Physical properties of seven binary and higher-order multiple OB systems

1.2 MB·

by  Pavel Mayer

Astronomy&Astrophysicsmanuscriptno.hd (cid:13)cESO2017
January25,2017
Physical properties of seven binary and higher-order multiple
⋆
OB systems
PavelMayer1,PetrHarmanec1,RolfChini2,3,AnitaNasseri2,JanaA.Nemravová1,HorstDrechsel4,
RodrigoCatalan-Hurtado5,BradN.Barlow5,YvesFrémat6,andLenkaKotková7
1 AstronomicalInstituteoftheCharlesUniversity,FacultyofMathematicsandPhysics,
VHolešovicˇkách2,CZ-18000Praha8,CzechRepublic
2 AstronomischesInstitut,Ruhr–UniversitätBochum,Universitätsstr.150,44801Bochum,Germany
7 3 InstitutodeAstronomía,UniversidadCatólicadelNorte,AvenidaAngamos0610,Casilla1280,Antofagasta,Chile
1 4 Dr.KarlRemeis-Observatory&ECAP,AstronomicalInstitute,Friedrich-Alexander-UniversityErlangen-Nuremberg, Sternwart-
0
str.7,96049Bamberg,Germany
2 5 DepartmentofPhysics,HighPointUniversity,OneUniversityWay,HighPoint,NC27268,USA
n 6 RoyalObservatoryofBelgium,Avenuecirculaire3,B-1180Brussels,Belgium
a 7 AstronomicalInstitute,AcademyofSciencesoftheCzechRepublic,CZ-25165Ondˇrejov,CzechRepublic
J
ReceivedJanuary25,2017;accepted
4
2
ABSTRACT

]
R Analysesofmulti-epoch,high-resolution(R ∼ 50000) opticalspectraofsevenearly-typesystemsprovidedvariousimportantnew
S insightswithrespect totheir multiplicity.Firstdeterminationsof orbitalperiods weremadefor HD92206 C(2d.022), HD112244
. (27d.665), HD 164438 (10d.25), HD 123056 A (∼ 1314d) and HD 123056 B (< 2d); the orbital period of HD 318015 could be
h improved(23d.445975). Concerningmultiplicity,athirdcomponent wasdiscoveredforHD92206 Cbymeansof Heilineprofiles.
p
ForHD93146A,whichwashithertoassumedtobeSB1,linesofasecondarycomponentcouldbediscerned.HD123056turnsout
-
o tobeamultiplesystemconsistingofahigh-masscomponentA(≈O8.5)displayingabroadHeii5411Åfeaturewithvariableradial
r velocity,andofaninnerpairB(≈B0)withdoubleHeilines.ThebinaryHD164816wasrevisitedandsomeofitssystemparameters
t wereimproved. Inparticular, wedetermined itssystemicvelocitytobe−7kms−1,which coincideswiththeradialvelocityof the
s
a clusterNGC6530.Thisfact,togetherwithitsdistance,suggeststheclustermembershipofHD164816.TheOBsystemHD318015
[ (V1082Sco)belongstotherareclassofeclipsingbinarieswithasupergiantprimary(B0.5/0.7).Ourcombinedorbitalandlight-curve
analysissuggeststhatthesecondaryresemblesanO9.5IIIstar.OurresultsforalimitedsamplecorroboratethefindingsthatmanyO
1 starsareactuallymassivemultiplesystems.
v
6 Key words. Stars: binaries: spectroscopic – stars: massive – stars: fundamental parameters – stars: individual: HD 92206C,
2 HD93146,HD112244,HD123056,HD164438,HD164816,HD318015=V1082Sco
8
6
01. Introduction tinuationofthisstudy,(Masonetal.2009),theyfurtherstrength-
.
1 enedthemultiplicityamongclustersandassociations.Sanaetal.
Duplicity or even multiplicity of O stars is a topic that has at-
0 (2008)re-investigatedtheduplicityofOstarsintheNGC6231
tractedattentionfromvariousaspects,mainlyrelatedtotheori-
7 clusterandconcludedthatmorethan63%ofOstarsmustbebi-
1ginandevolutionofmassivestars.WhileGarmanyetal.(1980), naries.Theypointedoutthatthisobservationalfactrepresentsan
:forexample,listonly40Ogalactic-typebinarieswithknownor- importantconstraintforthetheoriesofearlyevolutionofOstars.
v
bitsinthesurveyofthebinaryfrequencyofOstars,thisfraction
i Chinietal. (2012) studied a sample of 248 O and 581 mostly
Xhasbeengrowingsteadily.Masonetal.(1998)obtainedspeckle
southernstarsandconcludedthatmorethan82%ofstarsmore
interferometryof 227 O stars brighter than V = 8m.0 and com-
r massivethan16M areclosebinarysystemsandthatthisfrac-
⊙
apiled information about their spectroscopic duplicity or multi-
tion decreases to 20 % for 3 M stars. They also found differ-
⊙
plicity from the literature. They concludedthat the duplicity is
encesinthebinaryfractionsofOstarsindifferentenvironments:
higherforstars inclustersandassociations(72%) thanforthe
72±13%inclusters,73±8%inassociations,69±11%among
fieldstars(19%);thelowestbeingforrunawaystars(8%).They
runawaystarsand43±13%forthefieldstars.Thefactthatdu-
alsonotedthatmanyOstarsareactuallytriplesystems.Incon-
plicitymustbeakeyfactoraffectingtheevolutionofhigh-mass
binarieswasdiscussedindetailbySanaetal.(2012).Inseveral
⋆ Based on spectra from observations made with ESO tele-
recentstudiesthebinarynatureofmanyO-typestarswasfound
scopes at La Silla and Paranal Observatories under programs 065.1-
0526(A), 073.C-0337(A), 074.D-0300(A), 075.D-0103(A), 077.D- orsuspected.Sotaetal.(2014)presentedasurveyof448Galac-
0705(A), 077.B-0348(A), 079.D-0564(A), 081.D-2008(A), 083.D- ticOstarsfrombothhemispheres,basedonhighsignal-to-noise
0589(A), 085.D-0262(A), 086.D-0997(A), 087.C-0012(A), 087.D- (S/N)ratioR∼2500spectra,whichiscompletetoB=8m.0;fur-
0946(A), 089.C-0415(A), 089.D-0097(B), 089.D-0975(A), 090.C- ther142starswerelistedbyMaízApellánizetal.(2016).Com-
0280(A), 091.D-0145(A), 095.A-9032(A), and 178.D-0361(E), pro- biningresultsfromamulti-epoch,high-resolutionspectroscopic
gram TYCHO P2, on the BESO spectra and spectra from CTIO, and survey,OWN(Barbáetal.2010),withadditionalinformationon
ontheHipparcosH andASAS3Vphotometry.
