U Hya

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 U Hya, HR 4163, HD 92055, SAO 156110

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: 10h 37min 33,2sec DEC: -13 23' 4''
position (J1900) RA: 10h 32min 36,9sec DEC: -12 51' 52''
proper motion (J2000) RA: 0,034 arcsec/a DEC: -0,032 arcsec/a
radial velocity -25 km/s
note: suspected variable radial velocity


visual magnitude 4,82
(V on UBV Johnson system)

spectral / color information

spectral class C5II
B-V-magnitude 2,68
U-B-magnitude 5,78
R-I-magnitude 1,27
note (category: spectra): Technetium star.

variability information

variable star identification U Hya
note (category: variability): SRb 7.0 - 9.2p, 7.0 - 9.4B, about 450d. Amp. 0.12V in one cycle in 1971.

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

position, motion, parallax:

position (J2000) RA: 10h 37min 33,271sec DEC: -13 23' 4,75'' 0,19 arcsec source: 16
proper motion (J2000) RA: 0,0028 arcsec/a DEC: -0,043 arcsec/a source: 25
radial velocity -25 km/s source: 25
galactic coord. (B1950) longitude: 259,98 latitude: 38,07
GCI unit vector (J2000) X: -0,910566 Y: 0,342466 Z: -0,231487


visual 4,82 (observed) source: 25

spectral information:

spectral class Nb source: 29
Morgan-Keenan C5,4 source: 25
B-magnitude 7,5 0,05 B-V-magnitude 2,68
U-magnitude 13,28 0,05 U-B-magnitude 5,78

variability information:

source of data: 30
variability type 194
var. amplitude 2,4
var. period 450


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
25 Bright Star Catalogue, 5th edition
Hoffleit, D. and Warren, W.H. Jr., The Bright Star Catalogue, 5th Revised Edition, Version 2, 1994
29 SAOJ2000
SAO on FK5 at J2000, 1989
30 GCVS, 4th edition
Kholopov, P.N., et al., General Catalogue of Variable Stars, fourth edition, Moscow: Nauka Publishing House, 1985-88

data from Smithsonian Astrophysical Observatory Star Catalog (SAO Staff 1966; USNO, ADC 1990)

position and proper motion:

position (J1950) RA: 10h 35min 4,966sec DEC: -13 7' 26,18'' 0,026 arcsec
position (J2000) RA: 10h 37min 33,216sec DEC: -13 23' 3,95''
proper motion J1950 (FK4) RA: 0,002 arcsec/a DEC: -0,037 arcsec/a 0,005 arcsec/a in RA
0,005 arcsec/a in DEC
proper motion J2000 (FK5) RA: 0,0023 arcsec/a DEC: -0,032 arcsec/a
source of proper motion data Determined by source catalog


visual 4,8 (accuracy: 1 decimal)
source of visual magnitude data Source cited in source catalog introduction.

spectral information:

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

remarks for duplicity and variability

Variable star in visual magnitude in source catalog


source catalogue GC, catalogue number: 14611
Durchmusterung BD-12 3218
Boss General Catalogue 14611
Henry Draper Catalogue 92055

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


position (J1950) RA: 10h 35min 5sec DEC: -13 7' 26''

variability informations:

variability type SRB pulsating variable star
magnitute at max. brightness 7
magnitute at min. brightness 9,4
photometric system
period [d] 450 (uncertain)

spectral information

spectral class C6.5,3(N2)(Tc)


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)


ID in the GCVS catalogue 42/4
constellation Hydra
notes on existence The star is equivalent to '0420005 V'.

variability type description

variability type description
SRB Semiregular variables, which are giants or supergiants of intermediate and late spectral types showing noticeable periodicity in their light changes, accompanied or sometimes interrupted by various irregularities. Periods lie in the range from 20 to >2000 days, while the shapes of the light curves are rather different and variable, and the amplitudes may be from several hundredths to several magnitudes (usually 1-2 mag in V).

Semiregular late-type (M, C, S or Me, Ce, Se) giants displaying persistent periodicity and usually small (<2.5 mag in V) light amplitudes (Z Aqr). Amplitudes and light-curve shapes generally vary and periods are in the range of 35-1200 days. Many of these stars differ from Miras only by showing smaller light amplitudes;

Semiregular late-type (M, C, S or Me, Ce, Se) giants with poorly defined periodicity (mean cycles in the range of 20 to 2300 days) or with alternating intervals of periodic and slow irregular changes, and even with light constancy intervals (RR CrB, AF Cyg). Every star of this type may usually be assigned a certain mean period (cycle), which is the value given in the Catalogue. In a number of cases, the simultaneous presence of two or more periods of light variation is observed;

Semiregular late-type (M, C, S or Me, Ce, Se) supergiants (Mu Cep) with amplitudes of about 1 mag and periods of light variation from 30 days to several thousand days;

Semiregular variable giants and supergiants of F, G, or K spectral types, sometimes with emission lines in their spectra. Amplitudes of light variation are in the range from 0.1 to 4 mag, and the range of periods is from 30 to 1100 days (SX Her, SV UMa).