Chemical abundance analysis of three α-poor, metal-poor stars in the ultrafaint dwarf galaxy Horologium I

D. Q. Nagasawa; J. L. Marshall; J. D. Simon; T. T. Hansen; T. S. Li; R. A. Bernstein; E. Balbinot; A. Drlica-Wagner; A. B. Pace; L. E. Strigari; C. M. Pellegrino; D. L. DePoy; N. B. Suntzeff; K. Bechtol; T. M. C. Abbott; F. B. Abdalla; S. Allam; J. Annis; A. Benoit-Lévy; E. Bertin; D. Brooks; A. Carnero Rosell; M. Carrasco Kind; J. Carretero; C. E. Cunha; C. B. D'Andrea; L. N. da Costa; C. Davis; S. Desai; P. Doel; T. F. Eifler; B. Flaugher; P. Fosalba; J. Frieman; J. García-Bellido; E. Gaztanaga; D. W. Gerdes; D. Gruen; R. A. Gruendl; J. Gschwend; G. Gutierrez; W. G. Hartley; K. Honscheid; D. J. James; T. Jeltema; E. Krause; K. Kuehn; S. Kuhlmann; N. Kuropatkin; M. March; R. Miquel; B. Nord; A. Roodman; E. Sanchez; B. Santiago; V. Scarpine; R. Schindler; M. Schubnell; I. Sevilla-Noarbe; M. Smith; R. C. Smith; M. Soares-Santos; F. Sobreira; E. Suchyta; G. Tarle; D. Thomas; D. L. Tucker; A. R. Walker; R. H. Wechsler; R. C. Wolf; B. Yanny

doi:10.3847/1538-4357/aaa01d

Chemical abundance analysis of three α-poor, metal-poor stars in the ultrafaint dwarf galaxy Horologium I

D. Q. Nagasawa, J. L. Marshall, J. D. Simon, T. T. Hansen, T. S. Li, R. A. Bernstein, E. Balbinot, A. Drlica-Wagner, A. B. Pace, L. E. Strigari, C. M. Pellegrino, D. L. DePoy, N. B. Suntzeff, K. Bechtol, T. M. C. Abbott, F. B. Abdalla, S. Allam, J. Annis, A. Benoit-Lévy, E. BertinD. Brooks, A. Carnero Rosell, M. Carrasco Kind, J. Carretero, C. E. Cunha, C. B. D'Andrea, L. N. da Costa, C. Davis, S. Desai, P. Doel, T. F. Eifler, B. Flaugher, P. Fosalba, J. Frieman, J. García-Bellido, E. Gaztanaga, D. W. Gerdes, D. Gruen, R. A. Gruendl, J. Gschwend, G. Gutierrez, W. G. Hartley, K. Honscheid, D. J. James, T. Jeltema, E. Krause, K. Kuehn, S. Kuhlmann, N. Kuropatkin, M. March, R. Miquel, B. Nord, A. Roodman, E. Sanchez, B. Santiago, V. Scarpine, R. Schindler, M. Schubnell, I. Sevilla-Noarbe, M. Smith, R. C. Smith, M. Soares-Santos, F. Sobreira, E. Suchyta, G. Tarle, D. Thomas, D. L. Tucker, A. R. Walker, R. H. Wechsler, R. C. Wolf, B. Yanny

Institute of Cosmology & Gravitation

University of Southampton

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Abstract

We present chemical abundance measurements of three stars in the ultrafaint dwarf galaxy Horologium I, a Milky Way satellite discovered by the Dark Energy Survey. Using high-resolution spectroscopic observations, we measure the metallicity of the three stars, as well as abundance ratios of several α-elements, iron-peak elements, and neutron-capture elements. The abundance pattern is relatively consistent among all three stars, which have a low average metallicity of [Fe/H] ~ −2.6 and are not α-enhanced ([α/Fe] ~ 0.0). This result is unexpected when compared to other low-metallicity stars in the Galactic halo and other ultrafaint dwarfs and suggests the possibility of a different mechanism for the enrichment of Hor I compared to other satellites. We discuss possible scenarios that could lead to this observed nucleosynthetic signature, including extended star formation, enrichment by a Population III supernova, and or an association with the Large Magellanic Cloud.

Original language	English
Article number	99
Number of pages	16
Journal	The Astrophysical Journal
Volume	852
Issue number	2
DOIs	https://doi.org/10.3847/1538-4357/aaa01d
Publication status	Published - 11 Jan 2018

Keywords

astro-ph.SR
astro-ph.GA
RCUK
STFC
AST-1560223

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10.3847/1538-4357/aaa01d

Nagasawa_2018_ApJ_852_99
D. Q. Nagasawa et al 2018 ApJ 852 99. Reproduced by permission of the AAS.
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Nagasawa, D. Q., Marshall, J. L., Simon, J. D., Hansen, T. T., Li, T. S., Bernstein, R. A., Balbinot, E., Drlica-Wagner, A., Pace, A. B., Strigari, L. E., Pellegrino, C. M., DePoy, D. L., Suntzeff, N. B., Bechtol, K., Abbott, T. M. C., Abdalla, F. B., Allam, S., Annis, J., Benoit-Lévy, A., ... Yanny, B. (2018). Chemical abundance analysis of three α-poor, metal-poor stars in the ultrafaint dwarf galaxy Horologium I. The Astrophysical Journal, 852(2), Article 99. https://doi.org/10.3847/1538-4357/aaa01d

