Discovery of an OB Runaway Star Inside SNR S147

2.1 MB·English

by  Baha Dinçel

Mon.Not.R.Astron.Soc.000,1–10(2014) PrintedJanuary29,2015 (MNLATEXstylefilev2.2)
Discovery of an OB Runaway Star Inside SNR S147
B. Dinçel1(cid:63), R. Neuhäuser1, S.K. Yerli2, A. Ankay3, N. Tetzlaff1, G. Torres4, M. Mugrauer1
1AstrophysikalischesInstitutundUniversitäts-SternwarteJena,07745Jena,Germany
2OrtaDog˘uTeknikÜniversitesi,DepartmentofPhysics,06531Ankara,Turkey
5 3Bog˘aziçiUniversity,DepartmentofPhysics,34342I˙stanbul,Turkey
1 4Harvard-SmithsonianCenterforAstrophysics,60GardenSt.,MailStop20,CambridgeMA02138,USA
0
2

n Accepted2015January17.Received2014December12;inoriginalform2014May25
a
J

8 ABSTRACT
2 We present first results of a long term study: Searching for OB–type runaway stars inside
supernovaremnants(SNRs).Weidentifiedspectraltypesandmeasuredradialvelocities(RV)

] by optical spectroscopic observations and we found an early type runaway star inside SNR
R
S147.HD37424isaB0.5Vtypestarwithapeculiarvelocityof74±8 kms−1.Tracingback
S
thepasttrajectoriesviaMonteCarlosimulations,wefoundthatHD37424waslocatedatthe
.
h samepositionasthecentralcompactobject,PSRJ0538+2817,30±4 kyrago.Thisposition
p is only ∼4 arcmin away from the geometrical center of the SNR. So, we suggest that HD
- 37424wasthepre–supernovabinarycompaniontotheprogenitorofthepulsarandtheSNR.
o We found a distance of 1333+103 pc to the SNR. The zero age main sequence progenitor
r −112
t mass should be greater than 13 M . The age is 30±4 kyr and the total visual absorption
s (cid:12)
towardsthecenteris1.28±0.06mag.Fordifferentprogenitormasses,wecalculatedthepre–
a
[ supernovabinaryparameters.TheRocheLoberadiisuggestthatitwasaninteractingbinary

inthelatestagesoftheprogenitor.
1
v Keywords: OBRunaway Stars;HD 37424,Neutron Stars;pulsars; PSRJ0538+2817, Su-
0 pernovaRemnants;SNRS147
2
2
7
0
. 1 INTRODUCTION binarieslike4U1700-37(Ankayetal.2001)andVelaX–1(Kaper
1
etal.1997)aresuchexamples.
0
High space velocities of OB runaway stars are explained by two
5 Yet,thelowrateofX–raybinariesandthehighrateofisolated
independentmechanisms:dynamicalejectionduetogravitational
1 neutronstarsbytakingintoconsiderationtheselectioneffects,the
interactionsofmassivestarsinclustercores(Povedaetal.1967)
: binarydisruptionislikelytooccurinmostcases(Guseinovetal.
v and binary disruption as a result of a supernova explosion of the
2005)(hereafter,G05).Thekinematicsofthebinarydisruptiondue
i initiallymoremassivecomponent(Blaauw1961).Bothscenarios
X toanasymmetricsupernovaexplosioniswidelydiscussedinTauris
areviable,butwhetheroneofthemechanismsisdominantisstill
r &Takens(1998).However,asampleofobservationallyconfirmed
uncertain.Accordingtothevirialtheorem,throughasymmetricsu-
a OB runaway–NS couples is needed for a better understanding of
pernovaexplosioninabinarysystem,ifmorethanhalfofthetotal
theproblem.
massofthesystemisreleased,thenthenewbornneutronstar(or
The importance of searching for OB runaways inside SNRs
blackhole)andthenon–degeneratecomponentarenomoregravi-
wasfirstmentionedinvandenBergh(1980).However,thekine-
tationallybound(Blaauw1961).However,theenergystoredinthe
maticalstudyofknownOBstarsinsideSNRswasconcludedwith
orbit, in most cases, is not sufficient to produce the neutron star
kickvelocitiesthataretypicallyintherangeof300–500 kms−1 a lack of OB runaways due to the poor sample of SNRs and OB
stars.Still,thereisnoknownOorB–typerunawaystarthatcanbe
(Lyne & Lorimer 1994; Allakhverdiev et al. 1997; Hobbs et al.
directlylinkedtoanSNRgivenintheliterature.
2005;Hansen&Phinney1997).Theasymmetryinsupernovaex-
plosions is responsible for such high velocities (Wongwathanarat InG05,theoutcomeofexploringrunawaypairsfrombinary
etal.2013).Therefore,therearenopulsarcompanionstomanyof supernovadisruptionisbroadlydiscussed.Firstly,identifyingthe
theOBrunawaystars(Sayeretal.1996).Insomecases,thecom- explosion centers more precisely will be useful for determining
pactobjectdoesnotreceiveasignificantkickand/orthemajority thevelocitiesofyoungNSsofwhichpropermotionmeasurements
of thetotal mass isstored on thesecondary through conservative have high uncertainties. Thus, the kick that is gained by the NS
masstransfer,hence,thecompactobjectremainsboundtothecom- duetotheasymmetryoftheSNcanbedeterminedmoreprecisely.
panionstar(vandenHeuvel1993).TherunawayhighmassX–ray Secondly, the distance to the remnant can be measured more ac-
curatelybystudyingtherunawaystar,asitcannotmovefaraway
fromtheexplosioncenterintheobservationallifetimeoftheSNR.
(cid:63) Correspondenceaddress:[email protected] Finally,possibleeffectsofaclosebinarysystemontheasymmetry
(cid:13)c 2014RAS
2 Dinçeletal
oftheSNecanalsobeexamined.Additionally,itwouldbeadirect
Table1.DistanceestimatesforS147.(Rl)denotestheradiuslowerlimitof
evidenceofthebinarysupernovascenario(BSS).
theSNR.
The observational efforts are concentrated on runaway–NS
couplingandabundanceinvestigationsofrunawaystars.Someex- Distance(kpc) Method Reference
amples of the runaway–NS pairs (components are separated) are 1.6±0.3 Σ−D Sofueetal.(1980)
PSRB1929+10–ζ Oph(Hoogerwerfetal.2001;Bobylev2008; 0.8–1.37 Rl,Σ−D Kunduetal.(1980)
Tetzlaffetal.2010),PSRJ0630-2834–HIP47155(Tetzlaffetal. 0.6 Rl Kirshner&Arnold(1979)
2013) and PSRJ0826+2637 – HIP13962 (Tetzlaff et al. 2014). 0.9 Σ−D Clark&Caswell(1976)
Basedontheirmotionsinspace,thepulsarsandthecorresponding 0.8±0.1 AV Fesenetal.(1985)
1.06 Σ−D Guseinovetal.(2003)
runawaystarsweretracedbackintimebyusing3–DMonteCarlo
0.88< HighVelGas Sallmen&Welsh(2004)
simulations. They were found at the same position and the same
1.2 PulsarDM Krameretal.(2003)
timeinsideayoungopencluster.ThePSRJ0630-2834–HIP47155 1.47+0.42 PulsarPlx Ngetal.(2007)
pairisthoughttobeejectedfromveryoldSNRAntlia. 1.3+−0.02.227 PulsarPlx Chatterjeeetal.(2009)
Thereareconsiderableuncertaintiesinthesecasesasthesu- −0.16
pernova events took place more than 105 yr ago. The separation
betweentheobjectsisverylargeandtheSNRhasfadedawaylong angulardiameter(θ)oftherelatedSNR.Thisvalueissomewhatre-
agoand/orthecomponentsareoutsideoftheSNR(theAntliacase). laxedtoθ/6consideringtheuncertaintiesinthegeometricalcenters
Otherimportantobservationalevidenceistheenhancementofα– oftheSNRs.Thestarsinthisregionareexpectedtobeconsistent
process elements in the hyper–velocity star HD271791. The star withtherespectiveSNRintermsofdistanceandreddening.
