Brown dwarf around "the Black Widow" (2007)

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Brown dwarf around "the Black Widow" (2007)

Post by Edasich on 8th December 2008, 7:46 am

Yes, it's a bit old but it deserves attention.
It seems not the case of SWIFT J1756.9-2508 pulsar where secondary was once likely stellar and then turned into an exotic planet-sized object.
This object may have started its "life" as brown dwarf. Mass is around 22 times that of Jupiter and a very puffed radius (3 Jupiter radii).
Orbital period is very short of course: 9.17 hours. Assuming host pulsar's mass around 1.4 Mso, the average separation is close to 0.0115 AUs (=2.48 Solar radii).
It is not a white dwarf and orbits around a notable millisecond pulsar, nicknamed the "Black Widow": QX Sagittae.

Furthermore, if the secondary in PSR B1957+20 was a ∼ 0.025 M⊙ white dwarf, one would expect a radius of ∼ 0.1 R⊙ - again in contrast with the value of ∼0.3 R⊙ which we have determined from our modelling.

Paper The light curve of the companion to PSR B1957+20

SIMBAD note:

essential notes:

dM star
dM star

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