p
Articlenumber,page1of15
A&Aproofs:manuscriptno.hd
spectroscopicandvisualbinariesfromtheliterature,theauthors fromtheESOarchive.ThoseESOspectrathatweresecuredwith
conclude that only a very small fraction of stars with masses theechellespectrographFEROS(R∼48000Kauferetal.1997)
above15−20M arebornassinglesystems. attachedto the MPI 2.2m telescopeare labelled“F”, thespec-
⊙
In the ongoing multi-epoch survey started in 2009 trafromHARPS(Mayoretal.2003)mountedatthe3.6mESO
(Chinietal.2012),whichmeanwhilecomprisesmorethan2000 telescope are labelled “H”. Some of the FEROS spectra were
high-resolution spectra, a large number of hitherto unknown obtained in the framework of the observational program “Ty-
spectroscopic binaries was found. An example of the study cho Brahe" allocated to Czech astronomers; these spectra are
where the spectra of this survey were analysed in detail is denoted as “T”. In the case of V1082 Sco = HD 318015, we
HD 152246,discoveredasa binaryby Thackerayetal. (1973). alsousedthespectraobtainedatCTIO.TheCTIOspectrawere
Theanalysisofitsdouble-linedspectrayieldedasignificantdif- secured with the echelle spectrograph CHIRON (R ∼ 28.000,
ference of the orbital periods for both components. It suggests Tokovininetal. 2013) attached to the 1.5 m telescope and are
thatHD152246isatleastahierarchicaltriplesystemconsisting labelled“C”.Theinitialreductions(biassubtraction,flatfielding
ofaninnerpairBa/Bbwithapproximately17and6M ,respec- andwavelengthcalibration)werecarriedoutusingthestandard
⊙
tively,andanoutercomponentAwithamassofapproximately pipelines for individual instruments. Rectification of the spec-
20M (Nasserietal.2014). tra and smaller cosmics and flaw-removal were carried out in-
⊙
There are, of course, other studies of individual bina- teractively using the program SPEFO (Hornetal. 1996; Škoda
ries where the orbit of a third body is measured inter- 1996),thelatestversiondevelopedbythelateMr.J.Krpata.This
ferometrically (Mayeretal. 2014) and of members of as- program allows the user to define the continuum points on the
sociations (Kiminkietal. 2007; Kiminki&Kobulnicky 2012; computerscreenforonewell-exposedspectrum,throughwhich
Kobulnickyetal.2014;Sanaetal.2011,2013). thecontinuumissmoothlydefinedbyHermitepolynomials.The
Formoredetailsonthesubject,wereferreaderstoastudyby usercanseethefitandisabletomodifyitwhennecessary.When
Aldorettaetal. (2015), which represents a very good overview proceedingtothetextspectrum,allpreviouslychosenrectifica-
of the current status of duplicity of O stars and also gives a tion points are copied to it and the user can modify their po-
numberofrelevantreferences.Theauthorsidentifiednewbina- sitions if necessary, dependingon the noise and radial-velocity
rieswith the HubbleSpace Telescopefine guidancesensorand (RV)shifts.Wealsocarefullycomparedtherectificationofeach
carried out a very extendedliterature search that allowed them spectrumwiththefirst(template)spectrumtobesureaboutuni-
to providean estimate of the period distributionamongO type formityoftherectification.Similarly,theremovalofcosmicscan
binaries. They concluded that it is approximately flat and dis- becarriedoutinteractivelyonthe computerscreen,the deleted
cussedseveralselectioneffectsandtheneedforadditionaldata. pixels being replaced by a spline interpolation. Basic informa-
However,theircompletelistcontainsonly83spectroscopicand tionaboutallspectraisinTable1.
eclipsingbinarieswithknownorbitalperiod.
The present paper brings into focus seven early-type sys-
2.2.Radial-velocityandorbitdetermination
tems, for which we analysed between 18 and 98 multi-epoch
spectra, obtained mainly with the BESO and FEROS spectro- Dependingonthecharacterofspectraofindividualobjects,we
graphs. In addition to new orbital periods, our study reveals alternativelyapplied three differenttechniquesof RV measure-
higher multiplicitiesin some of the systems. Especially impor- ments:
tant in this context are systems with a supergiant component
(HD318015,HD112244),whicharestillrare.Reliabledetermi-
1. Fitthelineprofilesbyone,twoorthreeGaussianprofiles.
nationoftheirbasicphysicalpropertiesprovidesasensitivetest
2. Interactivecomparisonofthedirectandflippedlineprofiles
forthemodelsofstellarstructureandevolution,especiallythose displayedonthecomputerscreenusingtheprogramSPEFO.
that also include mass loss and/or rotation. We admit that our
3. Two-dimensional(2D)cross-correlationusingaFortranim-
selectionofobjectswasmainlyguidedbytheabove-mentioned plementationoftheTODCOR(Zucker&Mazeh1994)called
practicalconsiderations.Itisclear,however,(cf.Aldorettaetal. asTODCOR,developedbyoneofthepresentauthors(YF)and
2015)thatourcontributionisnotasmodestasitmightappearat
firstappliedtothestudyofAUMon(Desmetetal.2010).
firstsight.Sofar,theknowledgeofduplicityand/ormultiplicity
ofOBstarshasbeenmainlydocumentedonstatistical grounds
Wheneverusingthefirsttwotechniques,wepreferredspec-
while the orbital solutions are still missing in the majority of
trallineswithnoobviousblendsandthosestrongenoughtogive
cases.Zinnecker&Yorke(2007)andSana&Evans(2011),for
reliableresultsevenforspectrawithlowersignaltonoiseratio
instance, pointed out that their knowledge is important for the
(S/N). Throughoutthis paper, we record the times of observa-
understandingofthebinaryoriginandevolution.
tionsusingreducedheliocentricJuliandates
RJD=HJD-2400000.0.
