One, known as a white dwarf, is the cooling remnant of a much lighter star.
The pulsar and white dwarf pair emit gravitational waves and the binary star system gradually loses energy.
The ferocity of a typical supernovae explosion obliterates the white dwarf utterly, leaving behind no trace of it.
The white dwarf is thought to have later blown up in a supernova after siphoning matter, or fuel, from a nearby star.
FORBES: NASA Reveals the Mysteries of the First Known Supernova
Their goal was to measure distant Type 1a supernovae - the brilliant ends of a particular kind of dense star known as a white dwarf.
The observations also show for the first time that a white dwarf can create a cavity around it before blowing up in a Type Ia event.
FORBES: NASA Reveals the Mysteries of the First Known Supernova
The modeling of white dwarf stars that fail to detonate can be directly connected to the new class of very dim supernova explosions, according to Jordan and his team.
These new models of failed supernovae demonstrate how both normal brightness and extremely dim supernovae are generated from the same basic picture of a nuclear-burning white dwarf star, he added.
Those white dwarf stars that find themselves near a "companion" star can draw material from their neighbour, building up to a critical mass and eventually sparking nuclear fusion again in a nova.
Now, an international team of astronomers has trained the Fermi space-based gamma ray telescope on V407 Cygni, a "binary" system comprising a white dwarf star and a red giant companion, 9, 000 light-years away.
Standard Type Ia supernovae are binary systems in which a white dwarf star draws so much matter from its companion (often a red giant) that it undergoes a kind of energy overload and detonates.
Depending on its initial mass, it might collapse to a compact hot star known as a white dwarf (when the star's mass is less than 1.4 times the mass of our sun) or to a neutron star (for stars 1.4 to about three times the mass of our sun) or to a black hole (for stars more massive than three times the mass of our sun).
And when they aimed at Sirius they could see the dim white-dwarf which orbits what is the brightest star in the night sky.
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