The frequency of giant planets around metal-poor stars

Mortier, A.; Santos, N. C.; Sozzetti, A.; Mayor, M.; Latham, David W.; Bonfils, X.; Udry, S.

doi:10.1051/0004-6361/201118651

Cited by 67 publications

(92 citation statements)

References 50 publications

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“…In all the plots, the dotted and dashed horizontal lines denote the 10% and 1% false-alarm probability levels, respectively. These were derived using a permutation test as done in Mortier et al (2012). No significant signal appeared in any of the variables.…”

Section: Radial-velocity Fittingmentioning

confidence: 99%

“…We also computed the detection limits for additional planets in the system. For this we analysed the residuals of the fit presented above, using a Monte Carlo approach similar to the one used in Mortier et al (2012). In brief, for each period we injected signals in the best-fit residuals, assuming circular orbits, with varying amplitudes until the false-alarm probability of the detection was higher than 1%.…”

Section: Radial-velocity Fittingmentioning

confidence: 99%

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An extreme planetary system around HD 219828

Santos

Santerne

Faria

et al. 2016

A&A

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Context. With about 2000 extrasolar planets confirmed, the results show that planetary systems have a whole range of unexpected properties. This wide diversity provides fundamental clues to the processes of planet formation and evolution. Aims. We present a full investigation of the HD 219828 system, a bright metal-rich star for which a hot Neptune has previously been detected. Methods. We used a set of HARPS, SOPHIE, and ELODIE radial velocities to search for the existence of orbiting companions to HD 219828. The spectra were used to characterise the star and its chemical abundances, as well as to check for spurious, activity induced signals. A dynamical analysis is also performed to study the stability of the system and to constrain the orbital parameters and planet masses. Results. We announce the discovery of a long period (P = 13.1 yr) massive (m sin i = 15.1 M Jup ) companion (HD 219828 c) in a very eccentric orbit (e = 0.81). The same data confirms the existence of a hot Neptune, HD 219828 b, with a minimum mass of 21 M ⊕ and a period of 3.83 days. The dynamical analysis shows that the system is stable, and that the equilibrium eccentricity of planet b is close to zero. Conclusions. The HD 219828 system is extreme and unique in several aspects. First, ammong all known exoplanet systems it presents an unusually high mass ratio. We also show that systems like HD 219828, with a hot Neptune and a long-period massive companion are more frequent than similar systems with a hot Jupiter instead. This suggests that the formation of hot Neptunes follows a different path than the formation of their hot jovian counterparts. The high mass, long period, and eccentricity of HD 219828 c also make it a good target for Gaia astrometry as well as a potential target for atmospheric characterisation, using direct imaging or high-resolution spectroscopy. Astrometric observations will allow us to derive its real mass and orbital configuration. If a transit of HD 219828 b is detected, we will be able to fully characterise the system, including the relative orbital inclinations. With a clearly known mass, HD 219828 c may become a benchmark object for the range in between giant planets and brown dwarfs.

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Section: Radial-velocity Fittingmentioning

confidence: 99%

Section: Radial-velocity Fittingmentioning

confidence: 99%

An extreme planetary system around HD 219828

Santos

Santerne

Faria

et al. 2016

A&A

Self Cite

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“…Another consideration is a sudden lack of giant planets. Mortier et al (2012) suggested that there may be a lower limit in metallicity below which no giant planets can be formed. This lower limit is represented by parameter e. Option 5 takes both the constant and the stop into account, while options 6 and 7 take only the constant, resp.…”

Section: Functional Formsmentioning

confidence: 99%

“…Their suggestion has been discarded by Johnson et al (2010), based on a Bayesian analysis on a large SPOCS sample. Recently, it has also been suggested that there may be a lower limit below which no giant planets can be formed anymore (Mortier et al 2012). The issue of giant planet frequency dependence on stellar properties is still not resolved.…”

Section: Introductionmentioning

confidence: 99%

On the functional form of the metallicity-giant planet correlation

Mortier

Santos

Sousa

et al. 2013

A&A

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Context. It is generally accepted that the presence of a giant planet is strongly dependent on the stellar metallicity. A stellar mass dependence has also been investigated, but this dependence does not seem as strong as the metallicity dependence. Even for metallicity, however, the exact form of the correlation has not been established. Aims. In this paper, we test several scenarios for describing the frequency of giant planets as a function of its host parameters. We perform this test on two volume-limited samples (from CORALIE and HARPS). Methods. By using a Bayesian analysis, we quantitatively compared the different scenarios. Results. We confirm that giant planet frequency is indeed a function of metallicity. However, there is no statistical difference between a constant or an exponential function for stars with subsolar metallicities contrary to what has been previously stated in the literature. The dependence on stellar mass could neither be confirmed nor be discarded.

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“…A well-established direct dependence exists between the occurrence rate of giant planets and the metal content of their main-sequence hosts (Gonzalez 1997;Butler et al 2000;Laws et al 2003;Santos et al 2004;Fischer & Valenti 2005;Udry & Santos 2007;Sozzetti et al 2009;Mortier et al 2012). …”

Section: Introductionmentioning

confidence: 99%

The GAPS programme with HARPS-N at TNG

Biazzo

Gratton

Desidera

et al. 2015

A&A

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Binary stars hosting exoplanets are a unique laboratory where chemical tagging can be performed to measure the elemental abundances of both stellar components with high accuracy, with the aim to investigate the formation of planets and their subsequent evolution. Here, we present a high-precision differential abundance analysis of the XO-2 wide stellar binary based on high-resolution HARPS-N at TNG spectra. Both components are very similar K-dwarfs and host planets. Since they formed presumably within the same molecular cloud, we expect that they possess the same initial elemental abundances. We investigated whether planets can cause some chemical imprints in the stellar atmospheric abundances. We measure abundances of 25 elements for both stars with a range of condensation temperature T C = 40−1741 K, achieving typical precisions of ∼0.07 dex. The northern component shows abundances in all elements higher by +0.067 ± 0.032 dex on average, with a mean difference of +0.078 dex for elements with T C > 800 K. The significance of the XO-2N abundance difference relative to XO-2S is at the 2σ level for almost all elements. We discuss that this result might be interpreted as the signature of the ingestion of material by XO-2N or depletion in XO-2S that is due to locking of heavy elements by the planetary companions. We estimate a mass of several tens of M ⊕ in heavy elements. The difference in abundances between XO-2N and XO-2S shows a positive correlation with the condensation temperatures of the elements, with a slope of (4.7 ± 0.9) × 10 −5 dex K −1 , which could mean that both components have not formed terrestrial planets, but first experienced the accretion of rocky core interior to the subsequent giant planets.

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The frequency of giant planets around metal-poor stars

Cited by 67 publications

References 50 publications

An extreme planetary system around HD 219828

An extreme planetary system around HD 219828

On the functional form of the metallicity-giant planet correlation

The GAPS programme with HARPS-N at TNG

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