J/ApJ/877/44ivo://CDS.VizieR/J/ApJ/877/44doi:10.26093/cds/vizier.18770044CDSRoulston B.R.Green P.J.Ruan J.J.MacLeod C.L.Anderson S.F.,Badenes C.Brownstein J.R.Schneider D.P.Stassun K.G.2021-09-09T12:01:21Z2020-12-15T07:46:29ZCDS support team

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

cds-question@unistra.frcarbon-starsdwarf-starsvisible-astronomyspectroscopyradial-velocitysloan-photometryDwarf carbon (dC) stars (main-sequence stars showing carbon molecular bands) were initially thought to be an oxymoron because only asymptotic giant branch (AGB) stars dredge carbon into their atmospheres. Mass transfer from a former AGB companion that has since faded to a white dwarf seems the most likely explanation. Indeed, a few types of giants known to show anomalous abundances- notably, the CH, Ba and CEMP-s stars-are known to have a high binary frequency. The dC stars may be the enhanced-abundance progenitors of most, if not all of these systems, but this requires demonstrating a high binary frequency for dCs. Here, for a sample of 240 dC stars targeted for repeat spectroscopy by the SDSS-IV's Time Domain Spectroscopic Survey, we analyze radial velocity (RV) variability to constrain the binary frequency and orbital properties. A handful of dC systems show large velocity variability (>100km/s). We compare the dCs to a control sample with a similar distribution of magnitude, color, proper motion, and parallax. Using Markov chain Monte Carlo methods, we use the measured {Delta}RV distribution to estimate the binary fraction and the separation distribution assuming both a unimodal and bimodal distribution. We find the dC stars have an enhanced binary fraction of 95%, consistent with them being products of mass transfer. These models result in mean separations of less than 1 au corresponding to periods on the order of 1 yr. Our results support the conclusion that dC stars form from close binary systems via mass transfer.2019ApJ...877...44Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/877/44CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/294 : SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)I/345 : Gaia DR2 (Gaia Collaboration, 2018)J/A+A/375/366 : Carbon stars from the Hamburg/ESO survey (Christlieb+ 2001)J/MNRAS/330/792 : Radial velocity in Draco (Kleyna+, 2002)J/AJ/127/2838 : Faint high-lat. carbon stars SDSS photometry (Downes+, 2004)J/ApJ/765/12 : Carbon stars and DQ WDs from SDSS-DR7+DR8 (Green, 2013)J/ApJ/797/21 : Carbon-enhanced metal-poor stars (Placco+, 2014)J/other/RAA/15.1671 : New carbon stars from LAMOST survey (Si+, 2015)J/A+A/586/A158 : Binary properties of CH and CEMP stars (Jorissen+, 2016)J/AJ/155/252 : Astrometry & photometry of dwarf carbon stars (Harris+, 2018)http://www.sdss.org/ : SDSS home pagehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/877/44https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/877/44http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/877/44https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/877/44https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/877/44http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/877/44GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/877/44/table1 (Dwarf carbon (dC) properties)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/877/44/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/877/44/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/877/44/table1?GETtext/xml+votable180.050000true0.062628.16930.005555555555555556Cone search capability for table J/ApJ/877/44/table2 (Control properties)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/877/44/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/877/44/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/877/44/table2?GETtext/xml+votable180.050000true47.6415-0.27450.0055555555555555566/2 260 396 399 714 975 2089 2091 2092 2094 2206 4135 4406 4409 4487 4504 4528 4537 4840 4948 5050 5086 5105 5110 5114 5178 5197 5200 5203 5268 5311 5358 5375 5430 5435 5464 5489 5513 5518 5566 5568 5577 5579 5582 5591 5592 5594 5601 5604 5605 5677 5680 5682 5685 5695 5698 5717 5738 5743 5758 5759 5764 5782 5811 5829 5834 5837 5846 5859 5867 5880 5900 5917 5957 5959 5962 6004 