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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�

(2)

(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

(3)

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

(4)

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,

(5)

{ (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

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