DN Geminorum
Star in the constellation Gemini
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DN Geminorum or Nova Geminorum 1912 was a classical nova which lit up in 1912 in the constellation Gemini. It was discovered by Norwegian variable star observer Sigurd Einbu[3] on March 12, 1912 before reaching peak brightness, which allowed early-stage spectra to be collected by Yerkes Observatory.[5] The nova reached a maximum brightness of around 3.5 mag before declining,[6] which means it was visible to the naked eye. Its brightness decreased over the following 36 days by 3 magnitudes as it gradually faded from sight. The light curve saw two maxima a few months after the outburst, along with strong oscillations.[6] Today its brightness is visual magnitude 15.5.[2]
| |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Gemini |
| Right ascension | 06h 54m 54.34929s[1] |
| Declination | +32° 08′ 27.9247″[1] |
| Apparent magnitude (V) | 15.5±0.5[2] |
| Astrometry | |
| Proper motion (μ) | RA: −0.794[1] mas/yr Dec.: −4.323[1] mas/yr |
| Parallax (π) | 0.7288±0.0807 mas[1] |
| Distance | approx. 4,500 ly (approx. 1,400 pc) |
| Absolute magnitude (MV) | 5.02±0.60[2] |
| Details | |
| White dwarf | |
| Mass | 0.93±0.15[2] M☉ |
| Other designations | |
| Nova Gem 1912, Nova Geminorum II[3], DN Gem, AAVSO 0648+32, HD 50480[4] | |
| Database references | |
| SIMBAD | data |
This is a close binary star system consisting of a white dwarf with 93%[2] of the Sun's mass – the source for the nova explosion – and a lower mass red dwarf[6] companion from which the white dwarf is accreting matter.[2] The system is located approximately 4,500 light years from the Sun based on parallax, with its visual magnitude being diminished by an extinction of 0.53±0.12 due to interstellar dust.[2] Observations of this system showed a sinusoidal variation in luminosity with a period of 3.06840 ± 0.00012 h, which is likely the orbital period for the pair. This oscillation may be caused by irradiation of the companion star by the white dwarf.[6]