Beta Doradus (Beta Dor, β Doradus, β Dor) is the second brightest star in the southern constellation of Dorado. It has an apparent visual magnitude of 3.63, making it visible to the naked eye from the southern hemisphere. Based upon parallax measurements with the Hubble Space Telescope, it is located at a distance of 1,040 light-years (320 parsecs) from Earth.
Epoch J2000.0 Equinox J2000.0 (ICRS)
|Right ascension||05h 33m 37.51729s|
|Declination||−62° 29′ 23.3692″|
|Apparent magnitude (V)||3.63|
|U−B color index||+0.55|
|B−V color index||+0.70|
|R−I color index||+0.48|
|Variable type||δ Cephei|
|Radial velocity (Rv)||+7.2 km/s|
|Proper motion (μ)|| RA: +0.79 mas/yr |
Dec.: +12.74 mas/yr
|Parallax (π)||3.14 ± 0.16 mas|
|Distance||1,040 ± 50 ly |
(320 ± 20 pc)
|Absolute magnitude (MV)||−3.91 ± 0.11|
|Radius||67.8 ± 0.7 R☉|
|Surface gravity (log g)||1.3 cgs|
|Metallicity [Fe/H]||–0.13 dex|
|Rotational velocity (v sin i)||0 km/s|
Beta Doradus is a Cepheid variable that regularly changes magnitude from a low of 4.05 to a high of 3.45 over a period of 9.842 days. The light curve of this magnitude change follows a regular saw-tooth pattern. During each radial pulsation cycle, the radius of the star varies by ±3.9 times the Sun's radius around a mean of 67.8. Its spectral type and luminosity class are likewise variable, from F-type to G-type and from a supergiant to a bright giant.
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.
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