Nearest Neighbor: The Low-mass Milky Way Satellite Tucana III

J. D. Simon; T. S. Li; A. Drlica-Wagner; K. Bechtol; J. L. Marshall; D. J. James; M. Y. Wang; L. Strigari; E. Balbinot; K. Kuehn; A. R. Walker; T. M.C. Abbott; S. Allam; J. Annis; A. Benoit-Lévy; D. Brooks; E. Buckley-Geer; D. L. Burke; A. Carnero Rosell; M. Carrasco Kind; J. Carretero; C. E. Cunha; C. B. D'Andrea; L. N.Da Costa; D. L. Depoy; S. Desai; P. Doel; E. Fernandez; B. Flaugher; J. Frieman; J. García-Bellido; E. Gaztanaga; D. A. Goldstein; D. Gruen; G. Gutierrez; N. Kuropatkin; M. A.G. Maia; P. Martini; F. Menanteau; C. J. Miller; R. Miquel; E. Neilsen; B. Nord; R. Ogando; A. A. Plazas; A. K. Romer; E. S. Rykoff; E. Sanchez; B. Santiago; V. Scarpine; M. Schubnell; I. Sevilla-Noarbe; R. C. Smith; F. Sobreira; E. Suchyta; M. E.C. Swanson; G. Tarle; L. Whiteway; B. Yanny

doi:10.3847/1538-4357/aa5be7

Nearest Neighbor: The Low-mass Milky Way Satellite Tucana III

J. D. Simon, T. S. Li, A. Drlica-Wagner, K. Bechtol, J. L. Marshall, D. J. James, M. Y. Wang, L. Strigari, E. Balbinot, K. Kuehn, A. R. Walker, T. M.C. Abbott, S. Allam, J. Annis, A. Benoit-Lévy, D. Brooks, E. Buckley-Geer, D. L. Burke, A. Carnero Rosell, M. Carrasco KindJ. Carretero, C. E. Cunha, C. B. D'Andrea, L. N.Da Costa, D. L. Depoy, S. Desai, P. Doel, E. Fernandez, B. Flaugher, J. Frieman, J. García-Bellido, E. Gaztanaga, D. A. Goldstein, D. Gruen, G. Gutierrez, N. Kuropatkin, M. A.G. Maia, P. Martini, F. Menanteau, C. J. Miller, R. Miquel, E. Neilsen, B. Nord, R. Ogando, A. A. Plazas, A. K. Romer, E. S. Rykoff, E. Sanchez, B. Santiago, V. Scarpine, M. Schubnell, I. Sevilla-Noarbe, R. C. Smith, F. Sobreira, E. Suchyta, M. E.C. Swanson, G. Tarle, L. Whiteway, B. Yanny

Workflow Systems

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

87 Scopus citations

Abstract

We present Magellan/IMACS spectroscopy of the recently discovered Milky Way satellite Tucana III (Tuc III). We identify 26 member stars in Tuc III from which we measure a mean radial velocity of v _hel = -102.3 ±0.4 (stat.) ±2.0 (sys.)km ^s-1, a velocity dispersion of 0.1^+0.7 _-0.1 km ^s-1, and a mean metallicity of (Fe/H)= -2.42^+0.07 _-0.08. The upper limit on the velocity dispersion is σ < 1.5 at 95.5% confidence, and the corresponding upper limit on the mass within the half-light radius of Tuc III is 9.0 × 10⁴ M _o. We cannot rule out mass-to-light ratios as large as 240 M _oL/_o for Tuc III, but much lower mass-to-light ratios that would leave the system baryon-dominated are also allowed. We measure an upper limit on the metallicity spread of the stars in Tuc III of 0.19 dex at 95.5% confidence. Tuc III has a smaller metallicity dispersion and likely a smaller velocity dispersion than any known dwarf galaxy, but a larger size and lower surface brightness than any known globular cluster. Its metallicity is also much lower than those of the clusters with similar luminosity. We therefore tentatively suggest that Tuc III is the tidally stripped remnant of a dark matter-dominated dwarf galaxy, but additional precise velocity and metallicity measurements will be necessary for a definitive classification. If Tuc III is indeed a dwarf galaxy, it is one of the closest external galaxies to the Sun. Because of its proximity, the most luminous stars in Tuc III are quite bright, including one star at V = 15.7 that is the brightest known member star of an ultra-faint satellite.

