J/A+A/543/A45 Planets around metal-poor stars (Mortier+, 2012)
The frequency of giant planets around metal-poor stars.
Mortier A., Santos N.C., Sozzetti A., Mayor M., Latham D., Bonfils X.,
Udry S.
<Astron. Astrophys. 543, A45 (2012)>
=2012A&A...543A..45M 2012A&A...543A..45M
ADC_Keywords: Stars, double and multiple ; Planets ; Stars, giant
Keywords: techniques: radial velocities - planetary systems -
planets and satellites: formation - stars: abundances -
stars: statistics
Abstract:
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.
We analyzed two samples of metal-poor stars (-2.0<[Fe/H]<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.
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.
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 2.63+2.5-0.89%. Taking
into account the different metallicities of the stars, we show that
giant planets appear to be very frequent (4.48+4.04-1.38%) around
stars with [Fe/H]>-0.7, while they are rare around stars with
[Fe/H]←0.7.
We conclude that 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.
Description:
Table 1 contains relevant values, like amount of measurements and
metallicity for all the stars in the samples.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 62 248 Relevant values for the stars in the samples
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See also:
J/ApJ/697/544 : Planets orbiting metal-poor dwarfs. II. (Sozzetti+, 2009)
J/A+A/526/A99 : Metal-poor solar-type stars spectroscopy & masses (Sousa+ 2011)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Star Star name
12- 13 I2 --- N Amount of measurements
15- 19 F5.2 m/s rms Mean rms of measurements
21- 24 I4 d tspan Timespan of the measurements
26- 29 I4 K Teff Effective temperature
31- 33 I3 K e_Teff ? rms uncertainty on Teff
35- 39 F5.2 [Sun] [Fe/H] Metallicity
41- 44 F4.2 [Sun] e_[Fe/H] ? rms uncertainty on [Fe/H]
46- 49 F4.2 Msun Mass Stellar mass
51- 54 F4.2 Msun e_Mass ? rms uncertainty on Mass
56- 60 A5 --- Sample Sample the star belongs to (HARPS or KECK)
62 I1 --- Ref [1/2] Reference (1)
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Note (1): Reference for the stellar parameters as follows:
1 = Sousa et al., 2011, Cat. J/A+A/526/A99
2 = Sozzetti et al., 2009, Cat. J/ApJ/697/544
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Acknowledgements:
Annelies Mortier, amortier(at)astro.up.pt
(End) Annelies Mortier [CAUP-Porto, Portugal] Patricia Vannier [CDS] 31-May-2012