10 Hygeia a dwarf planet |
10 Hygeia a dwarf planet |
Oct 31 2019, 10:22 PM
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#1
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Member Group: Members Posts: 315 Joined: 1-October 06 Member No.: 1206 |
Did people notice this?
SPHERE is a powerful instrument, I'm waiting for it to have a go at the more recondite 704 Internamnia and 324 Bamberga. ESOCast 211 https://www.youtube.com/watch?v=VBi-KeZABl4 P |
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Oct 31 2019, 11:26 PM
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#2
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Senior Member Group: Members Posts: 2516 Joined: 13-September 05 Member No.: 497 |
Just because it's spherical now on account of an accident of formation doesn't mean that it meets the definition of a dwarf planet ("has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape")
I think ESO is reaching on this one. -------------------- Disclaimer: This post is based on public information only. Any opinions are my own.
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Oct 31 2019, 11:27 PM
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#3
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Merciless Robot Group: Admin Posts: 8783 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
Reminder to please review rule 1.9 carefully before posting; we're not gonna be debating planethood.
-------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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Nov 2 2019, 09:03 PM
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#4
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Member Group: Members Posts: 401 Joined: 5-January 07 From: Manchester England Member No.: 1563 |
@mcaplinger
QUOTE Just because it's spherical now on account of an accident of formation doesn't mean that it meets the definition of a dwarf planet ("has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape") I think ESO is reaching on this one. Without attempting to debate the definition of a planet... given some reasonable assumptions about composition, and what is known of Hygia's density and mass, surely this can be quickly settled by calculation, at least to a reasonable approximation? -------------------- |
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Nov 2 2019, 09:26 PM
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#5
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
Wikipedia gives presumably accurate (with noted error bars) physical dimensions for the larger asteroids.
However, whatever is known about mass and size, the internal physical structure is an unknown in every case. The exemplars on either side of the hydrostatic equilibrium boundary are all significantly larger than Hygeia, so it seems more likely to be an accident than actual hydrostatic equilibrium, but it's always possible that it's got a composition that flows more easily than other comparably-sized worlds. Or, that it underwent state changes in the past, and that was once true. |
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