The HARPS search for southern extra-solar planets

Dumusque, X.; Lovis, C.; Ségransan, D.; Mayor, M.; Udry, S.; Benz, W.; Bouchy, F.; Curto, G. Lo; Mordasini, C.; Pepe, F.; Queloz, D.; Santos, N. C.; Naef, D.

doi:10.1051/0004-6361/201117148

Cited by 126 publications

(146 citation statements)

References 49 publications

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“…Doing a weighted linear leastsquares fit and removing the trend with any of these activity indicators from the RVs results in reducing the correlations while preserving the long-period planet signal with high significance in a periodogram analysis. We additionally attempted the prescribed method of Dumusque et al (2011) of fitting a longperiod Keplerian first to an activity diagnostic and then (with period and phase fixed) the RVs. This method failed to remove the long-period power from the RVs regardless of whether S HK , BIS, or FWHM was used as the diagnostic.…”

Section: Analysis and Resultsmentioning

confidence: 99%

“…We expect the actual uncertainties to be somewhat higher owing to stellar noise and potential undiagnosed instrumental effects. To account for these factors, we added the pipeline-estimated errors in quadrature with a baseline error level of 1 m s −1 , following Dumusque et al (2011) and in accordance with the scatter in our own HARPS survey's quietest stars.…”

Section: Datamentioning

confidence: 99%

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The Solar Twin Planet Search

Bedell

Meléndez

Bean

et al. 2015

A&A

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Context. With high-precision radial velocity surveys reaching a sufficiently long time baseline, the domain of long-period planet detections has recently opened up. The search for Jupiter-like planets is especially important if we wish to investigate the prevalence of solar system analogs, but their detection is complicated by the existence of stellar activity cycles on similar timescales. Radial velocity data with sufficiently long-term instrumental precision and robust methods of diagnosing activity are crucial to the detection of extrasolar Jupiters. Aims. Through our HARPS survey for planets around solar twin stars, we have identified a promising Jupiter twin candidate around the star HIP11915. We characterize this Keplerian signal and investigate its potential origins in stellar activity. Methods. We carry out a Markov chain Monte Carlo (MCMC) analysis of the radial velocity data. To examine the signal's origin, we employ a variety of statistical tests using activity diagnostics such as the Ca II H and K lines and line asymmetry tracers. Results. Our analysis indicates that HIP11915 hosts a Jupiter-mass planet with a 3800-day orbital period and low eccentricity. Although we cannot definitively rule out an activity cycle interpretation, we find that a planet interpretation is more likely based on a joint analysis of radial velocity and activity index data. Conclusions. The challenges of long-period radial velocity signals addressed in this paper are critical for the ongoing discovery of Jupiter-like exoplanets. If planetary in nature, the signal investigated here represents a very close analog to the solar system in terms of both Sun-like host star and Jupiter-like planet.

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Section: Analysis and Resultsmentioning

confidence: 99%

Section: Datamentioning

confidence: 99%

The Solar Twin Planet Search

Bedell

Meléndez

Bean

et al. 2015

A&A

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“…Indeed asterioseismology analyses suggest that the short-term performance of the spectrographs are relatively similar (Bedding et al 2007). The HARPS spectrograph is shown to have good short-term stability (the reader is referred to the long series of publications titled "The HARPS search for southern extra-solar planets" of which two recent ones are: Dumusque et al 2011;Ségransan et al 2011), which could enable the detection of noise correlations over timescales of a few hours -possibly arising from stellar surface phenomena -from HARPS data.…”