6009 6048 6053 6058 6070 6092 6109 6211 6219 6220 6221 6286 6320 6391 6408 6491 6511 6516 6554 6558 6568 6572 6608 6612 6727 6928 7176 7251 7256 7266 7278 7303 7332 7338 7424 7456 8223 8258 8259 8262 8265 8270 8289 8348 8395 8562 8667 8669 8670 8671 8692 8730 8992 9036 9043 9120 9123 9212 9290 9320 9344 9346 9376 9507 9601 9734 9820 9834 9849 9869 9891 9932 9936 9944 9955 9979 9981 10008 10017 10115 10121 10124 10146 10234 10277 10287 10298 10364 10379 10383 10404 10455 10468 10477 10481 10482 10554 10576 10577 10584 10617 10628 10639 10652 10653 10669 10672 10692 10693 10708 10735 10741 10778 10781 10811 10818 10822 10823 10825 10831 10841 10860 10873 10880 10890 10915 10921 10924 10933 10936 10988 10990 11000 11002 11023 11032 11048 11060 11112 11147 11169 11171 11172 11174 11178 11180 11184 11186 11245 11274 11278 11291 11311 11325 11326 11336 11344 11371 11381 11390 11407 11424 11431 11445 11457 11464 17231 17243 17264 17328 17407 17469 17516 17584 17746 17751 17757 17762 17767 17768 17774 17805 17807 17811 17815 17827 17828 17831 17840 17841 17857 17983 18001 18005 18006 18008 18014 18018 18019 18026 18027 18030 18034 18062 18063 18068 18070 18071 18074 18075 18081 18085 18086 18087 18096 18098 18112 18176 18226 18233 18234 18404 18515 18520 18523 18539 18540 18544 18545 18606 18774 18787 18792 18794 18797 18829 18836 18842 18844 18858 18861 18865 18948 19028 19032 19041 19091 19092 19100 19410 19416 19457 19524 19525 19527 19538 19751 19757 20248 20284 21998 21999 22743 22827 22861 22866 22867 22873 22874 22876 22912 22913 23051 23060 23103 23181 23190 23197 23203 23206 23470 23480 23482 24345 25910 25962 25999 26018 26199 26281 26284 26475 26534 26962 26972 26983 27022 27047 27053 27107 27246 27250 27251 27397 27411 27451 27452 27641 27671 27693 27845 27858 28067 28247 28258 28263 28264 28265 28267 28269 28290 28291 28309 28383 28493 28514 28520 28522 28523 28556 28614 28658 28666 30044 31389 31436 31454 31704 32555 36717 36719 36730 36734 36794 36812 48886 48988https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/877/44?format=asciiOpticaldefaultJ/ApJ/877/44/table1Dwarf carbon (dC) propertiesSimbadNameSimbad column added by the CDSmeta.idcharFiber2[4/1000] SDSS FiberID for second epochmeta.noteintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeq[1/240] Object index across dC and control table (G1)meta.idintprimaryRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000[-9.3/63.8] Declination (J2000)degpos.eq.dec;meta.mainrmag[13.6/20.6] SDSS dereddened r band PSF (AB) magnitudemagphot.mag;em.opt.Rfloatg-r[-0.09/2.01] SDSS (g-r) color indexmagphot.color;em.opt.B;em.opt.RfloatPlate1[269/9180] SDSS plate for first epochmeta.noteintMJD1[51581/57693] First SDSS observing epochtime.epochintFiber1[3/861] SDSS FiberID first epochmeta.noteintPlate2[269/9583] SDSS plate for second epochmeta.noteintMJD2[51658/57933] Second SDSS observing epochtime.epochintdRVel[-303/365] Radial velocity difference between epochskm/sphys.veloc;arith.diffinte_dRVel[3/210] Error in dRVelkm/sstat.errorintG13Display data from Green, 2013, J/ApJ/765/12, within 3"meta.ref.urlcharSp1Interactive spectrum from SDSS-DR14meta.ref.urlcharSp2Interactive spectrum from SDSS-DR14meta.ref.urlcharJ/ApJ/877/44/table2Control propertiesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeq[1/240] Object index across dC and control table (G1)meta.idintprimaryRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000[-11.9/62.2] Declination (J2000)degpos.eq.dec;meta.mainrmag[15.9/20.3] SDSS dereddened r band PSF (AB) magnitudemagphot.mag;em.opt.Rfloatg-r[0.38/1.9] SDSS (g-r) color indexmagphot.color;em.opt.B;em.opt.RfloatPlate1[267/7275] SDSS plate for first epochmeta.noteintMJD1[51584/57093] First SDSS observing epochtime.epochintFiber1[2/1000] SDSS FiberID first epochmeta.noteintPlate2[283/8856] SDSS plate for second epochmeta.noteintMJD2[51660/57519] Second SDSS observing epochtime.epochintFiber2[3/1000] SDSS FiberID for second epochmeta.noteintdRVel[-104/108] Radial velocity difference between epochskm/sphys.veloc;arith.diffinte_dRVel[0/308] Error in dRVelkm/sstat.errorintSp1Interactive spectrum from SDSS-DR14meta.ref.urlcharSp2Interactive spectrum from SDSS-DR14meta.ref.urlchar