Beta Doradus
Variable star in the constellation Dorado
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Beta Doradus, Latinized from β Doradus, is the second brightest star in the southern constellation of Dorado.[12] It is a Classical Cepheid variable, with an apparent magnitude that varies between 3.46 and 4.08.[2] Based upon parallax measurements with the Hubble Space Telescope, it is located at a distance of 1,040 light-years (320 parsecs) from Earth.[6]
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Dorado |
| Right ascension | 05h 33m 37.51253s[1] |
| Declination | −62° 29′ 23.3231″[1] |
| Apparent magnitude (V) | 3.46 to 4.08[2] |
| Characteristics | |
| Spectral type | F4-G4Ia-II[3] |
| U−B color index | +0.55[3] |
| B−V color index | +0.70[4] |
| R−I color index | +0.48[4] |
| Variable type | δ Cephei[2] |
| Astrometry | |
| Radial velocity (Rv) | +7.2[5] km/s |
| Proper motion (μ) | RA: +0.800[1] mas/yr Dec.: +9.458[1] mas/yr |
| Parallax (π) | 3.14±0.16 mas[6] |
| Distance | 1,040 ± 50 ly (320 ± 20 pc) |
| Absolute magnitude (MV) | −3.91±0.11[7] |
| Details | |
| Mass | 7.7±0.2[8] M☉ |
| Radius | 67.8±0.7[9] R☉ |
| Luminosity | 3,200[7] L☉ |
| Surface gravity (log g) | 1.3[10] cgs |
| Temperature | 5,445[7] K |
| Metallicity [Fe/H] | –0.13[10] dex |
| Rotational velocity (v sin i) | 0[3] km/s |
| Age | 42.5±2.7[8] Myr |
| Other designations | |
| β Dor, Beta Doradus, Beta Dor, CD−62 214, CPD−62 487, FK5 212, GC 6944, HD 37350, HIP 26069, HR 1922, SAO 249311, PPM 354837[11] | |
| Database references | |
| SIMBAD | data |
Characteristics
Beta Doradus is a Cepheid variable that regularly changes magnitude from a low of 4.08 to a high of 3.46[2] over a period of 9.84318 days.[14] The light curve of this magnitude change follows a nearly regular saw-tooth pattern, with average amplitude variations period to period about 0.005 magnitude from average amplitude of 0.62 magnitude.[14] During each radial pulsation cycle, the radius of the star varies by 3.9 R☉ around a mean of 67.8 R☉.[9] Its spectral type and luminosity class are likewise variable, from F-type to G-type and from a supergiant to a bright giant.[3]
Far ultraviolet emissions have been detected from this star with the Far Ultraviolet Spectroscopic Explorer, while X-ray emissions were detected with the XMM-Newton space telescope. The X-ray luminosity is about 1 × 1029 erg/s and the emission varies with the pulsation period, suggesting a connection with the pulsation process. The peak X-ray emissions are in the 0.6–0.8 keV energy range, which occurs for plasmas with temperatures of 7–10 million K.[15]