Astronomy&Astrophysicsmanuscriptno.29465_hk_article (cid:13)cESO2017 January18,2017 V-type candidates and Vesta family asteroids in the Moving Objects VISTA (MOVIS) Catalogue J.Licandro1,2,M.Popescu3,4,D.Morate1,2,andJ.deLeón1,2 1 InstitutodeAstrofísicadeCanarias(IAC),CVíaLácteasn,38205LaLaguna,Spain 2 DepartamentodeAstrofísica,UniversidaddeLaLaguna,38206LaLaguna,Tenerife,Spain 3 AstronomicalInstituteoftheRomanianAcademy,5Cu¸tituldeArgint,040557Bucharest,Romania 4 InstitutdeMécaniqueCélesteetdeCalculdesÉphémérides(IMCCE)CNRS-UMR8028,ObservatoiredeParis,77avenueDenfert- Rochereau,75014ParisCedex,France Startworking01May2015 7 1 0 ABSTRACT 2 Context.Basalticasteroids(spectrallyclassifiedasV-types)arebelievedtobefragmentsoflargedifferentiatedbodies.Themajority n ofthemarefoundintheinnerpartoftheasteroidbelt,andarecurrentorpastmembersoftheVestafamily.Recently,someV-type a J asteroidshavebeendiscoveredfarfromtheVestafamilysupportingthehypothesisofthepresenceofmultiplebasalticasteroidsinthe earlysolarsystem.Thediscoveryofbasalticasteroidsintheouterbeltchallengedthemodelsoftheradialextentandthevariability 7 ofthetemperaturedistributionintheearlysolarsystem. 1 Aims.WeaimtoidentifynewbasalticV-typeasteroidsusingnear-infraredcolorsof∼40000asteroidsobservedbytheVHS-VISTA surveyandcompiledintheMOVIS-Ccatalogue.Wealsowanttostudytheirnear-infraredcolorsandtostudythenear-infraredcolor ] P distributionoftheVestadynamicalfamily. Methods.WeperformedasearchintheMOVIS-Ccatalogueofalltheasteroidswith(Y−J)and(J−Ks)intherange(Y−J)≥0.5 E and(J−Ks) ≤ 0.3,associatedwithV-typeasteroids,andstudiedtheircolordistribution.Wehavealsoanalyzedthenear-infrared . h colordistributionof273asteroidmembersoftheVestafamilyandcomparedthemwiththealbedoandvisiblecolorsfromWISEand p SDSSdata.WedeterminedthefractionofV-typeasteroidsinthefamily. - Results. Wefound477V-typecandidatesinMOVIS-C,244ofthemoutsidetheVestadynamicalfamily.Weidentified19V-type o asteroidsbeyondthe3:1meanmotionresonance,6ofthemintheoutermainbelt,and16V-typesintheinnermainbeltwithproper r inclinationi ≤3.0◦,wellbelowtheinclinationoftheVestafamily.Wecomputedthat∼85%ofthemembersoftheVestadynamical t p s familyareV-typeasteroids,andonly1-2%areprimitiveclassasteroidsandunlikelymembersofthefamily. a Conclusions.ThisworkalmostdoublesthesampleofbasalticasteroidcandidatesinregionsoutsidetheVestafamily.Spectroscopic [ studiesinthenear-infraredanddynamicalstudiesareneededtoconfirmtheirbasalticcompositionandtodeterminetheirorigin. 1 Keywords. minorplanets;techniques:photometric,spectroscopic;methods:observations,statistical v 1 2 61. Introduction Themajorityofbasalticasteroidsarefoundintheinnerpart 4 oftheasteroidmainbelt,between2.15and2.5AU.Mostofthem 0 arecurrentorpastmembersofthelargestasteroidfamilyinthe .Basaltic asteroids are believed to be fragments of large bod- belt, the Vesta family, dynamically defined as having members 1 ies whose interiors reached the melting temperature of silicate withpropersemi-majoraxis(a ),eccentricity(e ),andinclina- 0 p p 7rocksandsubsequentlydifferentiated(Gaffeyetal.2002),form- tion(ip)intheranges2.26≤ap ≤2.48,0.075≤ep ≤0.122,and 1ing a core of heavy minerals and a mantle of lighter minerals 5.6◦ ≤ ip ≤ 7.9◦,respectively(Nesvornýetal.2015).TheVesta :(olivineandpyroxene).Differentiationisafundamentalprocess collisional family originated from a collisional event that exca- vthat determines the later geological evolution of the objects, so vated a crater in the surface of Vesta (Asphaug 1997; Thomas Xideterminingwetherspecificasteroidsaredifferentiatedornotis et al. 1997) and that occurred more than 1.2 Gyr ago (Carruba ofscientificinterestforunderstandingtheprocessthatsculpted etal.2005).Consistently,spectralstudiesshowthatalargefrac- r athe asteroid belt. Taxonomically, basaltic asteroids are classi- tionoftheVestafamilymemberspresentabasalticcomposition fied as V-types, named after their most representative member (Binzel&Xu1993;Burbineetal.2001). (4) Vesta, which was for a long time the only known asteroid presenting a basaltic crust (McCord et al. 1970; Binzel & Xu Vestaanditsdynamicalfamilyarenottheonlyasteroidswith 1993). The NASA Dawn mission provided a detailed study of a basaltic composition. In the last decades, more V-type aster- Vesta’scomposition(seeMcCord&Scully2015andreferences oidswerediscoveredfarfromVestafamilyintheoutermainbelt therein).Thevisibletonear-infrared(VNIR,0.4-2.5µm)spec- (2.8-3.3AU),asisthecaseofasteroid(1459)Magnya(Lazzaro traofbasalticasteroidsarecharacterizedbytwodeepabsorption etal.2000),orinthemiddlemainbelt(2.5-2.8AU)(Moskovitz bandsaround1and2µm,associatedwiththepresenceofpyrox- etal.2008;Duffard&Roig2009).Theorbitsoftheseasteroids ene on their surfaces. This type of spectra are similar to those suggestthattheyarenotscatteredVestafamilyobjectsbecause of Howardite-Eucrite-Diogenite meteorites (known as HEDs), they cannot be explained by the typical ejection velocities pro- whicharethoughttooriginatefromV-typeasteroids. ducedduringthecrateringevent.Thecaseof(1459)Magnyais Articlenumber,page1of9 A&Aproofs:manuscriptno.29465_hk_article themostintriguingonebecauseitissofarawayfromtheVesta ESO’sCerroParanalObservatoryinChile,equippedwithanear- familythatitisalmostimpossibleforittobeafragmentofthe infrared camera with a 1.65◦ field of view. VISTA-VHS uses crustofVesta.Michtchenkoetal.