Found 36 talks width keyword exoplanets
Spectroscopic observations of stars do not only provide us with valuable information about the stars themselves, but over the last years such observations have lead to numerous exoplanet discoveries and new insights into planet formation. One important clue emerged at the dawn of the field: the existence of hot Jupiters, gas giants with orbital distances much smaller than an astronomical unit. We and other groups found some of these planets orbiting their stars on highly inclined or even retrograde orbits. I show how the orientation of the stellar axis in relation to the orbital plane (obliquity) reveals the mechanism by which these planets move inwards. Similar measurements in multiple transiting planet systems, with smaller planets will further enhance our understanding of the formation and evolution of planetary systems. In order to take those measurements we need to improve the way we analyze spectra. I present recent results obtained with such a new technique. These include multiple planet systems and results from my "BANANA" survey of close binaries, some of which, such as DI Herculis, also show strong misalignment. The same technique will allow for a reduction of stellar noise in radial velocity surveys, improving our ability to search for smaller, more Earth like planets around bright nearby stars.
Ultracool dwarfs represent the low-mass tail of the distribution of primary masses for which planets can be found with the Kepler satellite. Our team has identified 42 new ultracool dwarfs in the Kepler field of view that have started to be observed with this space telescope via its General Observer and Director Discretionary Time programs. First results of a study of Kepler light curves of 18 very low-mass dwarfs will be presented at this talk. It is demostrated that Kepler is sensitive to moon sized companions of ultracool dwarfs at short orbital periods (few days), and an intriguing candidate will be shown. Results from a ground-based infrared transit survey will also be presented which confirm the lack of Hot Jupiters around very low-mass primaries. Last but not least, a concept for a sustainable hybrid Hypertelescope that would be crucial to follow-up rocky planets will also be introduced.
So far more than 800 planets have been discovered and their
characterization is becoming more important. Transiting planets offer
the unique opportunity of detecting planetary atmospheres, helping to
improve the theoretical models of atmospheric composition under
different physical parameters (densities, irradiation, etc). However,
the precision needed to detect atoms and molecules, requires big
telescopes and stable instruments in order to obtain a good
signal-to-noise. In this talk I'll review the efforts, technical
challenges and current results that our group of Planets and Low Mass
stars is obtaining using GTC to study extra-solar planets.
CARMENES (Calar Alto high-Resolution search for M dwarfs with Exoearths with Near-infrared and optical Échelle Spectrographs) is a next-generation instrument being built for the 3.5m telescope at the Calar Alto Observatory by a consortium of German and Spanish institutions. It consists of two separated spectrographs covering the wavelength ranges from 0.5 to 1.0 mum and from 1.0 to 1.7 mum with spectral resolutions R = 82,000, each of which shall perform high-accuracy radial-velocity measurements (~1 m/s) with long-term stability. The fundamental science objective of CARMENES is to carry out a survey of ~300 late-type main-sequence stars with the goal of detecting low-mass planets in their habitable zones. We aim at being able to detect 2 MEarth planets in the habitable zone of M5V stars. The CARMENES first light is expected to occur in Spring 2014.
We review observations of a representative set of extrasolar planets that transit their stars, concentrating on those discovered and characterized by the XO Project. Spectra of these planets in transit and in eclipse have made significant contributions to our understanding of hot gas giant exoplanets, including 1) evidence for planet-planet scattering to transfer the planets from where they are formed to where we observe them, 2) hot stratospheres of these exoplanets, and two possible mechanisms to maintain them, and 3) water vapor detected in the near-IR spectrum of the exoplanet XO-1b in transit. For the latter case, we compare near-IR spectra obtained with two HST instruments: NICMOS and WFC3 with its new spatial scanning technique. We then present the spectrum of the super-Earth exoplanet GJ 1214b from the visible to the infrared, and focus on the definitive results obtained with HST WFC3 that show a featureless near-IR spectrum, indicative of either a large mean molecular weight in the planet's atmosphere, or obscuring haze (Berta et al. 2012). We identify similar observations that are being made with HST now, and will be made with JWST, and other telescopes in the future. We conclude by summarizing the Transiting Exoplanet Survey Satellite, TESS, which will discover the nearest, transiting rocky exoplanets, those most interesting and most suitable for follow-up characterization of the sort we have presented.