Original language	English
Article number	11
Journal	Astrophysical Journal
Volume	838
Issue number	1
DOIs	https://doi.org/10.3847/1538-4357/aa5be7
State	Published - Mar 20 2017

Funding

This publication is based upon work supported by the National Science Foundation under grant AST-1108811. We thank Dan Kelson for many helpful conversations regarding IMACS data reduction and the anonymous referee for suggestions that improved the paper. E.B. acknowledges financial support from the European Research Council (ERC-StG-335936).

Funders	Funder number
National Science Foundation	AST-1108811
Seventh Framework Programme	1138766, 335936, 1108811
European Research Council

Keywords

Local Group
dark matter
galaxies: dwarf
galaxies: individual (Tucana III)
galaxies: stellar content
stars: abundances

Access to Document

10.3847/1538-4357/aa5be7

Cite this

Simon, J. D., Li, T. S., Drlica-Wagner, A., Bechtol, K., Marshall, J. L., James, D. J., Wang, M. Y., Strigari, L., Balbinot, E., Kuehn, K., Walker, A. R., Abbott, T. M. C., Allam, S., Annis, J., Benoit-Lévy, A., Brooks, D., Buckley-Geer, E., Burke, D. L., Rosell, A. C., ... Yanny, B. (2017). Nearest Neighbor: The Low-mass Milky Way Satellite Tucana III. Astrophysical Journal, 838(1), Article 11. https://doi.org/10.3847/1538-4357/aa5be7

@article{0b4804dc2f2a4093883899612067bfde,

title = "Nearest Neighbor: The Low-mass Milky Way Satellite Tucana III",

abstract = "We present Magellan/IMACS spectroscopy of the recently discovered Milky Way satellite Tucana III (Tuc III). We identify 26 member stars in Tuc III from which we measure a mean radial velocity of v hel = -102.3 ±0.4 (stat.) ±2.0 (sys.)km s-1, a velocity dispersion of 0.1+0.7 -0.1 km s-1, and a mean metallicity of (Fe/H)= -2.42+0.07 -0.08. The upper limit on the velocity dispersion is σ < 1.5 at 95.5% confidence, and the corresponding upper limit on the mass within the half-light radius of Tuc III is 9.0 × 104 M o. We cannot rule out mass-to-light ratios as large as 240 M oL/o for Tuc III, but much lower mass-to-light ratios that would leave the system baryon-dominated are also allowed. We measure an upper limit on the metallicity spread of the stars in Tuc III of 0.19 dex at 95.5% confidence. Tuc III has a smaller metallicity dispersion and likely a smaller velocity dispersion than any known dwarf galaxy, but a larger size and lower surface brightness than any known globular cluster. Its metallicity is also much lower than those of the clusters with similar luminosity. We therefore tentatively suggest that Tuc III is the tidally stripped remnant of a dark matter-dominated dwarf galaxy, but additional precise velocity and metallicity measurements will be necessary for a definitive classification. If Tuc III is indeed a dwarf galaxy, it is one of the closest external galaxies to the Sun. Because of its proximity, the most luminous stars in Tuc III are quite bright, including one star at V = 15.7 that is the brightest known member star of an ultra-faint satellite.",

keywords = "Local Group, dark matter, galaxies: dwarf, galaxies: individual (Tucana III), galaxies: stellar content, stars: abundances",

