z Tauri

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 z Tau, zet Tau, 123 Tau, HR 1910, HD 37202, SAO 77336, FK5: 211
constellation Taurus

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: 5h 37min 38,7sec DEC: +21 8' 33''
position (J1900) RA: 5h 31min 40sec DEC: +21 4' 54''
proper motion (J2000) RA: 0 arcsec/a DEC: -0,021 arcsec/a
radial velocity 20 km/s
note: spectroscopic binaries, single lined spectra
note: orbital data avaible
rotational velocity 310 km/s (uncertain) (variable)
trigonometric parallax 0,008 arcsec
note (category: radial and/or rotational velocities): Rapidly rotating star. Rotational velocity varies with wavelength: vsini about 300k/s in visual, 150 or less in UV. Expanding circumstellar shell. Shell-line velocities do not correspond to orbital elements; possibly gaseous ring. Unstable shell star with pseudo-periodic phenomena.


visual magnitude 3
(V on UBV Johnson system)

spectral / color information

spectral class B4IIIpe
B-V-magnitude -0,19
U-B-magnitude -0,67
R-I-magnitude -0,1
note (category: spectra): Lyman beta observed from COPERNICUS. Spectra obtained from AEROBEE rocket show absorption features at 1920 (FeIII) and 1720A (AlII) associated with extended atmosphere or circumstellar shell. Also classified B2IVp.
note (category: colors): Color excess E(B-V) = +0.09.

variability information

variable star identification Zet Tau
note (category: variability): Gamma Cas 2.90 - 3.03V. Var. shell Sp. Widths H-lines vary in about 10 min. Polarization at H beta changes in tens of minutes, probably due to circumstellar matter.

double/multiple star system information

separation 0 arcsec
mag difference (of double or brightest multiple) 2
note doublicity discoverd by occultation
note (category: spectroscopic binaries): 132.91d, K 8.9k/s, V0 +21.8k/s, asini = 16.1. 3.2, 5.2v, sep. 0.007". Common circumstellar envelope. The 132.9d period is superimposed on a 7y pseudo-period related to oscillation of envelope.

miscellaneous information

note (category: group membership): Cas-Tau OB1.

data from SKY2000 - Master Star Catalog (Myers+ 1997)

position, motion, parallax:

position (J2000) RA: 5h 37min 38,681sec DEC: +21 8' 33,06'' 0,06 arcsec source: 15
proper motion (J2000) RA: 0 arcsec/a DEC: -0,021 arcsec/a source: 25
radial velocity 20 km/s source: 25
trigonometric parallax 0,008 0,001 arcsec source: 25
galactic coord. (B1950) longitude: 185,69 latitude: -5,64
GCI unit vector (J2000) X: 0,090833 Y: 0,928253 Z: 0,360689


visual 2,9 (observed) source: 31
photovisual 3 source: 2

spectral information:

spectral class B3 source: 96
Morgan-Keenan B4IIIpe source: 25
B-magnitude 2,81 0,05 B-V-magnitude -0,19
U-magnitude 2,14 0,05 U-B-magnitude -0,67

variability information:

source of data: 30
variability type 10
var. amplitude 0,29
var. period 132,97
var. epoch 2444937
28. November 1981, 12:00:00 UT
next max light 2451718,47
22. June 2000, 23:16:48 UT

double/multiple star system information:

source of data: 25
separation between brightest and second brightest component 0 arcsec
magnitude difference between brightest and second brightest component 2


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
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: 5h 34min 39,263sec DEC: +21 6' 50'' 0,004 arcsec
position (J2000) RA: 5h 37min 38,681sec DEC: +21 8' 33,03''
proper motion J1950 (FK4) RA: 0,0001 arcsec/a DEC: -0,022 arcsec/a 0,001 arcsec/a in RA
0,001 arcsec/a in DEC
proper motion J2000 (FK5) RA: 0 arcsec/a DEC: -0,022 arcsec/a
source of proper motion data Determined by source catalog


visual 3 (accuracy: 2 decimals)
source of visual magnitude data Taken from the "Henry Draper Catalogue".

spectral information:

spectral class B3p
source of spectral data Taken from the Henry Draper Catalogue or no spectrum in source catalog.


source catalogue FK4, catalogue number: 211
Durchmusterung BD+21 908
Boss General Catalogue 6985
Henry Draper Catalogue 37202

data from Combined General Catalogue of Variable Stars (Vol. I-III) (Kholopov+ 1998)


position (J1950) RA: 5h 34min 39,3sec DEC: +21 6' 50''

variability informations:

variability type E/GS+GCAS close binary eclipsing system
eruptive variable star
magnitute at max. brightness 2,88
magnitute at min. brightness 3,17
photometric system visual, photovisual or Johnson's V
epoch for maximum light [JD] 2444936,781
28. November 1981, 06:44:38 UT
period [d] 132,9735
next maximum light [JD] 2451718,4295
22. June 2000, 22:18:29 UT

spectral information

spectral class B1IVe+G8III:


to a study Vol. III GCVS
to a chart/photograph no chart is avaible, but the star is contained in the 'Bonner Durchmusterung'


ID in the GCVS catalogue 78/9006
constellation Taurus
notes on existence The star is equivalent to '07890082tet 2'.
There are notes in published catalog.

variability type description

variability type description
E 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.

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.

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.

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.
GS Systems with one or both giant and supergiant components; one of the components may be a main sequence star.
GCAS Eruptive irregular variables of the Gamma Cas type. These are rapidly rotating B III-IVe stars with mass outflow from their equatorial zones.
The formation of equatorial rings or disks is often accompanied by temporary fading. Light amplitudes may reach 1.5 mag in V.