(2002)proposedthatMagnya the Y, J, H, and Ks broadband filters and targets to image the isafragmentofanotherlargedifferentiatedasteroidthatexisted entire southern hemisphere of the sky, covering about 19.000 intheouterbeltregion. square degrees. Popescu et al. (2016) compiled the colors and Thepresenceofmultipledifferentiatedparentbodiesisalso the magnitudes of the minor planets observed by the VISTA supportedbythemeteoriterecord.Blandetal.(2009)reporton survey in three catalogues: the detections catalogue, MOVIS- thefallofabasalticmeteoritethathasorbitalpropertiesandan D; the magnitudes catalogue, MOVIS-M; and the colors cata- oxygen isotope composition that suggest a parent body distinct logue,MOVIS-C.Thecatalogueswerebuiltusingthethirddata fromVesta. releaseofthesurvey(VISTAVHS-DR3).Atotalof39.947ob- The existence of V-type asteroids outside the Vesta family jects were detected. The colors found for asteroids with known is currently explained by the presence of multiple basaltic as- spectralpropertiesrevealedwell-definedpatternscorresponding teroids in the early solar system; this hypothesis is supported to different mineralogies. The distribution of MOVIS-C data in by the study of HED meteorites. Huaman et al. (2014) found color-color plots shows clusters identified with different taxo- atleastthreelocalsourcesofV-typeasteroids,possiblyassoci- nomictypes.Allthediagramsthatuseinparticularthe(Y − J) ated with the parent bodies (349) Dembowska, (221) Eos, and colorseparatethespectralclassesmuchbetterthanthecommon (1459)Magnya.Thediscoveryofbasalticasteroidsintheouter (J −H) and (H −Ks) colors used to date: even for quite large mainbeltchallengedthemodelsoftheradialextentandthevari- colorerrors(∼0.1)thecolor-colorplots(Y−J)vs.(Y−Ks)and abilityofthetemperaturedistributionintheearlysolarsystem, (Y −J)vs.(J−Ks)clearlyseparatetheS-fromtheC-complex whichgenerallydidnotpredictmeltingtemperaturesinthisre- withoutoverlappingbetweentheregions.TheendmembersA-, gion(Hardersenetal.2014). D-,R-,andV-typesalsooccupywell-definedregions. Usingwidefieldsurveysthatcoverhugefractionsofthesky Based on their distinctive spectral features asteroids with with several filters in the visible and near-infrared it is possi- spectral properties similar to those of V-type asteroids can be ble to search for V-type candidates. Roig & Gil-Hutton (2006) easily identified using color-color diagrams obtained from ob- presented a systematic method for identifying possible basaltic servationswiththeY, J, H,and Ksfilters(Popescuetal.2016; (V-type) asteroids using the 3rd release of the Moving Objects Mommertetal.2016).InPopescuetal.(2016)weshowedthat Catalog (MOC) of the Sloan Digital Sky Survey (SDSS). The inthe(Y−J)vs.(J−Ks)plotV-typesappearasaseparategroup method is based on the Principal Components Analysis of the with(Y−J)≥0.5and(J−Ks)≤0.3(seeFig.15inPopescuetal. MOCcolorsinthevisible,combinedwithsomerefinedcriteria 2016).Infact,themeancolorsofasteroidswithknowtaxonomic of segregation of the taxonomical classes. They found 505 as- typeinMOVIS-Cshowthatthemean(Y−J)and(J−Ks)colors teroids exhibiting V-type colors, 263 of them outside the Vesta ofV-types((Y−J)=0.64±0.09and(J−Ks)=0.08±0.08)are family,almostallofthemintheinnerasteroidbelt,and8ofthem respectively0.2maglargerandmorethan0.3magsmallerthan inthemiddle/outerbelt.Moskovitzetal.(2008)alsostudiedthe anyotherspectralclass(seeTable1inPopescuetal.2016).This distributionofV-typeasteroidsinthemainbeltusingSDSScol- is explained well by the deep absorption bands around 1 and 2 orsanddynamicalcriteria.Theyfound50V-typecandidatesout- µm(BandIandBandII)thatcharacterizethenear-infraredspec- side the Vesta family and using visible and near-infrared spec- traofV-types(seeFig.1)andtheband-passoftheVISTAfilters. troscopytheyconfirmedthat10ofthe11objectstheyobserved Wenotethatthe(Y −J)colorisdeterminedbythefirstabsorp- areV-types. tion band and a large (red slope) value is indicative of a deep TheaimsofthispaperaretoidentifynewV-typecandidates 1 µm band. On the other hand, the (J −KS) is also determined usingthenear-infraredcolorsof∼40000asteroidsobservedby bythesecondabsorptionbandandalow(blueslope)valueisin- the VHS-VISTA survey and compiled in the MOVIS-C cata- dicativeofadeep2µmband.Basedonthetemplatespectrumfor logue (Popescu et al. 2016) and to study the near-infrared col- V-typesfromBus-DeMeotaxonomy(DeMeoetal.2009)wecan ors of all the Vesta family asteroids identified in the MOVIS-C