20:
1368:
161:
spectral classes (M, C and S) with a poorly expressed periodicity, i.e. with a different duration of individual cycles (which leads to the impossibility of predicting the epochs of maximum and minimum brightness), or with the replacement of periodical changes by slow irregular variations, or even by
129:
spectral classes (M, C and S), which retain periodicity with comparative stability and possess, as a rule, small (less than 2.5) light-variation amplitudes. Amplitudes and forms of light curves are usually liable to strong variations from period to period. Many of these stars differ from Mira Ceti
170:
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. Every star of this type may usually be assigned a certain
138:
Semiregular late-type (M, C, S or Me, Ce, Se) giants displaying persistent periodicity and usually small (<2.5 mag in V) light amplitudes. 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
659:
Soszyński, I.; Udalski, A.; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Wyrzykowski, Ł.; Szewczyk, O.; Ulaczyk, K.; Poleski, R. (2009). "The
Optical Gravitational Lensing Experiment. The OGLE-III Catalog of Variable Stars. IV. Long-Period Variables in the Large Magellanic Cloud".
77:
The semiregular variable stars have been sub-divided into four categories for many decades, with a fifth related group defined more recently. The original definitions of the four main groups were formalised in 1958 at the tenth general assembly of the
697:
Soszynski, I.; Dziembowski, W. A.; Udalski, A.; Kubiak, M.; Szymanski, M. K.; Pietrzynski, G.; Wyrzykowski, L.; Szewczyk, O.; Ulaczyk, K. (2007). "The
Optical Gravitational Lensing Experiment. Period--Luminosity Relations of Variable Red Giant Stars".
237:
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
318:
events have shown that essentially all cool evolved stars are variable, with the coolest stars showing very large amplitudes and warmer stars showing only micro-variations. The semiregular variable stars fall on one of five main
330:
Many semiregular variables show long secondary periods around ten times the main pulsation period, with amplitudes of a few tenths of a magnitude at visual wavelengths. The cause of the pulsations is not known.
298:
heading. In other situations, the term is expanded to cover almost all cool pulsating stars. The semi-regular giant stars are closely related to the Mira variables: Mira stars generally pulsate in the
57:
showing considerable periodicity in its light changes, accompanied or sometimes interrupted by various irregularities. Periods lie in the range from 20 to more than 2000
171:
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
258:
207:
Spectral-type (M, C, S or Me, Ce, Se) supergiants with amplitudes of about 1 mag and periods of light variation from 30 days to several thousand days.
576:
834:
254:
246:
432:
277:
250:
464:
143:
175:
381:
by the GCVS, but reported to be of SRb type by later research. These four are all class M giants, although some SRb variables are
86:(GCVS) has updated the definitions with some additional information and provided newer reference stars where old examples such as
323:
sequences identified, differing from the Mira variables only in pulsating in an overtone mode. The closely related OSARG (
162:
the constancy of brightness. Some of them are characterised by a certain mean value of the period, given in the catalogue.
1396:
572:
83:
827:
459:
1306:
79:
65:
may be rather different and variable with each cycle. The amplitudes may be from several hundredths to several
320:
273:
Semiregular pulsating red giants with short period (several days to a month), probably high-overtone pulsators
1269:
1124:
955:
820:
945:
1290:
1086:
912:
1348:
1145:
876:
315:
1177:
1169:
1119:
965:
469:
290:
The semiregular variable stars, particularly the SRa and SRb sub-classes, are often grouped with the
802:
1353:
1114:
396:
Catalogued SRc stars are less numerous, but include some of the brightest stars in the sky such as
1150:
1004:
983:
409:
378:
737:
The
Society for Astronomical Sciences 25th Annual Symposium on Telescope Science. Held May 23–25
1377:
1081:
1034:
1030:
999:
950:
311:
1225:
1009:
917:
762:
Otero, S. A.; Moon, T. (December 2006). "The
Characteristic Period of Pulsation of β Gruis".
438:
Most SRS variables have been discovered in deep large-scale surveys, but the naked-eye stars
404:. Although SRc stars are defined as being supergiants, a number of them have giant spectral
1330:
431:. Others are classified as giant stars, but the brightest example is the seventh-magnitude
354:
is listed as the next-brightest SRa example, but it is suggested that it may actually be an
1285:
940:
935:
892:
880:
771:
744:
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679:
623:
295:
8:
1343:
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180:
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748:
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683:
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1203:
1091:
707:
669:
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66:
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851:
636:
601:
428:
355:
645:
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521:
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300:
568:
1053:
887:
439:
420:
1338:
1236:
1047:
871:
401:
526:
509:
1390:
973:
843:
807:
339:
291:
54:
42:
19:
1197:
1060:
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242:
87:
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347:
62:
23:
1182:
1140:
447:
443:
416:
397:
386:
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370:
351:
50:
27:
1217:
1211:
735:
Watson, C. L. (2006). "The
International Variable Star Index (VSX)".