author = "Simon, {J. D.} and Li, {T. S.} and A. Drlica-Wagner and K. Bechtol and Marshall, {J. L.} and James, {D. J.} and Wang, {M. Y.} and L. Strigari and E. Balbinot and K. Kuehn and Walker, {A. R.} and Abbott, {T. M.C.} and S. Allam and J. Annis and A. Benoit-L{\'e}vy and D. Brooks and E. Buckley-Geer and Burke, {D. L.} and Rosell, {A. Carnero} and Kind, {M. Carrasco} and J. Carretero and Cunha, {C. E.} and D'Andrea, {C. B.} and Costa, {L. N.Da} and Depoy, {D. L.} and S. Desai and P. Doel and E. Fernandez and B. Flaugher and J. Frieman and J. Garc{\'i}a-Bellido and E. Gaztanaga and Goldstein, {D. A.} and D. Gruen and G. Gutierrez and N. Kuropatkin and Maia, {M. A.G.} and P. Martini and F. Menanteau and Miller, {C. J.} and R. Miquel and E. Neilsen and B. Nord and R. Ogando and Plazas, {A. A.} and Romer, {A. K.} and Rykoff, {E. S.} and E. Sanchez and B. Santiago and V. Scarpine and M. Schubnell and I. Sevilla-Noarbe and Smith, {R. C.} and F. Sobreira and E. Suchyta and Swanson, {M. E.C.} and G. Tarle and L. Whiteway and B. Yanny",

year = "2017",

month = mar,

day = "20",

doi = "10.3847/1538-4357/aa5be7",

language = "English",

volume = "838",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "American Astronomical Society",

number = "1",

}

Simon, JD, Li, TS, Drlica-Wagner, A, Bechtol, K, Marshall, JL, James, DJ, Wang, MY, Strigari, L, Balbinot, E, Kuehn, K, Walker, AR, Abbott, TMC, Allam, S, Annis, J, Benoit-Lévy, A, Brooks, D, Buckley-Geer, E, Burke, DL, Rosell, AC, Kind, MC, Carretero, J, Cunha, CE, D'Andrea, CB, Costa, LND, Depoy, DL, Desai, S, Doel, P, Fernandez, E, Flaugher, B, Frieman, J, García-Bellido, J, Gaztanaga, E, Goldstein, DA, Gruen, D, Gutierrez, G, Kuropatkin, N, Maia, MAG, Martini, P, Menanteau, F, Miller, CJ, Miquel, R, Neilsen, E, Nord, B, Ogando, R, Plazas, AA, Romer, AK, Rykoff, ES, Sanchez, E, Santiago, B, Scarpine, V, Schubnell, M, Sevilla-Noarbe, I, Smith, RC, Sobreira, F, Suchyta, E, Swanson, MEC, Tarle, G, Whiteway, L & Yanny, B 2017, 'Nearest Neighbor: The Low-mass Milky Way Satellite Tucana III', Astrophysical Journal, vol. 838, no. 1, 11. https://doi.org/10.3847/1538-4357/aa5be7

TY - JOUR

T1 - Nearest Neighbor

T2 - The Low-mass Milky Way Satellite Tucana III

AU - Simon, J. D.

AU - Li, T. S.

AU - Drlica-Wagner, A.

AU - Bechtol, K.

AU - Marshall, J. L.

AU - James, D. J.

AU - Wang, M. Y.

AU - Strigari, L.

AU - Balbinot, E.

AU - Kuehn, K.

AU - Walker, A. R.

AU - Abbott, T. M.C.

AU - Allam, S.

AU - Annis, J.

AU - Benoit-Lévy, A.

AU - Brooks, D.

AU - Buckley-Geer, E.

AU - Burke, D. L.

AU - Rosell, A. Carnero

AU - Kind, M. Carrasco

AU - Carretero, J.

AU - Cunha, C. E.

AU - D'Andrea, C. B.

AU - Costa, L. N.Da

AU - Depoy, D. L.

AU - Desai, S.

AU - Doel, P.

AU - Fernandez, E.

AU - Flaugher, B.

AU - Frieman, J.

AU - García-Bellido, J.

AU - Gaztanaga, E.

AU - Goldstein, D. A.

AU - Gruen, D.

AU - Gutierrez, G.

AU - Kuropatkin, N.

AU - Maia, M. A.G.

AU - Martini, P.

AU - Menanteau, F.

AU - Miller, C. J.

AU - Miquel, R.

AU - Neilsen, E.

AU - Nord, B.

AU - Ogando, R.

AU - Plazas, A. A.

AU - Romer, A. K.

AU - Rykoff, E. S.

AU - Sanchez, E.

AU - Santiago, B.

AU - Scarpine, V.

AU - Schubnell, M.

