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Hipparcos
Jean-Louis Prieur, Edouard Oblak, Patricia Lampens, Maria Kurpinska-Winiarska, Eric Aristidi, Laurent Koechlin, Ruymaekers G.
To cite this version:
Jean-Louis Prieur, Edouard Oblak, Patricia Lampens, Maria Kurpinska-Winiarska, Eric Aristidi, et
al.. Speckle observations of binary systems measured with Hipparcos. Astronomy and Astrophysics -
A&A, EDP Sciences, 2001, 367, pp.865-875. �hal-02444637�
(willbeinsertedbyhandlater)
Your thesaurus odes are:
03.13.12, 03.20.1,03.20.2,05.01.1,08.02.1,08.02.2,08.02.6
ASTRONOMY
AND
ASTROPHYSICS
Deember7,2000
Spekle observations of binary systems measured by
Hipparos
?
J.-L. Prieur 1
,E. Oblak 2
, P. Lampens 3
, M. Kurpinska-Winiarska 4
, E. Aristidi 5
, L. Koehlin 1
,and G.
Ruymaekers 3
1
UMR5572d'Astrophysique,ObservatoireMidi-Pyrenees{C.N.R.S.,14,AvenueEdouardBelin,31400Toulouse,Frane.
2
UMR6091,ObservatoiredeBesanon{C.N.R.S.,41bis,avenuedel'Observatoire,25010 Besanon, Frane.
3
KoninklijkeSterrenwahtvanBelgie,Ringlaan3,B-1180Brussel, Belgie.
4
CraowObservatory,JagiellonianUniversity,171uliaOrla,30244Krakow,Poland.
5
UMR6525Astrophysique,UniversitedeNieSophia-Antipolis{C.N.R.S.,Valrose,06108NieCedex2,Frane.
ReeivedDeember7,2000;aepted
Abstrat. From spekle observations made with the
PISCO spekle amera at the Pi du Midi Observatory,
we present high angular resolution astrometri data for
43 binarystars alreadyobserved bytheHipparossatel-
lite.ThissampleonsistsofmainlynewHipparoselips-
ingbinarieswithavisualompanionloserthanonear-
seond,hosenwith theaim to study thedynamial im-
pliations of athird omponentonthe observational pa-
rametersof theelipsingsystem.Inaddition, we alsoin-
ludedaseletionoflosevisualbinarieswithfewspekle
data in order to analyse possible systemati departures
between the spekleand the non-spekle orbits. The re-
dution method and the results are presented in detail.
Forthelosevisualbinariesweonfrontourobservations
withtheephemeridesbasedonthebestknownorbits.For
thewidevisualbinariestheonfrontationismadediretly
withtheHipparosdata. Ourobservationsareonsistent
bothwithpreviousspekledataandwithmostoftheHip-
parosmeasurements.
Key words:Methods:dataanalysis{Tehniques:image
proessing { Tehniques:interferometri { Astrometry {
Stars:binaries:lose,elipsing,visual
1. Introdution
This work is part of a larger observational program to
studyasampleofbinarysystemsfromtheHipparosCat-
alogueinvariousaspets:morphology,multipliity,orbits,
fundamental stellar parameters, dynamis and evolution
(Ribaset al.,1998;Aristidiet al.,1999;Lastennet etal.,
1999;Lampens&Strigahev,2000).
Aprimaryaspetonernstheharaterizationofthedy-
namialperturbationsdueto athird loseompanionon
Sendoprintrequeststo:J.-L.Prieur
?
Based onobservations made with the Telesope Bernard
LyotatthePidu MidiObservatory,Franeandondataob-
tained by the Hipparos astrometry satellite. This workhas
alsomadeuseoftheSimbaddatabase,operatedatCDS,Stras-
the orbital parameters of elipsing binaries. Among the
onehundredHipparoselipsingbinarieshaveaompan-
ionloserthanonearseond(Oblaketal.,2000),wehave
seleted26triplesystemsforinterferometriobservations
of theloseompanion,11beingelipsingbinariesnewly
disoveredbyHipparos.Forthesenewvariables,thelight
urvesare aquired at Craowand Kryonerion (Greee)
observatories,whiletheradialveloityurvesareobtained
at the Observatoire de Haute-Provene (OHP, Frane).
Some preliminary results are presented in (Kurpinska
et al.,2000b).
