The frequency of giant planets around metal-poor stars

A. Mortier; N. C. Santos; A. Sozzetti; M. Mayor; D. Latham; X. Bonfils; S. Udry

doi:10.1051/0004-6361/201118651

The frequency of giant planets around metal-poor stars

A. Mortier^*, N. C. Santos, A. Sozzetti, M. Mayor, D. Latham, X. Bonfils, S. Udry

^*Corresponding author for this work

Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

40 Citations (Scopus)

Abstract

Context.The discovery of about 700 extrasolar planets, so far, has lead to the first statistics concerning extrasolar planets. The presence of giant planets seems to depend on stellar metallicity and mass. For example, they are more frequent around metal-rich stars, with an exponential increase in planet occurrence rates with metallicity. Aims.We analyzed two samples of metal-poor stars (-2.0 ≤ [Fe/H] ≤2. 0.0) to see if giant planets are indeed rare around these objects. Radial velocity datasets were obtained with two different spectrographs (HARPS and HIRES). Detection limits for these data, expressed in minimum planetary mass and period, are calculated. These produce trustworthy numbers for the planet frequency. Methods.A general Lomb-Scargle (GLS) periodogram analysis was used together with a bootstrapping method to produce the detection limits. Planet frequencies were calculated based on a binomial distribution function within metallicity bins. Results.Almost all hot Jupiters and most giant planets should have been found in these data. Hot Jupiters around metal-poor stars have a frequency lower than 1.0% at one sigma. Giant planets with periods up to 1800 days, however, have a higher frequency of f _p = 2.63 ^+2.5 _-0.8%. Taking into account the different metallicities of the stars, we show that giant planets appear to be very frequent ( f _p = 4.48 ^+4.04 _-1.38%) around stars with [Fe/H] >-0.7, while they are rare around stars with [Fe/H] ≤-0.7 (≤2.36% at one sigma). Conclusions. Giant planet frequency is indeed a strong function of metallicity, even in the low-metallicity tail. However, the frequencies are most likely higher than previously thought.

Original language	English
Article number	A45
Journal	Astronomy and Astrophysics
Volume	543
DOIs	https://doi.org/10.1051/0004-6361/201118651
Publication status	Published - 2012

Bibliographical note

Funding Information:
The data presented herein are based on observations collected at the La Silla Parana Observatory, ESO (Chile) with the HARPS spectrograph at the 3.6-m telescope (ESO runs ID 72.C-0488, 082.C-0212, and 085.C-0063) and at the W. M. Keck Observatory that is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. This Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

Funding Information:
We thank the ananymous referee for his/her useful comments. This work was supported by the European Research Council/European Community under the FP7 through Starting Grant agreement number 239953. N.C.S. also acknowledges the support from Fundação para a Ciência e a Tecnologia (FCT) through program Ciência 2007 funded by FCT/MCTES (Portugal) and POPH/FSE (EC), and in the form of grants reference PTDC/CTE-AST/098528/2008 and PTDC/CTE-AST/09860/2008.

Keywords

Planetary systems
Planets and satellites: formation
Stars: abundances
Stars: statistics
Techniques: radial velocities

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.1051/0004-6361/201118651

Cite this

@article{b2a72a217ba3462b942b2da1b5227b83,

title = "The frequency of giant planets around metal-poor stars",

abstract = "Context.The discovery of about 700 extrasolar planets, so far, has lead to the first statistics concerning extrasolar planets. The presence of giant planets seems to depend on stellar metallicity and mass. For example, they are more frequent around metal-rich stars, with an exponential increase in planet occurrence rates with metallicity. Aims.We analyzed two samples of metal-poor stars (-2.0 ≤ [Fe/H] ≤2. 0.0) to see if giant planets are indeed rare around these objects. Radial velocity datasets were obtained with two different spectrographs (HARPS and HIRES). Detection limits for these data, expressed in minimum planetary mass and period, are calculated. These produce trustworthy numbers for the planet frequency. Methods.A general Lomb-Scargle (GLS) periodogram analysis was used together with a bootstrapping method to produce the detection limits. Planet frequencies were calculated based on a binomial distribution function within metallicity bins. Results.Almost all hot Jupiters and most giant planets should have been found in these data. Hot Jupiters around metal-poor stars have a frequency lower than 1.0% at one sigma. Giant planets with periods up to 1800 days, however, have a higher frequency of f p = 2.63 +2.5 -0.8%. Taking into account the different metallicities of the stars, we show that giant planets appear to be very frequent ( f p = 4.48 +4.04 -1.38%) around stars with [Fe/H] >-0.7, while they are rare around stars with [Fe/H] ≤-0.7 (≤2.36% at one sigma). Conclusions. Giant planet frequency is indeed a strong function of metallicity, even in the low-metallicity tail. However, the frequencies are most likely higher than previously thought.",

keywords = "Planetary systems, Planets and satellites: formation, Stars: abundances, Stars: statistics, Techniques: radial velocities",

author = "A. Mortier and Santos, {N. C.} and A. Sozzetti and M. Mayor and D. Latham and X. Bonfils and S. Udry",

