J/ApJ/840/70ivo://CDS.VizieR/J/ApJ/840/70doi:10.26093/cds/vizier.18400070CDSBond H.E.Schaefer G.H.Gilliland R.L.Holberg J.B.Mason B.D.,Lindenblad I.W.Seitz-McLeese M.Arnett W.D.Demarque P.Spada F.,Young P.A.Barstow M.A.Burleigh M.R.Gudehus D.2017-05-22T07:07:23Z2017-05-19T15:57:41ZCDS support team

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

cds-question@unistra.frmultiple-starsastrometrySirius, the seventh-nearest stellar system, is a visual binary containing the metallic-line A1 V star Sirius A, the brightest star in the sky, orbited in a 50.13 year period by Sirius B, the brightest and nearest white dwarf (WD). Using images obtained over nearly two decades with the Hubble Space Telescope (HST), along with photographic observations covering almost 20 years and nearly 2300 historical measurements dating back to the 19th century, we determine precise orbital elements for the visual binary. Combined with the parallax and the motion of the A component, these elements yield dynamical masses of 2.063+/-0.023M_{sun}_ and 1.018+/-0.011M_{sun}_ for Sirius A and B, respectively. Our precise HST astrometry rules out third bodies orbiting either star in the system, down to masses of ~15-25M_{Jup}_. The location of Sirius B in the Hertzsprung-Russell diagram is in excellent agreement with theoretical cooling tracks for WDs of its dynamical mass, and implies a cooling age of ~126Myr. The position of Sirius B on the mass-radius plane is also consistent with WD theory, assuming a carbon-oxygen core. Including the pre-WD evolutionary timescale of the assumed progenitor, the total age of Sirius B is about 228+/-10Myr. We calculated evolutionary tracks for stars with the dynamical mass of Sirius A, using two independent codes. We find it necessary to assume a slightly subsolar metallicity, of about 0.85Z_{sun}_, to fit its location on the luminosity-radius plane. The age of Sirius A based on these models is about 237-247Myr, with uncertainties of +/-15Myr, consistent with that of the WD companion. We discuss astrophysical puzzles presented by the Sirius system, including the probability that the two stars must have interacted in the past, even though there is no direct evidence for this and the orbital eccentricity remains high.2017ApJ...840...70Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/840/70CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/A+A/299/621 : Is Sirius a triple star? (Benest+, 1995)J/A+AS/136/293 : Sirius photographic observations (Jasinta+, 1999)J/ApJS/126/461 : Equivalent Widths in the Spectrum of Sirius (Zhao+, 2000)J/AJ/146/68 : Spectra of Vega, Sirius, GD153, and HD209458 (Linnell+, 2013)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/840/70https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/840/70http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/840/70https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/840/70https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/840/70http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/840/70GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapdefaultJ/ApJ/840/70/siriusAstrometry of Sirius B relative to AMethodMethod Code (5)meta.code;obschare_PAcorAdopted uncertainty in PAcor (3)degstat.errorfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDateObservation date; YYYY-MMM-DD (1)time.epoch;obsnullableYearBesselian YearyrtimedoublePAmeas? Measured position angledegpos.posAngfloatnullableSepmeas? Measured separationarcsecpos.angDistancedoublenullablePAcor? Corrected position angle (2)degpos.posAngfloatnullableSepcor? Corrected separation (2)arcsecpos.angDistancedoublenullablee_SepcorAdopted uncertainty in SepCor (3)arcsecstat.errorfloatObsCodeObserver name and reference code (4)pos.framecharTelSize of telescope apertureminstr.tel;instr.fovfloatNotesCode for additional notes (6)meta.notecharBibcode? Bibcode for the primary referencemeta.bib.bibcodecharRef? Additional reference codespos.framecharJ/ApJ/840/70/notesAdditional notesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNotesNote codemeta.notecharTextText of the notemeta.notecharJ/ApJ/840/70/refsReferencesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintObsCodeObserver and reference code from sirius.datpos.framecharBibcodeBibcode for the referencemeta.bib.bibcodecharTextFull reference text (1)meta.ref;pos.framechar