Sigma Draconis
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| Observation data Equinox J2000 |
|
|---|---|
| Constellation | Draco |
| Right ascension | 19h 32m 21.6s |
| Declination | +69° 39' 40" |
| Apparent magnitude (V) | 4.68 |
| Characteristics | |
| Spectral type | K0 V |
| U-B color index | 0.38 |
| B-V color index | 0.79 |
| Variable type | Suspected |
| Astrometry | |
| Radial velocity (Rv) | 27.7 km/s |
| Proper motion (μ) | RA: 598.43 mas/yr Dec.: -1738.81 mas/yr |
| Parallax (π) | 173.59 ± 0.41 mas |
| Distance | 18.79 ± 0.04 ly (5.76 ± 0.01 pc) |
| Absolute magnitude (MV) | 5.87 |
| Details | |
| Mass | 0.89 M☉ |
| Radius | 0.89 R☉ |
| Luminosity | 0.39 L☉ |
| Temperature | 4,850 K |
| Metallicity | 56-59% Sun |
| Rotation | |
| Age | 3.3 × 109 years |
| Other designations | |
Sigma Draconis (σ Dra / σ Draconis) is a star 18.8 light years away from Earth. Its traditional name is Alsafi. It is in constellation Draco. Its visual magnitude is 4.68.
The star is an orange main sequence dwarf of spectral type K0. No Jupiter-size or larger companion has yet been detected about this star and there is no indication of excess infrared radiation that would be evidence of circumstellar matter.[1]
The traditional name "Alsafi" (also Athafi) supposedly derives from an Arabic word al-athafi "the cooking tripods".
[edit] References
- ^ E. K. Holmes, H. M. Butner, S. B. Fajardo-Acosta, L. M. Rebull (2003). "A Survey of Nearby Main-Sequence Stars for Submillimeter Emission". The Astronomical Journal 125 (6): 3334-3343.
[edit] External links
[edit] See also
- Sigma Draconis in fiction
- Sigma Draconis (Honorverse) - a fictional version of Sigma Draconis
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