Theseondaspetonernsthestudyofasampleoflose
visualbinarieswhoseorbitsarebasedonaombinationof
non-spekleandspekledata,inordertoanalyzepossible
systematidepartures(partiularlyinangularseparation)
betweenthesetwomodesofobservation.Asthespekleor-
bitsaregenerallynotwelldenedfortheseobjets,spekle
observationsareneededto performthisanalysis.
Theobservationspresentedherewereperformedwiththe
2-meterBernardLyottelesope(TBL)ofthePiduMidi
ObservatorymakinguseofthePISCOspekleamerade-
velopedbytheObservatoireMidi-Pyrenees(Prieuret al.,
1994;Prieuretal.,1998).whihonstitutesapowerfultool
for investigating theeld of lose binary stars(Carbillet
et al., 1996; Aristidi et al., 1997b;Aristidi et al., 1999).
Under normalorgood observingonditions, the angular
resolutionreahedbyPISCOattheTBLisoftheorderof
60 milliarse in V, whih orresponds to the diration
limitofthetelesope.
Inthefollowingwedesribetheonditionsofourobserva-
tionsatPiduMidi(Set.2)andtheproeduresweused
toproessthedata(Set.3).Finallywepresentourresults
andomparethembothwithHipparosandground-based
measurements(Set. 4).
2.Observations
ObservationswerearriedoutonSeptember8thand9th,
1998.Additionnalobservationswereobtainedduringsome
observingrunsalloatedtootherprogrammesinJune7th
and September 1st 1998. Wealso added a measurement
Name Centralwavelength Bandwith
(nm) (nm)
B 447 47
OIII 501 11
V 530 57
R 644 70
R' 658 43
RL 743 69
I 855 74
W 650 418
Table 1. Filters availablewith PISCO.\W" means\white"
whennolterwasused,andthelimitationofthespetralband
wasonlydonebythespetralresponseoftheICCD amera.
PISCO with the CAR photon-ounting detetor (Prieur
et al.,1998).
ThePISCOspekleamerawasusedinitsfullpupilimag-
ing mode with its standardlter set (see Table 1). The
atmospheri hromati dispersionwasautomatiallyor-
retedwithRisleyprisms.Thereliabilityofourorretion
sheme wasonrmed by irular auto-orrelation peaks
(f.Set.3),exeptfortheobservationsofHIP15627(l-
terV)andHIP16042(lterW)duetoastrongwindthat
ausedanelongationofthese peaks.
The detetor was the intensied CCD detetor (Philips
IP800T,hereafteralledICCD)oftheUniversitedeNie,
whih is desribed in detail by (Aristidi et al., 1997b).
It generates video output at 50 frames/se reorded on
SVHSvideotapes.
During both nights of September 8thand 9th, 1998 the
weatheronditionswereratherbadwithstrongwindand
high humidity.As shown inTable2,theseeingwaspoor
and the average of the Full Width at Half Maximum
(FWHM)waslargerthan4 00
.Theimmediateonsequene
wasasatteringofthelightoveralargerareaandalower
apparent luminosity, whih requireda longerintegration
timefortheelementaryframes.Asthespeedofthewind
washigh, theoherene time of theatmosphere (i.e. the
time whentheturbulene oftheatmosphereanbeon-
sideredas\frozen")wasveryshort,sometimeslessthana
fewmillise. Letusreallthat whentheintegrationtime
t oftheelementaryframesissigniantlylargerthanthe
oherene time
of theatmosphere(e.g. t >5
),we
arenolongerinthespekleregimebutratherinthelong
exposure regime:allthespeklepatterns areblurredand
thehighangularfrequeniesarelost.
Hene the ombination of poor seeing and strong wind
may explain the rather low detetion rate for the om-
panions: 16 binaries out of the 43 targets ould not be
resolved.
3. Data redution
3.1. Proessing ofthe elementary frames
ThedatareordedonSVHSvideotapesduringtheobser-
vations weredigitized by a\FullRIO" PCI board made
byEllips(Ellips,2000).Itisan8-bitframegrabberwhih
Fig.1.Auto-orrelationfuntionofHIP25930,aftersubtrat-
ingthemeanross-orrelationofelementaryframesseparated
by100mseasexplainedinthetext.
aformatof288384pixels.Aprogrammewasdeveloped
by one of us (J.-L. Prieur, hereafter JLP) on a PC in
Borland C++ to ontrol the videoassettereorderand
automatially proessthedigitizedframes.
