e Eridani

The object was found in the following catalogues:
  1. The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version)

  2. SKY2000 - Master Star Catalog

  3. Smithsonian Astrophysical Observatory Star Catalog

  4. Combined General Catalogue of Variable Stars (Vol. I-III)

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)

object is infrared source (NASA merged infrared catalogue, Schmitz et al., 1978)

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


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


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:

source of data: 19
separation between brightest and second brightest component 0 arcsec
position angle 143


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


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.


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 (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


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'


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.