Extrasolar planets and brown dwarfs around A–F type stars

Galland, F.; Lagrange, Anne-Marie; Udry, S.; Chelli, A.; Pepe, F.; Beuzit, Jean-Luc; Mayor, M.

doi:10.1051/0004-6361:20054080

Cited by 25 publications

(24 citation statements)

References 18 publications

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“…We take this system as our reference case, since it is still by far the most extensively studied and best known debris disc system. Countless observational and theoretical studies have been dedicated to this system (e.g., the most recent ones: Chen et al 2007;Golimowski et al 2006;Tamura et al 2006;Galland et al 2006;Roberge et al 2006;Fernández et al 2006;Telesco et al 2005;Thébault & Augereau 2005;Brandeker et al 2004;Karmann et al 2003;Augereau et al 2001). The disc has a wide radial extension (up to 1000 AU), but most of the detected dust is thought to reside in a relatively narrow region between 80 and 120 AU (see for example the fit of the scattered and thermal light profiles derived by Augereau et al 2001).…”

Section: A Detailed Example: β Picmentioning

confidence: 99%

Survival of icy grains in debris discs

Grigorieva¹,

Thébault

Artymowicz

et al. 2007

A&A

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Aims. We put theoretical constraints on the presence and survival of icy grains in debris discs. Particular attention is paid to UV sputtering of water ice, which has so far not been studied in detail in this context. Methods. We present a photosputtering model based on available experimental and theoretical studies. We quantitatively estimate the erosion rate of icy and ice-silicate grains, under the influence of both sublimation and photosputtering, as a function of grain size, composition and distance from the star. The effect of erosion on the grain's location is investigated through numerical simulations coupling the grain size to its dynamical evolution. Results. Our model predicts that photodesorption efficiently destroy ice in optically thin discs, even far beyond the sublimation snow line. For the reference case of β Pictoris, we find that only > ∼ 5 mm grains can keep their icy component for the age of the system in the 50-150 AU region. When taking into account the collisional reprocessing of grains, we show that the water ice survival on grains improves (grains down to 20 µm might be partially icy). However, estimates of the amount of gas photosputtering would produce on such a hypothetical population of big icy grains lead to values for the O I column density that strongly exceed observational constraints for β Pic, thus ruling out the presence of a significant amount of icy grains in this system. Erosion rates and icy grains survival timescales are also given for a set of 11 other debris disc systems. We show that, with the possible exception of M stars, photosputtering cannot be neglected in calculations of icy grain lifetimes.

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Section: A Detailed Example: β Picmentioning

confidence: 99%

Survival of icy grains in debris discs

Grigorieva¹,

Thébault

Artymowicz

et al. 2007

A&A

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“…log a-log m phase space for alleged β Pic planet(s). The regions where radial velocity studies exclude a planet are shown in grey (Galland et al 2006). Line: a planet that could cause the observed warp (Mouillet et al 1997).…”

Section: β Pic -A Resonant System?mentioning

confidence: 99%

“…However, a long-standing question whether β Pic also hosts planets remains unanswered. Being an A5V star, β Pic is a difficult target for the radial velocity measurements: the currently achieved precision of hundreds m s −1 barely excludes the presence of a 10 M J planet at 1 AU (Galland et al 2006). The prominent edge-on disk rules out direct imaging.…”

Section: Introductionmentioning

confidence: 99%

Planets ofβ Pictoris revisited

Freistetter¹,

Krivov²,

Löhne³

2007

A&A

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Observations have revealed a large variety of structures (global asymmetries, warps, belts, rings) and dynamical phenomena ("fallingevaporating bodies" or FEBs, the "β Pic dust stream") in the disk of β Pictoris, most of which may indicate the presence of one or more planets orbiting the star. Because planets of β Pic have not been detected by observations yet, we use dynamical simulations to find "numerical evidence" for a planetary system. We show that one planet at 12 AU with a mass of 2 to 5 M J and an eccentricity < ∼ 0.1 can probably already account for three major features (main warp, two inner belts, FEBs) observed in the β Pic disk. The existence of at least two additional planets at about 25 AU and 45 AU from the star seems likely. We find rather strong upper limits of 0.6 M J and 0.2 M J on the masses of those planets. The same planets could, in principle, also account for the outer rings observed at 500−800 AU.

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“…Silicate dust is observed as circumstellar rings at 6, 16, and 30 AU from the star (Okamoto et al 2004), which could be explained by the presence of a 2−5-Jovian-mass (M Jup ) planet at ∼10 AU from the star (Freistetter et al 2007). Evaporating star-grazing comets have been identified (see, e.g., Lagrange et al 2000, for a review) and dynamical simulations have shown that the gravitational perturbation of at least one giant planet at ∼10 AU can account for the observed rate of evaporating bodies (Beust & Morbidelli 2000); however, no planets have been detected so far, either through direct imaging or through radial velocity studies, due to the instrumental limitations of both techniques (Galland et al 2006). In particular, the high spatial resolution imaging detection capabilities have so far been limited to distances typically of > ∼ 15−20 AU.…”

Section: Introductionmentioning

confidence: 99%

A probable giant planet imaged in the β Pictoris disk

Lagrange¹,

Gratadour

Chauvin³

et al. 2008

A&A

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473

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Context. Since the discovery of its dusty disk in 1984, β Pictoris has become the prototype of young early-type planetary systems, and there are now various indications that a massive Jovian planet is orbiting the star at ∼10 AU. However, no planets have been detected around this star so far. Aims. Our goal was to investigate the close environment of β Pic, searching for planetary companion(s). Methods. Deep adaptive-optics L -band images of β Pic were recorded using the NaCo instrument at the Very Large Telescope. Results. A faint point-like signal is detected at a projected distance of 8 AU from the star, within the northeastern extension of the dust disk. Various tests were made to rule out possible instrumental or atmospheric artefacts at a good confidence level. The probability of a foreground or background contaminant is extremely low, based in addition on the analysis of previous deep HST images. Its L = 11.2 apparent magnitude would indicate a typical temperature of ∼1500 K and a mass of ∼8 M Jup . If confirmed, it could explain the main morphological and dynamical peculiarities of the β Pic system. The present detection is unique among A-stars by the proximity of the resolved planet to its parent star. Its closeness and location inside the β Pic disk suggest a formation process by core accretion or disk instabilities rather than binary-like formation processes.

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Extrasolar planets and brown dwarfs around A–F type stars

Cited by 25 publications

References 18 publications

Survival of icy grains in debris discs

Survival of icy grains in debris discs

Planets ofβ Pictoris revisited

A probable giant planet imaged in the β Pictoris disk

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