07-18-2025, 12:38 PM
(This post was last modified: 07-19-2025, 12:20 AM by AstroChara.)
Tau Ceti is probably one of the most important stars to spectrographs. It's bright and nearby, and stable, so it's often used to test spectrographs, and there's lots of radial velocity measurements on this star.
There have been some claims of planets around this star, ones that we gleefully adopted for our project: those planets claimed in Tuomi et al. 2013 and Feng et al. 2017, a system of superterrans and subneptunians. These planets were practically scraped out of the noise floor though, and after many years they remained as candidates.
Earlier, we have a new preprint (accepted for publication) posted on arXiv: A comprehensive study on radial velocity signals using ESPRESSO: Pushing precision to the 10 cm/s level. This paper notably does not detect the signal "e", and casts doubt on the signal "g", suggesting it may be stellar activity rather than a planet. The signal f, meanwhile, was considered dubious in an earlier poster from 2020, while signal "h" has a period similar to that of the star's rotation. Combined with Tau Ceti's low metallicity, I think the existence of the system as we currently described is probably unlikely.
Currently I have been working with a few others (non-Orion's Arm) to create a new layout for this system; I'll post the result of this in the Forums later. Discussing about this subject with Steve, the change probably shouldn't be difficult, and ties in neatly with our current initiative to change terraformed planets into something else; the early history is already independent of the planets. Stuff like the Kingdom of Eyre could be space hab-based polity — and we can make it dissolve at some point in the timeline to prevent yet another eternal, unchanging polity syndrome. The Corporate War may be fought over something else. If it needs to remain a planet, Nova Terra could either become a sunshaded, worldhoused small planet maybe between the size of Mercury and Mars, or a supraplanetary shell world around a subneptunian planet.
There have been some claims of planets around this star, ones that we gleefully adopted for our project: those planets claimed in Tuomi et al. 2013 and Feng et al. 2017, a system of superterrans and subneptunians. These planets were practically scraped out of the noise floor though, and after many years they remained as candidates.
Earlier, we have a new preprint (accepted for publication) posted on arXiv: A comprehensive study on radial velocity signals using ESPRESSO: Pushing precision to the 10 cm/s level. This paper notably does not detect the signal "e", and casts doubt on the signal "g", suggesting it may be stellar activity rather than a planet. The signal f, meanwhile, was considered dubious in an earlier poster from 2020, while signal "h" has a period similar to that of the star's rotation. Combined with Tau Ceti's low metallicity, I think the existence of the system as we currently described is probably unlikely.
Currently I have been working with a few others (non-Orion's Arm) to create a new layout for this system; I'll post the result of this in the Forums later. Discussing about this subject with Steve, the change probably shouldn't be difficult, and ties in neatly with our current initiative to change terraformed planets into something else; the early history is already independent of the planets. Stuff like the Kingdom of Eyre could be space hab-based polity — and we can make it dissolve at some point in the timeline to prevent yet another eternal, unchanging polity syndrome. The Corporate War may be fought over something else. If it needs to remain a planet, Nova Terra could either become a sunshaded, worldhoused small planet maybe between the size of Mercury and Mars, or a supraplanetary shell world around a subneptunian planet.