J/AJ/168/143ivo://CDS.VizieR/J/AJ/168/143doi:10.26093/cds/vizier/be-58-4fCDSReipurth B.Briceno C.Geballe T.R.Baranec C.Mikkola S.Cody A.M.,Connelley M.S.Flores C.Skiff B.A.Armstrong J.D.Law N.M.,Riddle R.2026-07-02T11:44:51Z2025-05-27T08:02:10ZCDS support team

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

cds-question@unistra.frpre-main-sequence-starsmultiple-starsinfrared-astronomyspectroscopyvisible-astronomyWe have discovered that the H{alpha} emission-line star Haro 5-2, located in the 3-6Myr old Ori OB1b association, is a young quadruple system. The system has a 2+2 configuration, with an outer separation of 2.6" and with resolved subarcsecond inner binary components. The brightest component, Aa, dominates the A-binary; it is a weak-line T Tauri star with spectral type M2.5+/-1. The two stars of the B component are equally bright at J, but the Bb star is much redder. Optical spectroscopy of the combined B pair indicates a rich emission-line spectrum with a M3+/-1 spectral type. The spectrum is highly variable and switches back and forth between a classical and a weak-line T Tauri star. In the near-IR, the spectrum shows Paschen {beta} and Brackett {gamma} in emission, indicative of active accretion. A significant mid-IR excess reveals the presence of circumstellar or circumbinary material in the system. Most multiple systems are likely formed during the protostellar phase, involving flybys of neighboring stars followed by an inspiraling phase driven by accretion from circumbinary material and leading to compact subsystems. However, Haro 5-2 stands out among young 2+2 quadruples, as the two inner binaries are unusually wide relative to the separation of the A and B pair, allowing future studies of the individual components. Assuming the components are coeval, the system could potentially allow stringent tests of pre-main-sequence evolutionary models.2024AJ....168..143Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/168/143CatalogResearchIsServedByTAP VizieR generic servicerelated-toB/wds : The Washington Visual Double Star Catalog (Mason+ 2001-2020)IV/39 : TESS Input Catalog version 8.2 (TIC v8.2) (Paegert+, 2021)J/AJ/106/1059 : Lithium in the Pleiades (Soderblom+, 1993)J/A+A/478/667 : The Mayrit catalogue (Caballero, 2008)J/A+A/485/931 : Young stars and brown dwarfs in Ori OB1b (Caballero+, 2008)J/ApJS/190/1 : A survey of stellar families (Raghavan+, 2010)J/A+A/526/A21 : Collinder 69 X-ray sources (Barrado+, 2011)J/PASJ/63/S1 : Atlas & catalog 2MASS dark clouds (Dobashi+, 2011)J/A+A/527/A24 : Spectra of low-mass stars in Upper Sco (Lodieu+, 2011)J/AJ/146/85 : Spectral types of optical stars in ONC (Hillenbrand+, 2013)J/AJ/147/82 : Monitoring of disk-bearing stars in NGC 2264 (Cody+, 2014)J/ApJ/786/97 : Photospheric properties of T Tauri stars (Herczeg+, 2014)J/ApJ/794/36 : {sigma} Orionis cluster star population (Hernandez+, 2014)J/A+A/570/A30 : H{alpha} emission-line stars in M42 (Pettersson+, 2014)J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)J/AJ/147/87 : Binaries to multiples II. Statistical data (Tokovinin, 2014)J/AJ/150/100 : WISE YSO candidates, {sigma} & {lambda} Ori (Koenig+, 2015)J/ApJ/799/4 : Robo-AO observations of binary stars (Riddle+, 2015)J/AJ/152/213 : Interferometry & spectroscopy: {sigma} Ori (Schaefer+, 2016)J/MNRAS/469/3881 : Embedded binaries and their dense cores (Sadavoy+, 2017)J/AJ/154/14 : Low-mass stars in 25 Ori group & Orion OB1a (Suarez+, 2017)J/AJ/156/84 : APOGEE-2 survey of Orion Complex. II. (Kounkel+, 2018)J/AJ/157/85 : The CIDA Variab. Survey of Orion OB1. II. (Briceno+, 2019)J/AJ/158/95 : V348 And & V572 Per: heliocentric min & RVs (Zasche+, 2019)J/ApJ/925/21 : IRTF/iSHELL K-band sp. obs. of PMS stars (Flores+, 2022)J/ApJS/259/66 : Eclipsing quadruple star candidates: TESS (Kostov+, 2022)J/AJ/164/58 : Speckle Interferometry