J/AJ/160/35 NIR photometry in the T Tauri system with Keck (Schaefer+, 2020) ================================================================================ Orbital motion, variability, and masses in the T Tauri triple system. Schaefer G.H., Beck T.L., Prato L., Simon &.M. =2020AJ....160...35S (SIMBAD/NED BibCode) ================================================================================ ADC_Keywords: Stars, double and multiple; Photometry, infrared Keywords: Binary stars; Multiple stars Abstract: We present results from adaptive optics imaging of the T Tauri triple system obtained at the Keck and Gemini Observatories in 2015-2019. We fit the orbital motion of T Tau Sb relative to Sa and model the astrometric motion of their center of mass relative to T Tau N. Using the distance measured by Gaia, we derived dynamical masses of M_Sa_=2.05{+/-}0.14M_{sun}_ and M_Sb_=0.43{+/-}0.06M_{sun}_. The precision in the masses is expected to improve with continued observations that map the motion through a complete orbital period; this is particularly important as the system approaches periastron passage in 2023. Based on published properties and recent evolutionary tracks, we estimate a mass of ~2M_{sun}_ for T Tau N, suggesting that T Tau N is similar in mass to T Tau Sa. Narrowband infrared photometry shows that T Tau N remained relatively constant between late 2017 and early 2019 with an average value of K=5.54{+/-}0.07mag. Using T Tau N to calibrate relative flux measurements since 2015, we found that T Tau Sa varied dramatically between 7.0 and 8.8mag in the K band over timescales of a few months, while T Tau Sb faded steadily from 8.5 to 11.1mag in the K band. Over the 27yr orbital period of the T Tau S binary, both components have shown 3-4mag of variability in the K band, relative to T Tau N. Description: At the Keck Observatory, natural guide star Adaptive Optics (AO) observations were obtained using the Near InfraRed Camera 2 (NIRC2) narrow-field camera on the Keck II Telescope. At Gemini Observatory, observations were obtained using the Altair AO system and the Near Infra-Red Imager (NIRI) f/32 camera. Images were recorded in the narrowband K continuum filter during every epoch and in narrowband H continuum and L-band emission line filters (Br{alpha} and PAH) during some epochs. Objects: ---------------------------------------------------------------- RA (ICRS) DE Designation(s) ---------------------------------------------------------------- 04 21 59.4323326335 +19 32 06.439974179 T Tauri = V* T Tau 04 21 59.433 +19 32 06.42 T Tau N = NAME T Tau N 04 21 59.371 +19 32 05.95 T Tau Sa = NAME T Tau Sa 04 21 59.371 +19 32 05.95 T Tau Sb = NAME T Tau Sb ---------------------------------------------------------------- File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 84 153 NIR AO measurements of T Tau triple system table2.dat 50 35 Absolute photometry, Gemini observations -------------------------------------------------------------------------------- See also: J/ApJS/165/256 : Fluorescent H_2_ emission from T Tauri stars (Herczeg+, 2006) J/A+A/479/827 : UBVR light curves of weak-line T Tauri stars (Grankin+, 2008) J/ApJ/718/1353 : Light curve of the triple system NLTT 41135 (Irwin+, 2010) J/ApJ/744/121 : Far-UV spectroscopy of T Tau stars (Yang+, 2012) J/MNRAS/434/966 : Measurements of Li in T-Tauri stars (Sergison+, 2013) J/A+A/590/A78 : NGC2264 weak-line T Tauri lithium abundances (Bouvier+, 2016) J/AJ/152/11 : Orbits of four triple stars (Tokovinin, 2016) J/AJ/152/198 : Periods of 4-10Myr old T Tauri mem. of Orion OB1 (Karim+,2016) J/A+A/611/A69 : B,V and R band polarimetry of lambda Tau (Berdyugin+, 2018) J/A+A/622/A72 : Intermediate-mass T Tau stars spectra (Villebrun+, 2019) J/AJ/159/135 : LCs of the binary T Tauri star V582 Mon (Garcia Soto+, 2020) Byte-by-byte Description of file: table1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 4 I4 yr Obs.Y [2015/2019] UT Year of observation 5- 7 A3 "month" Obs.M UT month of observation 8- 9 I2 d Obs.d UT day of observation 12- 20 F9.4 yr JY [2015/2020] Julian Year 23- 27 A5 --- Comp Component identification (1) 30- 35 F6.2 mas Sep [65.2/692]? Separation 38- 42 F5.2 mas e_Sep [0.4/23.7]? Error in Sep 45- 51 F7.3 deg PA [6.25/358]? Position angle 53- 58 F6.3 deg e_PA [0.03/12]? Error in PA 61- 65 A5 --- Filt Filter (2) 68- 73 F6.4 --- Fratio [0.0004/2.94] Flux ratio; f2/f1 76- 81 F6.4 --- e_Fratio [0.0003/0.57] Error in Fratio 84 A1 --- Tel Code for telescope; G=Gemini North (129 occurrences), K=Keck II (24 occurrences) -------------------------------------------------------------------------------- Note (1): Component designation "X,Y" indicates that component Y was measured relative to X. Note (2): Filters as follows: Kcon = K continuum filter (72 occurrences) Hcon = H continuum filter (24 occurrences) BrA = Br{alpha}, L-band emission line filter (54 occurrences) PAH = PAH, L-band emission line filter (3 occurrences) -------------------------------------------------------------------------------- Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 9 F9.4 yr JY [2017/2020] Julian Year 12 A1 --- Filt Filter (5 H-, 16 K- or 14 L-band filter) 15- 18 F4.2 mag MAGN [5.02/6.44] Absolute magnitude of T Tau N 21- 24 F4.2 mag e_MAGN [0.03/1.9] Error in MagN 27- 31 F5.2 mag MAGSa [5/13] Absolute magnitude of T Tau Sa 34- 37 F4.2 mag e_MAGSa [0.08/1.9] Error in MagSa 40- 44 F5.2 mag MAGSb [8.36/13.3] Absolute magnitude of T Tau Sb 47- 50 F4.2 mag e_MAGSb [0.2/3.5] Error in MagSb -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Prepared by [AAS], Coralie Fix [CDS], 12-Oct-2020