  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Puppis |
| Right ascension | 07h 53m 03.63538s [1] |
| Declination | −49° 36′ 46.9530″ [1] |
| Apparent magnitude (V) | 4.63 [2] |
| Characteristics | |
| Spectral type | B2V [3] |
| U−B color index | −0.92 [2] |
| B−V color index | −0.23 [2] |
| Variable type | Constant [4] |
| Astrometry | |
| Radial velocity (Rv) | +8.00±4.2 [5] km/s |
| Proper motion (μ) | RA: −7.77 [1] mas/yr Dec.: +15.16 [1] mas/yr |
| Parallax (π) | 4.30±0.15 mas [1] |
| Distance | 760 ± 30 ly (233 ± 8 pc) |
| Absolute magnitude (MV) | −2.2±0.1 [6] |
| Details | |
| Mass | 9.6 M☉ [7] 10.1±0.5 [8] M☉ |
| Radius | 4.5±0.7 [8] R☉ |
| Luminosity | 5,908 [9] L☉ |
| Surface gravity (log g) | 4.01±0.09 [6] cgs |
| Temperature | 23,700 [9] K |
| Metallicity [Fe/H] | +0.01 [10] dex |
| Rotation | 1.33026 d [11] |
| Rotational velocity (v sin i) | 160 [12] km/s |
| Age | 12.6+7.4 −2.7 [8] Myr |
| Other designations | |
| CD−49°3137, CPD−49°1398, GC 10686, HD 64740, HIP 38500, HR 3089, SAO 219106, GSC 08143-03240 | |
| Database references | |
| SIMBAD | data |
HD 64740 is a single [13] star in the southern constellation Puppis, positioned near the line of sight to the Gum Nebula. [4] It has a blue-white hue and is faintly visible to the naked eye with an apparent visual magnitude of 4.63. [2] Parallax measurements give a distance estimate of approximately 760 light-years from the Sun, [1] and it is drifting further away with a radial velocity of +8 km/s. [5]
This is a massive B-type main-sequence star with a stellar classification of B2V. [3] It is a magnetic chemically peculiar star of the helium strong variety [6] with weak hydrogen alpha emission. [8] The polar magnetic field strength is 3,700 G . [4] The star is about halfway through its main sequence lifetime with an estimated age of ~13 million years. [8] It is spinning rapidly with an equatorial velocity of about 140±10 km/s, based on a polar inclination angle of 36°±15°, [4] giving it a rotation period of ~1.33 days. [11] The star is radiating over 5,900 times the luminosity of the Sun from its photosphere at an effective temperature of 23,700 K. [9]
Significant X-ray emission has been detected originating from this star, which may be connected to the magnetically-confined stellar wind. [14] The star does not display pulsation behavior, but it does show a magnetically-modulated variation from the wind. [15] Variation of ultraviolet lines of silicon has been detected, which may be due to surface abundance variations. [4] Two patches of helium overabundance are observed near the magnetic poles, which are inclined by about 20° to the star's pole of rotation. [11]