isproposedtobeejectedfromamassiveclosebinarysystemdue Forthiscomparison,theadopteddistancesofSNRsgivenin
to an SN that enriches its photosphere in elements which can be Guseinovetal.(2003,2004a,b),andA valuesfromNeckeletal.
V
synthesizedinlargeamountsduringtheevolutionoftheprogenitor (1980) were used. 48 SNRs within 5 kpc from the Sun were se-
(Przybillaetal.2008). lectedforinvestigation.
Themethodfollowedinourworkisadirectstudyofpossible Inthispaper,theresultoftherunawaysearchinSNRG180.0-
runawaystarsinsideSNRsasdescribedinG05. 1.7 (S147) is given. The kinematic relation between the runaway
Briefly,assumingthatthemassivebinarymassratioisgreater starHD37424andthepulsarPSRJ0538+2817isshown,thepossi-
than1:4,OB–typestarcandidatesaredeterminedbyacarefulstudy blehostOBassociationisdiscussed,theSNRparametersarecon-
of their BVJHK magnitudes obtained from the UCAC4 catalog strainedandthepre–supernovabinaryisconstructed.
(Zachariasetal.2012).Theangularseparationofthesourcesfrom
thegeometricalcentersoftheremnantsarewithinthelimitsofthe
maximumangulardistancethatarunawaystarcanhaveinalife-
2 S147,PSRJ0538+2817ANDHD37424
timeofanSNR.Thedistancemoduliarecalculatedforallsources
withinthisregion,andthesourceshavingextinctionsandradialdis- S147isashelltypeSNRlocatedintheGalacticanti–centerdirec-
tancesconsistentwiththoseoftheSNRsareconsideredas"candi- tion.Itis180arcminindiameterwithageometricalcenter(GC)
dates".Measuringtheradialvelocitiesandidentifyingthespectral atα = 05h39m00s,δ = +27◦50(cid:48)00(cid:48)(cid:48) (Green2009).Itwasfirst
typesoftheseobjectsviaspectroscopyrevealtheirrunawaynature, mentionedasanSNRcandidateinMinkowski(1958).Thecompact
theiryouthandtheexactspatialrelationswiththeSNRs,inother objectrelatedtotheSNRisradiopulsarPSRJ0538+2817(Ander-
words,thegeneticconnections. sonetal.1996).Inopticalbands,theshellstructureiswelldefined
AlthoughtherunawaystarsarisingfromBSSmayalsobelate and dominated by filamentary emission in Hα. The emission is
typestars,itistimeconsumingtocheckthepossiblerunawayna- brighter in the north and south edges and mainly concentrated in
tureofallthestarsinsideeachSNR.Also,thelatetypestarsare thesouthernparts.Despiteofitsoldage,itconservesthespherical
toofainttoobserveatlargedistances.Astarhavingthesameage symmetryexceptfortheblowoutregionsineastandwest(Figure
asasupernovaprogenitormustbeyoung.AsOBtypestarsevolve 1). The total absorption in the V band is A =0.7 ± 0.2 magni-
V
faster,theyautomaticallysatisfythiscondition.Furthermore,high tude(Fesenetal.1985).Radioobservationsrevealthatthespectral
massstarsarerareobjects.AnOBrunawaystardiscoveredinside index is unusually varying. The shell structure observed at radio
anSNRcanbeexplainedbytheBSS.Consideringtheveryshort wavelengthscoincideswiththatinopticalbandsandiswelldefined
observable lifetimes of SNRs and relatively short later evolution (Fuerst&Reich1986).But,noX–rayemissionisobservedfrom
stagesofstars,mostprobably,mainsequencestarsareexpectedas theremnant(Sauvageotetal.1990).Suggesteddistancesvaryfrom
OBrunawaysconnectedtoSNRs. 0.6to1.9 kpcinvariouspublications(Table1).Fourofthemea-
The space velocity of an OB runaway star is thought to be surementsarebasedonΣ−Drelationwhichisusefultoestimate
largerthan30−40 kms−1(Feast&Shuttleworth1965;Sayeretal. thedistancebyusingthesurfacebrightnessoftheSNR.InSofue
1996).AmoreprecisevalueisproposedinTetzlaffetal.(2011); etal.(1980)andKunduetal.(1980),themodelofMilne(1979)is
28 kms−1in3–Dand20 kms−1in2–D.Tosummarize,amain– used,whileinClark&Caswell(1976)andGuseinovetal.(2003),
sequence OB type star of which at least one component of the estimationsarebasedontheirownmodels.Theradiuslowerlimit
velocity vector is greater than 20 kms−1 is searched in selected calculatedthroughSNRdynamicsbasedonthemodelofChevalier
SNRs. (1974) sets another constraint on the SNR distance. The distance
Thefirstcriterionofthecandidateselectionistherestrictionof derivedfromthepulsar’sparallaxordispersionmeasureislarger
theangularposition.MostoftheOBrunawayshavepeculiarveloc- thanthedistancesuggestedforthebackgroundstarsofwhichspec-
itieslowerthan80 kms−1(Gies&Bolton1986;Philpetal.1996; trashowhighvelocitygasrelatedtotheSNR.
Tetzlaffetal.2011).AstheshockwavevelocityoftheSNRsarede- Theagewasestimatedasmorethan100 kyrfromtheSedov
celeratedfromroughly10000 kms−1toseveralhundred kms−1, solutionbyusingashockvelocity∼80–100 kms−1 (Sofueetal.
itisexpectedthattherunawaystarcannotexceedonetenthofthe 1980;Kunduetal.1980).ThisvelocitywasderivedfromtheRV
(cid:13)c 2014RAS,MNRAS000,1–10
RunawayinS147 3
Figure1. The4.8◦×4.1◦ HαimageofSNRS147takenattheUniversityObservatoryJena.Thegreencrossrepresentsthepulsar,thecyancrossshows
theGCoftheSNRandtheyellowcircleisHD37424.Theyellowvectorsshowthepropermotionoftheobjects.Theredboxisthezoom–inareashownin
therightpanel.Thewhitearrowsarethetracingbackconesofthepropermotionfor29300yr.Theanglebetweenthepmvectorsis139◦−148◦In2–D
calculations,bothobjectscometowardseachotherascloseas0.126 pcwhichmeansthattheyhaveacommonorigin;binarysupernovadisruption.
ofthefilamentaryknotsinLozinskaya(1976);Kirshner&Arnold
Table2.BVJHK(inmag)andpm(in masyr−1)valuesofHD37424.
