(1/5) well..the recurring planet-nine-is-not-real-because-of-observational-bias narrative has made its comeback yet again (+new KBOs that actually also cluster...). Obs bias is important, and @plutokiller & I looked into this back in '18. And the probability that this is a fluke: (2/5) is 0.2%. For details of the statistical account, see: arxiv.org/pdf/1901.07115… and for a explantation by @plutokiller check:

https://twitter.com/plutokiller/status/1087495838379651072

There are a couple new DES KBOs that also cluster only strengthening the case...

Continuing on, let's check higher masses as well. For a 10 Mearth P9, orbital parameters have to be fine-tuned to even remotely match the data, while a 20 Mearth P9 appears to be fully ruled out by the current dataset. An example of a pretty good-looking simulation is shown below. Observed dynamically (meta)stable KBOs (large purple, gray dots) indeed look like they've been randomly drawn from the phase-space distribution of simulated observable long-period KBOs (blue points).

Three years (and 2 fortnights) ago @plutokiller and I published our first #PlanetNine paper. But science is an iterative process, and since then we've made more progress. The result: an updated P9 Hypothesis (w/ Adams, Becker): arxiv.org/pdf/1902.10103…. Highlights in thread below. First, an exec summary of the paper: we did thousands of new P9 simulations, and realized that P9 is smaller (m~5Mearth), closer (a~400-500AU), more circular (e~0.2) and visually brighter (V~23) than we originally thought. Pic: @jtuttlekeane Now, let’s dig into the details a bit.