HD 147379 b - temperate super-Neptune around an M0 dwarf

Reiners et al. (2017) "The CARMENES search for exoplanets around M dwarfs: HD 147379 b: A nearby Neptune in the temperate zone of an early-M dwarf"
https://www.aanda.org/articles/aa/pdf/forth/aa32165-17.pdf

The star is part of a common proper motion binary, the secondary is EW Draconis. The planet HD 147379 b has minimum mass of about 25 Earth masses.

Now on arXiv.
https://arxiv.org/abs/1712.05797

An improved quantification of HD 147379 b
https://arxiv.org/abs/1801.10541

Quote :

We reanalyze the CARMENES and HIRES/KECK radial velocity data for HD 147379, and also analyze the SOPHIE data using the Agatha software in combination with MCMC posterior sampling. The analysis confirms the existence of HD 147379 b and improves the parameter estimation through modeling of red noise. The multiple radial velocity data sets for HD147379 provide a benchmark case for RV data analyses. Based on our analysis of the HD 147379 data, CARMENES radial velocity data is dominated by red noise and thus need to incorporate a red noise model.

Quote :

angular parameters ranging from 0 to 2π

Well obviously if the eccentricity is not significantly detected then the argument of periastron ω is going to be pretty much undefined and so will mean anomaly M (which essentially measures time since periastron). Nevertheless there are better ways to characterise the phase of the RV curve, mean longitude (M+ω) is probably going to be far better constrained.

Having worked on the Open Exoplanets Catalogue, it's amazing how many papers just go ahead and quote mean anomaly (or the equivalent time-domain value T_periastron) without considering whether that is actually an appropriate measure for characterising low-eccentricity orbits.

It seems we have missed this one too: a second planet in Gliese 617 A / HD 147379 system

The SOPHIE search for northern extrasolar planets XIII. Two planets around M-dwarfs Gl617A and Gl96

Quote :

We report the detection of two exoplanets and a further tentative candidate around the M-dwarf stars Gl96 and Gl617A, based on radial velocity measurements obtained with the SOPHIE spectrograph at the Observatoire de Haute-Provence. Both stars were observed in the context of the SOPHIE exoplanet consortium's dedicated M-dwarf subprogramme, which aims to detect exoplanets around nearby M-dwarf stars through a systematic survey. For Gl96, we present the discovery of a new exoplanet at 73.9 d with a minimum mass of 19.66 earth masses. Gl96 b has an eccentricity of 0.44, placing it among the most eccentric planets orbiting M stars. For Gl617A we independently confirm a recently reported exoplanet at 86.7 d with a minimum mass of 31.29 earth masses. Both Gl96 b and Gl617A b are potentially within the habitable zone, though Gl96 b's high eccentricity may take it too close to the star at periapsis.

Gl 617 Ac lies 1.036 UA away from the star (e_Ac = 0.15) and shows a minimum mass 27.26 times that of Earth (1.6x Neptune).