J/AJ/150/6ivo://CDS.VizieR/J/AJ/150/6doi:10.26093/cds/vizier.51500006CDSHosey A.D.Henry T.J.Jao W.-C.Dieterich S.B.Winters J.G.,Lurie J.C.Riedel A.R.Subasavage J.P.2024-10-11T20:09:40Z2015-07-27T08:23:16ZCDS support team

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

cds-question@unistra.frdwarf-starsm-starsinfrared-photometryvisible-astronomyphotometrytrigonometric-parallaxWe present an analysis of long-term photometric variability for nearby red dwarf stars at optical wavelengths. The sample consists of 264 M dwarfs south of decl.=+30 with V-K=3.96-9.16 and M_V_~~10-20, corresponding to spectral types M2V-M8V, most of which are within 25pc. The stars have been observed in the VRI filters for ~4-14yr at the CTIO/SMARTS 0.9m telescope. Of the 238 red dwarfs within 25pc, we find that only ~8% are photometrically variable by at least 20mmag (~2%) in the VRI bands. Only four stars have been found to vary by more than 50mmag, including GJ 1207 at 8.6pc, which experienced a single extraordinary flare, and GJ 2006 A, TWA 8 A, and TWA 8 B, which are all young stars beyond 25pc linked to moving groups. We find that high variability at optical wavelengths over the long term can in fact be used to identify young stars. Overall, however, the fluxes of most red dwarfs at optical wavelengths are steady to a few percent over the long term. The low overall rate of photometric variability for red dwarfs is consistent with results found in previous work on similar stars on shorter timescales, with the body of work indicating that most red dwarfs are only mildly variable. As expected, we find that the degree of photometric variability is greater in the V band than in the R or I bands, but we do not find any obvious trends in variability over the long term with red dwarf luminosity or temperature. We highlight 17 stars that show long-term changes in brightness, sometimes because of flaring activity or spots, and sometimes because of stellar cycles similar to our Sun's solar cycle. Remarkably, two targets show brightnesses that monotonically increase (G 169-029) or decrease (WT 460AB) by several percent over a decade. We also provide long-term variability measurements for seven M dwarfs within 25pc that host exoplanets, none of which vary by more than 20mmag. Both as a population, and for the specific red dwarfs with exoplanets observed here, photometric variability is therefore often not a concern for planetary environments, at least at the optical wavelengths where they emit much of their light.2015AJ....150....6Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/150/6CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/AJ/149/5 : Solar neighborhood. XXXV. M dwarfs distances (Winters+, 2015)J/AJ/147/94 : Solar neighborhood. XXXII. L and M dwarfs (Dieterich+, 2014)J/AJ/147/85 : Solar neighborhood. XXXIII. 45 M dwarfs (Riedel+, 2014)J/AJ/141/21 : CCD distance estimates of SCR targets (Winters+, 2011)J/AJ/130/1658 : New high proper motion stars (-47<DE< -00) (Subasavage+, 2005)J/AJ/129/413 : New high proper motion stars (-90<DE< -47) (Subasavage+, 2005)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/150/6https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/150/6http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/150/6https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/150/6https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/150/6http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/150/6GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/150/6/table1 (Red dwarfs studied for long-term variability)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/150/6/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/150/6/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/150/6/table1?GETtext/xml+votable180.050000true1.15-40.733890.0055555555555555566/250 309 1122 4158 4262 4462 4708 4867 8331 8446 9042 9384 10303 12454 16434-16435 16455 16543 16609 16827 16847 16993 17186 17302 17348 17534 17712 17813 17943 17964 18440 18496 18666 18726 18761 19777 19886 20507 20602 20646 20733 21420 21480 21737 21925 22030 22325 22535 22645 22739 23047 23078 23391 23443 23564 23897 24616 24734 24763 24824 24887 25198 25300 25310 25363 25596 25616 25669 25786 25954 26152 26699 26706 26714 26726 27462 27730-27731 28955 29458 29939 30011 30327 30771 30833 31019 32015 32033 32262 32444 32801 32854 33016 33203 33269 33379 33381 33403 33425 33435 33459 33477 33533 33655 33805 33964 34139 34145 34266 34289 34301 34448 34535 34561 34622 34701 34708 34776 34920-34921 34955 35112-35113 35154 35247 35499 35640 35670 35864 35923 35957 36061 36129 36160 36264 36693 36701 36842 36871-36872 36971 37005 37041 37073 37122 37257 37302 37332 37377 37379 37453 37602 37650 37678 38145 38152 38256 38322 38456 38464 38486 38551 38932 39242 39331 39585 40167 40181 40250 40275 40332 40435 40505 40513 40623 40801 40941 41090 41348 41591 42054 42225 42314 42426 42459 42558 42910 43149 43155 43187 43413 43565 43598 43611 43723 43758 43814 43911 44001 44226 44306 44308 44437 44456 44518 44696 44793 44921 44937 45102 45113 45213 45377 45419 45597 45626 45701 45740 45752 45850 45960 46015 46123 46203 46256 46377 46417 46463 46466 46665 46736 46750 46774 46840 46962 46986 47061 47251 47392 47453 47487 47677 47732 48093 48318 48648 48684 48800 48906 48935 48985 49029 490568.650015785639275e-20 3.852589004194616e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/150/6?format=asciiOpticalInfrareddefaultJ/AJ/150/6/table1Red dwarfs studied for long-term variabilityNameName of the red dwarf (1)meta.numbercharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintn_Name'Y' indicates star confirmed to be young in Riedel et al. 2014 (cat. J/AJ/147/85)meta.notecharRAJ2000Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of Declination (J2000)pos.eq.dec;meta.mainVmag[9.6/21.4] Johnson V-band magnitude (2)magphot.mag;em.opt.VfloatRmag[8.7/18.9] Kron-Cousins R-band magnitude (2)magphot.mag;em.opt.RfloatImag[7.3/16.5] Kron-Cousins I-band magnitude (2)magphot.mag;em.opt.Ifloatr_ImagReference for VRI magnitudes (in refs.dat file)meta.ref;pos.framecharCatSources in the VRI reference catalogs within 16''meta.ref.urlintnullableKmag[4.3/12.3] The 2MASS Ks band magnitudemagphot.mag;em.IR.Kfloat2MDisplay the 2MASS data (Cutri et al. 2003, Cat. II/246) within 10''meta.ref.urlcharV-K[3.9/9.2] The (V-Ks) color indexmagphot.color;em.opt.V;em.IR.KfloatFlt[VRI] Filter used in long-term photometry (V_J_, R_KC_, or I_KC_)instr.setup;instr.filtercharAmp[6/197] Photometric variability in Flt (3)mmagsrc.varfloatDate0[1999/2010] First epoch in the data serieyrtime.epochfloatDate1[2003/2014] Last epoch in the data serieyrtime.epochfloatNy[3.8/14.1] Number of years (from the first to last epoch)yrmeta.numberfloatNn[7/63] Number of observational nightsmeta.numberintNf[29/374] Total number of frames (typically ~5 frames per night)meta.numberintplx[20/769]? Trigonometric parallax {pi}_trig_ (4)maspos.parallax.trigfloatnullablee_plx[0.4/4.1]? 1{sigma} uncertainty in plxmasstat.error;pos.parallaxfloatnullabler_plxReference for plx (in refs.dat file)meta.ref;pos.framecharSimbadNameSimbad column added by the CDSmeta.idcharJ/AJ/150/6/refsReferencesAutAuthor's namemeta.bib.authorcharComCommentmeta.notecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRefReference identifierpos.framecharBibCodeBibliographic codemeta.bib.bibcodechar