2. Data
TheorbitalsolutionswereobtainedwiththeprogramFOTEL
Thedatacomprisetwocategories;thosethatweresecuredbyour (Hadrava 2004a) and the combined orbital and light-curve so-
own observationsandthose downloadedfrom the ESO archive lution for the eclipsing binary V1082 Sco was obtained with
tocomplementthephasecoverageoftheindividualsystems. the latest version of program PHOEBE 1 (Prša&Zwitter 2005,
2006). In a few cases, we also used the program KOREL for
spectradisentangling(Hadrava2004b).HavingtheGaussianfits
2.1.Spectrographs
we could converttheir widths to projected rotational velocities
The majority of spectra were secured with the echelle spec- vsini. There are several studies that provide such conversion
trograph BESO (R ∼ 48000, Fuhrmannetal. 2011) of the formulaefor specific spectrallines. A suitable one for us is by
Universitäts-SternwarteBochum,whichisfibre-fedtothe1.5m Munari&Tomasella(1999)fortheHei5876Åline.Weprefer
HexapodtelescopeatCerroArmazones,Chile;thecorrespond- thisparticularlinedespitethefactthatitiscontaminatedbysev-
ingspectraaredenotedas“B”.Furtherspectraweredownloaded eraltelluriclinessincethebluepartsofspectraareoftennoisier.
Articlenumber,page2of15
P.Mayeretal.:Sevenearly-typebinaryandmultiplesystems
Table1.Basicinformationaboutthespectraused.
Spectrograph Abbreviation SpectralRange(Å) Resolution S/Nrange
FEROS FplusT 3600–9100 48000 63–311
HARPS H 3800–6912 115000 84–106
BESO B 3800–8000 48000 26–196
CTIO C 4500–8900 28000 83–177
ThisisparticularlyacutefortheBESOspectrasincethesensitiv-
ity(duetotheopticalfibreusedatthetimeofourobservations)
droppedrapidlytowardsbluewavelengths.
3. HD92206C
The star CPD−57◦3580 (CD−57◦3378, LS 1695) is often re-
ferred to as HD 92206C, although it is not named so in WDS
orSIMBAD.Itisthesecondbrightestmemberoftheopenclus-
terNGC3324;thebrightestmemberbeingHD92206AB.The
open cluster is embedded in the H II region G 31. These two
clustermembersareseparatedby36′′andsurroundedbygroups
offainterstars. HD 92206C hasV = 9m.05 anda spectraltype
O8V+O9.7V(accordingtoSotaetal.2014).TheSB2 nature
ofthisstarwasfirstreportedbyChinietal.(2012);noRVshad
beenpublishedbefore.
Fig.1.TheGaussianprofilesoftheprimary,secondaryandthirdcom-
There are ten BESO spectra of HD 92206C; togetherwith
ponentsintheFEROSspectrumofHD92206CtakenonRJD54209.
eight FEROS spectra from the ESO archive, they are listed in
Table 2. RVs of both components were measured by Gaussian
fitting in the Hei 5876 Å line, while only the primary is also
visible in the Heii 5411 Å line. Therefore, the RVs measured
forthelatterlineappearmorerepresentativefortheprimaryRV
curve.NarrownebularlinesarepresentintheBalmeraswellas
in the Hei lines; due to the larger diameter of the BESO fiber,
theseemissionlinesaremorepronouncedthere.Despitethelow
numberofspectra,itwaspossibletofindaperiodof2d.0225.In
the Hei profiles, a third componentis also clearly present, see
Fig.1;thiscomponentwasnotdetectedbyMasonetal.(2009).
AsthediameterofthefiberinFEROSis2′′,thecomponentsep-
arationshouldbesmallerthan1′′.Thereareindicationsthatthe
RVsofthiscomponentarenotconstant.However,thesuperim-
posednebularemission and a low S/N of some spectraprevent
usfromfindingtheperiodofthethirdbody.
OrbitalelementsofthecloseorbitarelistedinTable3while
the RV curve is shown in Fig. 2. In the epoch before RJD ≈
55100, the negative O-Cs prevail; after RJD, the positive ones
aredominant.Thismightbeamanifestationofthemutualorbit Fig.2.TheorbitalRVcurveofHD92206Cforthe2d.0225orbit.
ofthebinaryandthethirdbody.
The equivalent widths (EWs) of the components in the
Hei4922Ålineare0.27(primary),0.21(secondary)and0.05A tions, possibly associated with the rotational period of the pri-
mary,buttheirobservationalfrequencywasoneobservationper
(tertiary);thethirdcomponentseemstobe2–3magfainterthan
night. Therefore,new dedicated whole-nightseries of observa-
theclosebinarysuggestingaspectraltypeofB2.Assumingrea-
tionswouldbeneededto(dis)provethesuspectedphysicallight
sonable masses and radii, one could speculate that the object-
changes.
might be an ellipsoidal or even an eclipsing binary. The latter
possibilityis lesslikely,however,since nosignificantRossiter-
McLaughlineffectwasdetected.Also,theobservedvsiniseems
4. HD93146A
torequirearatherhighorbitalinclinationincaseofspin-orbital
synchronisation,whichiscommonamongveryclosesystems. HD 93146 A (CPD−59◦2555, CD−59◦3278, LS 1826; V =
Recently,multicolourphotometryoftheobjectwasobtained 8.44) is a member of the open cluster Collinder 228 (No.
byHacksteinetal.(2015)andDr.Hacksteinkindlyprovidedus 65) in the Carina complex at a distance of approximately
with individualobservations.Regrettably,only infraredmagni- 2.3kpc;the latter valuedependson the adoptedreddeninglaw.
tudes were not saturated. They have sufficient phase coverage, Levato&Malaroda (1981) determined a spectral type of O6V
however, to exclude the presence of the binary eclipses. Fur- andnotedthevariabilityofRVs;Walbornetal.(1985)suggested
ther, they might indicate some low-amplitude physical varia- classification O6.5V from IUE spectra. Recently, (Sotaetal.
