EM Cephei
catalogues and names
| catalogues and names | EM Cep, HD 208392, SAO 19718, BD +61 2216, WDS 21538+6237A |
data from SKY2000 - Master Star Catalog (Myers+ 1997)
position, motion, parallax:
| position (J2000) | RA: 21h 53min 48.13sec | DEC: +62° 36' 52'' | ±0.35 arcsec | source: 17 |
| position (2000.73) | RA: 21h 53min 49sec | DEC: +62° 37' 4'' | JD: 2451810.12 | |
| proper motion (J2000) | RA: -0.0007 arcsec/a | DEC: -0.003 arcsec/a | source: 17 | |
| radial velocity | -26 km/s | source: 26 | ||
| galactic coord. (B1950) | longitude: 104.03° | latitude: 6.46° | ||
magnitude:
| visual | 7.02 (observed) | source: 26 |
| photovisual | 7.1 | source: 2 |
| photographic | 7.6 | source: 16 |
spectral information:
| spectral class | B3 | source: 96 | |
| Morgan-Keenan | B0.5V* | source: 26 | |
| B-magnitude | 7.28 ±0.2 | B-V-magnitude | 0.26 |
| U-magnitude | 6.72 ±0.2 | U-B-magnitude | -0.56 |
variability information:
| variability type | 330 |
| var. amplitude | 0.2 |
| var. period | 0.81 |
| var. epoch | 2440143.73 14. October 1968, 05:31:12 UT |
| next max light | 2451810.16 22. September 2000, 15:50:24 UT |
double/multiple star system information:
| separation between brightest and second brightest component | 62.5 arcsec |
| position angle | 145 ° |
| component | magnitude | spectral class | catalogue(s)/name(s) |
| A | 7.02 | B3 | |
| B | 7.94 | B8 |
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 | |
| 16 | PPM North and PPM South Catalogs and PPM Supplement |
| Roser, S., and U. Bastian, "Catalogue of Positions and Proper Motions," A&AS, Vol. 74, p. 449, 1988, and Bastian, U., et al., "Catalogue of Positions and Proper Motions - South," 1993 | |
| 17 | ACRS |
| Corbin, T.E., and S.E. Urban, Astrographic Catalog Reference Stars, United States Naval Observatory, 1991 | |
| 19 | WDS Catalog |
| Worley, C.E., and G.G. Douglass, Washington Catalog of Visual Double Stars 1996.0, United States Naval Observatory, 1996 | |
| 26 | Bright Star Supplement |
| Hoffleit, D. and Warren, W.H. Jr., A Supplement to the Bright Star Catalogue, 1994 | |
| 27 | Catalog of Red Magnitudes (CRM) |
| 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 (B1950) | RA: 21h 52min 21.842sec | DEC: +62° 22' 40.46'' | ±0.034 arcsec |
| position (2000.73) | RA: 21h 53min 50sec | DEC: +62° 37' 5'' | JD: 2451810.12 |
| position (J2000) | RA: 21h 53min 48.111sec | DEC: +62° 36' 53.27'' | |
| proper motion B1950 (FK4) | RA: -0.001 arcsec/a | DEC: 0.017 arcsec/a | ±0.006 arcsec/a in RA ±0.004 arcsec/a in DEC |
| proper motion J2000 (FK5) | RA: -0.0007 arcsec/a | DEC: 0.012 arcsec/a | |
| source of proper motion data | Determined by source catalog | ||
magnitude:
| visual | 7.1 (accuracy: 2 decimals) |
| source of visual magnitude data | Taken from Harvard or San Luis photometry. |
spectral information:
| spectral class | B3 |
| source of spectral data | Taken from the Henry Draper Catalogue or no spectrum in source catalog. |
remarks for duplicity and variability
| Double star in Aitken's Double Star Catalogue (Aitken 1932) |
catalogues
| source catalogue | GC, catalogue number: 30671 |
| Durchmusterung | BD+61 2216 |
| Boss General Catalogue | 30671 |
| Henry Draper Catalogue | 208392 |
data from The Washington Visual Double Star Catalog, 1996.0 (Worley+, 1996)
position and proper motion:
| position (J2000) | RA: 21h 53.8min | DEC: +62° 37' |
| proper motion (J2000) | RA: -0.005 arcsec/a | DEC: -0.003 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 |
| AB | 1824 | 10 | 145° | 62.5'' | - | 7.92 | - | S 800 |