The auto-orrelation was omputed for eah elementary
frame and averaged over a whole sequene. Likewise a
mean ross-orrelation between two elementary frames
separatedby 100mse(i.e., muh largerthanthe oher-
ene time
5 10mse)wasalsoomputed.Wethen
followedtheproeduredesribedby(Wordenetal.,1977)
andsubtratedthemeanauto-orrelationfromthisross-
orrelation, whih substanially redues the level of the
bakgroundandgreatlyfailitatesthedetetionandloal-
izationoftheseondarypeaks(e.g.Fig.1).Althoughthis
method wasoriginallydevelopedforphoton-ountingde-
tetors,wehaveexperiened(Aristidietal.,1999;Sardia
et al.,2000)that itis stillveryeÆientfor thedetetion
and the measurement of the relative positions of double
andmultiplestars,anditleadstothesameresultsofmore
elaborated(andtime-onsuming)methodssuhastheal-
gorithmsusingthebispetrum(see(Prieuretal.,1991)).
3.2. Astrometrimeasurements
The entre ofthe auto-orrelationpeakswasthendeter-
mined with a speially-designed programme written by
JLP.Therststepwastointerativelyseletadiskwhose
entre had to be determined. The bakgroundwasthen
omputedbyttinga3rdorderpolynomialinaonentri
annulus outsideof this disk and its interpolation on the
diskdisplayedbakontheoriginalimagetohekifitwas
orret. This proedure wasoriginallyused for removing
artefats in images (derived from \PATCH" of theU.K.
STARLINKpakage)andgeneratesasmoothbakground
with no disontinuityat the boundaries ofthe disk. The
entre was then determined by two methods: either by
omputingthebaryentreorbyttingatwo-dimensional
ial point being theseletionof theappropriatesize and
loation of the disk. Tomeasure the internal errorsand
obtain a more preise value, independent measurements
were made on eah auto-orrelation peak with dierent
values of the diameter of the disk and dierent parame-
tersfordisplayingtheimage(linearandlogarithmiinten-
sity transfertable). These internal errors were generally
smallerthanthealibrationerrors(Cf.Set.3).
We heked on a few well separated systems that this
method was in good agreement with the prole tting
tehniquedevelopedintheontextofsmall-eldCCDob-
servations of visual double stars (Cuypers, 1997), whih
was unfortunately not appliable to most of the losest
systemsduetoanonuniformbakground.
3.3. Calibration
The orientation of the frames was alibrated using the
traksofstarsobtainedbyallowingthetelesopetomove
in delination andrightasension. The estimated uner-
tainty of this alibration is 0.35 Æ
, whih is the main
soure of error for the position angle of our measure-
mentsintheaseofagoodsignal-to-noiseratio.
Themagniationsalewasobtainedbymeasuringaal-
ibratinggridthat wasplaedat theentranefoalplane
of the spekle amera. Using the value of 50.40.1 m
for thefoal lengthof theTBL (provided bytheServie
of Optis of the TBL), we derived the values of 0.0109
0.0001, 0.02580.0001and 0.16540.0005 arse/pixel
for the three available magniations obtained with the
eyepieesofrespetively10mm,20mmand50mmfoal
lengths.
Thevalidityofthesealibrationswasveriedintwoways:
(a)internallybyobservingthesameobjetwithdierent
magniationsand(b)externallywiththeobservationsof
the\astrometristandards"HIP1447/1446and4065.We
alsointendedtoobserveHIP109186but,duetoverybad
seeing, weouldnotresolvethispairatthat time.These
visualdoublestarswerereentlyobservedintheontextof
aEuropeanobservationalprogrammeofCCDphotometry
of visual double stars undertaken at ESO (Oblak et al.,
1999).Theywouldallowanaurateastrometrialibra-
tion ofthespekleobservations asthese datawereau-
ratelyalibratedusing theHipparosrelativeastrometry
(Cuypers & Seggewiss, 1999). Unfortunately, sine only
twopairsweremeasured,noimprovementofthealibra-
tion parametersould be derived. In Table 3we list our
measurementsof HIP 1447/1446and 4065, ompared to
the ESO data. Onean see that bothresiduals in angu-
larseparationandposition anglehaveoppositesignsand
therefore do not show any systemati deviation nor al-
lowto reduetheerrorsoftheusedalibration.Weshall
also seethat there are nosystematidierenes between
therestofourmeasurementsandtheHipparosdata(f.
