Bias and robustness of eccentricity estimates from radial velocity data

Hara, N.; Boué, G.; Laskar, Jacques; Delisle, J.-B.; Unger, N.

doi:10.1093/mnras/stz1849

Cited by 42 publications

(40 citation statements)

References 78 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The residuals of the nine-signals model plus white noise fit have a root mean square (RMS) of 3.1 m s −1 , which is higher than the nominal uncertainties of the SOPHIE data (1.2 m s −1 ). We studied the residuals with the methods of Hara et al (2019) and found that they are temporally correlated, which, if not accounted for, might corrupt the orbital element estimates. In Appendix E, we show that a consistent model of the data can be obtained with a noise model that includes white and correlated components.…”

Section: Radial Velocities Analysismentioning

confidence: 99%

“…(i) None of these periods clearly appear in the bisector span, log R hk , or photometry. (ii) While eccentric planets can be mistaken for planet pairs near a 2:1 MMR, they are very unlikely to appear as planets near a 3:2 resonance (Hara et al 2019). (iii) The periods could be due to instrument systematics.…”

Section: Periodicity Originmentioning

confidence: 99%

“…To check whether the model is consistent with the data, we study the residuals. Following Hara et al (2019), we define…”

Section: E2 Model Consistencymentioning

confidence: 99%

See 2 more Smart Citations

The SOPHIE search for northern extrasolar planets

Hara

Bouchy

Stalport

et al. 2020

A&A

View full text Add to dashboard Cite

Aims. Since 2011, the SOPHIE spectrograph has been used to search for Neptunes and super-Earths in the northern hemisphere. As part of this observational program, 290 radial velocity measurements of the 6.4 V magnitude star HD 158259 were obtained. Additionally, TESS photometric measurements of this target are available. We present an analysis of the SOPHIE data and compare our results with the output of the TESS pipeline. Methods. The radial velocity data, ancillary spectroscopic indices, and ground-based photometric measurements were analyzed with classical and ℓ1 periodograms. The stellar activity was modeled as a correlated Gaussian noise and its impact on the planet detection was measured with a new technique. Results. The SOPHIE data support the detection of five planets, each with m sin i ≈ 6 M⊕, orbiting HD 158259 in 3.4, 5.2, 7.9, 12, and 17.4 days. Though a planetary origin is strongly favored, the 17.4 d signal is classified as a planet candidate due to a slightly lower statistical significance and to its proximity to the expected stellar rotation period. The data also present low frequency variations, most likely originating from a magnetic cycle and instrument systematics. Furthermore, the TESS pipeline reports a significant signal at 2.17 days corresponding to a planet of radius ≈1.2 R⊕. A compatible signal is seen in the radial velocities, which confirms the detection of an additional planet and yields a ≈2 M⊕ mass estimate. Conclusions. We find a system of five planets and a strong candidate near a 3:2 mean motion resonance chain orbiting HD 158259. The planets are found to be outside of the two and three body resonances.

show abstract

Section: Radial Velocities Analysismentioning

confidence: 99%

Section: Periodicity Originmentioning

confidence: 99%

See 1 more Smart Citation

The SOPHIE search for northern extrasolar planets

Hara

Bouchy

Stalport

et al. 2020

A&A

View full text Add to dashboard Cite

show abstract

“…We performed a night binning of the dataset, as suggested in Dumusque et al (2012). This simple strategy has proved to be efficient to reduce the effect of short-term correlated noises on orbital elements (e.g., Hara et al 2019). In total, 145 individual measurements were available.…”