AU - Sevilla-Noarbe, I.

AU - Smith, R. C.

AU - Sobreira, F.

AU - Suchyta, E.

AU - Swanson, M. E.C.

AU - Tarle, G.

AU - Whiteway, L.

AU - Yanny, B.

PY - 2017/3/20

Y1 - 2017/3/20

N2 - We present Magellan/IMACS spectroscopy of the recently discovered Milky Way satellite Tucana III (Tuc III). We identify 26 member stars in Tuc III from which we measure a mean radial velocity of v hel = -102.3 ±0.4 (stat.) ±2.0 (sys.)km s-1, a velocity dispersion of 0.1+0.7 -0.1 km s-1, and a mean metallicity of (Fe/H)= -2.42+0.07 -0.08. The upper limit on the velocity dispersion is σ < 1.5 at 95.5% confidence, and the corresponding upper limit on the mass within the half-light radius of Tuc III is 9.0 × 104 M o. We cannot rule out mass-to-light ratios as large as 240 M oL/o for Tuc III, but much lower mass-to-light ratios that would leave the system baryon-dominated are also allowed. We measure an upper limit on the metallicity spread of the stars in Tuc III of 0.19 dex at 95.5% confidence. Tuc III has a smaller metallicity dispersion and likely a smaller velocity dispersion than any known dwarf galaxy, but a larger size and lower surface brightness than any known globular cluster. Its metallicity is also much lower than those of the clusters with similar luminosity. We therefore tentatively suggest that Tuc III is the tidally stripped remnant of a dark matter-dominated dwarf galaxy, but additional precise velocity and metallicity measurements will be necessary for a definitive classification. If Tuc III is indeed a dwarf galaxy, it is one of the closest external galaxies to the Sun. Because of its proximity, the most luminous stars in Tuc III are quite bright, including one star at V = 15.7 that is the brightest known member star of an ultra-faint satellite.

AB - We present Magellan/IMACS spectroscopy of the recently discovered Milky Way satellite Tucana III (Tuc III). We identify 26 member stars in Tuc III from which we measure a mean radial velocity of v hel = -102.3 ±0.4 (stat.) ±2.0 (sys.)km s-1, a velocity dispersion of 0.1+0.7 -0.1 km s-1, and a mean metallicity of (Fe/H)= -2.42+0.07 -0.08. The upper limit on the velocity dispersion is σ < 1.5 at 95.5% confidence, and the corresponding upper limit on the mass within the half-light radius of Tuc III is 9.0 × 104 M o. We cannot rule out mass-to-light ratios as large as 240 M oL/o for Tuc III, but much lower mass-to-light ratios that would leave the system baryon-dominated are also allowed. We measure an upper limit on the metallicity spread of the stars in Tuc III of 0.19 dex at 95.5% confidence. Tuc III has a smaller metallicity dispersion and likely a smaller velocity dispersion than any known dwarf galaxy, but a larger size and lower surface brightness than any known globular cluster. Its metallicity is also much lower than those of the clusters with similar luminosity. We therefore tentatively suggest that Tuc III is the tidally stripped remnant of a dark matter-dominated dwarf galaxy, but additional precise velocity and metallicity measurements will be necessary for a definitive classification. If Tuc III is indeed a dwarf galaxy, it is one of the closest external galaxies to the Sun. Because of its proximity, the most luminous stars in Tuc III are quite bright, including one star at V = 15.7 that is the brightest known member star of an ultra-faint satellite.

KW - Local Group

KW - dark matter

KW - galaxies: dwarf

KW - galaxies: individual (Tucana III)

KW - galaxies: stellar content

KW - stars: abundances

UR - http://www.scopus.com/inward/record.url?scp=85016570561&partnerID=8YFLogxK

U2 - 10.3847/1538-4357/aa5be7

DO - 10.3847/1538-4357/aa5be7

M3 - Article

AN - SCOPUS:85016570561

SN - 0004-637X

VL - 838

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1

M1 - 11

ER -

Nearest Neighbor: The Low-mass Milky Way Satellite Tucana III

Abstract

Funding

Keywords

Access to Document

Other files and links

Fingerprint

Cite this