J/ApJ/901/9ivo://CDS.VizieR/J/ApJ/901/9doi:10.26093/cds/vizier.19010009CDSHrivnak B.J.Henson G.Hillwig T.C.Lu W.Nault K.A.Volk K.2024-10-25T20:14:01Z2022-02-15T14:10:15ZCDS support team

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

cds-question@unistra.frplanetary-nebulaeinfrared-photometryvisible-astronomyphotometrystellar-spectral-typesWe have monitored over a 10-year interval the light variations of five evolved stars with very large mid-infrared excesses. All five objects appear to have oxygen-rich or mixed oxygen-rich and carbon-rich chemistries. They all vary in light: four over a small range of ~0.2mag and the fifth over a larger range of ~0.7mag. Spectral types range from G2 to B0. Periodic pulsations are found for the first time in the three cooler ones, IRAS18075-0924 (123d), 19207+2023 (96d), and 20136+1309 (142d). No significant periodicity is found in the hotter ones, but they appear to vary on a shorter timescale of a few days or less. Two also show some evidence of longer-term periodic variations (~4yr). Three appear to be protoplanetary nebulae (PPNe), in the post-asymptotic giant branch (post-AGB) phase of stellar evolution. Their light variations are in general agreement with the relationships among temperature, pulsation period, and pulsation amplitude found in previously studied PPNe. The other two, however, appear to have too low a luminosity (1000-1500L_{sun}_), based on Gaia distances, to be in the post-AGB phase. Instead, they appear to be Milky Way analogs of the recently identified class of dusty post-red giant branch (post-RGB) stars found in the Magellanic Clouds, which likely had their evolution interrupted by interaction with a binary companion. If this is the case, then these would be among the first dusty post-RGB objects identified in the the Milky Way.2020ApJ...901....9Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/901/9CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/118 : UBVRI standards around Celestial Equator (Landolt 1983)II/125 : IRAS catalogue of Point Sources, Version 2.0 (IPAC 1986)II/183 : UBVRI Photometric Standards (Landolt 1992)II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)I/305 : The Guide Star Catalog, Version 2.3.2 (GSC2.3) (STScI, 2006)I/347 : Distances to 1.33 billion stars in Gaia DR2 (Bailer-Jones+, 2018)J/ApJS/92/125 : Post-AGB evolution (Vassiliadis+, 1994)J/A+A/299/755 : Stellar evolution. II. Post-AGB (Bloecker+, 1995)J/A+A/458/173 : Optical spectroscopy of 253 IRAS sources (Suarez+, 2006)J/PAZh/36/281 : Variability of 3 protoplanetary nebulae (Arkhipova+, 2010)J/ApJ/709/1042 : Variability in C-rich proto-PNe. (Hrivnak+, 2010)J/ApJ/766/116 : Variability in proto-PNe. II. (Hrivnak+, 2013)J/MNRAS/439/2211 : Post-AGB/RGB and YSOs in SMC (Kamath+, 2014)J/ApJ/794/81 : Maser and IR studies of oxygen-rich AGB stars (Yung+, 2014)J/AJ/149/184 : Long-term photometry for 4 O-rich PPne (Hrivnak+, 2015)J/MNRAS/454/1468 : LMC post-AGB, post-RGB star and YSOs (Kamath+, 2015)J/MNRAS/447/1673 : Galactic post-AGB stars distances (Vickers+, 2015)J/A+A/588/A25 : Post-AGB & CSPNe models (Miller Bertolami, 2016)J/ApJ/826/44 : Spitzer/IRS obs. of Magellanic carbon stars (Sloan+, 2016)J/AJ/156/300 : Velocity and LC analysis of three PPNe (Hrivnak+, 2018)J/AJ/159/21 : V and Rc light curves of medium-bright PPNe (Hrivnak+, 2020)J/A+A/649/A164 : Protoplanetary nebulae & young PN CO sp. (Lorenzo+, 2021)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/901/9https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/901/9http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/901/9https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/901/9https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/901/9http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/901/9GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/901/9/table1 (List of protoplanetary nebula (PPN) targets observed)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/901/9/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/901/9/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/901/9/table1?GETtext/xml+votable180.050000true272.5630833-9.39308330.0055555555555555566/12813 29545 30652 30682 320933.322582951404819e-19 3.852589004194616e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/901/9?format=asciiOpticalInfrareddefaultJ/ApJ/901/9/table1List of protoplanetary nebula (PPN) targets observedSimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNpNumber of photometry measurements (link to Table A2)meta.numberintnullableIRASIRAS name (HHMMm+DDMM)meta.id;meta.maincharprimaryGSCGSC2.3.2 identifiermeta.id.crosschar2MASS2MASS name (JHHMMSSss+DDMMSSs)meta.id.crosscharRAJ20002MASS hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ20002MASS degree of declination (J2000)pos.eq.dec;meta.mainGLON[19.8/54.8] Galactic longitudedegpos.galactic.lonGLAT[-12/4.7] Galactic latitudedegpos.galactic.latfloatVmag[13.4/15.2] Johnson V magnitude (1)magphot.mag;em.opt.VfloatB-V[1/2.5] B-V color index (1)magphot.color;em.opt.B;em.opt.Vfloatu_B-V[:] : uncertainty flag on B-Vmeta.code.error;phot.color;em.opt.BcharSpTSpectral typesrc.spTypecharr_SpTFlag on SpT (2)meta.ref;pos.framecharSpT2Second spectral type for IRAS 20136+1309src.spTypecharr_SpT2Flag on second spectral type (2)meta.ref;pos.framecharS06Display data from Suarez+, 2006, J/A+A/458/173meta.ref.urlintnullableLCInteractive LC Plotmeta.ref.urlcharJ/ApJ/901/9/tablea2Differential standard magnitudesIRASIRAS name of PPN targetmeta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJDV[49558.7/58311.8]? Heliocentric Julian Date of V band; HJDV-2400000dtime.epochdoublenullableDelV[-0.08/1.88]? Differential V band magnitude (1)magphot.mag;arith.difffloatnullableHJDRc[49873.8/58311.8]? Heliocentric Julian Date of R_c_ band; HJDRc-2400000dtime.epochdoublenullableDelRc[-0.5/0.97]? Differential R_c_ band magnitude (1)magphot.mag;arith.difffloatnullableCodeTelescope-Detector-filter system code (2)meta.codechar