P. Rojo

Discovery and spectroscopy of the young jovian planet 51 Eri b with the Gemini Planet Imager

An exoplanet extracted from the bright Direct imaging of Jupiter-like exoplanets around young stars provides a glimpse into how our solar system formed. The brightness of young stars requires the use of next-generation devices such as the Gemini Planet Imager (GPI). Using the GPI, Macintosh et al. discovered a Jupiter-like planet orbiting a young star, 51 Eridani (see the Perspective by Mawet). The planet, 51 Eri b, has a methane signature and is probably the smallest exoplanet that has been directly imaged. These findings open the door to understanding solar system origins and herald the dawn of a new era in next-generation planetary imaging. Science, this issue p. 64; see also p. 39 The Gemini Planet Imager detects a Jupiter-like exoplanet orbiting the young star 51 Eridani. [Also see Perspective by Mawet] Directly detecting thermal emission from young extrasolar planets allows measurement of their atmospheric compositions and luminosities, which are influenced by their formation mechanisms. Using the Gemini Planet Imager, we discovered a planet orbiting the ~20-million-year-old star 51 Eridani at a projected separation of 13 astronomical units. Near-infrared observations show a spectrum with strong methane and water-vapor absorption. Modeling of the spectra and photometry yields a luminosity (normalized by the luminosity of the Sun) of 1.6 to 4.0 × 10−6 and an effective temperature of 600 to 750 kelvin. For this age and luminosity, “hot-start” formation models indicate a mass twice that of Jupiter. This planet also has a sufficiently low luminosity to be consistent with the “cold-start” core-accretion process that may have formed Jupiter.

Chromospheric activities and kinematics for solar type dwarfs and subgiants: analysis of the activity distribution and the AVR

Aims. In this work we present chromospheric activity indices, kinematics, radial-velocities, and rotational velocities for more than 850 FGK-type dwarfs and subgiant stars in the southern hemisphere and test how best to calibrate and measure S-indices from echelle spectra. Methods. We measured our parameters using the high-resolution and high-S /N FEROS echelle spectra acquired for this purpose. Results. We confirm the bimodal distribution of chromospheric activities for such stars and highlight the role that the more active K-dwarfs play in biasing the number of active stars. We show that the age-activity relationship does appear to continue to ages older than the Sun if we simply compare main sequence stars and subgiant stars with an offset of around 2.5 Gyr between the peaks of both distributions. Also we show evidence of an increased spin-down timescale for cool K dwarfs compared with earlier F and G type stars. We highlight that activities drawn from low-resolution spectra (R < 2500) significantly increase the rms scatter when calibrating onto common systems of measurements like the Mt. Wilson system. Also we show that older and widely used catalogues —————‐ ‐ ‐ ‐

CE 315: A New Interacting Double-Degenerate Binary Star*

We present spectroscopic observations of object CE 315 revealing a blue continuum with strong emission lines. Most of the detected lines are identified with He I or He II in emission, with a handful of faint lines of nitrogen. Notable is the complete absence of hydrogen lines. The He lines exhibit triple-peaked profiles with remarkably broad widths of ~2000 km s-1 (FWZP). The observations show that CE 315 is an interacting binary system with an orbital period of 65.1 ± 0.7 minutes and a mass ratio of 0.022. We conclude that the most likely scenario for this object is that of an accreting ~0.77 M☉ white dwarf with a ~0.017 M☉ helium white dwarf as mass donor.

Near-infrared integral-field spectra of the planet/brown dwarf companion AB Pictoris b

Context. We have already imaged a co-moving companion at a projected separation of ∼260 AU from the young star AB Pic A. Evolutionary model predictions based on JHK photometry of AB Pic b suggest a mass of ∼13−14 MJup, placing the object at the deuterium-burning boundary. Aims. We aim to determine the spectral type, the surface gravity, and the effective temperature of AB Pic b. From the comparison of our absolute photometry to surface fluxes generated by atmospheric models, we also aim at deriving mass and radius estimates that are independent of evolutionary model predictions to test and refine them. Methods. We used the adaptive-optics-fed integral field spectrograph SINFONI to obtain high-quality, medium-resolution spectra of AB Pic b (Rλ = 1500−2000) over the 1.1−2.5 μm range. Our analysis relie on comparing our spectra to young standard templates and to the latest libraries of synthetic spectra developed by the Lyon group. Results. AB Pic b is confirmed as a young early-L dwarf companion. We derive a spectral type L0–L1 and find several features indicative of an intermediate gravity atmosphere. A comparison to synthetic spectra yields Teff = 2000 +100 −300 K and log(g) = 4 ± 0. 5d ex. Determination of the derived atmospheric parameters of AB Pic b is limited by an imperfect match of current atmosphere spectra with our near-infrared observations of AB Pic b. The current treatment of dust settling and the missing molecular opacity lines in the atmosphere models could be responsible. By combining the observed photometry, the surface fluxes from atmosphere models and the known distance of the system, we derive new mass, luminosity, and radius estimates of AB Pic b. They independently confirm the evolutionary model predictions. We finally review the current methods used for characterizing planetary mass companions and discuss them in the perspective of future planet deep-imaging surveys that will be faced with the same limitations.

Transit Monitoring in the South (TraMoS) Project: Discarding Transit Timing Variations in WASP-5b

We report nine new transit epochs of the extrasolar planet WASP-5b, observed in the Bessell I band with the Southern Astrophysical Research Telescope at the Cerro Pachon Observatory and with the SMARTS 1 m Telescope at the Cerro Tololo Inter-American Observatory, between 2008 August and 2009 October. The new transits have been combined with all previously published transit data for this planet to provide a new Transit Timing Variation (TTV) analysis of its orbit. We find no evidence of TTV rms variations larger than 1 minute over a 3 year time span. This result discards the presence of planets more massive than about 5 M ⊕, 1 M ⊕, and 2 M ⊕ around the 1:2, 5:3, and 2:1 orbital resonances, respectively. These new detection limits exceed by ~5-30 times the limits imposed by current radial velocity observations in the mean motion resonances of this system. Our search for the variation of other parameters, such as orbital inclination and transit depth, also yields negative results over the total time span of the transit observations. This result supports formation theories that predict a paucity of planetary companions to hot Jupiters.

First results from the Calan–Hertfordshire Extrasolar Planet Search: exoplanets and the discovery of an eccentric brown dwarf in the desert

The original article can be found at: http://www3.interscience.wiley.com Copyright Royal Astronomical Society

Hot Jupiters with relatives: discovery of additional planets in orbit around WASP-41 and WASP-47

We report the discovery of two additional planetary companions to WASP-41 and WASP-47. WASP-41 c is a planet of minimum mass 3.18

Study of the impact of the post-MS evolution of the host star on the orbits of close-in planets - I. Sample definition and physical properties

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DETECTION OF PERIOD VARIATIONS IN EXTRASOLAR TRANSITING PLANET OGLE-TR-111b

0.20 M

Millimagnitude Photometry for Transiting Extrasolar Planetary Candidates. III. Accurate Radius and Period for OGLE-TR-111-b*

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