at SOAR in 2021 (Tokovinin+, 2022)J/A+A/682/A164 : Double eclipsing binaries from ZTF (Vaessen+, 2024)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/168/143https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/168/143http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/168/143https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/168/143https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/168/143http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/168/143GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticalInfrareddefaultJ/AJ/168/143/table1SOAR Goodman optical GHTS observations of Haro 5-2recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintComp[AB] Haro 5-2 Componentmeta.code.multipcharDateDate of observation (UT)'Y:M:D'time.epochnullableSetupInstrument setup (1)instr.setupcharResResolution ("low" or "high"); column added by CDS for technical purpose (1)pos.angResolutioncharSlitSlit widtharcsecspect.line.widthcharBinBinninginstr.setupcharNexp[1/3] Number of exposuremeta.numberintExp[120/1200] Exposure timestime.duration;obs.exposureintFileName of the FITS file in subdirectory "sp"; column added by CDSmeta.id;meta.fitscharfitsDownload the FITS filemeta.ref.urlcharspInteractive spectrum plotmeta.ref.urlcharJ/AJ/168/143/table2Equivalent Widths in SOAR low-resolution spectra of Haro 5-2recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintComp[AB] Haro 5-2 Componentmeta.code.multipcharSpTSpectral Typesrc.spTypecharTTS[CW] (C)lassical or (W)eak-lined T-Tauri starmeta.code.classcharDateUT Observation date'Y:M:D'time.epoch;obsnullableEWHa[-37.5/-3.3] Equivalent Width, H{alpha}0.1nmspect.line.eqWidth;em.line.Halphafloate_EWHa[0.1/2.0] Uncertainty in EWHa0.1nmstat.error;spect.line.eqWidth;em.line.HalphafloatEWHb[-12.0/-1.8] Equivalent Width, H{beta}0.1nmspect.line.eqWidth;em.line.Hbetafloate_EWHb[0.1/2.0] Uncertainty in EWHb0.1nmstat.error;spect.line.eqWidth;em.line.HbetafloatEWLi[0.2/0.4] Equivalent Width, Li0.1nmspect.line.eqWidthfloate_EWLi[0.1/0.1] Uncertainty in EWLi0.1nmstat.error;spect.line.eqWidthfloatEWNaI[1.2/1.8]? Equivalent Width, NaI (1)0.1nmspect.line.eqWidthfloatnullablee_EWNaI[0.1/0.1]? Uncertainty in EWNaI (1)0.1nmstat.error;spect.line.eqWidthfloatnullableEWCaII84[-2.34/0.6]? Equivalent Width, CaII 8498{AA}0.1nmspect.line.eqWidthfloatnullablee_EWCaII84[0.1/0.1]? Uncertainty in EWCaII840.1nmstat.error;spect.line.eqWidthfloatnullableEWCaII85[-1.6/1.3]? Equivalent Width, CaII 8542{AA}0.1nmspect.line.eqWidthfloatnullablee_EWCaII85[0.1/0.2]? Uncertainty in EWCaII850.1nmstat.error;spect.line.eqWidthfloatnullableEWCaII86[-1.3/1.0]? Equivalent Width, CaII 8662{AA}0.1nmspect.line.eqWidthfloatnullablee_EWCaII86[0.1/0.1]? Uncertainty in EWCaII860.1nmstat.error;spect.line.eqWidthfloatnullableJ/AJ/168/143/fig8List of SOAR TripleSpec NIR spectralambda2[1.2/2.5] Upper wavelength rangeumem.wl;stat.maxfloatspInteractive spectrum plotmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintComp[AB] Haro 5-2 Componentmeta.code.multipcharDateDate of observation (UT)'Y:M:D'time.epochnullableFileName of the FITS file in subdirectory "sp"meta.id;meta.fitscharfitsDownload the FITS filemeta.ref.urlcharlambda1[0.9/1.9] Lower wavelength rangeumem.wl;stat.minfloatJ/AJ/168/143/fig9aH-band spectra of the individual Ba component resolved with adaptive optics and GNIRS at the Gemini-North 8m telescoperecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintWave[1.45/1.8] Wavelength, micronsumem.wldoubleFlux[1.6e-15/7.5e-15] FluxW.m**-2.um**-1phot.flux;em.IR.HdoubleJ/AJ/168/143/fig9bH-band spectra of the individual Bb component resolved with adaptive optics and GNIRS at the Gemini-North 8m telescoperecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintWave[1.45/1.8] Wavelength, micronsumem.wldoubleFlux[1.6e-15/7.5e-15] FluxW.m**-2.um**-1phot.flux;em.IR.Hdouble