Vera Rubin Telescope Could Detect Mars, Mercury And Pluto Sized Planets from 2025-2035

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Researchers estimate that the number of captured free-floating planets in the outer solar system with mass strictly greater than that of Mars is ∼1.2 and that the number of such planets with a strict cutoff at the mass of Mercury is ∼2.4.

When they instead adopt logarithmic bins centered at the Mars mass and the Mercury mass, respectively, they find that the expected number of such planets is ∼2.7 for mass comparable to that of Mars and ∼5.2 for mass comparable to that of Mercury. These planets would have a median heliocentric distance of ∼1400 au, with ∼half of them existing in the range 600–3500 au.

This means their theoretical analysis indicates that there should be 1.2 to 2.7 Mars sized captured rogue planets between 600-3500 AU away. There should be 2.4 to 5.2 Mercury sized rogue planets.

It is not in the paper but there could be dozens of Pluto sized objects.

If the closest captured planet is currently in the Southern sky and has favorable orbital conditions for detection, it could potentially be discovered in LSST (Vera Rubin telescope) images with a sufficiently advanced blind shift-and-stack algorithm. The detectability of captured planets with surveys such as LSST should be explored in more detail. We should expect discoveries of free-floating planets with the Nancy Grace Roman Telescope and detections of extreme trans-Neptunian objects with LSST will help refine the estimates. If the statistics from Sumi et al. (2023) hold to significantly lower masses, we should detect captured dwarf planets (with masses comparable to the mass of Pluto) early in the LSST observing program.

4 thoughts on “Vera Rubin Telescope Could Detect Mars, Mercury And Pluto Sized Planets from 2025-2035”

  1. If you’re trying to locate Kuiper belt objects, an occultation survey is the better approach. Objects down to a kilometer in diameter are detectable that way, using modest sized telescopes. You just need multiple scopes to exclude false positives and get some measure of size and proper velocity.

    It’s mostly about the sensors and data processing, not mirror size.

    • Problem is you’re thinking like someone looking for solving the problem in a more efficient way, not thinking like a bureaucratic project manager, thinking on which option requires more budget and people, without looking like you’re obviously doing so.

      • Oh, I expect you could build a large enough bureaucratic fiefdom placing thousands of telescopes around the world, all in need of local staff. And many would inevitably end up in prime vacation spots.

    • Hmmm… really?

      My goatish spidy sense thinks that the occulting disk of a 1000 km chunk of ice at 500 AU is — from here — vanishingly small.

      Turns out not so much so! Plenty big enough for occultation. Exostar at 100 LY, Sol-sized, has angular extent of 1.5×10⁻⁹ radians. A 1000 km trans-KBO at 500 AU has 13.3×10⁻⁹ rads. So, total occultation possible. Figuring angular speed-of-orbit, occultation of 800 seconds for the pair.

      So… like you say, a very-likely good detection method. I suppose with large enough telescope area, billions of stars could be simultaneously ‘watched’ looking for blips. Maybe (still) way under 10% of the hoped-for orbital path in terms of angular extent, but still … enough for a study.

      Funny thing is, that “repointing the telescopes” to other views is almost futile. Maybe. Its all about vanishingly small probabilities … but trillions of background stars acting as ‘detectors’. Occulting targets. And, rather unsurprisingly, all occultations are within an order-of-magnitude or so of similar times. 250 to 2500 seconds.

      Spreadsheets are so helpful. … if I get the mathematics right hr.

      As you say — thousands of telescopes, millions of detector stars apiece.

      Thanks again.

      ⋅-⋅-⋅ Just saying, ⋅-⋅-⋅
      ⋅-=≡ GoatGuy ✓ ≡=-⋅

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