(1979).Howeverthepulsar–SNRrelationindicatesanageof30±
4 kyr(from the travel time from the GC to the present position) Parameter Value
(Krameretal.2003;Ngetal.2007).Foradistanceof1.3 kpc,and B 9.062±0.017
V 8.989±0.019
anangulardiameterof200arcmin,theradius(R)oftheSNRis38
J 8.666±0.017
pc.Then,assuminganageof30 kyr,theremnantisinitsSedov
H 8.696±0.026
Phasehavingablastwavevelocityof500 kms−1.Theestimated
K 8.699±0.019
explosionenergyisbetween1−3×1051ergandthecorresponding µ∗ 10.8±0.8
inter–cloud gas density is 0.03−0.1 cm−3 (Katsuta et al. 2012). µαδ -10.2±0.6
The SNRisexpanding in alow densitymedium, probablyin the
cavitygeneratedbytheprogenitor.
Thecentralsource,PSRJ0538+2817,isanextensivelystud-
ied radio and X–ray pulsar located at α = 05h38m25.1s, δ = etal.2003).ThehydrogenatmospheremodelwithB= 1×1012
+28◦17(cid:48)09.2(cid:48)(cid:48),∼28arcminawayfromtheGCtowardsnorth.The GgivesT=2.12×106KandR(cid:39)10 km(Zavlin&Pavlov2004).
143.16msperiodand3.67×10−15ss−1periodderivative(Ander- AfaintpulsarwindnebulaisobservedinX–raysbutnotinradio
son et al. 1996) imply a characteristic age of ∼620 kyr which is (Gaensleretal.2000).Itisnotknownwhethertheobservedelon-
∼20 times larger than its kinematic age of 30 kyr. This discrep- gatedstructureisthetorusorthejetsofthePWN.Butassuming
ancyisexplainedbyeitheralonginitialspinperiodofP = 139 thatitisduetothetorus,itprovidesvaluableinformationonthe
0
ms(Krameretal.2003)orstrongmagneticfielddecay(Guseinov spin–kickalignment.
et al. 2004c). The parallax distance was measured as 1.47+0.42 HD37424 is a sound OB runaway star at 10.3 arcmin
−0.27
kpc (Ng et al. 2007) and 1.3+0.22 kpc (Chatterjee et al. 2009) away from the GC to the west at α = 05h39m44.4s, δ =
−0.16
and the dispersion measure (DM) distance is 1.2 kpc (Kramer +27◦46(cid:48)51.2(cid:48)(cid:48).Photometricandkinematicinformationonthestar
etal.2003)byusingtheNE2001modelofCordes&Lazio(2002) isgiveninTable2.Whilepropermotionvalueswereretrievedfrom
whichareconsistentwitheachother.Themostpreciselymeasured theUCAC4catalog(Zachariasetal.2012),thephotometricmag-
propermotionisµ∗ =−23.57+0.10 masyr−1,µ =52.87+0.09 nitudes are obtained from the ASCC-2.5V3 catalog (Kharchenko
α −0.10 δ −0.10
masyr−1correspondingtoatransversevelocityof357+59 kms−1 2001). Its spectral type was previously identified as B0.5/1 IV/V
−43
at1.3+0.22 kpc(Chatterjeeetal.2009).Althoughitpresentsno (Clausen & Jensen 1979). As there was no public data nor a vi-
−0.16
clear γ–ray emission (Katsuta et al. 2012), the pulsar is observ- sualized spectrum, we established the spectral type again by tak-
able in soft X–rays due to thermal emission. PSRJ0538+2817 is ingaspectrum.Thestarhasaveryhighpropermotioncompared
famousforbeingoneofthefewthermalpulsars:Basedonablack- tootherearlytypeandpossiblydistantstars.Thereisnoreported
body model, the surface temperature and the emitting radius are variabilityorbinarityintheliterature.Hence,HD37424isagood
givenasT= 2.12×106 KandR= 1.68±0.05 km(McGowan OBrunawaystarcandidate.
(cid:13)c 2014RAS,MNRAS000,1–10
4 Dinçeletal
3 OBSERVATIONS
HD37424 was observed at the TÜB˙ITAK National Observa-
tory (TUG) with the TUG Faint Object Spectrograph and Cam-
era (TFOSC) mounted on the 150cm Russian Turkish Telescope
(RTT–150). The observations were carried out on 2013 August 9
and10.Twospectrawereobtainedwitha600sexposuretimefor
each. Grism 14 was used with a 67 micron slit. The wavelength
rangeinthisconfigurationis3270–6120Åandtheresolvingpower
(R)is∼1337.5Helampspectratakeninthesamenightwiththe
object were used for wavelength calibration, and 5 halogen lamp
spectrawereobtainedinthebeginningandattheendofthenight
forflat–fielding.Also,2moretargetshadbeenobservedinthesame
wayon2012September13and14forthesearchfortherunaway
star.Withthesamepurpose,12objectswereobservedattheCalar
Alto Observatory on 2013 January 29 with Calar Alto Faint Ob-
jectSpectrograph(CAFOS)onthe2.2metertelescope.Thecov-
ered wavelength range of the grism B–200 is 3200–7000 Å and
R∼550. 3 HgCdAr and 3 halogen spectra were taken in the be- Figure2.TFOSCspectrumofHD37424comparedtomainsequenceB
ginningandintheendofthenightforwavelengthcalibrationand typestars.Distinctivefeaturesaremarked.Fromlefttoright;SiIV λ4089,
flat–fielding.ThehighresolutionobservationsofHD37424were HeII λ4200, SiIII λ4552, OII λ4640, CIII+OII λ4650 blend, HeII
performedattheFredL.WhippleObservatoryon2013September λ4686,HeI λ4713
16and21.TheTillinghastReflectorEchelleSpectrograph(TRES)
mounted on the 1.5 meter telescope was used. Two spectra were
spectra retrieved from Walborn & Fitzpatrick (1990). To main-
takenatR∼44000inabroadwavelengthrange;3800–9100Åfor
tain equally resolved spectra, the standard spectra were boxcar
300s exposure time. HD36665 which is supposed to be a back-
smoothedby13.Figure2showstheTFOSCspectrumofHD37424
groundobjecttotheSNRwasobservedon2014February11with
comparing with main sequence B type stars from various sub-
theFibreLinkedEchelleAstronomicalSpectrograph(FLECHAS)
classes. HD37424 shows HeII λ4686 absorption indicating that
(Mugraueretal.2014)attheUniversityObservatoryJena.Thecov-
thespectraltypeisearlierthanB1.Thisfeatureisnotseeninstars
eredwavelengthrangeis3900–8100ÅandR∼9200.Threespec-
withaspectraltypelaterthanB0.7.Ontheotherhand,HeI lines
tra with 600 s exposure time were obtained. Three tungsten and
(i.e.HeI λ4713)arenotasweakasinOtypestarscomparedto
3 Th-Ar lamp spectra were taken immediately before this set for
HeII lines;λ4200,λ4686.TheSiIV λ4116lineistotallyblended
flat–fieldingandwavelengthcalibration.