note = "Funding Information: The data presented herein are based on observations collected at the La Silla Parana Observatory, ESO (Chile) with the HARPS spectrograph at the 3.6-m telescope (ESO runs ID 72.C-0488, 082.C-0212, and 085.C-0063) and at the W. M. Keck Observatory that is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. This Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Funding Information: We thank the ananymous referee for his/her useful comments. This work was supported by the European Research Council/European Community under the FP7 through Starting Grant agreement number 239953. N.C.S. also acknowledges the support from Funda{\c c}{\~a}o para a Ci{\^e}ncia e a Tecnologia (FCT) through program Ci{\^e}ncia 2007 funded by FCT/MCTES (Portugal) and POPH/FSE (EC), and in the form of grants reference PTDC/CTE-AST/098528/2008 and PTDC/CTE-AST/09860/2008.",

year = "2012",

doi = "10.1051/0004-6361/201118651",

language = "English",

volume = "543",

journal = "Astronomy and Astrophysics",

issn = "0004-6361",

publisher = "EDP Sciences",

}

TY - JOUR

T1 - The frequency of giant planets around metal-poor stars

AU - Mortier, A.

AU - Santos, N. C.

AU - Sozzetti, A.

AU - Mayor, M.

AU - Latham, D.

AU - Bonfils, X.

AU - Udry, S.

N1 - Funding Information: The data presented herein are based on observations collected at the La Silla Parana Observatory, ESO (Chile) with the HARPS spectrograph at the 3.6-m telescope (ESO runs ID 72.C-0488, 082.C-0212, and 085.C-0063) and at the W. M. Keck Observatory that is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. This Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Funding Information: We thank the ananymous referee for his/her useful comments. This work was supported by the European Research Council/European Community under the FP7 through Starting Grant agreement number 239953. N.C.S. also acknowledges the support from Fundação para a Ciência e a Tecnologia (FCT) through program Ciência 2007 funded by FCT/MCTES (Portugal) and POPH/FSE (EC), and in the form of grants reference PTDC/CTE-AST/098528/2008 and PTDC/CTE-AST/09860/2008.

PY - 2012

Y1 - 2012

N2 - Context.The discovery of about 700 extrasolar planets, so far, has lead to the first statistics concerning extrasolar planets. The presence of giant planets seems to depend on stellar metallicity and mass. For example, they are more frequent around metal-rich stars, with an exponential increase in planet occurrence rates with metallicity. Aims.We analyzed two samples of metal-poor stars (-2.0 ≤ [Fe/H] ≤2. 0.0) to see if giant planets are indeed rare around these objects. Radial velocity datasets were obtained with two different spectrographs (HARPS and HIRES). Detection limits for these data, expressed in minimum planetary mass and period, are calculated. These produce trustworthy numbers for the planet frequency. Methods.A general Lomb-Scargle (GLS) periodogram analysis was used together with a bootstrapping method to produce the detection limits. Planet frequencies were calculated based on a binomial distribution function within metallicity bins. Results.Almost all hot Jupiters and most giant planets should have been found in these data. Hot Jupiters around metal-poor stars have a frequency lower than 1.0% at one sigma. Giant planets with periods up to 1800 days, however, have a higher frequency of f p = 2.63 +2.5 -0.8%. Taking into account the different metallicities of the stars, we show that giant planets appear to be very frequent ( f p = 4.48 +4.04 -1.38%) around stars with [Fe/H] >-0.7, while they are rare around stars with [Fe/H] ≤-0.7 (≤2.36% at one sigma). Conclusions. Giant planet frequency is indeed a strong function of metallicity, even in the low-metallicity tail. However, the frequencies are most likely higher than previously thought.

AB - Context.The discovery of about 700 extrasolar planets, so far, has lead to the first statistics concerning extrasolar planets. The presence of giant planets seems to depend on stellar metallicity and mass. For example, they are more frequent around metal-rich stars, with an exponential increase in planet occurrence rates with metallicity. Aims.We analyzed two samples of metal-poor stars (-2.0 ≤ [Fe/H] ≤2. 0.0) to see if giant planets are indeed rare around these objects. Radial velocity datasets were obtained with two different spectrographs (HARPS and HIRES). Detection limits for these data, expressed in minimum planetary mass and period, are calculated. These produce trustworthy numbers for the planet frequency. Methods.A general Lomb-Scargle (GLS) periodogram analysis was used together with a bootstrapping method to produce the detection limits. Planet frequencies were calculated based on a binomial distribution function within metallicity bins. Results.Almost all hot Jupiters and most giant planets should have been found in these data. Hot Jupiters around metal-poor stars have a frequency lower than 1.0% at one sigma. Giant planets with periods up to 1800 days, however, have a higher frequency of f p = 2.63 +2.5 -0.8%. Taking into account the different metallicities of the stars, we show that giant planets appear to be very frequent ( f p = 4.48 +4.04 -1.38%) around stars with [Fe/H] >-0.7, while they are rare around stars with [Fe/H] ≤-0.7 (≤2.36% at one sigma). Conclusions. Giant planet frequency is indeed a strong function of metallicity, even in the low-metallicity tail. However, the frequencies are most likely higher than previously thought.

KW - Planetary systems

KW - Planets and satellites: formation

KW - Stars: abundances

KW - Stars: statistics

KW - Techniques: radial velocities

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U2 - 10.1051/0004-6361/201118651

DO - 10.1051/0004-6361/201118651

M3 - Article

AN - SCOPUS:84862737730

SN - 0004-6361

VL - 543

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

M1 - A45

ER -

The frequency of giant planets around metal-poor stars

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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