Articlenumber,page3of15
A&Aproofs:manuscriptno.hd
Table2.RVsofHD92206CmeasuredviaGaussianfitsofthelineprofiles.
RJD Phase 5411primary 5876secondary Spg.
RV error O−C RV error O−C
54209.5862 0.2537 −213.5 8 5.7 278 7 −12.3 F
54209.5979 0.2595 −212.5 8 6.4 277 7 −12.8 F
54246.5539 0.5313 19.5 11 −11.4 F
54246.5627 0.5357 32.0 8 −4.5 F
54247.5640 0.0321 −52.5 17 −0.6 F
54600.5388 0.5550 56.5 17 −4.4 −144 14 −47.4 F
54601.5493 0.0546 −95.0 14 −14.7 138 20 39.6 F
55016.4880 0.2180 −221.0 11 −6.4 304 17 19.5 B
55251.7260 0.5283 30.5 8 3.4 B
55252.7361 0.0276 −32.0 14 14.1 B
55255.7089 0.4976 −13.0 8 0.1 B
55256.7212 0.9981 3.0 14 10.5 B
55289.6709 0.2896 −208.5 11 4.3 270 7 −11.4 B
55294.7294 0.7908 206.5 11 14.0 −300 11 −21.6 B
56067.5121 0.8802 137.5 8 4.4 −171 5 25.3 F
56687.8253 0.6038 120.0 8 2.9 −162 14 12.2 B
56730.6903 0.7978 190.0 8 0.0 −266 7 8.9 B
56740.6454 0.7201 206.0 8 10.4 B
AllRVsareinkms−1.Thelastcolumn“Spg.”denotesthespectrograph.
Table3.OrbitalelementsforHD92206C.Allelementshavetheirusual Levatoetal.(1990)publishedtenRVs,someofwhichvary
meaning;rmsisthermsofoneobservationofunitweightderivedfrom by 25km s−1 from one day to another. In contrast, Sotaetal.
thedifferencebetweenthecalculatedandobservedRVs.
(2014) reportedthat OWN data suggesta period of 1130 days.
We analysed seven BESO and twelve FEROS spectra and de-
Element Value rived RVs using both the Gaussian fitting and asTODCOR; ex-
P[days] 2.022504(12) amples of the line profiles are in Fig. 3. Following the experi-
T [RJD] 55901.9142(67) ence of Harmanecetal. (2015), we first disentangled the spec-
super.conj.
e 0(fixed) trausingKORELandmadethepreliminaryorbitalsolutionbased
K [kms−1] 209.3(4.6) on the RVs from the Gaussian fitting of line profiles. Then we
1
K [kms−1] 289.1(7.8) usedthedisentangledspectraastemplatesforasTODCOR.Anew
2
γ [kms−1] -10.2(2.2) version (R3) of asTODCOR was used, which also provides er-
1
γ [kms−1] 1.2(7.8) ror estimates of individualRVs. Accordingto the Appendix in
2
m sin3i[M ] 15.0(6) Zuckeretal. (1995), the error estimate of the component RVs
1 ⊙ derived from multi-dimension cross-correlation techniques can
m sin3i[M ] 10.9(3)
2 ⊙ be obtained from a one dimensional (1D) error analysis car-
a sini[R ] 21.8(4)
⊙ ried outon each dimension.In this version of the program,we
v sini[kms−1] 146(30)
1 thereforeappliedarelationdeducedbyZucker(2003)fromthe
v sini[kms−1] 120(5)
2 maximum-likelihoodtheory that provides reliable estimates of
v sini[kms−1] 67(8)
3 the uncertainty as long as the errors are dominated by random
rms [kms−1] 8.0
1 processes.
rms [kms−1] 24
2
With both methods we could derive RVs also for the sec-
ondary component from the Hei 5876 Å line by fitting the
Gaussians, and in the spectral regionfrom 4460to 4723Å us-
ing asTODCOR. The spectra and RVs measured by both tech-
2014,R ∼ 2500)classifiedthestarasO7V((f))z.Inourspectra niques are listed in Table 4. For the orbital solution, we used
theHeii4541ÅlineisclearlystrongerthantheHei4471Åline, the asTODCORRVs individually weighted by weights inversely
sothespectraltypeO6.5Vappearsmoreappropriate.Withthis proportionalto the squareof their estimated errors.The orbital
classification, the minimum mass of the primary (see Table 5) RV curve is shown in Fig. 4. The orbital solution is in Table 5
is also in better agreement with the expectation (Martinsetal. andcorroboratesalongperiodof1131.6days.
2005).However,wenotethattheHeilinesarepartlyfilledbythe
secondarycomponent,whichshouldbetakenintoaccountwhen
classifying the spectraltype. We also note that the Washington The EWs of both components for the Hei 5876 Å line
DoubleStarCatalogue(WDSMasonetal. 2001)lists a nearby are 0.55 and 0.09 Å, respectively, which implies a spectral
(6′.′5) star that is 1.5mag fainter than HD 93146 A. Sotaetal. class of approximately B0.5 for the secondary. If the visible
(2014)usethedesignationHD93146Banddetermineaspectral O9.7IVneighbour(HD93146B)wereindeedphysicallybound,
typeofO9.7IV.Itisnotclearatthispointifthetwostarsform HD93146Awouldbeanotherhierarchicaltriplesystemofhigh-
aphysicallyboundsystem. massstars.
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P.Mayeretal.:Sevenearly-typebinaryandmultiplesystems
Table4.RVsofHD93146AmeasuredviaGaussianprofilesandusingasTODCORoverthespectralregionfrom4460to4723Å.
RJD Phase 5876 5411 asTODCOR Sp.
prim. prim. prim. sec.
