A crowded multi-planet system around HD 34445

Just incredible!  

A Six-planet System around the Star HD 34445

Quote :

We present a new precision radial velocity (RV) data set that reveals a multi-planet system orbiting the G0V star HD 34445. Our 18-year span consists of 333 precision RV observations, 56 of which were previously published and 277 of which are new data from the Keck Observatory, Magellan at Las Campanas Observatory, and the Automated Planet Finder at Lick Observatory. These data indicate the presence of six planet candidates in Keplerian motion about the host star with periods of 1057, 215, 118, 49, 677, and 5700 days, and minimum masses of 0.63, 0.17, 0.1, 0.05, 0.12, and 0.38 M J, respectively. The HD 34445 planetary system, with its high degree of multiplicity, its long orbital periods, and its induced stellar RV half-amplitudes in the range 2 m s−1 lesssim K lesssim 5 m s−1 is fundamentally unlike either our own solar system (in which only Jupiter and Saturn induce significant reflex velocities for the Sun), or the Kepler multiple-transiting systems (which tend to have much more compact orbital configurations).

Wow!

Interesting!

I guess the estimated eccentricity of HD 34445 b will end up decreasing. Hopefully the long-period signal doesn't turn out to be an activity cycle.

Now on arXiv.
https://arxiv.org/abs/1710.07337

I see, but lately EPE is taking very long to update exoplanet list and up to date there are tens of missing confirmed/validated exoplanets.

Stability analysis: Georgakarakos & Dobbs-Dixon "Do the planets in the HD 34445 system really exist?"

Fortunately this seems to be one of the times that Betteridge's law doesn't apply and it looks like the system is plausible on a dynamical basis.

The Rosenthal et al. (2021) paper only lists one planet in this system, HD 34445 b.

The signals at 214.74 days (HD 34445 c) and 117.69 days (HD 34445 d) are listed as false positives, with the cause listed as N: annual and/or instrumental systematic.

The signal at 49.231 days (HD 34445 e) is also listed as a false positive, cause R: stellar rotation.

The text mentions that the longest period candidate (HD 34445 g) "clearly correlates with HIRES S-values".

No detection of a signal corresponding to HD 34445 f (676.8 days) is mentioned.