3 Puppis
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Puppis |
| Right ascension | 07h 43m 48.46872s |
| Declination | −28° 57′ 17.3720″ |
| Apparent magnitude (V) | 3.93 |
| Characteristics | |
| Spectral type | A2.7Ib (A2Ia - A3IIpe) |
| Apparent magnitude (K) | 2.340 |
| U−B color index | −0.09 |
| B−V color index | +0.18 |
| Astrometry | |
| Radial velocity (Rv) | 26.4±2.0 km/s |
| Proper motion (μ) | RA: −5.09 mas/yr Dec.: +3.90 mas/yr |
| Parallax (π) | 0.59±0.17 mas |
| Distance | 2,100±280 ly (630±85 pc) |
| Absolute magnitude (MV) | −5.5 |
| Details | |
| A | |
| Mass | 8.8±0.5 M☉ |
| Radius | 54±7 R☉ |
| Luminosity | 12,600+3,300 −2,600 L☉ |
| Surface gravity (log g) | 1.9±0.1 cgs |
| Temperature | 8,500±500 K |
| Rotational velocity (v sin i) | 35±5 km/s |
| B | |
| Mass | 0.75±0.25 M☉ |
| Radius | 0.3 R☉ |
| Surface gravity (log g) | 5.0 cgs |
| Temperature | 50,000 K |
| Orbit | |
| Primary | A |
| Companion | B |
| Period (P) | 137.4±0.1 days |
| Semi-major axis (a) | 1.11±0.03 AU |
| Semi-amplitude (K1) (primary) | 5.0±0.8 km/s |
| Other designations | |
| l Puppis, GSC 06552-03228, HD 62623, HIP 37677, HR 2996, SAO 174400, CD−28°4774 | |
| Database references | |
| SIMBAD | data |
3 Puppis (3 Pup) is a spectroscopic binary in the constellation Puppis. It is a very rare A[e] supergiant, referred to as a B[e] star despite its spectral classification, and its apparent magnitude is 3.93.
3 Puppis is surrounded by a disc of circumstellar dust, which is unusual for an A-type star. It is caused by a low mass companion, a helium-rich subdwarf that is transferring mass to the supergiant. Due to mass transfer, its mass reduced from 3.6 M☉ when it formed to the current 0.75 M☉. Like most B[e] stars, 3 Pup rotates rapidly, at 20% of the speed at which it would start to break apart. The disc has its inner edge only 3.8 AU from the primary star and it is suspected that deceleration of the hot primary stellar wind by the companion allows the dust to form unusually close to such a luminous star.