U Hya
| catalogues and names | U Hya, HR 4163, HD 92055, SAO 156110 |
data from The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version) (Hoffleit+, 1991)
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 |
|
magnitude
| 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 | |
magnitude:
| 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:
| variability type | 194 |
| var. amplitude | 2,4 |
| var. period | 450 |
sources:
| 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 | ||
magnitude:
| 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 |
catalogues
| 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:
| 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) |
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 | 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). SRA 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; SRB 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; SRC 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; SRD 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). |