Alfirk
catalogues and names | Alfirk, b Cep, bet Cep, 8 Cep, HR 8238, HD 205021, SAO 10057, FK5: 809, WDS 21287+7034A |
other names | Alphirk |
constellation | Cepheus |
data from The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version) (Hoffleit+, 1991)
note (category: star names): | Alfirk; Alphirk. |
position, motion, parallax:
position (J2000) | RA: 21h 28min 39,6sec | DEC: +70° 33' 39'' |
position (J1900) | RA: 21h 27min 22,2sec | DEC: +70° 7' 18'' |
proper motion (J2000) | RA: 0,01 arcsec/a | DEC: 0,007 arcsec/a |
radial velocity | -8 km/s note: spectroscopic binaries note: orbital data avaible |
|
rotational velocity | 28 km/s (uncertain) (variable) | |
trigonometric parallax | 0,014 arcsec |
note (category: dynamical parallaxes): | 0.004". |
magnitude
visual magnitude | 3,23 (V on UBV Johnson system) |
spectral / color information
spectral class | B1IV |
B-V-magnitude | -0,22 |
U-B-magnitude | -0,95 |
R-I-magnitude | -0,22 |
variability information
variable star identification | Bet Cep |
note (category: variability): | ADS 15032A, Beta C 3.16 - 3.27V, 0.1904881d, modulation period 10.893d. SiIV and CIV vary. Satellite UV obs. indicate temp. varies 1340d, max./min. radius 1.038. |
double/multiple star system information
number of components of multiple star system | 3 |
separation | 13,4 arcsec |
mag difference (of double or brightest multiple) | 4,6 |
component ID | AB |
note (category: double and multiple data): | ADS 15032AB, 50y. B, 7.84V, +0.18(B-V), +0.06(U-B), A2.5V, vsini 60:k/s. Third component discovered by speckle interferometry, mag. diff about 4v. Sep. 0.025". Possible circumstellar material. |
note (category: spectroscopic binaries): | ADS 15032A, 10.893d, K 3.1k/s, V0 -3.1k/s, asini 0.397. Resolved by speckle interferometry 1986.45, sep. 0.11". |
miscellaneous information
note (category: group membership): | Cep OB1. |
data from SKY2000 - Master Star Catalog (Myers+ 1997)
position, motion, parallax:
position (J2000) | RA: 21h 28min 39,6sec | DEC: +70° 33' 38,61'' | ±0,06 arcsec | source: 15 |
proper motion (J2000) | RA: 0,0021 arcsec/a | DEC: 0,007 arcsec/a | source: 25 | |
radial velocity | -8 km/s | source: 25 | ||
trigonometric parallax | 0,014 | ±0,001 arcsec | source: 25 | |
galactic coord. (B1950) | longitude: 107,54° | latitude: 14,03° | ||
GCI unit vector (J2000) | X: 0,262845 | Y: -0,204141 | Z: 0,942995 |
magnitude:
visual | 3,2 (observed) | source: 31 |
photovisual | 3,3 | source: 2 |
spectral information:
spectral class | B1 | source: 96 | |
Morgan-Keenan | B1IV | source: 25 | |
B-magnitude | 3,01 ±0,05 | B-V-magnitude | -0,22 |
U-magnitude | 2,06 ±0,05 | U-B-magnitude | -0,95 |
variability information:
variability type | 140 |
var. amplitude | 0,11 |
var. period | 0,19 |
var. epoch | 2440445 11. August 1969, 12:00:00 UT |
next max light | 2451620,42 16. March 2000, 22:04:48 UT |
double/multiple star system information:
separation between brightest and second brightest component | 0,1 arcsec |
position angle | 51 ° |
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: 21h 28min 1,326sec | DEC: +70° 20' 27,85'' | ±0,003 arcsec |
position (J2000) | RA: 21h 28min 39,628sec | DEC: +70° 33' 38,67'' | |
proper motion J1950 (FK4) | RA: 0,002 arcsec/a | DEC: 0,013 arcsec/a | ±0,001 arcsec/a in RA ±0,001 arcsec/a in DEC |
proper motion J2000 (FK5) | RA: 0,0024 arcsec/a | DEC: 0,008 arcsec/a | |
source of proper motion data | Determined by source catalog |
magnitude:
visual | 3,3 (accuracy: 2 decimals) |
source of visual magnitude data | Taken from the "Henry Draper Catalogue". |
spectral information:
spectral class | B1 |
source of spectral data | Taken from the Henry Draper Catalogue or no spectrum in source catalog. |
catalogues
source catalogue | FK4, catalogue number: 809 |
Durchmusterung | BD+69 1173 |
Boss General Catalogue | 30118 |
Henry Draper Catalogue | 205021 |
data from The Washington Visual Double Star Catalog, 1996.0 (Worley+, 1996)
position and proper motion:
position (J2000) | RA: 21h 28,7min | DEC: +70° 34' |
proper motion (J2000) | RA: 0,01 arcsec/a | DEC: 0,007 arcsec/a |
double/multiple star system information:
component | year | number of measures | position angle | angular separation | magnitude of 1st component | magnitude of 2nd component | spectral class(es) | discoverer code |
Aa | 1971 | 30 | 48° | 0,3'' | 3,2 | - | B2III | LAB |
1990 | 51° | 0,1'' | ||||||
Aa-B | 1832 | 59 | 251° | 13,4'' | 3,2 | 7,8 | - | STF2806 |
1975 | 249° | - |
discoverer information:
discoverer code | discoverer | reference |
LAB | Labeyrie et al | |
STF2806 | Struve, F.G.W. | - |
notes:
note | Beta Cep. The third component was discovered recently by speckle interferometry. |
data from Combined General Catalogue of Variable Stars (Vol. I-III) (Kholopov+ 1998)
position:
position (J1950) | RA: 21h 28min 1,3sec | DEC: +70° 20' 28'' |
variability informations:
variability type | BCEP | pulsating variable star |
magnitute at max. brightness | 3,16 | |
magnitute at min. brightness | 3,27 | |
photometric system | visual, photovisual or Johnson's V | |
epoch for maximum light [JD] | 2440444,625 11. August 1969, 03:00:00 UT |
|
period [d] | 0,1904881 | |
next maximum light [JD] | 2451620,3713389 16. March 2000, 20:54:44 UT |
|
rising time | 50 % of period |
spectral information
spectral class | B2IIIeV |
references
to a study | Vol. I GCVS (see Kholopov et al. 1985-1988) |
to a chart/photograph | no chart is avaible, but the star is contained in the 'Bonner Durchmusterung' |
miscanellous
ID in the GCVS catalogue | 20/9002 |
constellation | Cepheus |
notes on existence | The star is equivalent to '0209004 del'. |
There are notes in published catalog. |
variability type description
variability type | description |
BCEP | Variables of the Beta Cephei type (Beta Cep, Beta CMa), which are pulsating O8-B6 I-V stars with periods of light and radial-velocity variations in the range of 0.1 - 0.6 days and light amplitudes from 0.01 to 0.3 mag in V. The light curves are similar in shape to average radial-velocity curves but lag in phase by a quarter of the period, so that maximum brightness corresponds to maximum contraction, i.e., to minimum stellar radius. The majority of these stars probably show radial pulsations, but some (V649 Per) display nonradial pulsations; multiperiodicity is characteristic of many of these stars. |