The HARPS search for southern extra-solar planets

Unger, N.; Ségransan, D.; Queloz, D.; Udry, S.; Mordasini, Christoph; Ahrer, Eva-Maria; Benz, W.; Bouchy, F.; Delisle, J.-B.; Díaz, R. F.; Dumusque, X.; Curto, G. Lo; Marmier, M.; Mayor, M.; Pepe, F.; Santos, N. C.; Stalport, M.; Alonso, R.; Cameron, A. Collier; Deleuil, M.; Figueira, P.; Gillon, M.; Moutou, C.; Pollacco, D.; Pompei, E.

doi:10.1051/0004-6361/202141351

Cited by 12 publications

(2 citation statements)

References 77 publications

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“…Without the context of hosting an S-type planet, DMPP-3AB is not a particularly close binary, but it is the most compact binary system to harbour an S-type planet observed thus far. It is also one of the few systems containing a radial velocity (RV) detected S-type super-Earth around an FGK star (B20; Unger et al 2021;Barros et al 2022). Su et al (2021) compare the known S-type RV discoveries, and show that DMPP-3A b is an extreme outlier in their sample.…”

Section: Introductionmentioning

confidence: 98%

DMPP-3: confirmation of short-period S-type planet(s) in a compact eccentric binary star system, and warnings about long-period RV planet detections

Stevenson,

Haswell,

Barnes

et al. 2023

Monthly Notices of the Royal Astronomical Society

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We present additional HARPS radial velocity observations of the highly eccentric (e ∼ 0.6) binary system DMPP-3AB, which comprises a K0V primary and a low-mass companion at the hydrogen burning limit. The binary has a 507 d orbital period and a 1.2 au semi-major axis. The primary component harbours a known 2.2 M⊕ planet, DMPP-3A b, with a 6.67 day orbit. New HARPS measurements constrain periastron passage for the binary orbit and add further integrity to previously derived solutions for both companion and planet orbits. Gaia astrometry independently confirms the binary orbit, and establishes the inclination of the binary is 63.89 ± 0.78○. We performed dynamical simulations which establish that the previously identified ∼800 d RV signal cannot be attributed to an orbiting body. The additional observations, a deviation from strict periodicity, and our new analyses of activity indicators suggest the ∼800 d signal is caused by stellar activity. We conclude that there may be long period planet “detections” in other systems which are similar misinterpreted stellar activity artefacts. Without the unusual eccentric binary companion to the planet-hosting star we could have accepted the ∼800 d signal as a probable planet. Further monitoring of DMPP-3 will reveal which signatures can be used to most efficiently identify these imposters. We also report a threshold detection (0.2 per cent FAP) of a ∼2.26 d periodicity in the RVs, potentially attributed to an Earth-mass S-type planet interior to DMPP-3A b.

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Section: Introductionmentioning

confidence: 98%

DMPP-3: confirmation of short-period S-type planet(s) in a compact eccentric binary star system, and warnings about long-period RV planet detections

Stevenson,

Haswell,

Barnes

et al. 2023

Monthly Notices of the Royal Astronomical Society

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“…A significant number of detections later suggested that these planets are among the most abundant in the exoplanet population (e.g. Mayor et al 2011;Lovis et al 2011;Lo Curto et al 2013;Bonfils et al 2013;Astudillo-Defru et al 2017b;Delisle et al 2018;Unger et al 2021). Their over-abundance was strengthened by the Kepler space telescope, which scrutinised a small area of the North sky for 3.5 yr in search for transiting planets (Latham et al 2011;Borucki et al 2011;Fabrycky et al 2014).…”

Section: Introductionmentioning

confidence: 99%

A review of planetary systems around HD 99492, HD 147379, and HD 190007 with HARPS-N

Stalport,

Cretignier,

Udry

et al. 2023

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Context. The Rocky Planet Search (RPS) program is dedicated to a blind radial velocity (RV) search of planets around bright stars in the northern hemisphere, using the high-resolution echelle spectrograph HARPS-N installed on the Telescopio Nazionale Galileo (TNG). Aims. The goal of this work is to revise and update the properties of three planetary systems by analysing the HARPS-N data with state-of-the-art stellar activity mitigation tools. The stars considered are HD 99492 (83Leo B), HD 147379 (Gl617 A), and HD 190007. Methods. We employ a systematic process of data modelling, which we selected from the comparison of different approaches. We use YARARA to remove instrumental systematics from the RV, and then use SPLEAF to further mitigate the stellar noise with a multidimensional correlated noise model. We also search for transit features in the Transiting Exoplanets Survey Satellite (TESS) data of these stars. Results. We report on the discovery of a new planet around HD 99492, namely HD 99492 c, with an orbital period of 95.2 days and a minimum mass of m sin i = 17.9 M⊕, and refine the parameters of HD 99492 b. We also update and refine the Keplerian solutions for the planets around HD 147379 and HD 190007, but do not detect additional planetary signals. We discard the transiting geometry for the planets, but stress that TESS did not exhaustively cover all the orbital phases. Conclusions. The addition of the HARPS-N data, and the use of advanced data analysis tools, has allowed us to present a more precise view of these three planetary systems. It demonstrates once again the importance of long observational efforts such as the RPS program. Added to the RV exoplanet sample, these planets populate two apparently distinct populations revealed by a bimodality in the planets’ minimum mass distribution. The separation is located between 30 and 50 M⊕.

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Efficient modeling of correlated noise

Delisle

Unger

Hara

et al. 2022

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The radial velocity method is a very productive technique used to detect and confirm extrasolar planets. The most recent spectrographs, such as ESPRESSO or EXPRES, have the potential to detect Earth-like planets around Sun-like stars. However, stellar activity can induce radial velocity variations that dilute or even mimic the signature of a planet. A widely recognized method for disentangling these signals is to model the radial velocity time series, jointly with stellar activity indicators, using Gaussian processes and their derivatives. However, such modeling is prohibitive in terms of computational resources for large data sets, as the cost typically scales as the total number of measurements cubed. Here, we present s+leaf 2, a Gaussian process framework that can be used to jointly model several time series, with a computational cost that scales linearly with the data set size. This framework thus provides a state-of-the-art Gaussian process model, with tractable computations even for large data sets. We illustrate the power of this framework by reanalyzing the 246 HARPS radial velocity measurements of the nearby K2 dwarf HD 138038, together with two activity indicators. We reproduce the results of a previous analysis of these data, but with a strongly decreased computational cost (more than two order of magnitude). The gain would be even greater for larger data sets.

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The HARPS search for southern extra-solar planets

Cited by 12 publications

References 77 publications

DMPP-3: confirmation of short-period S-type planet(s) in a compact eccentric binary star system, and warnings about long-period RV planet detections

DMPP-3: confirmation of short-period S-type planet(s) in a compact eccentric binary star system, and warnings about long-period RV planet detections

A review of planetary systems around HD 99492, HD 147379, and HD 190007 with HARPS-N

Efficient modeling of correlated noise

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