determinethataV-typeasteroidshouldhavecolorvaluesaround catalogue. (Y −J) = 0.625±0.095;(Y −H) = 0.708±0.095;(Y −Ks) = AgeneraldescriptionofMOVIS-Ccatalogueandthecrite- 0.660±0.095;(J−H)=0.082±0.095;(J−Ks)=0.035±0.111; riausedtoselectV-typecandidatesispresentedinSection2.In (H−Ks)=−0.047±0.050,whichareclosetothemiddleofthe Section3wedeterminethegoodnessoftheV-typecandidatese- regiondefinedbytheV-typecandidatesinthecolor-colorplots. lection by analyzing the candidates with known spectra, SDSS The equivalent colors of the V-types were computed using the colors,andalbedo.ThedistributionoftheV-typecandidatesin taxonomictemplatespectrum,theresponsecurveoftheVISTA themainbeltandtheirnear-infraredcolorsareanalyzedinSec- filters,andthesolarcolors,asexplainedinPopescuetal.(2016). tion4.Thenear-infraredcolorsoftheVestafamilyasteroidsare In this work we use the colors obtained from the recently studiedinSection5,andtheconclusionsarepresentedinSection updated VHS-VISTA survey data release (VHSv20160114) to 6. define V-type candidates in the MOVIS-C catalogue: asteroids having (Y − J) ≥ 0.5 and (J −Ks) ≤ 0.3 with uncertainties in bothcolors<0.1.Thesevaluescorrespondtotheaveragevalues 2. IdentificationofV-typeasteroidcandidatesin of the objects located close to the limit that separates V-types fromtherestoftheclassesinthe(Y−J)vs.(J−Ks)plotinFig. MOVIS-C 15fromPopescuetal.(2016).Thisplotshowsadistinctivegap The Moving Objects VISTA Survey (MOVIS) is a compilation between this group and the rest of the objects. We base our se- of the observations of known minor bodies of the solar sys- lectioncriteriainthesetwocolorsbecausetheyclearlyseparate tem observed during the VISTA-VHS survey (Popescu et al. theV-typesfromtheotherclassesandbecauseofobservational 2016).TheVISTAHemisphereSurvey(VHS)isanallskysur- constraintsduetotheparticularobservingprocedureusedinthe vey that uses the 4.1m Visible and Infrared Survey Telescope VHSsurvey:(1)thenumberofobjectswithK dataislargerthan s for Astronomy (VISTA) wide field survey telescope located at thosewithH dataand(2)the(J−Ks)colorsaremoreaccurate Articlenumber,page2of9 J.Licandroetal.:V-typecandidatesandVestafamilyasteroidsinMOVIScatalogue Table1.ListofMOVIS-CV-typecandidatesthatbelongtotheVesta collisional family and have color uncertainties ≤0.1. Objects marked withanasteriskarealsoidentifiedasV-typecandidatesbyRoig&Gil- Hutton(2006)basedontheirvisiblecolors. 1959 15781 29334 43388∗ 62406 96698 1979 15881 29979 44097 65068 96890 2011 16234 29994 44805 65504 98086∗ 2508 17139 30097 44877 66111 98167 3153 17162 30329 45792 67498 99381 3613 17431 30358 46281 68759 102813 4311 17562 30818 46698∗ 68782 103042 4444 17769 31132 48644 68801 103132 4993 17976 31517 48734 68879 107709 5051 18508 31575 50048 69742∗ 108250 5307 18581 31778 50082 70248 111976 6014 18754 32276 50084∗ 70277 112087 6085 19025 32541 50086 70940 117819 6096 19573 33049 50241 72246 118295 6506 19680 33100 50248 73109 118305 6877 20252 33477 51368 73174∗ 118532 Fig.1.TemplatespectrumofaV-typeasteroidintheBus-DeMeotax- 7005 20302 33491 51487 74010 119085 onomy.Ingraythefilterband-passoftheVISTAfilters.The(Y−J)and (J−Ks)colorsarestronglyaffectedbythetwodeepabsorptionbands 7012 21633 33512 51628 74898 119136 ofthespectrum(BandIcenteredat∼1µmandBandIIat∼1µm) 7810 21692 33590 51687 74924 122101 . 9076 21883 33875 52792 74936 130756 9204 22080 34081 53000 75636 131609 9616 22155 34534∗ 53580 77122 132010 thanthe(J−H)onesmainlybecauseoftheshortertimeinterval 10056 22654 35222 53734 77324 132347 betweentheobservationsinbothfilters(Popescuetal.2016). 10614 23522 35284 54084∗ 77590 136439 As discussed above, the existence of V-type asteroids out- 11189 24085 35414 54152 80798 137512 side the Vesta family can be explained by the presence of mul- 11326 24115 36021 55315 80800 138192 tiple basaltic asteroids in the early solar system; for the analy- 11522 24255 36761 56169 84328 147141 sisoftheV-typecandidates,wewilldifferentiatebetweenthose 12340 24261 36834 56599 86520 153392 candidates that are members of the Vesta family according to 12591 25220 37113 57104 88781 161029 Nesvornýetal.(2015)andthosethatarenon-Vestafamilymem- 13054 25708 37149 57818 88958 162518 bers. 13164 26238 37192 57930∗ 90548 170306 Atotalof477V-typecandidateshavebeenidentifiedinthe 13191 26611 37234 57943 90639 170309 MOVIS-C catalogue using the criteria described above, 233 of 13287 27539 38335 58271 91343 172447 them members of the Vesta family (see Table 1) and 244 non- 13530 27939∗ 38732∗ 59215 92646 175841 Vestafamilymembers(seeTable2).Only22ofourV-typecan- 13569 28397 38876 59336 92686 178112 didates,markedwithanasteriskinTables1and2,arealsoiden- 13855 28543 38879 59569 93339 225334 tified as V-type candidates by Roig & Gil-Hutton (2006) based 13994 28737 39949∗ 61521 93394∗ 243137 ontheirSDSScolors. 