linguistic:paraphrasing
Procyon B

Like Sirius B, Procyon B is a white dwarf that was inferred from astrometric data long before it was observed. Its existence had been postulated by German astronomer Friedrich Bessel as early as 1844, and, although its orbital elements had been calculated by his countryman Arthur Auwers in 1862 as part of his thesis, Procyon B was not visually confirmed until 1896 when John Martin Schaeberle observed it at the predicted position using the 36-inch refractor at Lick Observatory. It is more difficult to observe from Earth than Sirius B, due to a greater apparent magnitude difference and smaller angular separation from its primary.

At 0.6 M, Procyon B is considerably less massive than Sirius B; however, the peculiarities of degenerate matter ensure that it is larger than its more famous neighbor, with an estimated radius of 8,600 km, versus 5,800 km for Sirius B. The radius agrees with white dwarf models that assume a carbon core. It has a stellar classification of DQZ, having a helium-dominated atmosphere with traces of heavy elements. For reasons that remain unclear, the mass of Procyon B is unusually low for a white dwarf star of its type. With a surface temperature of 7740 K, it is also much cooler than Sirius B; this is a testament to its lesser mass and greater age. The mass of the progenitor star for Procyon B was about 2.59 +0.22 −0.18 M and it came to the end of its life some 1.19 ± 0.11 billion years ago, after a main-sequence lifetime of 680 ± 170 million years.