| |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquarius |
| Right ascension | 22h06m 26.22742s[1] |
| Declination | –13° 52′ 10.8615″[1] |
| Apparent magnitude (V) | 4.279[2] |
| Characteristics | |
| Spectral type | B8 V[3] |
| U−B color index | –0.288[2] |
| B−V color index | –0.062[2] |
| Variable type | constant[4] |
| Astrometry | |
| Radial velocity (Rv) | –10.0[5] km/s |
| Proper motion (μ) | RA: +36.89[1] mas/yr Dec.: –58.99[1] mas/yr |
| Parallax (π) | 18.62 ± 0.22 mas[1] |
| Distance | 175 ± 2 ly (53.7 ± 0.6 pc) |
| Absolute magnitude (MV) | +0.64[6] |
| Details[7] | |
| A | |
| Mass | 3.20+0.20 −0.16 M☉ |
| Radius | 2.7[8] R☉ |
| Luminosity | 74[6] L☉ |
| Surface gravity (log g) | 4.09±0.08[9] cgs |
| Temperature | 11,284±284[8] K |
| Metallicity [Fe/H] | −0.08±0.12[9] dex |
| Rotational velocity (v sin i) | 135[10] km/s |
| Age | 124+37 −62 Myr |
| B | |
| Mass | 1.00±0.03 M☉ |
| Temperature | 5,710±112 K |
| Metallicity [Fe/H] | −0.5 dex |
| Rotational velocity (v sin i) | 20 km/s |
| Other designations | |
ι Aqr, 33 Aquarii, BD–14 6209, FK5 828, HD 209819, HIP 109139, HR 8418, SAO 164861[11] | |
| Database references | |
| SIMBAD | data |
Iota Aquarii, Latinised from ι Aquarii, is the Bayer designation for a binary star[7] system in the equatorial constellationofAquarius. It is visible to the naked eye with an apparent magnitude of +4.279.[2] Based upon parallax measurements made during the Hipparcos mission, the distance to this star is around 175 light-years (54parsecs).[2] The system is drifting closer to the Sun with a radial velocity of −10 km/s.[5]
The binary nature of this system was reported in 2009 following a radial velocity survey using the HARPS instrument.[4] A 2010 infrared search for companions around this star was unsuccessful.[12] The presence of a stellar companion was confirmed through direct spectral detection in 2016. The companion shows a significant velocity variation over a 77-day interval, suggesting a short orbital period.[7]
The spectrum of the primary, component A, fits a stellar classification of B8 V,[3] showing that this is a B-type main-sequence star. It is roughly 124[7] million years old and is spinning rapidly with a projected rotational velocity of 135 km/s.[10] The star has 3.2[7] times the mass of the Sun and 2.7[8] times the Sun's radius. It is radiating 74[6] times the luminosity of the Sun from its photosphere at an effective temperature of ~11,284 km/s.[8] The secondary, component B, has a spectrum of a solar-mass star.[7] The system is a source for X-ray emission.[13]
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