TY - JOUR
T1 - Stellar kinematics of dwarf galaxies from multi-epoch spectroscopy
T2 - application to Triangulum II
AU - Buttry, Rachel
AU - Pace, Andrew B.
AU - Koposov, Sergey E.
AU - Walker, Matthew G.
AU - Caldwell, Nelson
AU - Kirby, Evan N.
AU - Martin, Nicolas F.
AU - Mateo, Mario
AU - Olszewski, Edward W.
AU - Starkenburg, Else
AU - Badenes, Carles
AU - Daher, Christine Mazzola
N1 - Publisher Copyright:
© 2022 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
PY - 2022/8/1
Y1 - 2022/8/1
N2 - We present new MMT/Hectochelle spectroscopic measurements for 257 stars observed along the line of sight to the ultrafaint dwarf galaxy Triangulum II (Tri II). Combining results from previous Keck/DEIMOS spectroscopy, we obtain a sample that includes 16 likely members of Tri II, with up to 10 independent redshift measurements per star. To this multi-epoch kinematic data set, we apply methodology that we develop in order to infer binary orbital parameters from sparsely sampled radial velocity curves with as few as two epochs. For a previously identified (spatially unresolved) binary system in Tri II, we infer an orbital solution with period 296.0-3.3+3.8 d, semimajor axis 1.12+0.41-0.24 au, and systemic velocity-380.0 ± 1.7 kms-1 that we then use in the analysis of Tri II's internal kinematics. Despite this improvement in the modelling of binary star systems, the current data remain insufficient to resolve the velocity dispersion of Tri II. We instead find a 95 per cent confidence upper limit of σv ≤ 3.4 kms-1.
AB - We present new MMT/Hectochelle spectroscopic measurements for 257 stars observed along the line of sight to the ultrafaint dwarf galaxy Triangulum II (Tri II). Combining results from previous Keck/DEIMOS spectroscopy, we obtain a sample that includes 16 likely members of Tri II, with up to 10 independent redshift measurements per star. To this multi-epoch kinematic data set, we apply methodology that we develop in order to infer binary orbital parameters from sparsely sampled radial velocity curves with as few as two epochs. For a previously identified (spatially unresolved) binary system in Tri II, we infer an orbital solution with period 296.0-3.3+3.8 d, semimajor axis 1.12+0.41-0.24 au, and systemic velocity-380.0 ± 1.7 kms-1 that we then use in the analysis of Tri II's internal kinematics. Despite this improvement in the modelling of binary star systems, the current data remain insufficient to resolve the velocity dispersion of Tri II. We instead find a 95 per cent confidence upper limit of σv ≤ 3.4 kms-1.
KW - binaries: spectroscopic
KW - galaxies: kinematics and dynamics
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U2 - 10.1093/mnras/stac1441
DO - 10.1093/mnras/stac1441
M3 - Article
AN - SCOPUS:85133618013
SN - 0035-8711
VL - 514
SP - 1706
EP - 1719
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 2
ER -