53363.8162 0.0887 −18.7 −22.9 −28.62±0.18 37.12±0.22 F
54209.6500 0.8389 24.6 24.8 24.14±0.13 −44.28±0.16 F
54248.5217 0.8734 26.5 27.0 25.81±0.12 −46.31±0.15 F
54600.5969 0.1856 −20.4 −20.3 −22.98±0.10 41.80±0.14 F
54927.6812 0.4757 −5.0 −3.0 – – B
55227.7110 0.7418 19.0 20.0 16.39±0.21 −31.08±0.30 B
55242.7476 0.7552 18.0 18.8 17.95±0.30 −32.48±0.26 B
55244.7298 0.7569 15.0 18.0 17.84±0.37 −31.57±0.42 B
55265.7237 0.7755 22.0 22.0 21.03±0.23 −35.31±0.21 B
55291.5929 0.7985 26.0 27.0 21.77±0.23 −39.16±0.18 B
55299.6685 0.8056 23.0 23.0 22.54±0.25 −38.81±0.22 B
55323.5905 0.8269 25.9 26.3 24.80±0.12 −41.71±0.14 F
55325.5834 0.8286 23.6 24.0 24.26±0.10 −43.29±0.12 F
55326.5139 0.8295 25.3 25.7 24.49±0.10 −43.12±0.12 F
55604.8774 0.0763 −18.0 −17.9 – – F
55641.6959 0.1090 −22.9 −23.7 −23.24±0.12 41.69±0.18 F
55643.6970 0.1108 −26.5 −27.0 −24.54±0.11 41.74±0.13 F
55698.6435 0.1595 −23.6 −23.4 −24.28±0.13 42.72±0.17 F
56068.5713 0.4876 −1.9 −1.9 −3.02±0.11 4.82±0.15 F
Table5.OrbitalelementsforHD93146A;samenotationasinTable3.
Element Value
P[days] 1131.4(2.9)
T [RJD] 54385.9(6.6)
periastr.
e 0.4069(87)
ω[◦] 83.6(1.7)
K [kms−1] 25.73(37)
1
K [kms−1] 54.10(1.05)
2
γ [kms−1] −0.41(0.41)
1
γ [kms−1] +0.35(0.70)
2
m sin3i[M ] 30.81(96)
1 ⊙
m sin3i[M ] 14.66(48)
2 ⊙
a sini[R ] 1631(31)
⊙
v sini[kms−1] 62(4)
1
Fig.3.TheprimaryandsecondarycomponentsofHD93146Ainthe v sini[kms−1] 50(10)
lineHei5876ÅinspectrafromRJD54248(black;phase0.873)and 2
rms [kms−1] 0.91
55643(red;phase0.111). 1
rms [kms−1] 0.61
2
5. HD112244 The spectradisentangledby KORELhaveRVs correspondingto
the systemic velocity. When used as templates for asTODCOR,
HD112244(HD112244A,HR4908,CD−56◦4699,HIP63117 RVscorrespondingtozerosystemicvelocityareobtained.
and 54 G Cru) has the spectral type O8.5Iab(f)p (Sotaetal.
2014) and a visual brightness of V = 5m.38. It has been part
of the monitoring program for stellar multiplicity (Chinietal. Jakate (1979), in his search for possible new β Cep vari-
2012) and attracted our attention because of its highly variable ables, foundHD 112244constanton six nightsof his observa-
spectrallineprofiles. tions.However,therangeof variationsfoundby theHipparcos
satellite H photometry from 5m.33 to 5m.41 (Perryman&ESA
Radialvelocitiesweremeasuredbyseveralinvestigatorsbut p
1997) seems to indicate some micro-variability. Indeed,
no periodicity of RV changes was reported. Stickland&Lloyd
Marchenkoetal.(1998)analysedH photometryandsuspected
(2001) measured RVs in 9 IUE spectra and tried to search for p
periodicityin them andin previouslypublishedRVs, butcould the presence of three possible periods, 4d.518, 3d.286 or 1d.156,
notfindany.TheyconcludedthattheobservedRV changesare theamplitudeofvariationsbeingslightlyover0m.02inallthree
mostlikelyduetoatmosphericinstabilities.Sotaetal.(2014)in cases. Repeated analysis of the same data by Koen&Eyer
their GOSSS survey mention that according to a parallel high- (2002) resulted in finding a period of 2d.00288 with a semi-
dispersion OWN survey (Barbáetal. 2010), HD 112244 is a amplitudeof0m.0085.
double-lined spectroscopic binary with a 7d.5 period. They re- Our observational material consists of 68 BESO and 30
markedthattheydonotseedoublelinesintheGOSSSspectra. FEROS spectra secured between May 2004 and August 2014
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Fig.5.ExamplesofvariabilityoflineprofilesoriginatinginthecircumstellarmatterintheyellowandredpartsofthespectraofHD112244.Left
panelsshowthediffuseinterstellarbandat5797.0Å,theCiv5801.3and5812.0Å,andtheHei5875.7Ålineprofiles,whiletherightpanelsshow
Hα,thediffuseinterstellar6613.6ÅbandandtheHei6678.2ÅandHeii6683Ålineprofilesforthesamespectra.Theupperpanelsillustrate
thevariabilityonatimescaleofdaysandthebottompanelsshowvariationsonlongertimescales.Theoffsetofindividualprofilesis0.25ofthe
continuumlevel.
(RJD 53127 - 56880). Ten FEROS spectra secured between RV measurementssince evenseeminglyphotosphericlinescan
RJD 53898.6647 and 53919.5607 have exposure times of 9 s bepartlyaffectedbythesephysicalvariations.
onlyandarerelativelynoisy.Also,thelastseriesofBESOspec-
To check whether HD 112244 is indeed a spectroscopic
trastartingwithRJD 56854.4909wasobtainedin veryadverse
binary, we measured RVs of several spectral lines using dif-
weatherconditionsandhasalowerquality.Forthatreason,we
ferent techniques. The RVs of basically photospheric lines of
measured the S/N for each spectrum and applied weights pro-
Hei 4921.9 Å and 6678.2 Å, Heii 5411.5 Å, Civ 5801.3 Å
portionaltothesquareofS/NandnormalisedtothemeanS/N.
and 5812.0 Å, and of two lines affected by emission (Hα and
Hei 5875.7 Å) were measured via a comparison of direct and
HD112244isanemission-lineobjectandhasstrongstellar
flippedlineprofilesinSPEFO.TheRVofthecleanHeii5411.5Å
wind.Martinsetal.(2015)haveshownthatrapidandapparently
line was also measured through a Gaussian fit of the profile.
irregularvariabilityofthewindline profilesischaracteristicof
UsingStellingwerf(1978)phasedispersionminimisationperiod
theOBsupergiants.ThisisalsotrueforHD112244asillustrated
searchtechnique,weanalysedalltheseRV datasubsetsforpe-
inFig.5,whereweshowpartsoftheyellowandredspectrafor
riodicityoverthefrequencyrangedownto10cd−1.Inallcases,
selected spectrograms. It is seen that the strength and shape of
thisled to the detectionof a dominantperiodof 27d.67 and RV
theHαlineandalsoofthefaintemissionattheredwingofthe
curvesindicativeofahighlyeccentricorbit.