15032 28902 41558 61741 94355 244232 15756 29186 42644 61986 94413 3. Visiblespectra,colors,andalbedoofMOVIS V-typecandidates and(J−Ks)colors:(2508)Alupka,(3498)Belton,(3536)Schle- icher,(3900)Knezevic,(4311)Zguridi,and(4993)Cossard.Ex- ToseehowefficientlyMOVIS-CcanidentifyV-typecandidates, ceptfor(3498)Belton,whichhasa(J−Ks)errorslightlylarger we searched for published spectra of these objects in the two than the 0.1 limit we used, all of them are identified as V-type largest spectroscopic databases: the Small Main-Belt Asteroid candidatesinthispaper.So,87%oftheV-typecandidatesiden- Spectroscopic Survey (SMASS, Xu et al. 1995, Bus & Binzel tified in MOVIS-C with known spectra are V-type, and all the 2002)andtheSmallSolarSystemObjectsSpectroscopicSurvey asteroidsinMOVIS-CclassifiedasV-typeintheSDSSareiden- (S3OS2,Lazzaroetal.2004).Nineofthecandidateshavespec- tified as V-type candidates. This is indicative of the very high traintheSMASSdatabase,whiletherearenoneintheS3OS2. successrateofidentifyingV-typesusingMOVIS-Candthecolor We also searched for visible and/or near-infrared spectra in the criteriapresentedinthiswork. literatureandfoundthattherearespectraldataofatotal15ofour We next looked at the SDSS colors and visible albedo (p ) V V-typecandidates,13ofwhichalreadyspectroscopicallyclassi- of our V-type candidates, confirming that most of them also fied as V-types (see Table 3). From those that are not, one is have visible colors and albedo compatible with V-type aster- classified as Sr, and the other is ambiguously classified as V- oids.TheSDSScolors(i−z)anda∗ (asdefinedbyIvezic´ etal. or R-type. We note that the spectra of R- or Sr-types are also 2001),andthe p calculatedfromtheWideInfraredSurveyEx- V characterizedbydeepabsorptionbandscloseto1and2µm.On plorer (WISE) data (Masiero et al. 2011) were retrieved using the other hand, eight objects with MOVIS-C data are already theMP3CMinorPlanetPhysicalPropertiesCatalogue1. classifiedasV-typesbasedontheirvisiblespectrumobtainedby SMASSsurvey.Sixoftheseobjectshavewell-determined(Y−J) 1 http://mp3c.oca.eu/ Articlenumber,page3of9 A&Aproofs:manuscriptno.29465_hk_article Table2.ListofMOVIS-CV-typecandidateswithcoloruncertainties Table3.MOVIS-CV-typecandidateswithknownspectralclass. ≤0.1thatdonotbelongtotheVestafamily.Theobjectsmarkedwithan asteriskarealsoidentifiedasV-typecandidatesbyRoig&Gil-Hutton Object Reference Vestafamily Class (2006)basedontheirvisiblecolors. 2011Veteraniya 4,11 Y V 2486Metsahovi 1,6 N V 2275 12172 26842 44878 70081 113910 2508Alupka 2 Y V 2452 12612 27343 44930 71826 114858 2763Jeans(*) 2,5 N V 2486 12787 27373 44953 71850 122008 3536Schleiche 2 N V 2763 12789 27383 45323 71960 122243 3613Kunlun 12 Y V 2888 13194 27770 45893 73076 122267 3900Knezevic 2 N V 3188 13380 28461 45942 73658 123786 4311Zguridi 2 Y V 3331∗ 13398 29384 47459 74596 126981 4993Cossard 2,4 Y V 3536 13721 29677 47476 74912 130972 5051Ralph 2 Y Sr 3882 13760 29733 47837 75080 133202 6406Vanavara 1,4 N V 3900 15121 30893∗ 48036 75289 135575 9147Kourakuen 3,10 N V 3954 15506 30961 49214 75661 136229 106141997UH1 3 Y VorR 4228 15678 31460 50035 77972 145887 27343Deannashea 8 N V 4693 15846 31599 50091 79426 147703 40521(1999RL95) 7,9 N V 5150 16169 31677 50105 80345 152165 5328 16352∗ 31775 50215 80463 152933 Notes. (1)Alvarez-Candaletal.(2006);(2)Bus&Binzel(2002);(3) 5524 16477 32581 51511 82349 159601 de Sanctis et al. (2011b); (4) de Sanctis et al. (2011a) ; (5) Duffard 5631 16605 33366 52132 82455 164235 etal.(2004);(6)Fulvioetal.(2016);(7)Moskovitzetal.(2008);(8) 5713 16873 33513 52819 86263 165142∗ Moskovitz et al. (2010); (9) Roig et al. (2008); (10) Popescu et al. 5758 17001 33562 52985 86284 166973 (2012);(11)Xuetal.(1995);(12)http://smass.mit.edu/catalog.php. 5875 17057 33628 52995 86768 177529 5952 17546 35062∗ 53608 89270 179851 144 present SDSS colors that place them in the region associ- 6046 17739 36644 54367 89729 180703 atedwiththeprimitiveC-complex(a∗ < 0.0),namely(166973) 6363 18012 37386 55456 89729 183004 2003OV and(15032)Alexlevin. 6406 18644 37404 55769 90223 188102 5 A total of 240 of our V-type candidates have visible albedo 6442 19257 37730 56369 94680 189231 (p ) obtained from WISE observations (Masiero et al. 2011). 6584 19281 38317 56456 96653 197480 V The albedo distribution (see Fig. 3) is typical of that of rocky 6587 19294 38744 57278 96823 203379 asteroids, with (p ) = 0.37 ± 0.12, with 232 objects (87%) 6853 19518 39175 57454 98231 207473 V with p > 0.2 and only 3 with p < 0.15 (compatible with 7223 19619 39465 59423 98654 218144 V V C-class objects within the uncertainties): (166973) 2003 OV , 7459 19679 39926 59834 99579 235061 5 7675 19738∗ 40258 61354 100772 240551 (5524)Lecacheux,and(112839)1998SA111.Low-albedoaster- oidscannotbebasaltic,sotheselectioncriteriaincludes∼1.5% 7823 19969 40378 61736 101029 245202 7998 19983 40521∗ 61985 102601 249866 ofasteroidsthatareclearlynotV-typelikelyowingtoerrorsin thecolordetermination. 