| Aa | 1902 | 1 | 281° | 19.8'' | 7.1 | 13.2 | - | ES 144 |
| Ab | 1902 | 1 | 43° | 22.4'' | 7.9 | 12.8 | B1V | ES 144 |
discoverer information:
| discoverer code | discoverer | reference |
| S 800 | South, J. | - |
| ES 144 | Espin, T.E. | - |
notes:
| note | A is the Beta Lyrae-type system EM Cep, P = 0.81d. Spectrum B0.5V+b1Ve. B is BD+61@2217, spectrum B1III/V. Proper motion of B +001 +001. |
data from Combined General Catalogue of Variable Stars (Vol. I-III) (Kholopov+ 1998)
position:
| position (equinox 1950.0) | RA: 21h 52min 21.8sec | DEC: +62° 22' 40'' |
variability informations:
| variability type | EW/KE | close binary eclipsing system |
| magnitute at max. brightness | 7.02 | |
| magnitute at min. brightness | 7.17 | |
| photometric system | visual, photovisual or Johnson's V | |
| epoch for maximum light [JD] | 2440134.7326 5. October 1968, 05:34:57 UT |
|
| period [d] | 0.806187 | |
| next maximum light [JD] | 2451810.738921 23. September 2000, 05:44:03 UT |
spectral information
| spectral class | B1IVe |
references
| to a study | Vol. I GCVS (see Kholopov et al. 1985-1988) |
| to a chart/photograph | Vol. I GCVS (see Kholopov et al. 1985-1988) |
miscanellous
| ID in the GCVS catalogue | 20/156 |
| constellation | Cepheus |
| notes on existence | The star is equivalent to '0200157 EN'. |
| There are notes in published catalog. | |
variability type description
| variability type | description |
| EW | Eclipsing binary systems. These are binary systems with orbital planes so close to the observer's line of sight (the inclination i of the orbital plane to the plane orthogonal to the line of sight is close to 90 deg) that the components periodically eclipse each other. Consequently, the observer finds changes of the apparent combined brightness of the system with the period coincident with that of the components' orbital motion. EA Algol (Beta Persei)-type eclipsing systems. Binaries with spherical or slightly ellipsoidal components. It is possible to specify, for their light curves, the moments of the beginning and end of the eclipses. Between eclipses the light remains almost constant or varies insignificantly because of reflection effects, slight ellipsoidality of components, or physical variations. Secondary minima may be absent. An extremely wide range of periods is observed, from 0.2 to >= 10000 days. Light amplitudes are also quite different and may reach several magnitudes. EB Beta Lyrae-type eclipsing systems. These are eclipsing systems having ellipsoidal components and light curves for which it is impossible to specify the exact times of onset and end of eclipses because of a continuous change of a system's apparent combined brightness between eclipses; secondary minimum is observed in all cases, its depth usually being considerably smaller than that of the primary minimum; periods are mainly longer than 1 day. The components generally belong to early spectral types (B-A). Light amplitudes are usually <2 mag in V. EW W Ursae Majoris-type eclipsing variables. These are eclipsers with periods shorter than 1 days, consisting of ellipsoidal components almost in contact and having light curves for which it is impossible to specify the exact times of onset and end of eclipses. The depths of the primary and secondary minima are almost equal or differ insignificantly. Light amplitudes are usually <0.8 mag in V. The components generally belong to spectral types F-G and later. |
| KE | Contact systems of early (O-A) spectral type, both components being close in size to their inner critical surfaces. |