Hei 5876 Å line both vary on timescales from days to years,
whilethelineprofilesofhigh-ionisationspeciesasHeiiorCiv For the final analysis, we selected the region from 5792 to
remainrelativelystable.Thisfactrepresentsacomplicationfor 5855Åandproceededinthefollowingway.Weformallydisen-
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P.Mayeretal.:Sevenearly-typebinaryandmultiplesystems
Fig.4.TheorbitalRVcurvesofHD93146 basedonasTODCOR RVs.
Theestimatederrorsaregenerallycomparabletothesizeofthesym-
bols(blackdotsandopencirclesfortheprimaryandsecondary,respec-
Fig.7.Stellingwerf’sθstatisticsperiodogramforasTODCORRVsfrom
tively),andarenot,therefore,shown.
the5792–5855Åregion.Acompleteperiodogramforperiodsdown
to0d.2isshownintheupperpanelandazoomedpartofitinthebottom
one.
Table6.OrbitalelementsforHD112244;samenotationasinTable3.
Element Value
P[days] 27.6652(22)
T [RJD] 55532.20(21)
periastr.
e 0.692(50)
ω[◦] 290.8(7.5)
K [kms−1] 17.4(1.9)
1
f(m)[M ] 0.00572(22)
⊙
v sini[kms−1] 122–1661
1
rms[kms−1] 5.8
1 The interval corresponds to full width at half maximum
Fig.6.ThedisentangledspectrumofHD112244andofdiffuseinter- (FWHM).
stellarbandsinthewavelengthregion5792–5855Å.
rangeof1.85−3.85M forarangeofinclinationsfrom90◦ to
⊙
tangledthestellarspectrumoftheCiv5801and5812Åandthe 30◦.
spectrumofdiffuseinterstellarlines.Thesedisentangledspectra, The periodic RV variability of the stellar lines seems to be
shown in Fig. 6, were then used as templatesfor the 2D cross- beyond doubt, especially if compared to the RVs of the dif-
correlationwiththeprogramasTODCOR. fuse interstellar bands. The light variations plotted vs. orbital
phaseappeartobeindicativeofsomeco-rotatingstructures,also
Figure 7 shows the phase-dispersion periodogram for
asTODCOR RVs down to a period of 0d.2. One can see that the known for some other OB stars (cf., e.g. Owockietal. 1995;
Harmanec 1989, 1999). More observations are required, how-
period of 27d.67 (frequency 0.036 cd−1) represents the domi-
ever,toproveordisprovethisclassification.
nantminimumintheperiodogram.Otherdeeperminimacanbe
identified with the second harmonic at 0.072 cd−1, 1 d alias at
0.963 cd−1 and 1 yr alias at 0.039 cd−1. We note that there is
6. HD123056
noevidenceoftheearlierreported7d.5period(f =0.133cd−1).
OurorbitalsolutionbasedontheseasTODCORRVswithweights HD 123056 (CPD−59◦5404, CD−59◦5090, LS 3200) is a
proportionaltothesquareoftheS/NissummarizedinTable6. field star with V = 8.14 and was classified as O9.5V((n))
The secondary must be much less massive and indeed our at- (Walborn1973);Sotaetal.(2014)giveanintegralspectraltype
tempts to disentangle it failed. The correspondingRV curve is ofO9.5IV(n).Feastetal.(1963)publishedfourRVsandnoted
depictedinFig.8.Itisclearthatlargerdeviationsfromthecurve their variability; Chinietal. (2012) found varying double lines
come invariably from spectra of lower quality. Regrettably, no andassignedthestatusSB2.Sotaetal.(2014)suggestedthatthe
RVs of superb quality are available at the bottom part of the staris“atleastSB2”,speculatingthatitmightalsobeatripleor
RV curve. We postpone the discussion of binary properties to multiplesystem.
thefuture,whenadedicatedseriesofwellexposedspectrawill We could secure ten spectra with BESO; five more spectra
be obtained. Nevertheless, a crude estimate of the secondary wereobtainedwithintheprogram"TychoBrahe"inMay2015,
mass can be obtained from the mass function f(m). Adopting when the 2.2 m MPI telescope was allocated to programspro-
m = 31.54 for O8.5I (Martinsetal. 2005), we obtain a mass posed by Czech astronomers (see Table 7). Furthermore, there
1
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Fig. 9. An attempt to resolve the profile of the line Hei 6678 Å in
HD123056 obtainedatRJD54960. TheRVofthecentrallineofthe
profile(binaryA)hasbeenassumedtobeidenticaltotheRVmeasured
forthelineHeii5411Å.ThethicklineshowstheHeiiline5411(with
DIBsatapproximately+390and−390kms−1).Thegreylineistheob-
servedlineHei6678Åandthethinlinesrepresentcomponentsofthe
binaryB.ThelineHeii6683ÅinthebinaryAisalsopresent.
Table8.ProbableorbitalelementsofthelongABorbitofHD123056;
samenotationasinTable3.
Element Value
P[days] 1314.1(1.8)
T [RJD] 54648(95)
periastr.
e 0.182(70)
K [kms−1] 23.4(2.7)
1
γ [kms−1] −28.0(1.5)
1
f(m)[M ] 1.66(72)
⊙
a sini[R ] 598(76)
1 ⊙
v sini[kms−1] 140(20)
1
v sini[kms−1] 140(20)
2
v sini[kms−1] 225(30)
3
rms [kms−1] 5.85
1
Fig.8.Upperpanel:theorbitalRVcurveplotofHD112244basedon findingprogramfounda periodnear1310daysasthe best one
asTODCORRVsfromthe5792–8555Åregion.RVsfromspectrawith andthefreeorbitalsolutionimprovedthisvalueto1314.1±1.8d;
weights higher than 1.5 are shown by large black circles, those with
theprobableorbitalelementsarelistedinTable8.Weadmitthat
weights between 1 and 1.5 withsmaller black circles, and those with
thismustnotbetheonlypossiblesolution,sincesomeoftheRVs
weightslowerthan1withblackdots.Middlepanel:asTODCORRVsof
arenotcompletelyreliable.ComponentsofthebinaryBaredis-
the diffuse absorption bands shown on the same scale to characterise
tinguishable near elongationsof their orbit in the Hei lines (cf
theuncertaintiesoftheRVdetermination.Thesamesymbolsasabove.