and unmeasurable. SiIII λ4552 is in low strength compared to
TheobservationsofSNRS147wereperformedattheUniver-
SiIV λ4089likeintheB0Vtypespectrum.Thisratiodecreases
sityObservatoryJenawiththeSchmidt-Teleskop-Kamera(STK),
towardshighertemperatures,butHeI λ4541isnotstrongerthan
operatedintheSchmidt-focusofthe90cmtelescopeoftheobser-
SiIII λ4552asseeninB0VandO9.5Vspectra.Giventheequal
vatory(seeMugrauer&Berthold(2010)).Theobservationswere
strengthsofOII λ4640,HeII λ4686,HeI λ4713andmorein-
carried out with the narrow–band Hα filter of the STK, which
tenseCIII+OII λ4650blends,HD37424matchesbestwithB0.2V.
spansafull–width–half–maximumof5nm.Intotal,22fieldson
ConsideringtheslightlystrongerHeI λ4713,B0.5wouldbethe
theskywereobservedduring5nights,eachwithafieldofviewof
best approach to the temperature class of the star. SiIV λ4089
52.8(cid:48)×52.8(cid:48).Ateachpositiontwo600sintegrationsweretaken
strengthincreasesagainstHeI λ4026–4144astheluminosityclass
withtheSTK,i.e.about7.3hoursofintegrationtimeintotal.The
goes higher. However, neutral helium lines are strong enough to
individualrawimagesperfieldweredark-andflatfield–corrected
judgethatHD37424isamainsequencestar;B0.5V.Thespectral
andfinallyaveraged.Pointsourcesdetectedintheoverlapregions
typeisbetweenB0.2V–B0.7V,butitisassumedasB0.5±0.5Vin
ofthefullyprocessedimageswerethenusedtocreatethemosaic
thedistanceandextinctioncalculationstoavoidunderestimationof
imageofSNRS147,showninFigure1,whichcoversatotalfield
theerrors.
ofviewof4.8◦×4.1◦.
ThesourcesobservedbyCAFOSareforegroundstarswitha
FLECHAS, TFOSC and CAFOS data were reduced with maximumdistanceof671+96 pc.Theirspectralpropertieswere
−56
IRAF. All raw frames from TFOSC and CAFOS were over–scan identifiedbythesameprocedureasdoneforHD37424.However,
strippedandnofurthersubtractionwasdoneaslongastheover– duetothelowerresolutionCAFOSspectrahavehigheruncertainty
scanneddarkframesyieldsnullcount.Yet,FLECHASimageswere (Table3).WeusedFLECHAStoidentifythespectraltypesofthe
subtractedbythedarkframestakeninthepreviousnight.Theex- backgroundstarHD36665.ThisisaB1±0.5Vtypestar(Figure3).
posuretimeofadarkframeisthesameasthatofthecorresponding
scienceorcalibrationframe.Hence,theilluminationeffectwasre- TRESdatawereusedforradialvelocity(RV)measurements
moved. of HD37424. Due to the low signal to noise, 10 absorption fea-
Then, the flat images were combined while rejecting the turescouldbeused(Table4).Doubletsortripletlinesareavoided
frames having minimum and maximum counts. Next, the object as these features increased the dispersion significantly. The lines
spectrawereextractedbyassigninganappropriatebackgroundre- were fitted by Gaussian functions and the best shifts were deter-
giontoeach.Thearcspectrawereextractedastracedbythecorre- mined.TwomoreGaussianfitswithdifferentcenterswereapplied
spondingapertureoftheobjectspectra.Afterwavelengthcalibra- foreachline;onefitstheouteredgeofthenoiseoftheblueside
tionwasperformed,allspectrawerenormalized. whilefittingtheinneredgeofthered.Theotherfitstheouteredge
The final spectra were compared with MK standard star oftheredandtheinneredgeoftheblue.Bydoingthis,underesti-
(cid:13)c 2014RAS,MNRAS000,1–10
RunawayinS147 5
Table4.RadialvelocitymeasurementsofHD37424.Thelaboratorywave-
lengthofthefeatures,theGaussianwidth(σ)ofthefit,thewavelengthshift
obtainedbythebestfittingGaussian,upperandlowerlimitsoftheshift
fromdifferentGaussianfitsandthefinalerrorarepresented.Thefeatures
aregiveninÅwhileallothercolumnsarein kms−1
ObservationsonSeptember16th,2013
Feature σ BF UL LL E
3889.051 164 -10.1 19.3 -29.2 29.4
3970.074 137 -0.5 21.4 -22.3 21.9
4101.737 144 -9.4 12.2 -32.3 22.9
4143.759 98 +4.0 17.1 -10.9 14.9
4340.468 142 -10.6 6.2 -28.8 18.2
4387.928 81 -13.1 -7.1 -24.1 11
4861.332 139 -13.8 0.9 -18.9 14.7
4921.929 89 -16.5 -1.6 -32.4 15.9
Figure3. TheFLECHASspectrumofHD36665(black)incomparison
6562.817 115 -14.7 0.3 -21.5 15
withaB1Vtemplate.
6678.149 82 -7.5 0.3 -14.5 7.8
ObservationsonSeptember21st,2013
Table3.Observedstarsintheregion.Names,angularseparationstothe Feature σ BF UL LL E
SNRGC(inarcmin),spectraltypes,instrumentsusedanddistanceswith 3889.051 164 -12.6 6.2 -28.2 18.8
upper and lower errors (in pc) are given. The error in temperature sub- 3970.074 137 -1.4 18.0 -19.8 19.4
classes is ±1 for those with integer value and ±0.5 for those with half 4101.737 144 -5.1 14.9 -21.2 20
integervalue.TheresolutionofCAFOSisnotenoughtodistinguishthe 4143.759 98 -1.9 7.2 -8.7 9.1
luminosityclassesIVandV.Yet,thestarsareassumedtobeinluminosity 4340.468 142 -11.5 11.9 -36.6 25.1
classV. 4387.928 81 -8.8 -4.1 -19.3 10.5
4861.332 139 -11.7 -3.0 -19.5 8.7
Name Angular Spec. Inst.1 Distance Distance 4921.929 89 -17.2 -4.9 -31.6 14.4
Separation Type (Error) 6562.817 115 -14.4 1.4 -29.7 15.8
TYC1869-01281-1 19.4 A2V C 574 +73/-41 6678.149 82 -6.7 3.3 -15.1 10
TYC1869-01317-1 5.5 B9.5V T 1013 +183/-174
BF:Bestfit,UL:UpperLimit,LL:LowerLimit,E:Error
TYC1869-01334-1 25.5 F2V C 289 +38/-34
TYC1869-01376-1 27.9 A7V C 428 +18/-32
TYC1869-01505-1 23.5 F1V C 380 +50/-44
TYC1869-01610-1 17.6 F7V C 245 +18/-16 Table5.MeasuredvelocitiesforinterstellarCaII–KandHandNaI–D1
TYC1869-01632-1 27.2 F8V C 316 +37/-26 andD2lines.TheselineshavealowGaussianwidthunliketheintrinsic
TYC1869-01642-1 5.61 B9.5V T 952 +172/-163 featuresofthestar.Theaveragevelocityis12.1 kms−1 withastandard
TYC1869-01679-1 25.6 G2V C 170 +11/-9 deviation0.5 kms−1ineachobservation.Thedatainthefirstcolumnare
TYC1869-01749-1 20.1 F8V C 166 +19/-14 in(Å)whiletheothersarein kms−1.
