Polaris
catalogues and names | Polaris, a UMi, alf UMi, 1 UMi, HR 424, HD 8890, SAO 308, FK5: 907, WDS 02309+8915A |
other names | Alruccabah, Cynosura, Phoenice, Lodestar, Pole Star, Tramontana, Angel Stern, Navigatoria, Star of Arcady, Yilduz, Mismar |
constellation | Ursa Minor |
data from The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version) (Hoffleit+, 1991)
note (category: star names): | POLARIS; Alruccabah; Cynosura; Phoenice; Lodestar; Pole Star; Tramontana; Angel Stern; Navigatoria; Star of Arcady; Yilduz; Mismar. |
position, motion, parallax:
position (J2000) | RA: 2h 31min 48,7sec | DEC: +89° 15' 51'' |
position (J1900) | RA: 1h 22min 33,7sec | DEC: +88° 46' 26'' |
proper motion (J2000) | RA: 0,038 arcsec/a | DEC: -0,015 arcsec/a |
radial velocity | -17 km/s note: spectroscopic binaries note: orbital data avaible |
|
rotational velocity | 17 km/s (uncertain) (variable) | |
trigonometric parallax | 0,007 arcsec |
note (category: dynamical parallaxes): | 0.006". |
magnitude
visual magnitude | 2,02 (V on UBV Johnson system) |
spectral / color information
spectral class | F7:Ib-II |
B-V-magnitude | 0,6 |
U-B-magnitude | 0,38 |
R-I-magnitude | 0,31 |
note (category: spectra): | Also classified F7Ib-F8Ib. |
variability information
variable star identification | Alp UMi |
note (category: variability): | CDelta 1.92 - 2.07V, 3.969778d. Period increases 53 sec./century. Probably unreddened. |
double/multiple star system information
number of components of multiple star system | 5 |
separation | 18,4 arcsec |
mag difference (of double or brightest multiple) | 6,8 |
component ID | AB |
note (category: double and multiple data): | A* 2.0 var. F8Ib, 30.46y, a = 0.038". AB physical; B, 8.20V, +0.49(B-V), +0.16(U-B), F3V, 0.0 color excess, vsini =<60k/s; C, 13v at 43"; D, 14v at 83". |
note (category: spectroscopic binaries): | ADS 1477A, K 4.1k/s, V0 -16.4k/s, asini 482. Period 6-8y? Unresolved by speckle interferometry. RV varies in 2 periods, 3.968d pulsation, 27.6y revolution of unseen blue companion. |
miscellaneous information
note (category: group membership): | Red star Pleiades group. |
data from SKY2000 - Master Star Catalog (Myers+ 1997)
position, motion, parallax:
position (J2000) | RA: 2h 31min 48,704sec | DEC: +89° 15' 50,72'' | ±0,06 arcsec | source: 15 |
proper motion (J2000) | RA: 0,1988 arcsec/a | DEC: -0,015 arcsec/a | source: 25 | |
radial velocity | -17 km/s | source: 25 | ||
trigonometric parallax | 0,007 | ±0,001 arcsec | source: 25 | |
galactic coord. (B1950) | longitude: 123,28° | latitude: 26,46° | ||
GCI unit vector (J2000) | X: 0,010127 | Y: 0,007899 | Z: 0,999918 |
magnitude:
visual | 1,9 (observed) | source: 31 |
photovisual | 2,1 | source: 2 |
spectral information:
spectral class | F8 | source: 96 | |
Morgan-Keenan | F7:Ib-II | source: 25 | |
B-magnitude | 2,62 ±0,05 | B-V-magnitude | 0,6 |
U-magnitude | 3 ±0,05 | U-B-magnitude | 0,38 |
variability information:
variability type | 115 |
var. amplitude | 0,27 |
var. period | 3,97 |
var. epoch | 2431496 9. February 1945, 12:00:00 UT |
next max light | 2451623,9 20. March 2000, 09:36:00 UT |
double/multiple star system information:
separation between brightest and second brightest component | 18,4 arcsec |
magnitude difference between brightest and second brightest component | 7 |
position angle | 216 ° |
component | magnitude | spectral class | catalogue(s)/name(s) |
A | 1,9 | F8 | Polaris, a Ursae Minoris, 1 UMi, HR 424, HD 8890, SAO 308 |
B | 8,2 | F1 |
sources:
2 | HD and HDE Catalogs |