Bottompanel:HipparcosH magnitudeplottedvs.orbitalphase. Fig.9).
p
Itisnotclearwhetherthislongperiodisthatofabinaryor
ofthethirdbodyorbit(A)aroundthecloserbinary(B).Never-
are eight FEROS spectra in the ESO archive. The profiles of theless,thebodywiththelongperiodmustbeofearlierspectral
theHei6678ÅandtheHeii5411Ålines(FEROSspectra)are type (say ≈ O8.5).As the componentsof the binaryB are bet-
showninFig.9. terseenintheHeilines(areinvisibleinHeii5411Å),theyare
As the Heii 5411 Å line is broad and any indications for oftype≈B0;adiscriminationbetweencomponentsB1andB2
duplicity are virtually missing, we conclude that it belongs to isdifficult.TheamplitudesofRVsinallorbitsarerathersmall,
a third component, hereafter referred to as “A”. From its posi- thereforetheaccuracyofthederivedperiodsisalsoaffected.The
tionchanges,weconcludethatAhasavariableRV.Thenumber periodofthebinaryBseemstobeslightlyshorterthan2days.
ofspectraisnotsufficientforareliabledeterminationofthepe- To summarise, HD 123056 appears to be another hierarchical
riod.WiththeRadcliffeobservatoryspectraincluded,theperiod- triplesystemofhigh-massstars.
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P.Mayeretal.:Sevenearly-typebinaryandmultiplesystems
Table7.SPEFORVsofthewingsandtwolinecoresoftheHei5876ÅlineandRVsfromGaussianfitsoftheHeii5411ÅlineofHD123056(in
kms−1).ThefourearlyRadcliffeRVs(R)arethemeanRVsofseveralspectrallines.
RJD 5876 O−C 5876 5876 5411 O−C Spectro-
wings core 2ndcore graph
34825.5256 −30.00 −5.0 R
34834.4991 −23.00 3.3 R
35181.5451 −59.00 −8.3 R
35208.4685 −44.00 5.0 R
54935.6907 −38.23 9.7 −2.10 – −36 9.8 B
54952.7769 −53.41 −6.8 −3.59 – −48 −3.3 B
54954.7400 −52.74 −6.2 19.43 −88.48 −53 −8.4 F
54960.7492 −48.83 −2.8 −47.60 – −51 −6.8 B
54976.6593 −39.31 5.5 −49.72 – −38 5.1 F
55240.9051 −10.76 12.1 28.73 −68.46 −12 10.9 B
55241.9183 −18.94 3.8 14.42 – −23 −0.2 B
55251.8066 −19.02 3.0 −31.34 – −22 0.1 B
55253.8783 −35.55 −13.7 19.24 −96.36 −28 −6.1 B
55605.8938 −11.34 −4.6 7.84 −89.40 −13 −7.8 F
55642.7878 −14.63 −7.3 −3.83 – −11 −5.2 F
55697.7150 −1.42 8.0 −60.12 22.53 −2 6.2 F
55698.7538 −5.48 4.0 −4.33 – −5 3.2 F
55794.9821 −16.54 1.0 3.44 – −15 2.8 B
55803.9761 −13.59 5.0 −37.69 – −16 3.1 B
55805.9746 −12.87 6.0 7.33 – −7 12.3 B
56067.7858 −48.14 4.2 −57.94 – −45 5.5 F
56068.7840 −52.54 −0.1 −4.48 – −53 −2.5 F
57155.8197 −24.22 −0.6 −41.14 29.73 −33 −8.3 F
57156.8305 −27.45 −3.7 −38.31 – −28 −3.2 F
57157.7282 −19.56 4.4 24.60 −88.29 −27 −2.0 F
57159.7152 −26.52 −2.3 18.48 – −26 −0.7 F
57160.5437 −33.10 −8.8 −56.91 – −30 −4.6 F
To estimate the measurement errors of the components of Hei 5876 Å in SPEFO, we repeated the measurements several times
independently.Theresultsforthewingsusuallydifferedbylessthan1kms−1,whilethesettingsforthelinecoresarelesscertain,
especiallyforlowerS/NBESOspectra.
7. HD164438
HD 164438 (BD−19◦4800, LS 4567) is a star in the Sgr OB1
association with V = 7.48 and a spectral type of O9.2IV
(Sotaetal. 2014). Masonetal. (1998) found a possible binary
companionataseparationof0′.′05,which,however,needscon-
firmation as it was not seen by Sanaetal. (2014). Chinietal.
(2012) classified HD 164438 as SB1, which was recently cor-
roboratedbyOWNdata(Sotaetal.2014).
Wewereabletosecure15BESOspectraanddownloaded5
FEROSspectrafromtheESOarchive.TheRVsweremeasured
from the Hei 5876 Å and Heii 5411 Å lines via Gaussian fits.
The corresponding results are listed in Table 9, the orbital el-
ements are given in Table 10, while the RV curve is shown in
Fig 11. When inspecting the line profiles, one cannot find any
traceofthelinesfromthesecondary.Weattemptedtodetectthe
Fig.10.ThelongorbitofHD123056(binaryA).Thecurvecorresponds
toelementsP=1314days,e=0.18,K=23kms−1,V =−27kms−1). secondary through disentangling with KOREL, but without suc-
γ
Blackfullcirclesindicatemeasurement ofthelineHei5876 Åwhile cess.ThismeansthattheEWsofthesecondarycomponentmust
redplussymbols represent measurement of thelineHeii5411 Åand be approximately 20 times smaller than those of the primary,
blueopencirclesindicateRadcliffedata. implyingaspectraltypelaterthanB3.Usingthemassfunction
f(m)andadoptingm = 19M forO9.2IV(ascanbeobtained
1 ⊙
byintepolatingintablesby,e.g. Martinsetal.2005)weobtain
amassrangeof2.02−4.32M forarangeofinclinationsfrom
⊙
90◦−30◦.