TYC1873-00145-1 25.0 A3V C 603 +46/-50
TYC1873-00307-1 29.2 F8V C 326 +40/-29 Feature σ Velocity Velocity
TYC1873-00347-1 19.8 A0V C 671 +96/-56 (Day1) (Day2)
UCAC4-589-020390 22.1 F4V C 381 +14/-16 3933.664 7.5 12.3 11.8
1Instruments:C:CAFOS,T:TFOSC 3968.47 5.9 12.8 12.7
5889.953 9.0 11.6 11.6
5895.923 8.3 11.9 12.0
matingtheerrorsisavoided.Asthefeaturesarewideandthedata Day1:Sep.16th,2013;Day2:Sep21st,2013.
arenoisy,thecentersofthesesecondaryfitsarefarawayfromthe
best fits, 16 kms−1 on average. The difference between the best
fitandtheupperlimit(towardsred)fitisdistinctfromthebestfit radioandγ–rayimages(Kunduetal.1980;Katsutaetal.2012).As
andthelowerlimit(towardsblue)difference.Toavoidunderesti- thestarcanhardlybeaforegroundsource,wesuggestthat,inthis
matingtheerror,thegreaterdifferenceisassignedasthefinalerror. direction,theshockedejectahasnotreachedthedenseinterstellar
Theaverageheliocentricvelocitiesofthefirstandthesecondspec- gasyet.Thereadermustnotethat,thebackgroundstarsdisplaying
tra are -9.2 and -9.1 kms−1 with line to line scattering standard high velocity CaII lines in Sallmen & Welsh (2004) are located
deviationsbeing6.5and5.5 kms−1respectively. behindbrightfilamentknots.Thehighvelocitygasisfoundwhere
Aslongasthestarisinsidethesupernovaremnant,highve- thefilamentsareconcentrated(Lozinskaya1976).
locity gas accelerated by the SNR is expected to reveal itself as UsingtheabsolutevisualmagnitudefromAlleretal.(1982),
blue–shiftedcomponentstoCaII–KandHand/orNaI–D1andD2 for a spectral type B0.5V±0.5, the distance modulus yields
absorption features. The spectra show no clear high velocity fea- 1868+410 pc for HD37424. Using the luminosity of the same
−403
tures(Figure4).Theaverageheliocentricvelocityoftheinterstel- spectral type from Hohle et al. (2010), we find the distance as
largasis12.1±0.5 kms−1(Table5).Thisistypicalfortheneigh- 1318±119 pc which is well consistent with the distance of the
boringstars(Silk&Wallerstein1973).Thestarhasnopositional pulsar.Thetotalvisualabsorptionwastakenintoaccountinboth
correspondencewithbrightfilaments,butwithfainter Hαemitting calculations.
regions.Itislocatedatthevicinityoftheeasterncavityseeninthe Astheabsolutemagnitudesforearlytypestarscanrangefrom
(cid:13)c 2014RAS,MNRAS000,1–10
6 Dinçeletal
Figure4.ThestronginterstellarlinesofHD37424.Left:CaII–KlinefromTRESspectrum.Despiteaweakblendedfeatureat-13 kms−1,thereisnoclear
highvelocitycomponent.Middle:CaII–Hline(H(cid:15)asabackground)fromthesamespectrum.Againthereisnoclearhighvelocitygascomponent.Right:
InterstellarNaI–D1andD2lines.ThefeaturewithhighFWHMistheHeI λ5875triplet.ThosearoundSodiumdoubletaretellurics.
star to star in the same temperature, interstellar CaII lines are aration dmin and the past time τ at which it occurred. The dis-
also used in distance determination. By using the following rela- tributionofseparationsd issupposedtoobeythedistribution
min
tionfromMegieretal.(2009), ofabsolutedifferencesoftwo3DGaussians(seee.g.Hoogerwerf
(cid:32) (cid:33) et al. 2001, equations A3 and A4; Tetzlaff et al. 2012, equations
2.60 1 and 2), if it is assumed that the stellar 3D positions are Gaus-
D=77+ 2.78+ EW(H) (1)
EW(K) −0.932 siandistributed.Sincetheactual(observed)caseisdifferentfrom
EW(H)
this simple model (no 3D Gaussian distributed positions, due to
the distance to HD37424 is found to be 1288+304 pc which is e.g.theGaussiandistributedparallaxthatgoesintothepositionre-
−193
almostinthesamerangeasthepulsar.Theequivalentwidthsare ciprocally,uniformradialvelocitydistributionoftheNS,etc.),we
243±7and160±15mÅforCaII–KandCaII–Hlinesrespectively. adaptthetheoreticalformulae(weuseequations1and2inTetzlaff
The extinction towards the star was also derived from 4430 etal.(2012)withthesymbolsµandσfortheexpectationvalueand
and4502ÅDIB’s.Themeasuredequivalentwidthshavehigher- standarddeviation,respectively)onlytothefirstpartofthed
min
ror due to the blending. Using the EW’s, the E(B-V) was calcu- distribution(uptothepeakplusafewmorebins,seeTetzlaffetal.
lated based on the relation mentioned in Herbig (1975). It yields 2012).Thederivedparameterµthengivesthepositionaldifference
0.42±0.08 mag; points to somewhat larger color excess but does betweenthetwoobjects.1
notexclude0.35±0.04magderivedfromphotometry. Wefindthatbothstarswereatthesamepositioninthepast
i.e.µ=0at(l,b)=(84.82±0.01,27.84±0.01)degat30±4
kpc(Figure5).Thispredictedpositionofthesupernovais4.2+0.8
−0.6
arcmin offset from the nominal geometric center. The predicted
4 KINEMATICS
distance of the supernova (as it is seen from the Earth today) is
HD37424 and PSRJ0538+2817 have proper motions receding 1333+103 pc.