8644 20188 40708 63673 102986 284907 Wenotethat(166973)2003OV hasbothSDSScolorsand 8921 21307 41433 63708 103105 313008 5 p compatiblewithaprimitiveclassasteroid.Ontheotherhand, 9064 22880 41463 65949 103828 322744 V 9147∗ 22892 41776 67477 109080 326769 the albedo of (15032) Alexlevin is too high (pV = 0.29) and (5524)Lecacheuxand(112839)1998SA havea∗ >0(0.132± 9197 24140 41793 67792 111947 354036 111 9495 24604∗ 42656 67876 112839 364694 0.016and0.105±0.034,respectively). Finally, of the 477 candidates, 76 have both SDSS colors 9495 25979 43885 68141 112841 andWISEalbedo,and56ofthese76(74%)havethealbedoand 9746 26097 44541 69255 113516 SDSS colors of the V-types (p > 0.20, a∗ > 0 and (i−z) < V −0.2). We note that the 74% success rate of detecting objects that are V-types according to MOVIS, SDSS, and WISE data Using SDSS colors from the 3rd release of the MOC, Roig dependsonthesuccessrate(anduncertainties)ofallthesurveys. &Gil-Hutton(2006)identifiedafewhundredV-typecandidates. ThesuccessrateofMOVISaloneofdetectingV-typecandidates TheyshowedthatV-typeasteroidsappearwellsegregatedinthe among those that have been already classified because of their (i − z) vs. a∗ color-color plot, forming a cluster in the region visibleornear-infraredspectrum(confirmedV-types)ishigher, a∗ >0and(i−z)<−0.2.Atotalof144ofourV-typecandidates ∼87%(13of15objects). presentedSDSScolors(Ivezic´ etal.2002)inthe4threleaseof the MOC. Following this criterion (see Fig. 2), 111 out of the 4. V-typecandidatesoutsidetheVestafamily 144V-typecandidatespresentedinthispaper(77%)haveSDSS colors compatible with V-type asteroids. We note that only 22 4.1. DistributionofV-typecandidatesinthemainbelt of our 144 V-type candidates are identified as V-types in Roig & Gil-Hutton (2006), likely because they used the 3rd release As discussed above, the existence of V-type asteroids outside oftheMOCthathavephotometricdatafor204,305movingob- theVestafamily,andinparticularinorbitsthatarenotlikelyto jects, while the 4th MOV release used in this paper have data be attained by any asteroid scattered from the Vesta family, is for 471,569 moving objects. Considering the error bars of the challenging,andsuggeststhatthereweremultiplebasalticaster- SDSS colors only 10 asteroids present visible colors far from oidsintheearlysolarsystem.Forthisreasonwefirstanalyzed the V-type cluster (a < 0.1 and (i−z) < −0.1). Only 2 of the theorbitaldistributioninthespaceofproperelementsandsep- Articlenumber,page4of9 J.Licandroetal.:V-typecandidatesandVestafamilyasteroidsinMOVIScatalogue family.AccordingtoRoig&Gil-Hutton(2006),onlyfragments of the Vesta family ejected at very high velocities (> 700 m/s) are able to be injected in the MMB. We identified 13 V-type candidates in the MMB (see Table 4), Moskovitz et al. (2008) identified 12 more, and Roig & Gil-Hutton (2006) another 2; asteroid (40521) was identified in all three samples. A total of 27 V-type candidates are identified in the MMB either by their near-infrared(thiswork)orSDSScolors(Moskovitzetal.2008; Roig&Gil-Hutton2006). AccordingtoNesvornýetal.(2015)twooftheV-typeaster- oidsintheMMBidentifiedinthiswork,(197480)and(180703), belong to the (173) Ino collisional family; among those identi- fiedinMoskovitzetal.(2008),asteroid(208899)belongstothe (2732) Witt family, (84021) belongs to the (170) Maria family, and (55550) belongs to the (15) Eunomia family. The case of (55550)isveryinterestingbecausetheEunomiafamilyhasbeen suggested as a possible source of basaltic-type asteroids (Car- rubaetal.2007;Roigetal.2008).TwelveoftheV-typecandi- Fig.2. SDSScolorsoftheV-typecandidatespresentedinTables1and dates identified in the MMB are in the vicinity of the Eunomia 2.ThegreatmajorityofthemareintheregionoftheV-typesaccording familyinthespaceofproperorbitalelements. toRoig&Gil-Hutton(2006). The case of V-type asteroids in the OMB and the possible link with (1459) Magnya is crucial in order to validate the hy- pothesis of the presence of multiple basaltic asteroids in the early solar system. We identified six V-type candidates in the OMB (see Table 4), one of which – (126981) – belongs to the (9506)Telramundfamily.Moskovitzetal.(2008)identifiedfour V-types in the OMB, and Roig & Gil-Hutton (2006) identified anothersixV-types. Finally,itisinterestingtostudytheV-typecandidatesinthe IMB that are far from the space of proper orbital elements of theVestadynamicalfamily.Thiscanhelpexplainwhatdynam- icalpathwastakenbytheVestaasteroidstoreachtheseorbits, andcantestwhethertherearebasalticasteroidsintheIMBthat are not chunks of the crust of Vesta. In particular there are two groups:(1)thosewitha ≤ 2.22AUthatarewellinsidethe7:2 p mean motion resonance (between 2.23 and 2.27 AU), which is theinneredgeoftheVestafamily,and(2)thosewithproperin- clination well below the proper inclination of the Vesta family. Nesvornýetal.