600:
Nicholls, C. P.; Wood, P. R.; Cioni, M.-R. L.; Soszyński, I. (2009).
390:
362:
343:
211:
46:
34:
792:
304:
215:
797:
764:
The
Journal of the American Association of Variable Star Observers
712:
674:
618:
130:
type stars only owing to the smaller amplitude of light variation.
812:
696:
358:, which would make it by far the brightest member of that class.
327:
small amplitude red giant) variables pulsate in an unknown mode.
808:
OGLE Atlas of
Variable Star Light Curves - Semiregular Variables
1311:
658:
361:
There are numerous naked-eye SRb stars, with third-magnitude
342:
is the brightest SRa variable, and also an eclipsing binary.
1192:
373:
are also third-magnitude SRb stars at maximum brightness.
324:
1367:
599:
58:
793:
EU Delphini and the Small-Amplitude
Pulsating Red Giants
514:
606:Monthly Notices of the Royal Astronomical Society
1388:
577:Sternberg Astronomical Institute, Moscow, Russia
602:"Long Secondary Periods in variable red giants"
828:
227:semi-regular variable giants and super-giants
803:Pulsating variable stars and the H-R diagram
303:; semiregular giants pulsate in one or more
465:Low-dimensional chaos in stellar pulsations
377:is a second magnitude star classified as a
835:
821:
69:(usually 1-2 magnitudes in the V filter).
761:
711:
673:
635:
617:
525:
365:being the brightest listed in the GCVS.
507:
18:
563:
561:
559:
557:
408:and some such as α Her are known to be
1389:
734:
555:
553:
551:
549:
547:
545:
543:
541:
539:
537:
510:"27. Commission des Etoiles Variables"
415:Many SRd stars are extremely luminous
816:
755:
595:
593:
503:
501:
499:
497:
495:
493:
491:
489:
487:
485:
229:belonging to spectral classes F, G, K
652:
573:General Catalogue of Variable Stars
534:
350:with a maximum magnitude of 4.95.
84:General Catalogue of Variable Stars
13:
842:
728:
590:
482:
460:List of semiregular variable stars
334:
193:semi-regular variable super-giants
53:of intermediate and late (cooler)
14:
1408:
786:
690:
72:
1366:
637:10.1111/j.1365-2966.2009.15401.x
80:International Astronomical Union
321:period-luminosity relationship
94:Semiregular variable subtypes
1:
956:Blue large-amplitude pulsator
475:
26:of semiregular variable star
285:
155:semi-regular variable giants
123:semi-regular variable giants
7:
453:
310:Photometric studies in the
10:
1413:
1397:Semiregular variable stars
419:, including the naked-eye
316:gravitational microlensing
61:, while the shapes of the
1362:
1329:
1299:
1278:
1262:
1255:
1168:
1133:
1107:
1072:
1029:
1022:
992:
964:
926:
859:
850:
527:10.1017/S0251107X00020988
470:Variable star designation
90:have been re-classified.
39:semiregular variable star
569:"GCVS Variability Types"
508:Kukarkin, B. V. (2016).
389:or S-type stars such as
1005:Solar-like oscillations
946:Slowly pulsating B-type
410:asymptotic giant branch
379:slow irregular variable
346:is an SRa variable and
1082:Luminous blue variable
913:Rapidly oscillating Ap
312:Large Magellanic Cloud
30:
22:
16:Type of variable star
1270:Rotating ellipsoidal
1178:AM Canum Venaticorum
1125:RS Canum Venaticorum
296:long-period variable
1307:α Canum Venaticorum
776:2006JAVSO..34..156O
749:2006SASS...25...47W
722:2007AcA....57..201S
684:2009AcA....59..239S
628:2009MNRAS.399.2063N
95:
1291:FK Comae Berenices
1087:R Coronae Borealis
877:Classical cepheids
450:are also members.
