Eta Scorpii
Template:Short description Template:Cs1 config
Template:Location mark Location of η Sco (circled) | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Scorpius |
| Right ascension | Template:RA[1] |
| Declination | Template:DEC[1] |
| Apparent magnitude (V) | 3.33[2] |
| Characteristics | |
| Spectral type | F5 IV[3] |
| U−B Template:Engvar | +0.09[2] |
| B−V Template:Engvar | +0.41[2] |
| Astrometry | |
| Radial velocity (Rv) | −27.0[4] km/s |
| Proper motion (μ) | RA: +24.47[1] mas/yr Dec.: −288.55[1] mas/yr |
| Parallax (π) | 44.39±0.16 mas[1] |
| Distance | Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc) |
| Absolute magnitude (MV) | +1.58[5] |
| Details[6] | |
| Mass | Template:Val[7] Template:Solar mass |
| Radius | Template:Val Template:Solar radius |
| Luminosity | Template:Val Template:Solar luminosity |
| Surface gravity (log g) | Template:Val cgs |
| Temperature | Template:Val K |
| Metallicity [Fe/H] | Template:Val dex |
| Rotational velocity (v sin i) | 150.00 km/s |
| Age | 1.1[5] Gyr |
| Metallicity [Fe/H] | {{{metal_fe2}}} dex |
| Other designations | |
| Template:Odlist[8] | |
| Database references | |
| SIMBAD | data |
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Eta Scorpii, Latinized from η Scorpii, is a star in the southern zodiac constellation of Scorpius. With an apparent visual magnitude of 3.33,[2] this is one of the brighter members of the Scorpius and is the furthest south of the constellation stars with a Bayer designation.[9] The distance to this star can be estimated using parallax measurements, yielding a value of Template:Convert with a 0.4% margin of error.[1]
The stellar classification of this star has undergone some revision over time, with the star being classified anywhere from an F-type main sequence star to a giant star.[8] In 2006, the NStars program assigned it a class of F5 IV,[3] where the luminosity class of 'IV' indicates this is a subgiant star that is exhausting the supply of hydrogen at its core and is in the process of evolving into a giant star. It has around 1.6 times the Sun's mass[7] with an estimated age of 1.1 billion years.[5] The star is radiating about 18 times the luminosity of the Sun from its outer atmosphere at an effective temperature of 6,533 K.[6] It is this heat that gives it a yellow-white hue that is typical for an F-type star.[10]
Eta Scorpii is rotating rapidly, with a projected rotational velocity of 150 km s−1.[11] This is causing the star to spin on its axis with a period of less than a day.[12] It is an X-ray emitter with its stellar corona giving off an X-ray luminosity of Template:Val.[13] In 1991 it was identified as a possible barium star, as it displays an enhanced abundance of the element barium in its spectrum.[14] Overall, the abundance of elements other than hydrogen and helium, what astronomers term the star's metallicity, is similar to the abundance in the Sun.[5]
References
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