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/506/303 [less ▲]

Rate and nature of false positives in the CoRoT exoplanet search

in Astronomy and Astrophysics (2009), 506

Context: The CoRoT satellite searches for planets by applying the transit method, monitoring up to 12 000 stars in the galactic plane for 150 days in each observing run. This search is contaminated by a ... [more ▼]

Context: The CoRoT satellite searches for planets by applying the transit method, monitoring up to 12 000 stars in the galactic plane for 150 days in each observing run. This search is contaminated by a large fraction of false positives, caused by different eclipsing binary configurations that might be confused with a transiting planet. <BR />Aims: We evaluate the rates and nature of false positives in the CoRoT exoplanets search and compare our results with semiempirical predictions. <BR />Methods: We consider the detected binary and planet candidates in the first three extended CoRoT runs, and classify the results of the follow-up observations completed to verify their planetary nature. We group the follow-up results into undiluted binaries, diluted binaries, and planets and compare their abundances with predictions from the literature. <BR />Results: 83% of the initial detections are classified as false positives using only the CoRoT light-curves, the remaining 17% require follow-up observations. Finally, 12% of the candidates in the follow-up program are planets. The shape of the overall distribution of the false positive rate follows previous predictions, except for candidates with transit depths below about 0.4%. For candidates with transit depths in the range from 0.1-0.4%, CoRoT detections are nearly complete, and this difference from predictions is probably real and dominated by a lower than expected abundance of diluted eclipsing binaries. The CoRoT space mission, launched on December 27th 2006, has been developed and is operated by CNES, with the contribution of Austria, Belgium, Brazil , ESA (RSSD and Science Programme), Germany and Spain. [less ▲]