(2008)showedthatscatteredVestafamilyaster- oidspopulatemostofthesemi-majoraxisextentoftheIMB,but Fig.3.Visiblealbedo(p )distributionoftheV-typecandidatesinTa- V do not extend to proper inclinations much smaller than that of bles1and2.Themajorityoftheobjectshavelargealbedos(p >0.2), compatiblewithV-typeasteroids. V the family (e.g., ip < 3◦). There are 19 V-type candidates with a ≤ 2.22 AU and 16 with i ≤ 3.0◦ in our sample. From our p p listofV-typecandidatesintheIMB13ofthemdynamicallybe- aratedmembersandnonmembersoftheVestadynamicalfamily longtothe(8)Florafamily,5belongtothe(44)Nysafamily,2 accordingtoNesvornýetal.(2015). belongtothe(434)Hungaria,and1belongstothe(27)Euterpe Figure4showsthedistributioninproperorbitalelementsof family. the V-type candidates presented in Tables 1 and 2. It is clearly Spectroscopic observations of V-type candidates in the seen that the great majority of the non-Vesta candidates are in MMB, the OMB, and other non-Vesta family V-types are ex- theinnermainbelt(objectswithsemi-majoraxisa < 2.5AU, tremelyimportantinordertoconfirmtheirtaxonomicalclassifi- p hereafter IMB), most of them close to the region occupied by cationasV-types,andtoallowmineralogicalstudiestocompare the Vesta family asteroids. This suggests that the large major- their surface properties to those of Vesta family asteroids (e.g., ity of those IMB V-type asteroids outside the Vesta family are Duffard&Roig2009;Fulvioetal.2016;Ievaetal.2016).These probablyfragmentsof(4)Vesta;someofthemareprobablynot asteroids,togetherwithdynamicalstudiestodeterminetheirori- included in the family because of the distance criterium d gin (e.g., Carruba et al. 2014; Nesvorný et al. 2008; Huaman cutoff used by Nesvorný et al. (2015) or because some of them have et al. 2014; Roig et al. 2008), are crucial to understanding the beenscatteredfromthefamily(Nesvornýetal.2008). population and origin of basaltic asteroids in this region of the On the other hand, V-type candidates that are in the outer belt. main belt (objects with semi-major axis between 2.8 - 3.3 AU, hereafterOMB)andinthemiddlemainbelt(objectswithsemi- 4.2. Near-infraredcolordistributionoftheV-typecandidates majoraxisbetween2.5-2.8AU,hereafterMMB)areveryinter- estingbecausetheyareunlikelyscatteredVestafamilyasteroids. The(Y−J)vs.(J−K )plotoftheV-typecandidatesispresented s Asteroids in the MMB are objects that are beyond the 3:1 inFigure5.Afirstlookatthisfiguresuggeststhatthecolorsof meanmotionresonancewithJupiter,theouteredgeoftheVesta the Vesta and non-Vesta V-types are slightly different. To bet- Articlenumber,page5of9 A&Aproofs:manuscriptno.29465_hk_article Table4.Near-infraredcolorsandproperorbitalelementsoftheV-typecandidatesidentifiedintheouterandmiddlemainbelt. Number Name (Y−J) (Y−J) (J−K ) (J−K ) a e sin(i ) err S S err p p p 2452 Lyot 0.548 0.006 0.216 0.017 3.157603 0.157434 0.203073 26842 Hefele 0.543 0.019 0.200 0.054 3.070801 0.161099 0.11862 47837 2000EB118 0.513 0.052 0.188 0.099 3.047409 0.116868 0.198066 112839 2002QJ18 0.847 0.057 0.297 0.090 3.161972 0.090493 0.263182 123786 2001BS17 0.560 0.081 0.143 0.096 3.094369 0.199381 0.045462 126981 2002FW26 0.615 0.042 0.231 0.087 2.985409 0.064602 0.152313 6442 Salzburg 0.545 0.032 0.023 0.078 2.686807 0.058888 0.047547 7459 Gilbertofranco 0.788 0.010 0.125 0.019 2.597774 0.135546 0.088471 13760 Rodriguez 0.558 0.029 0.142 0.072 2.556707 0.106708 0.040244 20188 1997AC18 0.693 0.024 0.067 0.058 2.593472 0.12641 0.133965 40521 1999RL95 0.668 0.034 0.073 0.075 2.531127 0.05667 0.218938 52132 5034P-L 0.602 0.073 0.216 0.046 2.590746 0.247551 0.188448 59423 1999GE4 0.520 0.027 0.270 0.075 2.648131 0.120942 0.228428 61354 2000PY10 0.690 0.027 0.029 0.084 2.516033 0.105526 0.206352 61985 2000RW30 0.679 0.024 0.101 0.045 2.564561 0.090761 0.153342 100772 1998FN34 0.614 0.043 0.289 0.092 2.748188 0.246466 0.076894 180703 2004HW46 0.502 0.031 0.141 0.093 2.721743 0.1747 0.237132 197480 2004BE8 0.510 0.020 0.221 0.052 2.724477 0.171389 0.231051 249866 2001QM165 0.929 0.077 0.273 0.097 2.666192 0.196148 0.172099 ter analyze this possible difference the normalized histograms showingthe(Y−J)and(J−K )colordistributionofbothgroups s are presented in Figure 6, and the mean value and correspond- ing standard deviation (σ) of the colors as well as the number of objects used to compute them (N), separated into Vesta and non-Vestafamilyasteroids,arepresentedinTable5. The(Y−J)colorsoftheVestafamilycandidatesseemtohave a narrower distribution than the colors of the non-Vesta family asteroids.The(Y−J)colorsofnon-Vestacandidatesspreadover awiderrangeofvaluesandpeakatalarger(Y−J),butthemean (Y−J) values of the two distributions are similar within a 1-σ deviation. To check if the (Y − J) color distribution of the two groupsarestatisticallydifferent,weuseaKolmogorov-Smirnov (K-S)test.Thistestassumesthatbothdistributionsarecompat- ible and compute the probability that the two distributions are equal.TheprobabilityvaluePobtainedwiththeK-Stestforthe (Y −J)distributionsisP = 2.5x10−11,andforthe(J−K ) (Y−J) s is P = 0.24. To reject the null hypothesis the K-S rejec- (J−Ks) tioncriteriarangefromthelessstrictP<0.05tothemorestrict P < 0.03 (or even P < 0.01), so the test cannot reject the null hypothesisinthecaseofthe(J−K )distributions,butshowsthat s the (Y − J) distributions of the Vesta and non-Vesta candidates aresignificantlydifferent. The different (Y − J) color distribution of both groups can beinterpretedintermsof(1)adifferentcompositionofthenon- Vesta asteroids with respect to Vesta, supporting an origin in a differentparentbodythanVestawithaslightlydifferentbasaltic composition;(2)adifferentdegreeofspace-weatheringthatei- theraffectsthespectralslopeorthedepthofthebands(see,e.g., Pietersetal.1993;Brunettoetal.2006;andreferencestherein); and (3) a different degree of contamination of the two samples Fig.4.DistributioninproperorbitalelementsofourV-typecandidates. by the incorrect identification of V-types using MOVIS. In this Theupperpanelshowsthepropersemi-majoraxis(a )vs.theproper context the observed narrower distribution of the (Y − J) color p eccentricity(e ).Thelowerpanelcorrespondstothepropersemi-major oftheV-typecandidatesintheVestafamilyisexpectedasthey p axis vs. the sine of the proper inclination (ip). Red circles are Vesta arechunksofthesameasteroid(Vesta),ejectedatthesametime familymembers,whilebluecirclesindicatetheobjectsnotintheVesta (thustheaffectedbyweatheringduringthesameamountoftime family.Theverticaldashedlinescorrespondtothemostrelevantmean inasimilarregionofthesolarsystem),andthesampleislikely motionresonances. less affected by objects that are incorrectly identified as V-type asitisbiasedinfavorofVestoids. Articlenumber,page6of9 J.Licandroetal.:V-typecandidatesandVestafamilyasteroidsinMOVIScatalogue DifferencesinthecompositionofV-typesoutsidetheVesta Table5.Meanvaluesofthenear-infraredcolorsofourV-typecandi- dates,separatedintomembersandnonmembersoftheVestacollisional familyhavebeensuggestedbyIevaetal.(2016)forV-typesin family. the MMB and OMB from the analysis of four V-types outside the3:1resonance.Asdiscussedabove,(Y−J)isrelatedtoBand Color Mean σ N IoftheV-typespectrumand(J−K )isrelatedtoBandII(see s Vestafamily Fig.1).Thepositionandthedepthofthebandsisusedtostudy (Y−J) 0.62 0.07 233 themineralogicalcompositionoftheV-typeasteroids(see,e.g., Duffard et al. 2005). In particular, the Band I center vs. Band (Y−H) 0.75 0.12 90 II / Band I area ratio (BAR) is a diagnostic of different surface (Y−Ks) 0.68 0.12 232 composition.ForV-typeasteroidswithsimilar(J−K ),alarger (J−H) 0.12 0.13 94 s (Y−J)valuecanbeduetoeitheradeeperBandI(thanasmaller (J−Ks) 0.05 0.13 233 (H−Ks) -0.07 0.12 233 BAR value), or a lager value of Band I center. In any case, the interpretation in terms of mineralogical composition with only Non-Vestafamily these two broadband colors is not straightforward and needs to (Y−J) 0.68 0.11 244 be studied further, for example by using the spectra of basaltic (Y−H) 0.78 0.14 117 meteorites,butthisisbeyondofthescopeofthispaper. (Y−Ks) 0.73 0.14 244 On the other hand, when considering only the OMB and (J−H) 0.10 0.14 120 MMB V-types (the non-Vesta asteroids that are more likely (J−Ks) 0.05 0.13 244 chunksofotherbasalticparentbodies),weobtainameanvalue (H−Ks) -0.05 0.13 121 of(Y−J)=0.63±0.12,almostthesamevalueobtainedforthe Vesta family candidates (see Table 5). Unfortunately, there are not enough V-types in theOMB and MMB to perform a statis- ticallysignificant(Y −J)distributiontocomparewiththeVesta asteroids, so we cannot claim any compositional difference be- tween the two populations. Visible and near-infrared spectra of asignificantnumberofthesenon-VestaV-types,inparticularin the OMB and MMB, is needed in order to perform a detailed mineralogical analysis and to compare their composition with thatofVestafamilyasteroids. Fig. 5. VISTA colors of our V-type candidates. In red the objects be- longingtotheVestafamilyaccordingtoNesvornýetal.(2015);inblue theasteroidsthatarenotmembersoftheVestafamily. 5. TheVestafamily Fig.6.Normalizedhistogramsshowingthe(Y−J)and(J−K )color s WealsousedMOVIS-Ctostudythenear-infraredcolorsofthe distributionsofourV-typecandidates.Inredtheobjectsbelongingto Vesta dynamical family and to combine them with the analysis theVestafamilyaccordingtoNesvornýetal.(2015);inbluetheaster- ofvisiblecolorsfromtheSDSSandvisiblealbedos p fromthe oidsthatarenotmembersoftheVestafamily. V WISEdata. Thereare273VestafamilyasteroidsaccordingtoNesvorný et al. (2015) observed in the MOVIS-C catalogue with (Y − J) etal.