Section: Harpsmentioning

confidence: 99%

Planetary system LHS 1140 revisited with ESPRESSO and TESS

Lillo-Box

Figueira

Leleu

et al. 2020

A&A

View full text Add to dashboard Cite

Context. LHS 1140 is an M dwarf known to host two transiting planets at orbital periods of 3.77 and 24.7 days. They were detected with HARPS and Spitzer. The external planet (LHS 1140 b) is a rocky super-Earth that is located in the middle of the habitable zone of this low-mass star. All these properties place this system at the forefront of the habitable exoplanet exploration, and it therefore constitutes a relevant case for further astrobiological studies, including atmospheric observations. Aims. We further characterize this system by improving the physical and orbital properties of the known planets, search for additional planetary-mass components in the system, and explore the possibility of co-orbitals. Methods. We collected 113 new high-precision radial velocity observations with ESPRESSO over a 1.5-yr time span with an average photon-noise precision of 1.07 m s−1. We performed an extensive analysis of the HARPS and ESPRESSO datasets and also analyzed them together with the new TESS photometry. We analyzed the Bayesian evidence of several models with different numbers of planets and orbital configurations. Results. We significantly improve our knowledge of the properties of the known planets LHS 1140 b (Pb ~ 24.7 days) and LHS 1140 c (Pc ~ 3.77 days). We determine new masses with a precision of 6% for LHS 1140 b (6.48 ± 0.46 M⊕) and 9% for LHS 1140 c (mc = 1.78 ± 0.17 M⊕). This reduces the uncertainties relative to previously published values by half. Although both planets have Earth-like bulk compositions, the internal structure analysis suggests that LHS 1140 b might be iron-enriched and LHS 1140 c might be a true Earth twin. In both cases, the water content is compatible to a maximum fraction of 10–12% in mass, which is equivalent to a deep ocean layer of 779 ± 650 km for the habitable-zone planet LHS 1140 b. Our results also provide evidence for a new planet candidate in the system (md = 4.8 ± 1.1M⊕) on a 78.9-day orbital period, which is detected through three independent methods. The analysis also allows us to discard other planets above 0.5 M⊕ for periods shorter than 10 days and above 2 M⊕ for periods up to one year. Finally, our co-orbital analysis discards co-orbital planets in the tadpole and horseshoe configurations of LHS 1140 b down to 1 M⊕ with a 95% confidence level (twice better than with the previous HARPS dataset). Indications for a possible co-orbital signal in LHS 1140 c are detected in both radial velocity (alternatively explained by a high eccentricity) and photometric data (alternatively explained by systematics), however. Conclusions. The new precise measurements of the planet properties of the two transiting planets in LHS 1140 as well as the detection of the planet candidate LHS 1140 d make this system a key target for atmospheric studies of rocky worlds at different stellar irradiations.

show abstract

“…The first arises from the fact that eccentricity is a positive-definite quantity: it cannot be negative. Therefore, the fitted eccentricities for planets on circular or low-eccentricity orbits are biased towards higher values (Lucy & Sweeney 1971;Shen & Turner 2008;Zakamska et al 2011;Hara et al 2019). For example, Zakamska et al (2011) show that the fraction of low eccentricity systems could be underestimated by as much as a factor of 3.…”

Section: Rv Mischaracterization Of Planet Eccentricitymentioning

confidence: 99%

Resilient habitability of nearby exoplanet systems

Kokaia

Davies

Mustill

2019

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We investigate the possibility of finding Earth-like planets in the habitable zone of 34 nearby FGK-dwarfs, each known to host one giant planet exterior to their habitable zone detected by RV. First we simulate the dynamics of the planetary systems in their present day configurations and determine the fraction of stable planetary orbits within their habitable zones. Then, we postulate that the eccentricity of the giant planet is a result of an instability in their past during which one or more other planets were ejected from the system. We simulate these scenarios and investigate whether planets orbiting in the habitable zone survive the instability. Explicitly we determine the fraction of test particles, originally found in the habitable zone, which remain in the habitable zone today. We label this fraction the resilient habitability of a system. We find that for most systems the probability of planets existing [or surviving] on stable orbits in the habitable zone becomes significantly smaller when we include a phase of instability in their history. We present a list of candidate systems with high resilient habitability for future observations. These are: HD 95872, HD 154345, HD 102843, HD 25015, GJ 328, HD 6718 and HD 150706. The known planets in the last two systems have large observational uncertainties on their eccentricities, which propagate into large uncertainties on their resilient habitability. Further observational constraints of these two eccentricities will allow us to better constrain the survivability of Earth-like planets in these systems.

show abstract

Bias and robustness of eccentricity estimates from radial velocity data

Cited by 42 publications

References 78 publications

The SOPHIE search for northern extrasolar planets

The SOPHIE search for northern extrasolar planets

Planetary system LHS 1140 revisited with ESPRESSO and TESS

Resilient habitability of nearby exoplanet systems

Contact Info

Product

Resources

About