J/A+A/677/A177ivo://CDS.VizieR/J/A+A/677/A177doi:10.26093/cds/vizier.36770177CDSNetzel H.Molnar L.Plachy E.Benko J.2026-06-11T20:02:33Z2023-09-26T11:23:12ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frvariable-starshorizontal-branch-starsAdditional low-amplitude signals are observed in many RR Lyrae stars, beside the pulsations in radial modes. The most common ones are short-period signals forming a period ratio of around 0.60--0.65 with the first overtone, or long-period signals forming a period ratio of around 0.68. The RR Lyrae stars may also exhibit quasi-periodic modulation of the light curves, known as the Blazhko effect. We used the extensive sample of the first-overtone RR Lyrae stars observed by the Kepler telescope during the K2 mission to search for and characterize these low-amplitude additional signals. K2 data provides space-based photometry for a statistically significant sample. Hence this data is excellent to study in detail pulsation properties of RR Lyrae stars. We used K2 space-based photometry for RR Lyrae candidates from Campaigns 0-19. We selected RR Lyrae stars pulsating in the first overtone and performed a frequency analysis for each star to characterize their frequency contents. We classified 452 stars as first-overtone RR Lyrae. From that sample, we selected 281 RR_0.61_ stars, 67 RR_0.68_ stars, and 68 Blazhko stars. We found particularly interesting stars which show all of the above phenomena simultaneously. We detected signals in RR0.61 stars that form period ratios lower than observed for the majority of stars. These signals likely form a new sequence in the Petersen diagram, around a period ratio of 0.60. In 32 stars we detected additional signals that form a period ratio close to that expected in RRd stars, but the classification of these stars as RRd is uncertain. We also report a discovery of additional signals in eight stars that form a new group in the Petersen diagram around the period ratio of 0.465-0.490. The nature of this periodicity remains unknown.2023A&A...677A.177Nhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/677/A177CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toIV/34 : K2 Ecliptic Plane Input Catalog (EPIC) (Huber+, 2017)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/677/A177https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/677/A177http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/677/A177https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/677/A177https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/677/A177http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/677/A177GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/677/A177/table1 (RRc stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/677/A177/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/677/A177/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/677/A177/table1?GETtext/xml+votable180.050000true229.3261-21.00190.0055555555555555565/4631 4685 7233 7296 11119 6/280 295 360 470 474 1051 4306 4314-4315 4317-4318 4328 4335 4348 4351 4514 4632 4675 4677 4687 4701 4719 4726 4731-4734 4757 4816 4870 4879 4882 4898 17149 17290-17291 17317 17326 17328 17336 17339 17382 17990 18009 18017 18022 18041 18121 18178 18182 18218 18224 18308 18312 18330-18332 18334 18354 18551 18692 18699 18702 18708 18710 18712 18715-18716 18724-18725 18732 18734 18738 18746 18750-18753 18763 18797 18823 18830 18832 18836 18838 18840 18847 18883-18884 18888 18912 23508 23951 24205 25426 25444 25446 25456 25458-25459 25551 25553 25562-25563 25565 25590 25611 25614 25627-25628 25631 25637 25644 25646 25650-25652 25661 25671 25677 25679 25696 25698-25700 25709 25712 25715 25719 25721-25722 25725 25746 25750 25752-25753 25755 25757 25759 25771 25792 25794-25795 25797 25799 25802 25804-25805 25809-25811 25817 25820-25821 25823 25829 25834 25846-25847 25853 25896 25992-25993 26113 26115 26133 26150-26151 26158 26166 26174-26175 26180 26192-26193 26216 26243 26245 26251 26258 26263 26273-26274 26276-26277 26292-26293 26300 26307 26314 27047 27053 27055 27057 27059 27066 27104 27392-27393 27395-27396 27398 27404-27405 27410 27425 27431 27433 27443 27457 27460 27480 27483 27491 27495 27498 27508 27513 27550 27585 28815 28841 28844 28847 28929 28940-28942 28946 28952 28956 29021 29034 29192 29195 29202-29203 29207 29241 29250-29251 29257 29259 29291 29294 29298 29340 29376 29379-29380 29696 30725 42867 42870 42942 42950 44159 44254-44255 44312 44316-44317 44319 44323 44349-44351 44384 44392 44395 44417 44421 44426-44427 44434-44435 44441-44442 44445 44451 44453-44454 44462 44466 44468-44469 44482 44504 44506 44512-44513 44515 44520 44522 44526 44530 44719 44771 44804-44805 44807 44816 48043 48046-48047 48058 48811https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/677/A177?format=asciidefaultJ/A+A/677/A177/table1RRc starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintEPICEPIC numbermeta.id;meta.mainlongprimaryn_EPIC[*] Note on EPIC (1)meta.notecharRAJ2000Right Ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainKpmagBrightness in Kp passbandmagphot.mag;em.optfloatPPeriod of pulsationdtime.perioddoubleSimbadSimbad column added by the CDSmeta.ref.urlcharPropindicates porperties in tables 2-4meta.ref.urlcharJ/A+A/677/A177/table2Properties of RR0.61 starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintEPICEPIC numbermeta.id;meta.mainlongPFirst-overtone perioddtime.perioddoublee_PFirst-overtone period errordstat.errordoubleP0.61Period of the 0.61 signaldtime.perioddoublee_P0.61Period of the 0.61 signal errordstat.errordoubleP0.61/PPeriod ratio of the 0.61 signal with the first overtonestat.fit.omcdoubleAmpFirst-overtone Fourier amplitudemagsrc.var.amplitudedoublee_AmpFirst-overtone Fourier amplitude errormagstat.errordoubleA061/AAmplitude ratio of the 0.61 signal with the first overtonestat.fit.omcfloatRemarksAdditional remarks (1)meta.notecharJ/A+A/677/A177/table3Properties of RR0.68 starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintEPICEPIC numbermeta.id;meta.mainlongPFirst-overtone perioddtime.perioddoublee_PFirst-overtone period errordstat.errordoubleP0.68Period of the 0.61 signaldtime.perioddoublee_P0.68Period of the 0.61 signal errordstat.errordoubleP/P0.68Period ratio of the 0.68 signal with the first overtonestat.fit.omcdoubleAFirst-overtone Fourier amplitudemagsrc.var.amplitudedoublee_AFirst-overtone Fourier amplitude errormagstat.errordoubleA068/AAmplitude ratio of the 0.68 signal with the first overtonestat.fit.omcfloatRemarksAdditional remarks (1)meta.notecharJ/A+A/677/A177/table4Properties of Blazhko starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintEPICEPIC numbermeta.id;meta.mainlongPFirst-overtone perioddtime.perioddoublee_PFirst-overtone period errordstat.errordoublePBLBlazhko perioddtime.perioddoublee_PBLBlazhko period errordstat.errordoubleAFirst-overtone Fourier amplitudemagsrc.var.amplitudedoublee_AFirst-overtone Fourier amplitude errormagstat.errordoubleA+? Fourier amplitude of the higher-frequency sidepeakmagsrc.var.amplitudedoublenullablee_A+? Fourier amplitude of the higher-frequency sidepeak errormagstat.errordoublenullableA-? Fourier amplitude of the lower-frequency sidepeakmagsrc.var.amplitudedoublenullablee_A-? Fourier amplitude of the lower-frequency sidepeak errormagstat.errordoublenullableRemarksAdditional remarks (1)meta.notechar