(2016)arealsoshown.TheVestafamilyasteroidsarecon- and (J −K ) colors with uncertainties < 0.10 magnitudes. The centrated in two clearly differentiated groups, one in the upper s (Y − J) vs. (J −K ) color-color plot of the asteroids belonging left (in the region of the V-type asteroids) and the other in the s to the Vesta dynamical family is shown in Fig. 7. The regions lowerright(intheregionoftheS-andC-typeasteroids).Atotal betweentheV-,S-,andC-typeclassesasdeterminedinPopescu of233Vestafamilyasteroids(∼85%)areV-types,39(∼11%) Articlenumber,page7of9 A&Aproofs:manuscriptno.29465_hk_article arelocatedintheregionofS-types,and11(∼4%)intheregion and only 23 (2.5%) are in the region of C-type primitive class ofC-typeasteroids. asteroids.Wenotethatalargefractionoftheasteroidsinthere- Inthissampleof273Vestafamilyasteroids139ofthemhave gionoftheS-typesareconcentratedveryclosetotheregionof visible albedo (p ) based on WISE data (Masiero et al. 2011). the V-types, 179 of them having (i−z) color in the range -0.2 V Only two of them (∼ 1.5 %) have an albedo compatible with <(i−z)<−0.1). primitiveasteroids(p <0.1).Thesameresultisobtainedwhen V considering all the Vesta family asteroids observed by WISE withdetermined p (seeFig.8).Only31objectshave p < 0.1 V V of a total of 1933, equivalent to 1.5% of the sample. We note thattheregionoccupiedbytheC-typesinthe(Y−J)vs.(J−K ) s plot also includes the X-types and the K-types. Some X-types (M- and E- types) and the K-type asteroids present p > 0.1, V so the Vesta family contains a very small fraction of primitive interlopers. Fig. 9. SDSS colors of the sample of Vesta family asteroids having SDSSobservations.Thegreatmajorityofthemareintheregionofthe V-typesaccordingtoRoig&Gil-Hutton(2006). 6. Conclusions InthispaperweusedtheMovingObjectsVISTASurveyColor Fig.7. ColorsofasteroidsbelongingtotheVestafamilyintheMOVIS- Catalog (MOVIS-C, Popescu et al. 2016), a compilation of the Ccataloguewithuncertainties< 0.1mag.Thegreatmajorityofthem near-infraredcolorsof∼40000knownminorbodiesofthesolar areintheregionoftheV-typeasteroidsasexpected. system observed during the VISTA-VHS survey, to search for V-typeasteroidsandtostudythecolordistributionoftheVesta dynamicalfamily. Atotalof477V-typecandidateswereidentifiedinMOVIS- Cbasedontheirnear-infrared(Y −J)and(J−Ks)colors,455 of them not previously recognized by any other spectroscopic or spectrophotometric survey. This sample almost doubles the numberofknownV-typesoutsidetheVestafamily.TheMOVIS success rate of detecting V-types is ∼ 87%, 15 objects in our list have a previous taxonomical classification based on spec- troscopicobservations,13ofthemwerealreadyclassifiedasV- types.Wefoundthat244oftheV-typecandidatesarenotVesta family members according to Nesvorný et al. (2015). We also enlarged the sample of V-types with an unlikely origin in the Vesta family: we identified 19 V-type asteroids beyond the 3:1 meanmotionresonance,13ofwhichinthemeanmainbeltand 6intheoutermainbelt,andwefoundother16intheinnermain belt with proper inclination well below that of the Vesta fam- ily(i ≤ 3.0◦)andwellbellowthei valuethatscatteredVesta p p familyobjectscouldattain(Nesvornýetal.2008). We also found that the (Y − J) colors of the Vesta family Fig.8. VisiblealbedodistributionofalltheVestafamilyasteroidsob- candidatesseemtohaveanarrowerdistributioncomparedtothe servedbyWISE. colorsofthenon-Vestafamilyasteroids,andpeaksatasmaller (Y −J)value.Ievaetal.(2016)foundthatV-typesintheMMB UsingtheSDSSdata(Ivezic´ etal.2002)andonlyconsider- andOMBseemstopresentadifferentsurfacecompositionwith ingobjectswithuncertaintiesinthespectralslopeσ(a∗) < 0.03 respecttoVestafamilyasteroids,butwhenconsideringonlythe anduncertaintiesinthecolorσ(i−z) <0.13,therearedatafor OMBandMMBV-typesinoursamplewefoundthattheircolor 910 Vesta family asteroids (see Fig. 9). A total of 659 of these distribution is almost equal to that of the Vesta family. There- objects ( ∼ 73%) fulfill the criteria used by Roig & Gil-Hutton fore, we conclude that a careful visible and near-infrared spec- (2006) to determine a V-type, i.e., (i−z) > −0.2 and a∗ > 0, troscopic study of the V-types in this region of the main belt is Articlenumber,page8of9 J.Licandroetal.:V-typecandidatesandVestafamilyasteroidsinMOVIScatalogue neededinordertoperformadetailedmineralogicalanalysisand comparetheircompositionwiththatofVestafamilyasteroids. Finallythenear-infraredcolorsofthealltheVestafamilyas- teroidsinMOVIS-C(atotalof273asteroids)arepresentedand analyzedtogetherwiththeirSDSScolorsandvisiblealbedo p . V Weconcludethatthegreatmajorityoftheasteroidsidentifiedas VestafamilymembersbypuredynamicalconsiderationsareV- types(∼85%),andonlyafew∼1−2%areprimitiveasteroids andsounlikelymembersofthecollisionalfamily. Acknowledgements. ThisarticleisbasedonobservationsacquiredwiththeVis- ibleandInfraredSurveyTelescopeforAstronomy(VISTA).Theobservations wereobtainedaspartoftheVISTAHemisphereSurvey,ESOProgram,179.A- 2010(PI:McMahon).WethankDanielaLazzaroforherusefulcommentsthat helpedtoimprovethismanuscript.J.Licandro,D.Morate,andJ.deLeónac- knowledgesupportfromtheAYA2015-67772-R(MINECO,Spain).Thework ofM.PopescuwassupportedbyagrantoftheRomanianNationalAuthorityfor ScientificResearch–UEFISCDI,projectnumberPN-II-RU-TE-2014-4-2199. 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