J/AJ/159/27ivo://CDS.VizieR/J/AJ/159/27CDSRabinowitz D.L.Benecchi S.D.Grundy W.M.Verbiscer A.J.Thirouin A.2020-04-16T12:49:30Z2020-03-30T09:03:36ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frasteroidssolar-systeminfrared-photometryvisible-astronomybroad-band-photometryabsolute-magnitudeKuiper Belt Object (385446) Manwe-Thorondor is a multiobject system with mutual events predicted to occur from 2014 to 2019. To detect the events, we observed the system at 4 epochs (UT 2016 August 25 and 26, 2017 July 22 and 25, 2017 November 9, and 2018 October 6) in g, r, and VR bands using the 4m SOAR and the 8.1m Gemini South telescopes at Cerro Pachon, Chile, and Lowell Observatory's 4.3m Discovery Channel Telescope at Happy Jack, Arizona. These dates overlap the uncertainty range ({+/-}0.5 day) for four inferior events (Thorondor eclipsing Manwe). We clearly observe variability for the unresolved system with a double-peaked period 11.88190{+/-}0.00005hr and ~0.5mag amplitude together with much longer-term variability. Using a multicomponent model, we simultaneously fit our observations and earlier photometry measured separately for Manwe and Thorondor with the Hubble Space Telescope. Our fit suggests Manwe is bilobed, close to the "barbell" shape expected for a strengthless body with density ~0.8g/cm^3^ in hydrostatic equilibrium. For Manwe, we thereby derive maximum width to length ratio ~0.30, surface area equivalent to a sphere of diameter 190km, geometric albedo 0.06, mass 1.4x1018kg, and spin axis oriented ~75deg from Earth's line of sight. Changes in Thorondor's brightness by ~0.6mag with a ~300day period may account for the system's long-term variability. Mutual events with unexpectedly shallow depth and short duration may account for residuals to the fit. The system is complex, providing a challenging puzzle for future modeling efforts.2020AJ....159...27Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/159/27CatalogResearchIsServedByTAP VizieR generic servicerelated-toB/hst : HST Archived Exposures Catalog (STScI, 2007)B/astorb : Orbits of Minor Planets (Bowell+, 2014)J/A+A/380/347 : BVRI photometry of 27 Kuiper Belt Objects (Delsanti+, 2001)J/A+A/407/1139 : RVB photometry Kuiper-Belt obj. 1999 TD10 (Rousselot+, 2003)J/AJ/127/3023 : R magnitudes Kuiper Belt object 2001QG298 (Sheppard+, 2004)J/AJ/135/55 : NIR spectra Centaurs & Kuiper Belt objects (Barkume+, 2008)J/A+A/509/A94 : Lightcurves of 14 NEAs (Kwiatkowski+, 2010)J/A+A/511/A49 : Lightcurves of 12 NEAs (Kwiatkowski+, 2010)J/ApJ/720/1691 : Observations of the distant Kuiper belt (Schwamb+, 2010)J/A+A/546/A86 : R absolute magnitudes Kuiper Belt objects (Peixinho+, 2012)J/ApJ/749/10 : SDSS observations of Kuiper belt objects (Ofek, 2012)J/A+A/556/A8 : 100 asteroids rotational parameters (Lhotka+, 2013)J/A+A/562/A48 : Light curves of asteroid (25143) Itokawa (Lowry+, 2014)J/ApJS/227/20 : Rotation periods of asteroids using iPTF (Chang+, 2016)J/AJ/154/62 : Orbital parameters of Kuiper Belt objects (Volk+, 2017)J/AJ/154/241 : Photometry Kuiper Belt object: 2002 CC249 (Thirouin+, 2017)J/A+A/627/A172 : Near-Earth asteroid (1917) Cuyo opt. & IR obs. (Rozek+,2019)J/AJ/157/228 : Cold Classical TNOs LCs & rot. properties (Thirouin+,2019)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/159/27https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/159/27http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/159/27https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/159/27https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/159/27http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/159/27GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tap2.76124552865182e-19 3.9057996558789745e-19OpticalInfrareddefaultJ/AJ/159/27/kpoBinary orbital parameters for Manwe-Thorondor (Table 1) and multicomponent model parameters (Table 6)MMMass of Manwekgphys.massdoublee_aError on akmstat.errorintpTAlbedo of Thorondorphys.albedofloatMT/MMUpper limit to Thorondor/Manwe mass ratio (1)phys.mass;arith.ratiofloatpMAlbedo of Manwephys.albedofloatPerMRotation period of Manwehtime.perioddoublet1Reference Julian date for absolute magnitudesdtime.epochdoublebetaLinear dependence on solar phase angle ({beta})mag/degsrc.orbitalfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintOrbitDisplay the orbit data from B/astorb for Manwemeta.ref.urlcharPerManwe-Thorondor orbital perioddtime.periodfloate_PerError on Perdstat.errorfloataManwe-Thorondor semi-major axiskmphys.angSize.smajAxis;src.orbitalinteManwe-Thorondor eccentricitysrc.orbital.eccentricityfloate_eError on estat.errorfloatMsysSystem masskgphys.massdoublee_MsysError on Mkgstat.errordoubleincManwe-Thorondor inclinationdegsrc.orbital.inclinationfloate_incError on incdegstat.errorfloatOmegaManwe-Thorondor ascending nodedegsrc.orbital.nodeinte_OmegaError on Omegadegstat.errorfloatLCg, r and VR LCs interactive plotmeta.ref.urlcharLChstHST F606W LC interactive plotmeta.ref.urlcharDiamMDiameter of sphere with equivalent area as ManwekmphysintDiamMVolDiameter of sphere with equivalent volume as Manwekmmeta.bib.volumeintDiamTDiameter of Thorondorkmphys.size.diameterintrhoAverage density of the Manwe/Thorondor system ({rho})g.m**-3phys.densityfloatepsTJulian date of minimum brightness for Thorondor ({epsilon}_T_)time.epochdoubleOmegaMAscending node of Manwe's equator ({Omega}) (2)degsrc.orbital.nodefloatincMInclination of Manwe's equator (2)degsrc.orbital.inclinationfloatRotMRotation angle of Manwe's long axis ({mu}) (3)deginstr.offsetfloataMAverage angle between Manwe's spin and Manwe-Earth direction (<{alpha}_M_>)deginstr.offsetfloatPerTRotation period of Thorondor (single-peaked)dtime.periodfloatAmpTLight-curve amplitude of Thorondor (peak-to-peak)magsrc.var.amplitudefloatgMAGAbsolute g-band magnitude of Manwe/Thorondor (H_g_) at epoch t1magphys.magAbsfloatrMAGAbsolute r-band magnitude of Manwe/Thorondor (H_r_) at epoch t1magphys.magAbsfloatMMAGAbsolute F606W-band magnitude of Manwe (H_M_) at epoch t1magphys.magAbsfloatTMAGAbsolute F606W-band magnitude of Thorondor (H_T_) at epoch t1magphys.magAbsfloatJ/AJ/159/27/table2Observing circumstancesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintEpoch[1/4] Epoch numbermeta.idintDateUT observation datetime.epoch;obsnullableTelTelescope used: DCT, Gemini and SOAR, 2 occurrences for eachinstr.setupcharNobsNumber of observations with this telescopemeta.numberintnullableFiltFilter used: VR 1 occurrences, g 4 occurrences and r 5 occurrencesinstr.setup;instr.filtercharObs.startUT start time of the observationtime.epochnullableObs.endUT end time of the observationtime.epochnullableMidptUT event midpoint (1)time.epochnullableDepth[0.05/0.66]? Event depth (1)magsrc.var.amplitudefloatnullabletheta[0.4/1.1] Solar phase angle ({Theta})degsrc.orbitalfloatrhel[43.4/43.7] Heliocentric distance (r_hel_)AUpos.distance;pos.heliocentricfloatrgeo[42/43] Geocentric distance (r_geo_)AUpos.distance;pos.geocentricfloatJ/AJ/159/27/table3Photometric observations of Manwe-ThorondorrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTelTelescope used (1)instr.setupcharJD[7625/8398] Julian Date of observation, JD-2450000dtime.epochdoubleFiltFilter used: "VR" 34 occurrences, "g" 43 occurrences or "r" 148 occurrencesinstr.setup;instr.filtercharomag[21.7/24.6] Observed magnitude in Filtmagphot.magfloate_omag[0.02/0.25] Uncertainty in omagmagstat.error;phot.magfloatExp[150/600] Exposure timestime.duration;obs.exposureintO-C[-0.28/0.31] Fit Residualsmagstat.fit.residualfloatJ/AJ/159/27/table4F606W-band photometry of Manwe-Thorondor with HSTrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintObs[2007/2013] Year of observation, UTtime.epochJD[4306/6618] Julian date of observation, JD-2450000dtime.epochdoubleMmag[23.2/24.1] Manwe HST/WFPC2 F606W magnitudemagphot.mag;em.opt.Rfloatf_Mmag[*] *: rejected measurementmeta.codechare_Mmag[0.05/0.11] Uncertainty in Mmagmagstat.error;phot.mag;em.opt.RfloatTmag[24.2/26.1]? Thorondor HST/WFPC2 F606W magnitudemagphot.mag;em.opt.Rfloatnullablef_Tmag[*] *: rejected measurementmeta.codechare_Tmag[0.05/0.69]? Uncertainty in Tmagmagstat.error;phot.mag;em.opt.RfloatnullableM*mag[22.9/23.5] Pseudo magnitude for Manwe+Thorondor (1)magphot.mag;meta.modelledfloatf_M*mag[*] *: rejected measurementmeta.codechartheta[0.08/1.21] Solar phase angle of the Manwe/Thorondor system ({Theta})degsrc.orbitalfloatSep[0.03/0.33] Separation ({Delta})arcsecpos.angDistance;src.orbitalfloat