−112
fromeachotheranddepartingfromthesamelocationonthesky
(Figure 1). The proper motion of both objects are corrected for
Galacticrotationandsolarmotion.TheGalactocentricdistanceto
5 ASSOCIATIONS
the Sun is taken as 8.5 kpc and the solar rotational velocity as
220 kms−1. The local standard of rest was taken from Tetzlaff ThereisnoknownOBassociationwithin4.5◦ (∼100 pcat1300
et al. (2011) as (U ,V ,W ) = (10.4±0.4, 11.6±0.2, 6.1±0.2) pc)fromSNRS147.Consideringtheangularseparationsandradial
(cid:12) (cid:12) (cid:12)
kms−1.TheresultantvaluesforHD37424areµ∗ = 10.0±0.8 distances,theprogenitorstarcannotbelinkedtoanyoftheyoung
α
masyr−1,µ = −5.9±0.6 masyr−1 andforthepulsar,µ∗ = openclusteraround.Hence,itisconsideredtobearunawaystar
δ α
−24.4±0.1 masyr−1,µ =57.2±0.1 masyr−1.Togetherwith ejectede.g.fromtheclusterNGC1960,whichis217 pcawayfrom
δ
the−20.0±6.5 kms−1 peculiarradialvelocity,HD37424hasa theSNR,severalmillionsyearsago(Ngetal.2007).However,bi-
spacevelocityof74±8 kms−1at1.3 kpc.HD37424isarunaway narityamongclusterejectedrunawaystarsarerare(Gies&Bolton
starofwhichvelocityishigherthantypicalrunawayvelocities40– 1986).So,astheprogenitorwasthepreviousbinarycompanionto
50 kms−1.The2–Dspacevelocityofthepulsaratthesamedis- HD37424,itmaybeunlikelythattheywereejectedfromaclus-
tanceis382.2±0.8 kms−1. ter.Therefore,theneighboringstarsareinvestigatedtosearchfor
We constructed the past 3D trajectories of PSRJ0538+2817 anyassociation.AlloftheOBtypestarswithin4.5◦(100pcat1.3
andtherunawaystarHD37424toevaluatewhetherthesetwoob-
jects could have been at the same place at the same time in the
past.Sinceweappliedthesamemethodalreadyinprecedingpa- 1 Theuncertaintiesontheseparationaredominatedbythekinematicun-
certainties of the NS that are typically of the order of a few hundred
pers (Tetzlaff et al. 2010, 2011, 2012), we refer to these publi-
kms−1(becauseoftheassumedradialvelocitydistribution).Asaconse-
cations for details. We construct three million past trajectories of
PSRJ0538+2817andHD37424throughoutMonteCarlosimula- quence,thedistributionofseparationsdmin showsalargetailforlarger
separations. However, the first part of the dmin distribution (slope and
tionsbyvaryingtheobservables(parallax,propermotion,radialve-
peak)canstillbeexplainedwellwiththetheoreticalcurve(hereequation2
locity)withintheirerrorintervals.FortheradialvelocityoftheNS, inTetzlaffetal.2012)sincethekinematicdispersionforonlythoserunsare
weassumeauniformdistributionintherangeof-1500to+1500 muchsmaller,afewtensof kms−1fortheNS,i.e.afewtensofpcafter1
kms−1.Fromallpairsoftrajectories,weevaluatethesmallestsep- Myr.
(cid:13)c 2014RAS,MNRAS000,1–10
RunawayinS147 7
Table7.Visualabsolutemagnitudesat1.3±0.1 kpcforthestarsofthepos-
sibleOBassociationofwhichHD37424isamember.Errorsaremainlydue
tothedistancerange1.2−1.4 kpc.TheexpectedMV forthecorresponding
spectraltypesanditsdispersionfromWegner(2006)(W06)aregiven.All
valuesareinmag.
MV error MV Disp.
Name (@1.3±0.1 kpc) (W06) (W06)
TYC1869-01317-1 -0.14 +0.26/-0.27 +0.29 1.40
TYC1869-01642-1 -0.28 +0.26/-0.27 +0.29 1.40
HD37424 -2.86 +0.22/-0.23 -3.34 2.40
HD36993 -3.67 +0.22/-0.23 -4.02 2.30
HD37318 -4.46 +0.31/-0.32 -3.34 2.40
BD+27797 -2.97 +0.30/-0.31 -3.34 2.40
HD37696 -3.72 +0.22/-0.23 -3.34 2.40
BD+27850 -2.52 +0.20/-0.21 -2.95 1.16
HD245770 -3.49 +0.29/-0.30 -3.34 2.40
Figure5.Distributionsofminimumseparationsdminandcorresponding HD36441 -3.46 +0.29/-0.30 -2.95 1.16
flighttimesτforencountersbetweenPSRJ0538+2817andHD37424.The BD+26943 -2.36 +0.30/-0.31 -2.64 1.40
solidcurvesdrawninthedminhistogram(bottompanel)representthethe- HD38010 -5.04 +0.26/-0.27 -4.10 2.20
oreticallyexpecteddistributionwithµ = 0andσ = 0.35 pc,adaptedto BD+30938 -2.95 +0.20/-0.21 -2.32 1.50
thefirstpartofthehistogram. Sh2-2421 -2.74 +0.29/-0.30 -3.34 2.40
HD37366 -4.15 +0.22/-0.23 -4.49 2.27
BD+30987 -1.86 +0.24/-0.25 -1.49 2.00
kpcdistance)ofthegeometricalcenter(GC)oftheSNRwerese- BD+30976 -1.18 +0.33/-0.34 -0.63 1.40
lectedfromTheCatalogueofStellarSpectralClassifications(Skiff BD+25989 -2.41 +0.29/-0.30 -2.95 1.16
2013).Thespectraltypesareknownthroughspectroscopicobser- BD+27909 -2.96 +0.26/-0.27 -2.63 2.20
BD+311065 -1.76 +0.20/-0.21 -2.32 1.50
vations.Therearesomediscrepanciesinspectraltypesreportedby
BD+311050 -2.30 +0.19/-0.20 -2.32 1.50
different papers. So, always the latest reference was chosen. To-
HD38909 -2.98 +0.19/-0.20 -2.32 1.50
getherwith14starsfromourobservationsatTUGandCalarAlto,
BD+311021 -1.15 +0.28/-0.29 -0.63 1.40
99 stars are used. The photometric data were obtained from the
HD40297 -4.37 +0.29/-0.30 -3.75 1.30
catalogASCC-2.5V3(Kharchenko2001)exceptforUCAC4–589–
020390ofwhichphotometricdatawasretrievedfromtheUCAC4
catalog. magnitudesfromAlleretal.(1982).Errorsindistancesaredueto
Foreachstarhavinganintegerspectralsubclass,distanceand theuncertaintyinspectraltypeandtheerrorinA werealsotaken
V
extinction are calculated in an interval between one spectral sub- intoaccount.
classaboveandbelow,e.g.B0V–B2VforaB1Vtypestar.Forthose The spectro–photometric distance alone is not enough due
havinghalfintegersubclass,halfspectralsubclassaboveandbelow to the high dispersion in the brightness of OB–type stars (Weg-
areusede.g.B0V–B1VforaB0.5Vtypestar.Thetotalvisualex- ner 2006) (Thereafter W06). Assuming the stars beyond 1 kpc
tinction,A ,wasdeterminedbyusingBVJHKcolorsandintrinsic are within 100 pc from the SNR GC, the absolute visual magni-
V
colordifferencesofcorrespondingspectraltypes.Usingthefollow- tudeswerecalculated.AlthoughthedispersionmentionedinW06
ingrelation,A valueswerederivedforeachcolordifference;B-J, is high, 24 of the stars fit well in the comparison with the W06
V
B-H,B-K,V-J,V-H,V-K. values.Hence,wesuggestthatthesestarsaremembersofanOB
association.(Table6,Table7,19ofthemhavesimilarpmvalues.
