U Sagittarii
catalogues and names
| catalogues and names | U Sgr, HR 6947, HD 170764, SAO 161571, BD -19 5047, WDS 18319-1908A |
data from The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version) (Hoffleit+, 1991)
position, motion, parallax:
| position (J2000) | RA: 18h 31min 53.3sec | DEC: -19° 7' 30'' | ||
| position (2000.72) | RA: 18h 31min 56sec | DEC: -19° 7' 28'' | ||
| position (B1900) | RA: 18h 25min 59.9sec | DEC: -19° 11' 42'' | ||
| proper motion (J2000) | RA: -0.009 arcsec/a | DEC: 0.001 arcsec/a | ||
| radial velocity | 2 km/s note: spectroscopic binaries |
|||
| galactic coordinates | longitude: 13.71° | latitude: -4.46° | ||
magnitude
| visual magnitude | 6.68 (V on UBV Johnson system) |
spectral / color information
| spectral class | G1.5Ib |
| B-V-magnitude | 1.13 |
| U-B-magnitude | 0.69 |
| R-I-magnitude |
variability information
| variable star identification | U Sgr |
| note (category: variability): | CDelta 6.34 - 7.08V, 6.744925d. May have blue companion. |
double/multiple star system information
| number of components of multiple star system | 17 |
| separation | 430.7 arcsec |
| mag difference (of double or brightest multiple) | 2 |
| component ID | AG |
| note | Worley (1978) update of the IDS |
miscellaneous information
| note (category: group membership): | M25; in cluster IC 4725 #103. |
data from SKY2000 - Master Star Catalog (Myers+ 1997)
position, motion, parallax:
| position (J2000) | RA: 18h 31min 53.347sec | DEC: -19° 7' 30.18'' | ±0.19 arcsec | source: 16 |
| position (2000.72) | RA: 18h 31min 56sec | DEC: -19° 7' 28'' | JD: 2451806.24 | |
| proper motion (J2000) | RA: 0.0004 arcsec/a | DEC: 0 arcsec/a | source: 25 | |
| radial velocity | 2 km/s | source: 25 | ||
| galactic coord. (B1950) | longitude: 13.71° | latitude: -4.46° | ||
magnitude:
| visual | 6.28 (observed) | source: 30 |
| photovisual | 6.9 | source: 16 |
spectral information:
| spectral class | F8 | source: 96 | |
| Morgan-Keenan | G1.5Ib | source: 25 | |
| B-magnitude | 7.81 ±0.05 | B-V-magnitude | 1.13 |
| U-magnitude | 8.5 ±0.05 | U-B-magnitude | 0.69 |
variability information:
| variability type | 111 |
| var. amplitude | 0.87 |
| var. period | 6.75 |
| var. epoch | 2430118 3. May 1941, 12:00:00 UT |
| next max light | 2451812.5 25. September 2000, 00:00:00 UT |
double/multiple star system information:
| separation between brightest and second brightest component | 66.5 arcsec |
| magnitude difference between brightest and second brightest component | 2.9 |
| position angle | 253 ° |
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 | |
| 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 | |
| 30 | GCVS, 4th edition |
| Kholopov, P.N., et al., General Catalogue of Variable Stars, fourth edition, Moscow: Nauka Publishing House, 1985-88 | |
| 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 (B1950) | RA: 18h 28min 56.533sec | DEC: -19° 9' 42.32'' | ±0.035 arcsec |
| position (2000.72) | RA: 18h 31min 56sec | DEC: -19° 7' 27'' | JD: 2451806.24 |
| position (J2000) | RA: 18h 31min 53.279sec | DEC: -19° 7' 29.66'' | |
| proper motion B1950 (FK4) | RA: -0.0007 arcsec/a | DEC: 0 arcsec/a | ±0.006 arcsec/a in RA ±0.006 arcsec/a in DEC |
| proper motion J2000 (FK5) | RA: -0.0006 arcsec/a | DEC: 0.001 arcsec/a | |
| source of proper motion data | Determined by source catalog | ||
magnitude:
| visual | 6.5 (accuracy: 1 decimal) |
| source of visual magnitude data | Source cited in source catalog introduction. |
spectral information:
| spectral class | F8 |