Cannon, A.J., and E.C. Pickering, Harvard Annals, Vols 91-99, 1918-24, Cambridge, Massachusetts: Harvard University; Cannon, A.J., Harvard Annals, Vol. 100, 1925-36, Cambridge, Massachusetts: Harvard University; and Cannon, A.J., and M. Walton Mayall, Harvard Annals, Vol. 112, 1949, Cambridge, Massachusetts: Harvard University | |
15 | FK5, FK5 Extension and FK5 Supplement |
Fricke, W., H. Schwan and T. Lederle, "Fifth Fundamental Catalogue (FK5), Part I. The Basic Fundamental Stars," Veroff. Astronomisches Recheninstitut, No. 32, Heidelberg, Germany, 1988, and Fricke, W., H. Schwan, and T.E. Corbin, "Fifth Fundamental Catalogue (FK5), Part II. The FK5 Extension," Veröff. Astronomisches Recheninstitut, No. 33, Heidelberg, Germany, 1991 | |
19 | WDS Catalog |
Worley, C.E., and G.G. Douglass, Washington Catalog of Visual Double Stars 1996.0, United States Naval Observatory, 1996 | |
25 | Bright Star Catalogue, 5th edition |
Hoffleit, D. and Warren, W.H. Jr., The Bright Star Catalogue, 5th Revised Edition, Version 2, 1994 | |
30 | GCVS, 4th edition |
Kholopov, P.N., et al., General Catalogue of Variable Stars, fourth edition, Moscow: Nauka Publishing House, 1985-88 | |
31 | CRM' (non-GCVS variable data) |
Warren, W.H. Jr., Northern Hemisphere Catalog of Red Magnitudes, 1994 | |
96 | SAO or HD/HDE Catalog |
Reference from Value 1 or Reference from Value 2 |
data from Smithsonian Astrophysical Observatory Star Catalog (SAO Staff 1966; USNO, ADC 1990)
position and proper motion:
position (J1950) | RA: 1h 48min 48,786sec | DEC: +89° 1' 43,74'' | ±0,003 arcsec |
position (J2000) | RA: 2h 31min 48,711sec | DEC: +89° 15' 50,64'' | |
proper motion J1950 (FK4) | RA: 0,1811 arcsec/a | DEC: -0,004 arcsec/a | ±0,001 arcsec/a in RA ±0,001 arcsec/a in DEC |
proper motion J2000 (FK5) | RA: 0,2012 arcsec/a | DEC: -0,016 arcsec/a | |
source of proper motion data | Determined by source catalog |
magnitude:
visual | 2,1 (accuracy: 2 decimals) |
source of visual magnitude data | Arithmetic mean of maximum and minimum magnitudes of a variable star |
spectral information:
spectral class | F8v |
source of spectral data | Taken from the Henry Draper Catalogue or no spectrum in source catalog. |
remarks for duplicity and variability
Variable star in visual magnitude in source catalog |
catalogues
source catalogue | FK4, catalogue number: 907 |
Durchmusterung | BD+88 8 |
Boss General Catalogue | 2243 |
Henry Draper Catalogue | 8890 |
data from Combined General Catalogue of Variable Stars (Vol. I-III) (Kholopov+ 1998)
position:
position (J1950) | RA: 1h 48min 48,8sec | DEC: +89° 1' 44'' |
variability informations:
variability type | DCEPS | pulsating variable star |
magnitute at max. brightness | 1,86 | |
magnitute at min. brightness | 2,13 | |
photometric system | visual, photovisual or Johnson's V | |
epoch for maximum light [JD] | 2431495,813 9. February 1945, 07:30:43 UT |
|
period [d] | 3,9696 | |
next maximum light [JD] | 2451625,6546 22. March 2000, 03:42:37 UT |
|
rising time | 50 % of period |
spectral information
spectral class | F7Ib-F8Ib |
references
to a study | Vol. III GCVS |
to a chart/photograph | no chart is avaible, but the star is contained in the 'Bonner Durchmusterung' |
miscanellous
ID in the GCVS catalogue | 84/9001 |
constellation | Ursa Minor |
notes on existence | The star is equivalent to '0849003 gam'. |
There are notes in published catalog. |
variability type description
variability type | description |
DCEPS | These are Delta Cep variables having light amplitudes <0.5 mag in V (<0.7 mag in B) and almost symmetrical light curves (M-m approx. 0.4 - 0.5 periods); as a rule, their periods do not exceed 7 days. They are probably first-overtone pulsators and/or are in the first transition across the instability strip after leaving the main sequence (SU Cas). |