J/ApJ/926/17ivo://CDS.VizieR/J/ApJ/926/17doi:10.26093/cds/vizier.19260017CDSOtani T.Lynas-Gray A.E.Kilkenny D.Koen C.von Hippel T.,Uzundag M.Vuckovic M.Pennock C.M.Silvotti R.2023-11-26T12:58:35Z2023-10-27T13:58:35ZCDS support team

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

cds-question@unistra.frsubdwarf-starsphotometryvisible-astronomymultiple-starsAQ Col (EC 05217-3914) is one of the first detected pulsating subdwarf B (sdB) stars and has been considered to be a single star. Photometric monitoring of AQ Col reveals a pulsation timing variation with a period of 486 days, interpreted as time delay due to reflex motion in a wide binary formed with an unseen companion with expected mass larger than 1.05M_{sun}_. The optical spectra and color-magnitude diagram of the system suggested that the companion is not a main-sequence star but a white dwarf or neutron star. The pulsation timing variation also shows that the system has an eccentricity of 0.424, which is much larger than any known sdB long period binary system. That might be due to the existence of another short period companion to the sdB star. Two optical spectra obtained on 1996-December-5 show a radial velocity change of 49.1km/s in 46.1min, which suggests the hot subdwarf in the wide binary is itself a close binary formed with another unseen white dwarf or neutron star companion; if further observations show this interpretation to be correct, AQ Col is an interesting triple system worthy of further study.2022ApJ...926...17Ohttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/926/17CatalogResearchIsServedByTAP VizieR generic servicerelated-toVI/39 : Model Atmospheres (Kurucz, 1979)VI/65 : Evolutionary models of evolved stars (Dorman+ 1993)I/352 : Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+, 2021)J/ApJ/419/596 : Pop I UV radiation models (Dorman+, 1993)J/MNRAS/287/867 : Edinburgh-Cape Blue Object Survey. Zone 1. (Kilkenny+ 1997)J/A+A/513/A6 : NOT survey of subdwarf B stars (Ostensen+, 2010)J/MNRAS/421/2798 : Radial velocity monitoring of PG 1018-047 (Deca+, 2012)J/MNRAS/431/240 : Edinburgh-Cape Blue Object Survey. III. (O'Donoghue+, 2013)J/A+A/576/A44 : Hot subdwarf binaries from MUCHFUSS (Kupfer+, 2015)J/MNRAS/459/4343 : Edinburgh-Cape Blue Object Survey. (Kilkenny+, 2016)J/MNRAS/466/1290 : Metal-rich SX Phe stars in Kepler field (Nemec+, 2017)J/A+A/610/A17 : RV of candidate hybrid variable stars (Lampens+, 2018)J/MNRAS/474/4322 : Orbital parameters of 341 new binaries (Murphy+, 2018)J/ApJ/859/145 : 20yr observations of EC 20117-4014 (Otani+, 2018)J/A+A/611/A48 : Seven sdB eclipsing binaries data (Pulley+, 2018)J/A+A/611/A85 : Time-series photometry of V391 Peg (Silvotti+, 2018)J/A+A/621/A38 : Gaia catalogue of hot subluminous stars (Geier+, 2019)J/A+A/638/A108 : 4 p-mode pulsators arrival times (Mackebrandt+, 2020)J/A+A/649/A3 : Gaia EDR3 photometric passbands (Riello+, 2021)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/926/17https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/926/17http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/926/17https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/926/17https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/926/17http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/926/17GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/ApJ/926/17/table1*Observation log for AQ ColrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDateDate of observation (UT)time.epochnullableBJD[-3388.6/5430.28] Mean observation time; BJD-2453500dtime.epochdoubleDur[86.8/460.4] Observation lengthmintime.expofloatObsObservatory (1)meta.id;instr.obstycharJ/ApJ/926/17/table4Pulsation timing variation data for F1 (4.67mHz), F2 (4.63mHz), and F3 (4.60mHz) pulsation modes after removing the quadratic fitsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJD[-3368.71/5430.28] Mid observation time; BJD-2454000dtime.epochdoubleO-CF1[-252.5/333.7]? F1 pulsation timing variationssstat.fit.residualfloatnullablee_O-CF1[1.7/41.1]? Uncertainty in O-C(F1)sstat.errorfloatnullableO-CF2[-256.3/299.3]? F2 pulsation timing variationssstat.fit.residualfloatnullablee_O-CF2[4.2/29.7]? Uncertainty in O-C(F2)sstat.errorfloatnullableO-CF3[-248.8/303.8]? F3 pulsation timing variationssstat.fit.residualfloatnullablee_O-CF3[4.1/31.5]? Uncertainty in O-C(F3)sstat.errorfloatnullableJ/ApJ/926/17/fig1Light curve for AQ ColrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJDBarycentric Julian Datedtime.epochdoubleindexedmag[-0.2/0.21] Observed magnitudemagphot.mag;em.optdouble