Eta Cassiopeia, a white main-sequence star in Cassiopeia
Eta Cassiopeia is a white main-sequence star in the constellation Cassiopeia. At 19.4 light years away, it is the 272nd brightest star in the Earth's sky, where it shines at an apparent visual magnitude of 3.46.
Eta Cassiopeia (HIP 3821)
Eta Cassiopeia is a white main-sequence star in the constellation Cassiopeia. At 19.4 light years away, it is the 272nd brightest star in the Earth's sky, where it shines at an apparent visual magnitude of 3.46. Eta Cassiopeia is the primary component of a multiple-star system. The star's age is estimated to be 5.1 billion years but is certainly no less than 2 billion years and no greater than 8.4 billion years. The iron abundance of Eta Cassiopeia is -0.28 (52.5% of the Sun). It is moving through the Galaxy at a speed of 35.5 km/s relative to the Sun. Its projected Galactic orbit carries it between 23,100 and 27,400 light years from the center of the Galaxy.
Sky position: RA 0h 49.1m, Dec +57° 49.2'
Common designations: Eta Cassiopeiae, Achird, 24 Cassiopeiae, HIP 3821, HD 4614, Gliese 34 A, Wolf 24
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Brightest stars in Cassiopeia:
(list all)
| Rank | Mag. | Star |
| 1 | 2.15 | Gamma Cassiopeiae |
| 2 | 2.24 | Schedar |
| 3 | 2.28 | Caph |
| 4 | 2.66 | Ruchbah |
| 5 | 3.35 | Segin |
6
| 3.46
) Eta Cassiopeia
| Rank | Mag. | Star |
| 7 | 3.69 | Zeta Cassiopeiae |
| 8 | 3.95 | 50 Cassiopeiae |
| 9 | 4.17 | Kappa Cassiopeiae |
| 10 | 4.34 | Marfak |
| 11 | 4.46 | Iota Cassiopeiae |
| 12 | 4.48 | Omicron Cassiopeiae |
| 13 | 4.49 | A Cassiopeiae |
| 14 | 4.51 | Rho Cassiopeiae |
| 15 | 4.62 | Upsilon-2 Cassiopeiae |
| 16 | 4.68 | Chi Cassiopeiae |
| 17 | 4.72 | Psi Cassiopeiae |
Hover over other bright stars to identify or click to jump.
Galactic Orbit of Eta Cassiopeia
(compared to the Sun)
E
ccentricity: 8.6% vs. 16.0%Angle φ : -62.8°vs. 26.0°
Semi-major axis : 7,751 pc vs. 8,686 pc
Semi-minor axis: 7,722 pc vs. 8,574 pc
Focus-to-center
: 665 pcvs. 1,388 pcSemilatus rectum : 7,694 pc vs. 8,464 pc
Perigalacticon: 7,086 pc vs. 7,297 pc
Apogalacticon
: 8,416 pcvs. 10,074 pcSome Tabulated XHIP Data for Eta Cassiopeia
(see also: SIMBAD)
Astrometry
2007A&A...474..653V
| Position | Proper Motion | |
| Right Ascension: | 12.27125307° ±0.30 mas | 1,086.59 ±0.40 mas/yr. |
| Declination: | 57.81654753° ±0.27 mas | -559.43 ±0.33 mas/yr. |
| Galactic Longitude: | 122.61739279° | 1,081.41 mas/yr. |
| Galactic Latitude: | -5.05376554° | -569.37 mas/yr. |
Parallax: 167.98 ± 0.48 mas
Spectrography
Spectral Type: F9V 2008ApJS..176..216A.
Radial Velocity:
8.33 ±0.10 km/s [A rating]
2002ApJS..141..503N, 2005ApJS..159..141V.
This star is a spectroscopic binary with a solved orbit.
Iron Abundance [Fe/H]:
-0.28 dex
2011A&A...525A..71W, 2009A&A...501..941H, 2007A&A...465..271R, 2006ApJ...652.1604B, 2006AJ....131.3069L, 2005PASJ...57...27T, 2005ApJS..161..444T, 2005ApJS..159..141V, 2005AJ....129.1063L, 2004A&A...420..183A, 2004A&A...418..551M, 2003AJ....126.2015H, 2000Priv.C........F, 1996A&A...314..191G, 1993A&A...275..101E.
Photometry
| band | magnitude | Abs. Mag. |
| U | ||
| B | 4.05 | 5.17 |
| V | 3.46 | 4.59 |
| R | 3.10 | 4.23 |
| I | 2.80 | 3.93 |
| J | 2.11 | 3.24 |
| H | 2.09 | 3.21 |
| K | 1.99 | 3.11 |
B-V: +0.59 V-I: +0.66
Derivations
Heliocentric distance: 5.95 pc (0.3% margin of error)
Galactocentric distance: 7,403 pc
Transverse velocity: 34.5 km/s
3D heliocentric position and motion:
|
toward: |
Galactic center | Galactic rotation | North Galactic Pole |
| Position ( X, Y, Z) | -3.2 pc | 5.0 pc | -0.5 pc |
| Velocity (U, V, W) | -29.4 km/s | -10.7 km/s | -16.7 km/s |