e Eridani
| catalogues and names | e Eri, eps Eri, 18 Eri, HR 1084, HD 22049, SAO 130564, FK5: 127, WDS 03330-0928 |
| constellation | Eridanus |
data from The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version) (Hoffleit+, 1991)
position, motion, parallax:
| position (J2000) | RA: 3h 32min 55,8sec | DEC: -9° 27' 30'' |
| position (J1900) | RA: 3h 28min 13,1sec | DEC: -9° 47' 48'' |
| proper motion (J2000) | RA: -0,974 arcsec/a | DEC: 0,021 arcsec/a |
| radial velocity | 15 km/s note: suspected variable radial velocity |
|
| rotational velocity | <17 km/s (uncertain) (variable) | |
| trigonometric parallax | 0,303 arcsec | |
magnitude
| visual magnitude | 3,73 (V on UBV Johnson system) |
spectral / color information
| spectral class | K2V |
| B-V-magnitude | 0,88 |
| U-B-magnitude | 0,59 |
| R-I-magnitude | 0,47 |
double/multiple star system information
| separation | 2 arcsec |
| mag difference (of double or brightest multiple) | 3 |
| note | astrometric binary |
| note (category: double and multiple data): | Astrometric binary, 25y. Unresolved by speckle interferometry. |
data from SKY2000 - Master Star Catalog (Myers+ 1997)
position, motion, parallax:
| position (J2000) | RA: 3h 32min 55,846sec | DEC: -9° 27' 29,72'' | ±0,06 arcsec | source: 15 |
| proper motion (J2000) | RA: -0,0658 arcsec/a | DEC: 0,021 arcsec/a | source: 25 | |
| radial velocity | 15 km/s | source: 25 | ||
| trigonometric parallax | 0,303 | ±0,03 arcsec | source: 25 | |
| galactic coord. (B1950) | longitude: 195,86° | latitude: -48,04° | ||
| GCI unit vector (J2000) | X: 0,590429 | Y: 0,790183 | Z: -0,164329 | |
magnitude:
| visual | 3,73 (observed) | source: 25 |
| photovisual | 3,8 | source: 2 |
| photographic | 4,8 | source: 2 |
spectral information:
| spectral class | K0 | source: 96 | |
| Morgan-Keenan | K2V | source: 25 | |
| B-magnitude | 4,61 ±0,05 | B-V-magnitude | 0,88 |
| U-magnitude | 5,2 ±0,05 | U-B-magnitude | 0,59 |
double/multiple star system information:
| separation between brightest and second brightest component | 0 arcsec |
| position angle | 143 ° |
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 | |
| 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: 3h 30min 34,355sec | DEC: -9° 37' 34,76'' | ±0,004 arcsec |
| position (J2000) | RA: 3h 32min 55,854sec | DEC: -9° 27' 29,65'' | |
| proper motion J1950 (FK4) | RA: -0,0662 arcsec/a | DEC: 0,019 arcsec/a | ±0,001 arcsec/a in RA ±0,001 arcsec/a in DEC |
| proper motion J2000 (FK5) | RA: -0,0657 arcsec/a | DEC: 0,021 arcsec/a | |
| source of proper motion data | Determined by source catalog | ||
magnitude:
| visual | 3,8 (accuracy: 2 decimals) |
| source of visual magnitude data | Taken from the "Henry Draper Catalogue". |
spectral information:
| spectral class | K0 |
| source of spectral data | Taken from the Henry Draper Catalogue or no spectrum in source catalog. |
catalogues
| source catalogue | FK4, catalogue number: 127 |
| Durchmusterung | BD-09 697 |
| Boss General Catalogue | 4244 |
| Henry Draper Catalogue | 22049 |
data from Combined General Catalogue of Variable Stars (Vol. I-III) (Kholopov+ 1998)
position:
| position (J1950) | RA: 3h 30min 34,4sec | DEC: -9° 37' 35'' |
variability informations:
| variability type | BY | rotating variable star |
| magnitute at max. brightness | 3,73 | |
| magnitute amplitude | 0,05 | |
| photometric system | visual, photovisual or Johnson's V |
references
| to a study | G.J.Frey, B.Grim, D.S.Hall, P.Mattingly, S.Robb, J.Wood, K.Zeigler, AJ 102, No.5, 1813, 1991. |
| to a chart/photograph | no chart is avaible, but the star is contained in the 'Bonner Durchmusterung' |
miscanellous
| ID in the GCVS catalogue | 36/9005 |
| constellation | Eridanus |
| notes on existence | The star is equivalent to '72012'. |
variability type description
| variability type | description |
| BY | BY Draconis-type variables, which are emission-line dwarfs of dKe-dMe spectral type showing quasiperiodic light changes with periods from a fraction of a day to 120 days and amplitudes from several hundredths to 0.5 mag in V. The light variability is caused by axial rotation of a star with a variable degree of nonuniformity of the surface brightness (spots) and chromospheric activity. Some of these stars also show flares similar to those of UV Cet stars, and in those cases they also belong to the latter type and are simultaneously considered eruptive variables. |