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| Observation data Epoch J2000.0 Equinox | |
|---|---|
| Constellation | Eridanus [1] |
| Right ascension | 04h 12m 26.327s [2] |
| Declination | −11° 17′ 47.28″ [2] |
| Apparent magnitude (V) | 15.5 [3] |
| Characteristics | |
| Evolutionary stage | Magnetized WD + non-magnetized WD [3] |
| Spectral type | DA [4] |
| Astrometry | |
| Radial velocity (Rv) | 58.0±3.9 [3] km/s |
| Proper motion (μ) | RA: 202.726 [2] mas/yr Dec.: −37.248 [2] mas/yr |
| Parallax (π) | 28.4737±0.0345 mas [2] |
| Distance | 114.5 ± 0.1 ly (35.12 ± 0.04 pc) |
| Details | |
| NLTT 12758A | |
| Mass | 0.83 [3] M☉ |
| NLTT 12758B | |
| Mass | 0.69 [3] M☉ |
| Database references | |
| SIMBAD | data |
NLTT 12758 is a binary system of two white dwarf stars. The pair of white dwarfs are orbiting each other on a 1.154 day orbital period. The total combined mass of these white dwarfs is higher than the Chandrasekhar mass limit which is at 1.4 solar masses. This is important as their orbits are degrading. When they collide, one of two outcomes will likely occur. Either they will accrete their mass and collapse into a neutron star or trigger a type Ia supernova. This will occur in the far future of 10 Hubble times, roughly 140 billion years from now. [3]
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Most binary systems of white dwarfs form through common-envelope evolution. It occurs when the more massive star fills its Roche limit during its red giant phase. The second star then starts to accrete material from the red giant in a dynamically unstable process of mass transfer. Then the shedding of the envelope strips both envelopes and the orbital distance shrinks leaving behind two white dwarfs with an orbital period of a few days to a few hours. NLTT 12758A likely underwent this process twice. [5] [3]