Table 3. Astrometrialibration: omparison with measure-
ments made at ESO with a CCD amera (Epoh 1991.797,
Cuypers&Seggewiss,1999).
Identier ESO PISCO PISCO-ESO
pos Ratio
"
Æ
"
Æ
"
Æ
"
HIP1447 11.811 210.36 11.770 210.9 -.041 .54 .118 0.997
.005 .01 .06 .8
HIP4065 2.250 351.78 2.253 351.4 .003 -.38 .015 1.001
.003 .02 .01 .8
3.4. Problem of 180 Æ
-ambiguity
As the position angle was measured on the auto-
orrelationfuntion,whihissymmetrial(f.Fig.1)this
determinationleavesa180 Æ
ambiguity.Toremovethisam-
biguity,weused themethodproposedby(Aristidi et al.,
1997a)basedontheanalysisofazeroplaneof thetriple
orrelationofelementaryframes.Unfortunately,thisteh-
nique didnotproduelearresultsformanyobjets,be-
ause the aquisition wasmade at averylow ux, lose
to the photon-ountingmode. Thisproedure fails when
the dynamial range of the elementary frames beomes
loseto unity.A possiblealternativein someaseswasa
full image restoration with bispetral tehniques (Prieur
et al.,1991).
4.Resultsand disussion
Thelistofobservedtargets(f.Set.4.1/Table2)displays
mainly threetypes:
{ elipsing binaries with a lose ompanion, most of
whihweredisoveredbyHipparosandforwhihthe
existinginformationisinsuÆient;
{ visualdoublestarswithanangularseparationsmaller
than1 00
whihrequirenewobservationstobetteron-
strainthespekleorbits;
{ \astrometri standards" hosen among visual double
stars with an angular separation larger than 1 00
and
thoughttohaveastableongurationusefultodeter-
minethesaleoftheinstrument.
Twoadditionalobjetswereseletedbeausetheyaresus-
petedbinariesbyHipparos:bothomponentsofthevery
widesystemCCDM19282-0932(HIP95724/95726)arry
avariabilityag\D"intheataloguemeaningvariability
induedby dupliity;howeverweould notresolvethese
objets.
Thefollowingonventionwasusedtoassignatypetoeah
programmestar:
{ (a)an\astrometristandard".
{ (b)aloseompanionwasdisoveredbyHipparos
{ (e)aknownelipsingbinary,
{ (h)anewelipsingbinarydisoveredbyHipparos,
{ (u) a new unsolved Hipparos variable: variable star
entry in the Hipparos Variability Annex without a
perioddetermination(Part2).
InourlistHIP6287, 22050,25252,93867,96840,101236
belong to the OHP programme for the determination of
theradialveloityurvesinordertofullyunderstandthe
dynamisofthesesystems.Allofthemhavebeenresolved
bytheseobservationswhihwillthenprovideusefuldata
fortheorbitdetermination ofthevisualompanion.
Someobjetsofthelistwerenotresolved.Thismaybethe
onsequeneofapartiularlypoorFWHMseeing.Several
objetsmay also presenta onguration of lose perias-
tronpassage:e.g.,forHIP98234,(MAlisteretal.,1987)
givesanangular separationlessthan0.038 00
whih isbe-
yondourdetetionlimit.
Among thefour objets ofourlist disoveredto bedou-
ble byHipparos,weonrm thebinarityfor HIP16083
and27309,but wehavenotbeenabletodothesamefor
HIP14542and116167.
4.1. Astrometri measurements
The astrometrimeasurementsare presented in Table 2.
The position angle (relative to the Northand inreas-
ing to the East) was generally measured on the auto-
orrelation funtion whih leaves a 180 Æ
ambiguity (f.
Set. 3.4). An asteriskfollowing the valueof indiates
that the absolute angle ould be determined by using
a omplementary proessing: Aristidi's triple orrelation
tehniquefor HIP 1447, 10280,54061, 58112,97091and
101769, and a full image restoration with a bispetrum
method forHIP23699and101236.