406:luminosity classes
93:
31:
1384:
1383:
1349:Planetary transit
1325:
1324:
1246:
1239:
1220:
1206:
1188:Luminous red nova
1164:
1163:
1146:Gamma Cassiopeiae
1099:Yellow hypergiant
1095:
1063:
1056:
1018:
1017:
904:
884:
356:RV Tauri variable
283:
282:
274:
239:
230:
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172:
163:
140:
131:
1404:
1371:
1370:
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1242:
1235:
1216:
1202:
1120:FS Canis Majoris
1089:
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856:
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700:Acta Astronomica
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662:Acta Astronomica
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639:
621:
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587:
585:
584:
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531:
529:
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301:fundamental mode
272:
236:
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199:spectral classes
191:
183:
169:
153:
139:light amplitudes
137:
121:
96:
92:
1412:
1411:
1407:
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1403:
1402:
1401:
1387:
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1373:Star portal
1365:
1358:
1354:W Ursae Majoris
1321:
1300:Magnetic fields
1295:
1274:
1251:
1160:
1129:
1115:Double periodic
1108:Eruptive binary
1103:
1074:
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1014:
988:
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927:Blue-white with
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335:Bright examples
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108:GCVS definition
75:
17:
12:
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5:
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1237:Symbiotic nova
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1185:
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1151:Lambda Eridani
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984:Slow irregular
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844:Variable stars
840:
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787:External links
785:
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770:(2): 156–164.
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292:Mira variables
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102:IAU definition
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73:Classification
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1279:Stellar spots
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1263:Non-spherical
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951:PV Telescopii
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931:
929:early spectra
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579:. 12 Feb 2009
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55:spectral type
52:
48:
44:
43:variable star
40:
36:
29:
25:
21:
1364:
1244:Z Andromedae
1226:SW Sextantis
1204:Intermediate
1043:Herbig Ae/Be
978:
918:SX Phoenicis
865:cepheid-like
767:
763:
757:
740:
736:
730:
703:
699:
692:
665:
661:
654:
609:
605:
581:. Retrieved
517:
513:
437:
414:
395:
383:carbon stars
360:
338:
329:
314:looking for
309:
289:
226:
196:
192:
158:
154:
126:
122:
82:(IAU). The
76:
63:light curves
41:, a type of
38:
32:
1286:BY Draconis
1170:Cataclysmic
1075:supergiants
1010:White dwarf
979:Semiregular
966:Long-period
941:Beta Cephei
936:Alpha Cygni
893:BL Herculis
881:Delta Scuti
612:(4): 2063.
520:: 398–431.
417:hypergiants
348:S-type star
24:Light curve
1344:Beta Lyrae
1317:SX Arietis
1183:Dwarf nova
1156:Wolf–Rayet
1073:Giants and
1054:FU Orionis
897:W Virginis
668:(3): 239.
583:2010-11-24
476:References
398:Betelgeuse
294:under the
67:magnitudes
51:supergiant
28:Betelgeuse
1331:Eclipsing
1231:Symbiotic
1218:Hypernova
1212:Supernova
1092:DY Persei
1031:Protostar
852:Pulsating
713:0710.2780
675:0910.1354
619:0907.2975
305:overtones
286:Pulsation
105:GCVS code
35:astronomy
1391:Category
1256:Rotating
1023:Eruptive
908:RR Lyrae
901:RV Tauri
861:Cepheids
798:Y Lyncis
646:19019968
454:See also
440:V428 And
425:V509 Cas
385:such as
111:Standard
1061:T Tauri
888:Type II
772:Bibcode
745:Bibcode
718:Bibcode
706:: 201.
680:Bibcode
624:Bibcode
412:stars.
99:Subtype
45:, is a
1312:Pulsar
872:Type I
743:: 47.
644:
448:EL Psc
446:, and
444:AV Ari
433:LU Aqr
427:, and
391:Pi Gru
387:UU Aur
344:GZ Peg
278:AU Ari
259:SV UMa
255:SX Her
251:AG Aur
247:UU Her
216:RW Cyg
181:RR CrB
176:AF Cyg
113:stars
1339:Algol
1198:Polar
1141:Flare
1134:Other
1048:Orion
993:Other
708:arXiv
670:arXiv
642:S2CID
614:arXiv
429:ο Cen
421:ρ Cas
402:α Her
375:β Gru
371:ρ Per
367:σ Lib
363:L Pup
352:T Cen
340:η Gem
243:S Vul
212:μ Cep
144:Z Aqr
88:S Vul
47:giant
1378:List
1193:Nova
1033:and
974:Mira
400:and
369:and
325:OGLE
269:SRS
238:days
233:SRD
222:SRd
203:SRC
197:late
188:SRc
166:SRB
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