3 Aquarii
 Location of 3 Aquarii (circled) |
|
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Andromeda |
| Right ascension | 20h 47m 44.23898s[1] |
| Declination | –05° 01′ 39.7220″[1] |
| Apparent magnitude (V) | 4.429[2] |
| Characteristics | |
| Spectral type | M3 III[3] |
| U−B color index | +1.914[2] |
| B−V color index | +1.651[2] |
| Variable type | Semiregular |
| Astrometry | |
| Radial velocity (Rv) | –22.0[4] km/s |
| Proper motion (μ) | RA: +1.68[1] mas/yr Dec.: –40.06[1] mas/yr |
| Parallax (π) | 5.57 ± 0.28[1] mas |
| Distance | 590 ± 30 ly (180 ± 9 pc) |
| Details | |
| Radius | 108[5] R☉ |
| Temperature | 3,933[6] K |
| Other designations | |
3 Aquarii (abbreviated 3 Aqr) is a variable star in the equatorial constellation of Aquarius. 3 Aquarii is the Flamsteed designation; it also bears the Bayer designation k Aquarii and the variable star designation EN Aquarii. With a mean apparent visual magnitude of 4.429,[2] it is visible to the naked eye in dark skies. It has an annual parallax shift of 5.57 milliarcseconds with a 5% margin of error,[1] which translates to a physical distance of around 590 light-years (180 parsecs) from Earth.
| Period (days) |
Amplitude (Magnitude) |
|---|---|
| 20.2 | 0.020 |
| 24.9 | 0.038 |
| 27.2 | 0.027 |
| 35.0 | 0.021 |
| 36.9 | 0.024 |
| 143.9 | 0.022 |
| 197.2 | 0.027 |
With a stellar classification of M3 III,[3] this is a red giant star that has exhausted the hydrogen at its core and evolved away from the main sequence of stars like the Sun. The luminosity of this star varies over time, following multiple periods of variability.[8] The measured angular diameter of this star, after correction for limb darkening, is 5.60 ± 0.70 mas.[9] At the estimated distance of 3 Aquarii,[1] this yields a physical size of about 108 times the radius of the Sun.[5] The effective temperature of the outer atmosphere is 3,933 K,[6] giving this star the cool reddish hue of an M-type star.
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 2.0 2.1 2.2 2.3 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 3.0 3.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 5.0 5.1 Lua error in package.lua at line 80: module 'strict' not found.. The radius (R*) is given by:
- ↑ 6.0 6.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 8.0 8.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
