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Name
  alf UMi  
AAVSO UID
000-BBF-045 (723 observations)  
Constellation
Ursa Minor Sequence
J2000.0
02 31 49.08 +89 15 50.8  (37.95450 +89.26411) Search nearby
B1950.0 01 48 44.92 +89 01 43.7
Proper motion
RA: 44.48 +/- 0.11 mas/yDec: -11.85 +/- 0.13 mas/ySource: F. Van Leeuwen, 2007
Galactic coord. 123.281 +26.461
Other names

(Internal only)
1 UMi 3XMM J023145.5+891548 AAVSO 0122+88
ADS 1477 A BD+88 8 CCDM J02319+8915A
CXO J023149.5+891550 CXOGSG J023150.1+891550 HD 8890
HIP 11767 HR 424 IRAS 01490+8901
Polaris RAFGL 273 SAO 308
TYC 4628-237-1 WDS J02318+8916Aa  
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Variability type
DCEPS
Spectral type F7Ib-F8Ib
Mag. range
1.97 - 2.00 V
Discoverer Ejnar Hertzsprung (1911)
Epoch
09 Feb 1945 (HJD 2431495.813) Ephemeris
Outburst --
Period 3.9696 d
Rise/eclipse dur. 50%
Remarks
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1 Otero, Sebastian Alberto Amplitude decrease during the 20th century. Currently, amplitude varies but always below 0.05 mag. Period is increasing.
2 GCVS Team VB A (B 8.20m, F3V, 18.3", 218deg); SB1 (Porb = 10969d, E = 0.655 [K.W.Kamper, N.R.Evans, R.W. Lyons, JRAS Can 78, N5, 173, 1984.]). P var. There is a non-linear term in the elements: +1.9877d*10**(-7)*E**2. The amplitude of light and radial velocity variation decreased in 1982. A(V) = 0.04m (1984).
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References
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1 A.Arellano Ferro, ApJ 274, 755, 1983. 1983ApJ...274..755A
2 Hertzsprung, E., 1911, Nachweis der Veränderlichkeit von alpha Ursae
minoris
1911AN....189...89H
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Catalog Data
Information from selected catalogs obtained by cross-matching to 2 arc seconds using the CDS X-Match Service. These data may not be complete.
2MASS J = 0.80H = 0.46K = 0.46J - K = 0.34
AllWISE W3 = 0.58W4 = 0.57W3 - W4 = 0.02
Images
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Supporting Documents
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1 Alpha Ursae Minoris light curve Otero, Sebastian Alberto 2007-12-04 14:56 UTC Light curve using Hipparcos data transformed to V. showing the current small amplitude of the star.
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Revision History
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4 Schmeer, Patrick 2018-07-05 06:46 UTC Discoverer added from 1911AN....189...89H.
3 Otero, Sebastian Alberto 2007-12-04 14:56 UTC HIP position. HIP photometry transformed to V used for the range.
2 Koppelman, Michael 2007-12-04 02:36 UTC The SIMBAD links fills in Polaris for this star but you can't search for it by that name. I'm hoping this fixes that.
1 Admin, VSX 2005-12-17 20:33 UTC Initial database population.