At the end of 2008, on ideas of teams from the Observatoire de la Côte d’Azur (OCA) and IAC, the CoRoT satellite observed the star HD 46375, known to host a non-transiting Saturn-mass exoplanet with a 3.023 day period. HD 46375 is the brightest star with a known close-in planet in the CoRoT accessible field of view. As such, it was targeted by the CoRoT additional program and observed in a CCD normally dedicated to the asteroseismology program, to obtain an ultra-precise photometric lightcurve and detect or place upper limits on the brightness of the planet. In addition, a ground-based support was simultaneously performed with the high-resolution NARVAL spectro-polarimeter to constrain the stellar atmospheric and magnetic properties. In this seminar, I will present the main results, in particular the stellar constrain we obtained thanks to the detection of the oscillation mode signature and the plausible detection of the planetary signal, which, if confirmed with future observations, would be the first detection of phase changes in the visible for a non-transiting planet.
I present a general overview of the PLAnetary Transits and Oscillations of stars (PLATO) space mission. PLATO was approved by ESA’s Science Programme Committee, together with Euclid and Solar Orbiter missions, to enter the so-called definition phase, i.e. the step required before the final decision is taken (only two missions will be implemented). To be launched in 2018, PLATO is a third generation mission, which will take advantage of the scientific return from the currently flying space missions CoRoT (CNES, ESA, launched in 2006), and Kepler (NASA, launched in 2009). Moreover, the preparation and exploitation of the missions will benefit from the GAIA (ESA) mission data, together with new generation ground-based instrumentation like North-HARPS, GIANO, CARMENES, etc. Finally, I summarize the current organization status of the mission,focusing on the Spanish role within the consortium.
AbstractThe RV method is responsible for discovering the majority of planets that orbit stars other than our Sun. However, one problem with this technique is that stellar jitter can cause RV variations that mimic or mask out a planet signature. There have been several instances in the past when stars have shown periodic RV variations which are firstly attributed to a planet and later found to be due to stellar spots, e.g. BD+20 1790 (Figueira, P et al. 2010) and CJ674 (Turnball et al. 204). So far the method of choice to overcome these problems is to avoid observing stars which show levels of high activity. However, this does not solve the problem: it merely avoids it. We have therefore been developing a code which separates out stellar jitter from the RVs to enable active planets to be looked at for planets. I will talk about our technique as well as show some exciting preliminary results.
AbstractThe main goal of the MASTER-Net project is to produce a unique fast sky survey with all sky observed over a single night down to a limiting magnitude of 21. Such a survey will make it possible to address a number of fundamental problems: search for dark energy via the discovery and photometry of supernovae (including SNIa), search for exoplanets, microlensing effects, discovery of minor bodies in the Solar System, and space-junk monitoring. All MASTER telescopes can be guided by alerts, and we plan to observe prompt optical emission from gamma-ray bursts synchronously in several filters and in several polarization planes.
Among the over 450 known exoplanets, the planets that transit their central star stand out, due to the wealth of information that can be gained about both planet and central star. The CoRoT mission has been designed to detect smaller and longer-periodic transiting exoplanets than can be found from ground observations. CoRoT-9b was detected by the satellite in summer 2008 and underwent follow-up observations from ground for another year. It stands out as having the largest periastron distance of all transiting planets, being expected to maintain permanently a moderate surface temperature, estimated between 250 and 430K. It is also the first exoplanet to which planet evolution models can be applied, without uncertain corrections that have been needed for 'hot' transiting planets. These models indicate it to be rather similar to Jupiter. Temperate gas-giant planets with low-to-moderate eccentric orbits constitute the largest group of currently known planets; they are probably similar to the gas giants of the solar system. With CoRoT-9b being this group’s first transiting planet, it may give rise to a much better understanding of these common planets. While CoRoT-9b itself is certainly not habitable, moons around it could be similar to Titan and provide some chance of habitability. Upcoming observations with the Spitzer space telescope are designed to improve on planet parameters and to perform a deeper search for the detection of its moons.
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