(λ −λ )−(λ −λ )
AV = A1 /A2 −A1 /A2 0, (2) The average pm in right ascension is -1.39 masyr−1 and -4.17
λ1 V λ2 V masyr−1 in declination with 0.99 masyr−1 and 1.45 masyr−1
TheintrinsiccolorsareobtainedfromKenyon&Hartmann(1995) standarddeviationrespectively(Table8).At1.3 kpc,5ofthemare
andWegner(1994),whileAλ/AV ratiosarefromRieke&Lebof- runawaystarsexceeding20 kms−12–Dpeculiarvelocity.Thisis
sky(1985).Colordifferencesofshortintervals,i.e.H-Khavehigh consistentwiththegeneralratiooftherunawaystarstothenormal
errorsastheyaremultipliedbyhighercoefficients.Thecolorex- starswhichis10–30percent(Gies1987).
cessE(B-V)ismentionedseparately.(Table6)A valuesobtained
V
fromsixcolordifferenceswereaveragedandtheirstandarddevia-
tionwerecalculated.Thiswasappliedforallthreepossiblespec-
6 DISCUSSION
tral types of the source. As long as the error due to the spectral
typeuncertaintyislargerthanthestandarddeviationofthecolor TherunawaynatureofHD37424isclear.Thechanceprojectionof
differences,itwasassignedtobethefinalerror.Whentheerroris suchamassiverunawaystarmovingawayfromtheGCofanSNR
asymmetric due to the intrinsic colors of different spectral types, intheGalacticanti–centerdirectionmustbeverylow.Inaddition,
thelargeronewasaccepted.Insomecases,theuncertaintyisdom- combiningwiththecentralcompactobjectaftertracingbackboth
inatedbytheerrorincolordifferences.Then,thesewerepreferred objectsatthesametimeshowsthatHD37424isclearlythepre–
tobethefinalerrorforsuchsources.E(B-V)versusA fityieldsa supernova binary companion of the progenitor of SNR S147 and
V
totaltoselectiveabsorptionratiois3.24±0.06.Inindividualcases, PSRJ0538+2817.BSSisthefavoredexplanationforitsrunaway
E(B-V)deviatesstronglyfromA .However,thelargesamplere- nature.
V
vealsthattheratiooftotaltoselectiveabsorptionhasausualvalue. HD37424 is a B0.5V type star with a mass of ∼13 M
(cid:12)
Thedistanceswerederivedfromdistancemoduliusingtheabsolute (Hohle et al. 2010). So, the progenitor of the pulsar must have a
(cid:13)c 2014RAS,MNRAS000,1–10
8 Dinçeletal
Table6.24starsbeyond1 kpcarepresented.Angulardistancesaregivenindegrees,distancesinparsecs,extinctionsandbrightnessinvisualbandin
magnitudes.Inthecolumn;SpTadopted,theaveragespectraltypesthatareusedindistancecalibrationsaregiven.
Ang.Sep. Name SpT SpT AV AV E(B-V) E(B-V) Distance Distance V Ref#∗
(adopted) (Err) (Err) (Err)
0.09 TYC1869-01317-1 B9.5V B9.5V 0.83 0.1 0.26 0.090 1013 +183/-174 11.258 tw
0.09 TYC1869-01642-1 B9.5V B9.5V 1.00 0.1 0.3 0.090 952 +172/-163 11.293 tw
0.17 HD37424 B0.5V B0.5V 1.28 0.06 0.35 0.036 1868 +410/-403 8.989 tw
0.52 HD36993 B0.5/1III/IV B0.5III-IV 1.35 0.06 0.39 0.028 1961 +636/-628 8.248 1
0.63 HD37318 B0.5Ve B0.5V 2.29 0.15 0.59 0.026 903 +231/-228 8.399 1
1.00 BD+27797 B0.5Ve B0.5V 2.50 0.14 0.62 0.094 1788 +485/-465 10.095 2
1.35 HD37696 B0.5IV/V B0.5IV-V 1.12 0.06 0.29 0.023 1549 +565/-558 7.973 1
1.35 BD+27850 B1.5IVe B1.5V 1.31 0.04 0.35 0.056 1525 +313/-305 9.362 2
1.52 HD245770 O9/B0III/Ve B0III-V 2.11 0.13 0.79 0.053 2595 +1090/-1066 9.187 3
1.76 HD36441 B0.5/1.5V B1V 1.13 0.13 0.33 0.058 1153 +628/-389 8.239 1
1.97 BD+26943 B2V B1.5V 1.41 0.14 0.37 0.040 1357 +723/-511 9.623 8
2.61 HD38010 B1III B1III 1.29 0.1 0.22 0.028 967 +437/-236 6.817 4
2.95 BD+30938 B3III B3III 1.44 0.04 0.45 0.030 1332 +741/-255 9.062 7
2.98 Sh2-2421 B0V B0V 2.17 0.13 0.78 0.056 2318 +853/-842 9.996 5
3.06 HD37366 O9.5V O9.5V 1.22 0.06 0.35 0.016 1375 +201/-199 7.640 6
3.07 BD+30987 B5III: B5III 0.73 0.08 0.25 0.044 1523 +398/-287 9.444 7
3.24 BD+30976 B7V B7V 0.89 0.17 0.18 0.020 994 +264/-226 10.277 7
3.45 BD+25989 B1Vn B1V 1.59 0.13 0.43 0.082 1872 +1061/-649 9.751 8
3.61 BD+27909 B2III B2III 1.87 0.1 0.55 0.076 2004 +683/-761 9.479 8
4.05 BD+311065 B3III B3III 0.67 0.04 0.27 0.043 2304 +1286/-442 9.482 7
4.07 BD+311050 B3III B3III 1.01 0.03 0.35 0.047 1791 +988/-338 9.276 7
4.09 HD38909 B3II-III B3II-III 0.56 0.03 0.17 0.033 2057 +1007/-992 8.145 9
4.28 BD+311021 B7V B7V 1.05 0.12 0.14 0.106 1007 +250/-218 10.465 7
4.46 HD40297 B9.5Ib/II B9.5Ib/II 1.07 0.13 0.25 0.015 1337 +693/-688 7.270 1
∗Ref#:1:Clausen&Jensen(1979);2:Steeleetal.(1999);3:Wang&Gies(1998);4:Cucchiaroetal.(1976);5:Hunter&Massey
(1990);6:Walborn(1971);7:Bouigueetal.(1961);8:Christy(1977);9:Morganetal.(1955);10:Christy(1977);tw:Thiswork.
mighthavebeenaninteractingbinary.Hence,theprogenitorstar
Table8.19starswithcommonpropermotionarepresented.Theaverage
PMRAis-1.39 masyr−1andPMDecis-4.17 masyr−1.Thelastthreecol- shouldbeanakedheliumstaratthefinalstageofitsevolutionwith
umnrepresentsthe2–Dspacevelocityofthestarswithrespecttotheaver- a mass even as low as 2 M(cid:12) (van den Heuvel 1993), (Woosley
agemotionofthegroupwithmaximumandminimumvaluesin kms−1. etal.1995).However,howconservativethemasstransferwas,will
Allthevaluesofpropermotionsarein masyr−1. beunderstoodafterfurtherobservations.Assumingacircularorbit,
pre–supernovabinaryparametersarecalculatedfor2,5,10,15,20
and25 M (Table9)progenitormasses.
