Alzirr, a white subgiant star in Gemini
Alzirr is a white subgiant star in the constellation Gemini. At 59 light years away, it is the 247th brightest star in the Earth's sky, where it shines at an apparent visual magnitude of 3.35.
Alzirr (HIP 32362)
Alzirr is a white subgiant star in the constellation Gemini. At 59 light years away, it is the 247th brightest star in the Earth's sky, where it shines at an apparent visual magnitude of 3.35. The star's age is estimated to be 1.5 billion years but is certainly no less than 1.4 billion years and no greater than 1.6 billion years. The iron abundance of Alzirr is +0.14 (138.0% of the Sun). It is moving through the Galaxy at a speed of 33.2 km/s relative to the Sun. Its projected Galactic orbit carries it between 21,800 and 24,600 light years from the center of the Galaxy. It came closest to the Sun 435,000 years ago when it had brightened to magnitude 2.14 from a distance of 34 light years.
Sky position: RA 6h 45.3m, Dec +12° 54'
Common designations: Alzirr, Xi Geminorum, 31 Geminorum, HIP 32362, HD 48737, Gliese 242
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Brightest stars in Gemini:
(list all)
| Rank | Mag. | Star |
| 1 | 1.16 | Pollux |
| 2 | 1.58 | Castor |
| 3 | 1.93 | Alhena |
| 4 | 2.87 | Tejat Posterior |
| 5 | 3.06 | Mebsuta |
| 6 | 3.31 | Tejat Prior |
7
| 3.35
) Alzirr
| Rank | Mag. | Star |
| 8 | 3.50 | Wasat |
| 9 | 3.57 | Kappa Geminorum |
| 10 | 3.58 | Lambda Geminorum |
| 11 | 3.60 | Theta Geminorum |
| 12 | 3.78 | Propus |
| 13 | 4.01 | Mekbuda |
| 14 | 4.06 | Upsilon Geminorum |
| 15 | 4.13 | Nu Geminorum |
| 16 | 4.16 | Propus |
| 17 | 4.16 | Rho Geminorum |
Hover over other bright stars to identify or click to jump.
Galactic Orbit of Alzirr
(compared to the Sun)
E
ccentricity: 6.0% vs. 16.0%Angle φ : -135.9°vs. 26.0°
Semi-major axis : 7,122 pc vs. 8,686 pc
Semi-minor axis: 7,109 pc vs. 8,574 pc
Focus-to-center
: 429 pcvs. 1,388 pcSemilatus rectum : 7,096 pc vs. 8,464 pc
Perigalacticon: 6,693 pc vs. 7,297 pc
Apogalacticon
: 7,550 pcvs. 10,074 pcSome Tabulated XHIP Data for Alzirr
(see also: SIMBAD)
Astrometry
2007A&A...474..653V
| Position | Proper Motion | |
| Right Ascension: | 101.32263990° ±0.20 mas | -115.66 ±0.18 mas/yr. |
| Declination: | 12.89605512° ±0.11 mas | -190.57 ±0.14 mas/yr. |
| Galactic Longitude: | 200.73906802° | 117.88 mas/yr. |
| Galactic Latitude: | 4.50238969° | -189.21 mas/yr. |
Parallax: 55.56 ± 0.19 mas
Spectrography
Spectral Type: F5IV-V 2003AJ....126.2048G.
Radial Velocity: 27.20 ±0.70 km/s [A rating] 2006AstL...32..759G.
Iron Abundance [Fe/H]:
0.14 dex
2011A&A...525A..71W, 2009A&A...501..941H.
Photometry
| band | magnitude | Abs. Mag. |
| U | ||
| B | 3.79 | 2.52 |
| V | 3.35 | 2.07 |
| R | 3.10 | 1.82 |
| I | 2.80 | 1.52 |
| J | 2.00 | 0.72 |
| H | 1.81 | 0.53 |
| K | 1.69 | 0.41 |
B-V: +0.44 V-I: +0.55
Derivations
Heliocentric distance: 18.00 pc (0.3% margin of error)
Galactocentric distance: 7,417 pc
Transverse velocity: 19.0 km/s
3D heliocentric position and motion:
|
toward: |
Galactic center | Galactic rotation | North Galactic Pole |
| Position ( X, Y, Z) | -16.8 pc | -6.4 pc | 1.4 pc |
| Velocity (U, V, W) | -23.0 km/s | -19.5 km/s | -14.0 km/s |