This has to be one of the most bizarre planets yet discovered. Not "merely" a pulsar planet, but a Jupiter-sized diamond orbiting a pulsar with a year lasting 2.2 hours. I wonder what the tidal forces are?

(I would think that radio telescopes are covered under "Telescopic Observations")

Pulsar in the Sky, With Diamonds

The object orbiting it is Jupiter mass, with some uncertainty in the exact mass due to as yet unmeasured inclination, has an orbital period of 2.2 hours! That implies an orbital radius less than a solar radius! The orbit is, near as we can tell, perfectly circular. Further, the object is not overflowing its Roche lobe, implying a minimum mean density of 23! Possibly considerably larger.

From both observational constraints, and from theoretical grounds based on models of the origin of the object, it is most likely a pure cold crystalline carbon core of a low mass star, with the rest of the star accreted, blown away and ablated by the millisecond pulsar formation process.

Yes, it is a 10^31 carat diamond. That is 10,000,000 trillion trillion carats of hot sparkly rock!

A density of 23? I doubt if the familiar diamond lattice structure survives at that density. Liquid carbon perhaps??

If it's the remnant of a white dwarf, isn't it realistic to entertain the idea of degenerate matter?

I am not sure. The interior of the object was surely degenerate when the object was much more massive, but is matter degeneracy stable when the mass of the object gets below a couple of Jupiter masses? I would expect that as the pressure at the core decreases, the matter would 'rebound' to a normal non-degenerate state, meaning that each carbon atom would have close to a full complement of electrons. Although the remaining free electrons suggest to me that some form of 'metallic carbon', rather than 'diamond-like carbon' might exist there.

In any case, this is surely one of the most unusual planetary-mass objects discovered so far, in my opinion.

It's a remarkable find, and a remarkable object.

Of course, my wife found it quite entertaining, and the jokes wrote themselves!

"In space you don't wear diamond ring...ring wears YOU!"

How long until the media starts calling PSR J1719-1438 "Lucy" as in, "...in the sky with diamonds"

Here is the ARXIVE preprint:

Transformation of a Star into a Planet in a Millisecond Pulsar Binary

As soon as they forget about having already used that for BPM 37093.