Name µ∗α err µδ err VREL max min (cid:12)
HD37318 -0.8 0.6 -5.9 0.6 11.2 16.1 6.9 As discussed in the previous section, the OB stars around
TYC1869-01642-1 -1.5 1.1 -2.4 1.2 11.0 19.8 7.1 mightbemembersofanunidentifiedoldOBassociationofwhich
HD38010 -1.7 1.0 -3.3 1.0 5.7 14.1 0.0 alloftheOtypestarsunderwentsupernovaexplosions.Thisalso
BD+30976 -3.5 0.9 -5.3 0.5 14.7 21.1 8.4 makesaplausibleexplanationforthelowdensitymediuminwhich
BD+311021 -2.8 0.7 -5.5 0.8 11.9 18.4 5.4 the SNR expands symmetrically. But, an ejection of the pre-SN
TYC1869-01317-1 -0.9 0.9 -5.1 0.9 6.5 14.2 0.0 systemisalsopossible.AmembershiptoanOBassociationorto
HD36441 -2.0 0.6 -6.6 0.6 15.4 20.1 11.2
aclusterisimportantalsoregardingthedistancedetermination.In
BD+30938 -1.7 0.8 -3.6 0.6 4.0 9.9 0.0
thiswork,thedistancederivedfrompulsarparallax(1.3+0.20 kpc)
HD40297 -1.4 1.0 -3.7 1.0 2.9 11.0 0.0 −0.16
isacceptedasthemostreliableestimation.Also,thedistancetothe
BD+26943 -0.9 0.8 -3.7 0.8 4.2 11.2 0.0
starmeasuredfrominterstellarlinesisinthesamerange,1288+304
BD+30987 -2.0 0.6 -4.7 1.2 4.9 13.0 0.0 −193
BD+27797 -0.1 0.7 -3.1 1.4 10.4 19.6 4.2 (see section 3). The spectro–photometric distance is much larger
BD+311050 -1.0 0.6 -4.0 0.6 2.7 7.8 0.0 byusingabsolutemagnitudesfromAlleretal.(1982).Yet,byus-
BD+25989 -1.5 0.9 -2.5 1.6 10.3 21.1 4.9 ing typical luminosities for B0.5V type suggested in Hohle et al.
HD36993 -0.2 0.9 -5.8 0.6 12.4 18.8 6.6 (2010),itis1318±119 pc.Hence,thedistancetothestarandthe
HD38909 +0.7 0.5 -4.2 1.5 12.9 18.4 0.0 SNR can be assumed to be 1.3 kpc. However, the A measured
V
BD+311065 -1.0 0.6 -1.3 0.5 17.9 21.7 14.7 directlytowardsS147ismuchlowerthantheA towardsthestars
V
Sh2-2421 -0.1 0.7 -1.8 1.0 16.7 24.2 9.2
beyond1 kpc.Furthermore,twostars,HD36665andHD37318,
HD245770 -2.0 0.5 -4.3 1.1 3.8 10.2 0.0
showhighlyshiftedinterstellarCaII andNaI linesrelatedtothe
SNRimplyingthattheseobjectsarebackgroundsources(Sallmen
&Welsh2004).Theirdistancesbasedonthereportedspectraltypes
highermass.BasedonthelackofOtypestarsinthefield(seeTa- are closer to the Sun than HD37424 is. HD36665 has 837+347
−285
ble6)wesetanuppermasslimitof20–25 M .Itmayevenimply pcforB1VtypeandHD37318is903+231 pcfarawayadopting
(cid:12) −228
atwinbinary.TheRocheLoberadiicalculatedfor15,20and25 B0.5V.Ontheotherhand,thedistanceforHD36665isidentified
M vary between 91 and 311 R which shows that the system as 1860 pc in Neckel et al. (1980) through H measurements. It
(cid:12) (cid:12) β
(cid:13)c 2014RAS,MNRAS000,1–10
RunawayinS147 9
Table9.Thebinaryseparations,theorbitalvelocitiesoftheprogenitor,theorbitalperiodsandtheRocheLoberadiiofthepre–supernovabinaryforvarious
finalmassesoftheprogenitorwith13 M(cid:12)HD37424aregiven.RocheLoberadiiarecalculatedbasedonEggleton(1983).
ProgenitorMass(M(cid:12)) 2 5 10 15 20 25
BinarySeparation(R(cid:12)) 9−+31 49−+191 152−+3276 281−+6489 425−[phone]−+113071
OrbitalVelocity(kms−1) 481±49 192±20 96±10 64±7 48±5 38±4
OrbitalPeriod(days) 0.85−0.22 9−2 45−11 103−26 176−44 259−65
+0.32 +4 +17 +39 +66 +98
RocheLobeRadius(R(cid:12)) 110−+2179 177−+4321 251−+6404
hasahighA of1.74mag.IfweassumethatHD36665isalsoat ACKNOWLEDGEMENTS
V
1.3±0.1 kpc,thenitmustbeabrightB1Vtypestarwhichis1–1.5
ThisworkwasconceivedbythelateOktayH.GUSE˙INOV(1938-
magbrighterthantheaveragevaluegiveninW06.HD37318also
2009). The authors acknowledge the leading role he had in all
canbeamemberofthepossibleOBassociation.
stages of this work and other related topics. His contribution to
Thesupernovaeventhadoccurredquitenearbyinafairlyred-
GalacticAstrophysicsandhisscholarshipwillbegreatlymissed.
dened medium. Assuming a very faint SN (M = −14 mag), the
V We thank Janos Schmidt and Christian Ginski for their observa-
apparentvisualmagnitudeis−2.1mag,andforabrightSNwith
tionalsupportandRonnyErrmannforusefuldiscussions.BD,NT
M = −21mag,theapparentvisualmagnitudeis−9.1mag;as
V andRNacknowledgesupportfromDFGintheSFB/TR-7Gravita-
brightasSN1006.Theeventmighthavealsocausedthe10Bepeak
tionalWaveAstronomy.ThisresearchhasmadeuseofAladin.We
at35±2 kyrmeasuredinRaisbecketal.(1987)fromthedeepice
wouldliketothanktheCalarAltoobservatorystafffortheirhelp
coresfromDomeCandVostokAntarctica.
inourobservations;andwewouldliketothankDFGinNE515/
53-1forfinancialsupportfortheCalarAltoobservingrun.Wealso
thankTÜB˙ITAKNationalObservatoryfortheirsupportsinusing
7 CONCLUSION
RTT–150withprojectnumber12ARTT150-267.
HD37424 is a B0.5V type runaway star from a binary ejec-
tion due to the supernova which gave birth to SNR S147 and
PSRJ0538+2817. The star has −9.2 ± 6.5 kms−1 heliocentric
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