| 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: 25287 |
| Durchmusterung | BD-19 5047 |
| Boss General Catalogue | 25287 |
| Henry Draper Catalogue | 170764 |
data from The Washington Visual Double Star Catalog, 1996.0 (Worley+, 1996)
position and proper motion:
| position (J2000) | RA: 18h 31.9min | DEC: -19° 8' |
| proper motion (J2000) | RA: 0.006 arcsec/a | DEC: -0.006 arcsec/a |
double/multiple star system information:
| component | year | number of measures | position angle | angular separation | magnitude of 1st component | magnitude of 2nd component | spectral class(es) | discoverer code |
| AB | 1879 | 7 | 253° | 66.5'' | 6.7 | 9.6 | G1.5Ib | BU 966 |
| AE | 1890 | 4 | 282° | 145'' | 6.7 | 9.1 | - | BU 966 |
| AG | 1893 | 1 | 254° | 430.7'' | - | 8.4 | B8 | BU 966 |
| AH | 1890 | 4 | 295° | 72.2'' | - | 10 | - | BU 966 |
| Aa | 1890 | 4 | 195° | 164'' | - | 9.3 | - | BU 966 |
| AR | 1890 | 4 | 90° | 76.8'' | - | 11 | - | BU 966 |
| BC | 1880 | 8 | 122° | 0.7'' | 9.6 | 10.1 | - | BU 966 |
| BH | 1890 | 1 | 358° | 50.8'' | 9.6 | 10 | - | BU 966 |
| Bb | 1890 | 4 | 200° | 110.4'' | 9.6 | 10.4 | - | BU 966 |
| CD | 1879 | 4 | 172° | 11.2'' | 9.3 | 10 | - | BU 966 |
| CQ | 1890 | 1 | 38° | 56.4'' | 9.3 | 9.9 | - | BU 966 |
| EF | 1890 | 4 | 291° | 25.2'' | 9.1 | 9.6 | - | BU 966 |
| EK | 1890 | 4 | 27° | 30.4'' | 9.1 | 9.5 | - | BU 966 |
| EL | 1890 | 4 | 123° | 21'' | 9.1 | 9.7 | - | BU 966 |
| GT | 1890 | 1 | 63° | 61.5'' | 8.4 | 9.2 | B9 | BU 966 |
| HJ | 1890 | 4 | 311° | 44'' | 10 | 9.8 | - | BU 966 |
| JK | 1890 | 1 | 263° | 29.5'' | 9.1 | 9 | - | BU 966 |
| JM | 1890 | 4 | 345° | 70.2'' | 9.8 | 10 | - | BU 966 |
| PB | 1890 | 1 | 351° | 184'' | 8.7 | 8.5 | - | BU 966 |
| PC | 1890 | 4 | 264° | 93.6'' | 9.3 | 9.3 | - | BU 966 |
| SE | 1890 | 1 | 142° | 131.3'' | 8.3 | 9.1 | B9 | BU 966 |
discoverer information:
| discoverer code | discoverer | reference |
| BU 966 | Burnham, S.W. | - |
notes:
| note | Cluster M 25. A is the Cepheid U Sgr. Identifications on Hyd. ph. -19@, 18:28 are as follows: A 51273 G 51291 P 51300 B 51272 H 51271 Q 51299 C 51297 J 51270 R 51274 D 51298 K 51267 S 51263 E 51266 L 51268 T 51292 F 51265 M 51269 U Close comp. to B. |
data from Combined General Catalogue of Variable Stars (Vol. I-III) (Kholopov+ 1998)
position:
| position (equinox 1950.0) | RA: 18h 28min 56.5sec | DEC: -19° 9' 42'' |
variability informations:
| variability type | DCEP | pulsating variable star |
| magnitute at max. brightness | 6.28 | |
| magnitute at min. brightness | 7.15 | |
| photometric system | visual, photovisual or Johnson's V | |
| epoch for maximum light [JD] | 2430117.925 3. May 1941, 10:12:00 UT |
|
| period [d] | 6.745226 | |
| next maximum light [JD] | 2451810.571816 23. September 2000, 01:43:25 UT |
|
| rising time | 28 % of period |
spectral information
| spectral class | F5Ib-G1.5Ib |
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 | 72/4 |
| constellation | Sagittarius |
| notes on existence | The star is equivalent to '0720005 V'. |
| There are notes in published catalog. | |
variability type description
| variability type | description |
| DCEP | These are the classical cepheids, or Delta Cep-type variables. Comparatively young objects that have left the main sequence and evolved into the instability strip of the Hertzsprung-Russell (H-R) diagram, they obey the well-known Cepheid period-luminosity relation and belong to the young disk population. DCEP stars are present in open clusters. They display a certain relation between the shapes of their light curves and their periods. |