Articlenumber,page9of15
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Table 9. RVs based on the Gaussian fits of Hei 5876 Å line of the 8. HD164816
primarycomponentofHD164438(inkms−1).
HD 164816 (CPD−24◦6146, CD−24◦13816, LS 4597; V =
7.08) is located towards the young open cluster NGC 6530. It
RJD Phase RVwitherror O−C Spg.
wasoriginallyclassifiedasO9.5III–IV(n)(Walborn1973).The
54600.8993 0.1841 6.5±1.3 0.6 F spectral type B3Ve assigned by Levenhagen&Leister (2006)
54937.8665 0.0576 −19.0±2.2 0.6 B
must be a mistake, since the O-type character of the spectrum
54943.8670 0.6430 −2.7±1.8 1.5 B is without any doubt; the emission is present as narrow lines,
54976.9109 0.8667 −33.6±1.6 0.8 F so it originates from the surrounding H II region. Chinietal.
55072.6480 0.2065 6.6±1.8 −1.7 B
(2012)classifiedHD164438asSB2.Doublelinesarealsoseen
55121.5368 0.9759 −39.7±1.8 −0.1 B by Sotaetal. (2014), who derived spectral types of O9.5V +
55697.9411 0.2082 8.0±1.2 −0.8 F B0Vforthetwocomponents.
55698.8548 0.2973 13.1±1.2 0.7 F
Trepletal. (2012) have published an extensive multi-
55798.6818 0.0362 −27.8±2.0 −1.4 B
wavelength (X-ray, γ-ray, optical and radio) study of the bi-
55812.6264 0.3966 10.2±1.8 −0.9 B
nary HD 164816.They find an orbital period of 3.82 days and
55813.6076 0.4923 6.4±1.9 −0.4 B projected masses of m sin3i = 2.355(69)M and m sin3i =
55814.6200 0.5910 −1.0±1.9 −1.0 B 1 ⊙ 2
2.103(62)M . They also identified an associated X-ray source
55815.6204 0.6886 −9.7±1.6 −0.3 B ⊙
witha softX-rayexcessanda 10spulsation,whichtheyinter-
55816.6211 0.7863 −23.3±1.8 −1.4 B
pretasthesignatureofaneutronstarinthesystem.
55817.6199 0.8837 −37.3±1.6 −0.9 B
Duringaninterferometricinfraredsurvey,Sanaetal.(2014)
55818.6224 0.9815 −38.3±1.6 0.6 B
detected a faint companionseparated by 57mas. This objectis
55819.6209 0.0789 −13.0±1.6 0.8 B
not a component of the SB2 system itself because this pair is
55821.6047 0.2724 11.9±1.7 −0.1 B
separatedbyonly0.07masassumingadistanceof1kpcassug-
56067.9290 0.3031 13.6±1.3 2.0 F
gestedbyTrepletal.(2012).ThedifferenceoftheHmagnitude
56441.9326 0.7898 −21.3±1.7 1.2 B
of HD 164816 and the faint companionis ∆H = 3.4, suggest-
ing quite different masses. Because the object is also detected
inX-rays,Sanaetal.(2014)suggestedthattheyprobablyseean
activelater-typeobject,whichmayprovideanalternativeexpla-
nationtotheX-rayexcessofHD164816.
We re-analysed the existing BESO spectra and also in-
cluded two FEROS spectra from the ESO archive in our anal-
ysis. In general,we can confirm the orbitalelements published
by Trepletal. (2012). However, we obtain a systemic veloc-
ity equal to the velocity of the cluster. We suspect that in
the cited paper the spectra were not reduced correctly. Note
thatStickland&Lloyd (2001) publishedthe followingRVs (in
kms−1)
RJD43782.337:V =39.7,V =−34.5,
1 2
RJD44899.205:V =77.7,V =−81.9,
1 2
which clearly suggest that the systemic velocity is close to
zero (or close to the RV of the cluster, which is approximately
−7 km s−1). We believe that the reason why Trepletal. (2012)
obtainedananomaloussystemicvelocityliesinthefactthatthey
Fig. 11. The RV curve of HD 164438 based on Gaussian fits of the overlookedthatthefirstpixelofBESOspectraisnumbered−51
Hei5876ÅlineplottedfortheephemerisofTable10. in their reduction and therefore the spectra must be shifted by
1.56Å.FortheHei5876Åline,thiscorrespondsto78kms−1,
Table 10. New orbital elements for HD 164438; same notation as in which is close to the value of the erroneous systemic velocity
Table3. publishedbyTrepletal.(2012).
As a consequence, the distance of the binary might well
Element Value be equal to the distance of NGC6530 whose latest deter-
P[days] 10.25042(40) minations are 1250pc (Prisinzanoetal. 2005) and 1322pc
T [RJD] 55501.05(6) (Kharchenkoetal. 2005), respectively. Likewise, the clus-
periasrt.
e 0.310(13) ter was found to be affected by anomalous extinction with
ω[◦] 218.5(2.5) R = 4.5 (Fernandesetal. 2012). Although SIMBAD classi-
K [kms−1] 26.9(4) fies HD 164816 as a Be star (Levenhagen&Leister 2006), it
1
γ [kms−1] −8.0(3) seems that among eight sources of UBV photometry there are
1
no pronouncedlight or colour changes observed. We therefore
f(m)[M ] 0.0178(8)
⊙
v sini[kms−1] 89(2) used mean photometric values V = 7.092 and B − V = 0.02
rm1 s [kms−1] 1.1 (Mermilliod1986). De-reddeningleads to EB−V = 0.292,(B−
1 V) =−0.29and(U−B) =−1.09resultingincoloursthatagree
0 0
wellwithanO9.5V+B0Vspectrum.Atadistanceof14arcmin
fromtheclustercentreandaclusterradiusof15arcmin,thestar
islocatedattheoutskirtsofNGC6530.UsingR=4.5toderive
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