When this ambiguity ould not be solved, we hose the
valuebetween0and180 Æ
,or,whenavailable,weseleted
avalueompatible with previousdatasoures(Hartkopf
et al.,1998;ESA, 1997)forthefollowingstars: HIP981,
4065, 15627, 16083, 19201, 22050, 25252, 27309, 96840,
103505,107162,111805and116164.
IntheaseofHIP93867,(Hartkopfetal.,1998)listposi-
tion angles between 140 Æ
and 121 Æ
for the period 1987-
1993, whereas Hipparos and mirometri observations
(Heintz, 1996b) give respetively =305 Æ
and 305.6 Æ
. It
seems there is simply aproblem of 180 Æ
ambiguitywith
thespeklemeasurements.Tokeepquadrantonsisteny
withthevisualobservations,wehose=289:3 Æ
.
When two ormore measurements were available,wede-
terminedthebestvalueusingthefollowingproedure:
- ifavailable,weadoptedthevaluewiththemagnia-
tionsaleof10mmsinetheauraywaslargerthan
withthe20mmsaleandtherewerelessartefatsnear
theentre;
- elseweomputedthemeanvalueandtheorrespond-
ingerrorbytakingthesignal-to-noiseratioofthedata
intoaount(measurementinbrakets).
This value, oded \Best" in Table 2, was used for the
4.2. Comparisonwith Hipparosmeasurements:visual
binaries withoutknownorbits
In addition to some information retrieved from the Hip-
parosMainCatalogue(ESA1997)welistthedierenes
in,andinrelativepositioninthesense(PISCO-HIP)
in Table4.Sometimes,asintheaseofthedouble entry
HIP1447/1446,werefertotheDoubleandMultipleStar
Annex (ESA1997).
The bottom part of Table 4 ontains the systems with
aknown orbitthat will notbeonsidered here,sinewe
shall ompare more adequately the Hipparos measure-
mentswith theephemeridesomputedforepoh 1991.25
in Set.4.3.
To evaluate possible systemati dierenes, we have se-
letedfromtheupperpartofTable4alltheobjetswhih
didnotshowanyrelativemotionaordingtotheobserva-
tionaldataavailableintheliterature(asteriskedinols.11
and12inTable4).Thederivedmeandierenesbetween
PISCOandHipparosmeasurementsforthesesystemsare
hi=-0.16 Æ
andhi=+0.001".Notethatthetypial
errorvaluesfor PISCOmeasurementsof0:8 Æ
in and
0:01" in are atually lowerlimits for the error esti-
mates for hi and hi respetively, ifwe donot take
into onsiderationHipparoserrors.As thederivedmean
dierenes aremuh smallerthan theirestimated errors,
one anstate that no signiant systemati diereneis
presentbetweenthesemeasurements.
With thesameseletionoftheasteriskedobjets,weob-
tainedanestimate ofthestandarderror:
= 0.99 Æ
,and
= 0.014". Applying a3- level riterion and heking
the value of pos allowed us to point some objets as
possibleandidatesfororbitalmotion:HIP16083,22050,
93867and101236.
HIP16083isaninterestingase.Weresolvedit,whereas
veunresolvedobservationsarelistedin (Hartkopfet al.,
1998),probablyduetoalargemagnitudediereneofthe
twoomponents:m=3.8mag.Asmentionedin(Mason
et al.,1999), theCHARAteam foundonepreviousmea-
surement among their arhival data of 1983. They sug-
gested that thehange in relativeposition betweentheir
andtheHipparosdatamightbeduetorapidorbitalmo-
tion. Fromour measurementswededue amean motion
of3.6 Æ
/yr (f.Table5and(Kurpinska&Oblak,2000a)).
Assumingairularmotion,theperiod would thenbeof
order100-150yrs.
Table 5.Evideneofrapidmotionfor HIP16083
Epoh Soure Derivedmotion
Æ
"
1983.713297.80.689Masonetal.,1999
1991.25 315 0.628Hipparos 2.3 Æ
/yr;-8.09mas/yr
1998.688341.90.459PISCO 3.6 Æ
/yr;-22.7mas/yr
HIP 22050,93867and101236 areknown tobevisualbi-
nariesshowingsmall hanges in measured positions over
the last20 years, but itis stilltooearly todeide about