Stellar kinematics of dwarf galaxies from multi-epoch spectroscopy: application to Triangulum II

Rachel Buttry; Andrew B. Pace; Sergey E. Koposov; Matthew G. Walker; Nelson Caldwell; Evan N. Kirby; Nicolas F. Martin; Mario Mateo; Edward W. Olszewski; Else Starkenburg; Carles Badenes; Christine Mazzola Daher

doi:10.1093/mnras/stac1441

Stellar kinematics of dwarf galaxies from multi-epoch spectroscopy: application to Triangulum II

Rachel Buttry, Andrew B. Pace, Sergey E. Koposov, Matthew G. Walker, Nelson Caldwell, Evan N. Kirby, Nicolas F. Martin, Mario Mateo, Edward W. Olszewski, Else Starkenburg, Carles Badenes, Christine Mazzola Daher

School of Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

Abstract

We present new MMT/Hectochelle spectroscopic measurements for 257 stars observed along the line of sight to the ultra-faint dwarf galaxy Triangulum II. Combining with results from previous Keck/DEIMOS spectroscopy, we obtain a sample that includes 16 likely members of Triangulum 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+3.8−3.3 days , semi-major axis 1.12+0.41−0.24 AU, and a systemic velocity −380.0±1.7 km s−1 that we then use in the analysis of Tri~II's internal kinematics. Despite this improvement in the modeling of binary star systems, the current data remain insufficient to resolve the velocity dispersion of Triangulum II. We instead find a 95% confidence upper limit of σv≲3.4 km s−1.

Original language	English
Pages (from-to)	1706-1719
Number of pages	14
Journal	Monthly Notices of the Royal Astronomical Society
Volume	514
Issue number	2
Early online date	30 May 2022
DOIs	https://doi.org/10.1093/mnras/stac1441
Publication status	Published - 1 Aug 2022

Keywords / Materials (for Non-textual outputs)

binaries: spectroscopic
galaxies: kinematics and dynamics

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10.1093/mnras/stac1441

2108.10867v2Accepted author manuscript, 1.12 MBLicence: Creative Commons: Attribution (CC-BY)

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Buttry, R., Pace, A. B., Koposov, S. E., Walker, M. G., Caldwell, N., Kirby, E. N., Martin, N. F., Mateo, M., Olszewski, E. W., Starkenburg, E., Badenes, C., & Daher, C. M. (2022). Stellar kinematics of dwarf galaxies from multi-epoch spectroscopy: application to Triangulum II. Monthly Notices of the Royal Astronomical Society , 514(2), 1706-1719. https://doi.org/10.1093/mnras/stac1441

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title = "Stellar kinematics of dwarf galaxies from multi-epoch spectroscopy: application to Triangulum II",

abstract = "We present new MMT/Hectochelle spectroscopic measurements for 257 stars observed along the line of sight to the ultra-faint dwarf galaxy Triangulum II. Combining with results from previous Keck/DEIMOS spectroscopy, we obtain a sample that includes 16 likely members of Triangulum 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+3.8−3.3 days , semi-major axis 1.12+0.41−0.24 AU, and a systemic velocity −380.0±1.7 km s−1 that we then use in the analysis of Tri~II's internal kinematics. Despite this improvement in the modeling of binary star systems, the current data remain insufficient to resolve the velocity dispersion of Triangulum II. We instead find a 95% confidence upper limit of σv≲3.4 km s−1. ",

keywords = "binaries: spectroscopic, galaxies: kinematics and dynamics",

author = "Rachel Buttry and Pace, {Andrew B.} and Koposov, {Sergey E.} and Walker, {Matthew G.} and Nelson Caldwell and Kirby, {Evan N.} and Martin, {Nicolas F.} and Mario Mateo and Olszewski, {Edward W.} and Else Starkenburg and Carles Badenes and Daher, {Christine Mazzola}",

note = "Publisher Copyright: {\textcopyright} 2022 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.",

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doi = "10.1093/mnras/stac1441",

language = "English",

volume = "514",

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Buttry, R, Pace, AB, Koposov, SE, Walker, MG, Caldwell, N, Kirby, EN, Martin, NF, Mateo, M, Olszewski, EW, Starkenburg, E, Badenes, C & Daher, CM 2022, 'Stellar kinematics of dwarf galaxies from multi-epoch spectroscopy: application to Triangulum II', Monthly Notices of the Royal Astronomical Society , vol. 514, no. 2, pp. 1706-1719. https://doi.org/10.1093/mnras/stac1441

TY - JOUR

T1 - Stellar kinematics of dwarf galaxies from multi-epoch spectroscopy: 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

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 ultra-faint dwarf galaxy Triangulum II. Combining with results from previous Keck/DEIMOS spectroscopy, we obtain a sample that includes 16 likely members of Triangulum 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+3.8−3.3 days , semi-major axis 1.12+0.41−0.24 AU, and a systemic velocity −380.0±1.7 km s−1 that we then use in the analysis of Tri~II's internal kinematics. Despite this improvement in the modeling of binary star systems, the current data remain insufficient to resolve the velocity dispersion of Triangulum II. We instead find a 95% confidence upper limit of σv≲3.4 km s−1.

AB - We present new MMT/Hectochelle spectroscopic measurements for 257 stars observed along the line of sight to the ultra-faint dwarf galaxy Triangulum II. Combining with results from previous Keck/DEIMOS spectroscopy, we obtain a sample that includes 16 likely members of Triangulum 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+3.8−3.3 days , semi-major axis 1.12+0.41−0.24 AU, and a systemic velocity −380.0±1.7 km s−1 that we then use in the analysis of Tri~II's internal kinematics. Despite this improvement in the modeling of binary star systems, the current data remain insufficient to resolve the velocity dispersion of Triangulum II. We instead find a 95% confidence upper limit of σv≲3.4 km s−1.

KW - binaries: spectroscopic

KW - galaxies: kinematics and dynamics

U2 - 10.1093/mnras/stac1441

DO - 10.1093/mnras/stac1441

M3 - Article

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 -

Stellar kinematics of dwarf galaxies from multi-epoch spectroscopy: application to Triangulum II

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