Section: Aaps and Hires Radial Velocitiesmentioning

confidence: 99%

Signals embedded in the radial velocity noise

Tuomi

Jones

Jenkins

et al. 2013

A&A

125

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Context. The abilities of radial velocity exoplanet surveys to detect the lowest-mass extra-solar planets are currently limited by a combination of instrument precision, lack of data, and "jitter". Jitter is a general term for any unknown features in the noise, and reflects a lack of detailed knowledge of stellar physics (asteroseismology, starspots, magnetic cycles, granulation, and other stellar surface phenomena), as well as the possible underestimation of instrument noise. Aims. We study an extensive set of radial velocities for the star HD 10700 (τ Ceti) to determine the properties of the jitter arising from stellar surface inhomogeneities, activity, and telescope-instrument systems, and perform a comprehensive search for planetary signals in the radial velocities. Methods. We performed Bayesian comparisons of statistical models describing the radial velocity data to quantify the number of significant signals and the magnitude and properties of the excess noise in the data. We reached our goal by adding artificial signals to the "flat" radial velocity data of HD 10700 and by seeing which one of our statistical noise models receives the greatest posterior probabilities while still being able to extract the artificial signals correctly from the data. We utilised various noise components to assess properties of the noise in the data and analyse the HARPS, AAPS, and HIRES data for HD 10700 to quantify these properties and search for previously unknown low-amplitude Keplerian signals.Results. According to our analyses, moving average components with an exponential decay with a timescale from a few hours to few days, and Gaussian white noise explains the jitter the best for all three data sets. Fitting the corresponding noise parameters results in significant improvements of the statistical models and enables the detection of very weak signals with amplitudes below 1 m s −1 level in our numerical experiments. We detect significant periodicities that have no activity-induced counterparts in the combined radial velocities. Three of these signals can be seen in the HARPS data alone, and a further two can be inferred by utilising the AAPS and Keck data. These periodicities could be interpreted as corresponding to planets on dynamically stable close-circular orbits with periods of 13.9, 35.4, 94, 168, and 640 days and minimum masses of 2.0, 3.1, 3.6, 4.3, and 6.6 M ⊕ , respectively.

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“…We thus infer that the outer radial-velocity companion detected by Dumusque et al (2011) around HD 7449 and later reanalyzed in Rodigas et al (2016) is seen in SPHERE images and is a low-mass star with a mass of 0.173 ± 0.006 M . The inner planet HD 7449 Ab has a minimum mass of 1.09 +0.52 −0.19 M Jup and period of 1200 +16 −12 days, eccentricity of 0.8 and semi-major axis of 2.33 +0.01 −0.02 (Rodigas et al 2016).…”

Section: Hd7449mentioning

confidence: 77%

Eccentricity in planetary systems and the role of binarity

Moutou

Vigan

Mesa

et al. 2017

A&A

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We explore the multiplicity of exoplanet host stars with high-resolution images obtained with VLT/SPHERE. Two different samples of systems were observed: one containing low-eccentricity outer planets, and the other containing high-eccentricity outer planets. We find that 10 out of 34 stars in the high-eccentricity systems are members of a binary, while the proportion is 3 out of 27 for circular systems. Eccentric-exoplanet hosts are, therefore, significantly more likely to have a stellar companion than circular-exoplanet hosts. The median magnitude contrast over the 68 data sets is 11.26 and 9.25, in H and K, respectively, at 0.30 arcsec. The derived detection limits reveal that binaries with separations of less than 50au are rarer for exoplanet hosts than for field stars. Our results also imply that the majority of high-eccentricity planets are not embedded in multiple stellar systems (24 out of 34), since our detection limits exclude the presence of a stellar companion. We detect the low-mass stellar companions of HD 7449 and HD 211847, both members of our high-eccentricity sample. HD 7449B was already detected by Rodigas et al. (2016) and our independent observation is in agreement with this earlier work. HD 211847's substellar companion, previously detected by the radial velocity method, is actually a low-mass star seen face-on. The role of stellar multiplicity in shaping planetary systems is confirmed by this work, although it does not appear as the only source of dynamical excitation.

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The HARPS search for southern extra-solar planets

Cited by 126 publications

References 49 publications

The Solar Twin Planet Search

The Solar Twin Planet Search

Signals embedded in the radial velocity noise

Eccentricity in planetary systems and the role of binarity

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