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Interstellar Interloper, Coming in from the great beyond
fredk
post Yesterday, 01:06 AM
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It's worth pointing out that the lightcurve brightness range (a factor of ten) determines the ratio of only two axes (on the assumption its shape is roughly ellipsoidal). So for axis length ratios a:b:c they can say that a:b is roughly 10:1, but c is unconstrained. So the shape could be crudely slab-shaped, if c ~ a (or cigar-shaped if c ~ b ). I don't know if formation scenarios would be any easier for a 10:1 thickness slab vs the cigar.

The authors also claim that it's unlikely to be roughly spherical with albedo markings explaining the lightcurve. But perhaps a combination of both would be easier to swallow: a less extreme cigar or slab together with albedo markings.

Either way I'd think there are prospects to learn more about this, since that paper shows a lightcurve over only less than a day in total. A cigar configuration lightcurve would be sensitive to the angle between line of sight and spin axis, so data over a longer stretch may tell us whether geometry or albedo or some combination is the best explanation.
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dudley
post Yesterday, 02:31 AM
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The linked article is a few days old, so has the old 6:1 aspect ratio. However, they do characterize the dimensions as 30 by 30 by 180 meters, which sounds cigar-, rather than slab-shaped.

NOAO article
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fredk
post Yesterday, 05:26 AM
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You can read in the original Nature paper linked in the ESO release that c is unconstrained from the lightcurve.
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moustifouette
post Yesterday, 09:29 AM
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QUOTE (fredk @ Nov 21 2017, 07:26 AM) *
You can read in the original Nature paper linked in the ESO release that c is unconstrained from the lightcurve.


I may break some rule, but I can't help noting that a galatical battleship wreck fits the shape.
wink.gif
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Floyd
post Yesterday, 01:36 PM
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There must be Psyche-like bodies in other systems. A metal fragment could certainly have that shape, but could its surface turn that particular red (definitely not thinking iron rust red).


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Floyd
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Explorer1
post Today, 12:17 AM
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Have we confirmed (from any 'precovery images') that there is no coma, and there wasn't even at perihelion? Would any observatory have been looking in the right direction back then, or even before?
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dudley
post Today, 03:22 AM
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The trend in thinking about this object now, is that it is quite dense. Presumably, it has to be dense, so it won't spin itself to pieces, given its fairly rapid rotation, and strange shape. The spectra taken of this object suggested a likeness to class D and P asteroids in our solar system. However, these aren't very dense at all, only about 1.4 times that of water. A very peculiar object, all around.
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