@article{35209bc1a8b043199f412b45234a6748,

title = "Chemical abundance analysis of three α-poor, metal-poor stars in the ultrafaint dwarf galaxy Horologium I",

abstract = "We present chemical abundance measurements of three stars in the ultrafaint dwarf galaxy Horologium I, a Milky Way satellite discovered by the Dark Energy Survey. Using high-resolution spectroscopic observations, we measure the metallicity of the three stars, as well as abundance ratios of several α-elements, iron-peak elements, and neutron-capture elements. The abundance pattern is relatively consistent among all three stars, which have a low average metallicity of [Fe/H] ~ −2.6 and are not α-enhanced ([α/Fe] ~ 0.0). This result is unexpected when compared to other low-metallicity stars in the Galactic halo and other ultrafaint dwarfs and suggests the possibility of a different mechanism for the enrichment of Hor I compared to other satellites. We discuss possible scenarios that could lead to this observed nucleosynthetic signature, including extended star formation, enrichment by a Population III supernova, and or an association with the Large Magellanic Cloud.",

keywords = "astro-ph.SR, astro-ph.GA, RCUK, STFC, AST-1560223",

author = "Nagasawa, {D. Q.} and Marshall, {J. L.} and Simon, {J. D.} and Hansen, {T. T.} and Li, {T. S.} and Bernstein, {R. A.} and E. Balbinot and A. Drlica-Wagner and Pace, {A. B.} and Strigari, {L. E.} and Pellegrino, {C. M.} and DePoy, {D. L.} and Suntzeff, {N. B.} and K. Bechtol and Abbott, {T. M. C.} and Abdalla, {F. B.} and S. Allam and J. Annis and A. Benoit-L{\'e}vy and E. Bertin and D. Brooks 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 C. Davis and S. Desai and P. Doel and Eifler, {T. F.} and B. Flaugher and P. Fosalba and J. Frieman and J. Garc{\'i}a-Bellido and E. Gaztanaga and Gerdes, {D. W.} and D. Gruen and Gruendl, {R. A.} and J. Gschwend and G. Gutierrez and Hartley, {W. G.} and K. Honscheid and James, {D. J.} and T. Jeltema and E. Krause and K. Kuehn and S. Kuhlmann and N. Kuropatkin and M. March and R. Miquel and B. Nord and A. Roodman and E. Sanchez and B. Santiago and V. Scarpine and R. Schindler and M. Schubnell and I. Sevilla-Noarbe and M. Smith and Smith, {R. C.} and M. Soares-Santos and F. Sobreira and E. Suchyta and G. Tarle and D. Thomas and Tucker, {D. L.} and Walker, {A. R.} and Wechsler, {R. H.} and Wolf, {R. C.} and B. Yanny",

year = "2018",

month = jan,

day = "11",

doi = "10.3847/1538-4357/aaa01d",

language = "English",

volume = "852",

journal = "The Astrophysical Journal",

issn = "0004-637X",

publisher = "IOP Publishing",

number = "2",

}

Nagasawa, DQ, Marshall, JL, Simon, JD, Hansen, TT, Li, TS, Bernstein, RA, Balbinot, E, Drlica-Wagner, A, Pace, AB, Strigari, LE, Pellegrino, CM, DePoy, DL, Suntzeff, NB, Bechtol, K, Abbott, TMC, Abdalla, FB, Allam, S, Annis, J, Benoit-Lévy, A, Bertin, E, Brooks, D, Rosell, AC, Kind, MC, Carretero, J, Cunha, CE, D'Andrea, CB, Costa, LND, Davis, C, Desai, S, Doel, P, Eifler, TF, Flaugher, B, Fosalba, P, Frieman, J, García-Bellido, J, Gaztanaga, E, Gerdes, DW, Gruen, D, Gruendl, RA, Gschwend, J, Gutierrez, G, Hartley, WG, Honscheid, K, James, DJ, Jeltema, T, Krause, E, Kuehn, K, Kuhlmann, S, Kuropatkin, N, March, M, Miquel, R, Nord, B, Roodman, A, Sanchez, E, Santiago, B, Scarpine, V, Schindler, R, Schubnell, M, Sevilla-Noarbe, I, Smith, M, Smith, RC, Soares-Santos, M, Sobreira, F, Suchyta, E, Tarle, G, Thomas, D, Tucker, DL, Walker, AR, Wechsler, RH, Wolf, RC & Yanny, B 2018, 'Chemical abundance analysis of three α-poor, metal-poor stars in the ultrafaint dwarf galaxy Horologium I', The Astrophysical Journal, vol. 852, no. 2, 99. https://doi.org/10.3847/1538-4357/aaa01d

TY - JOUR

T1 - Chemical abundance analysis of three α-poor, metal-poor stars in the ultrafaint dwarf galaxy Horologium I

AU - Nagasawa, D. Q.

AU - Marshall, J. L.

AU - Simon, J. D.

AU - Hansen, T. T.

AU - Li, T. S.

AU - Bernstein, R. A.

AU - Balbinot, E.

AU - Drlica-Wagner, A.

AU - Pace, A. B.

AU - Strigari, L. E.

AU - Pellegrino, C. M.

AU - DePoy, D. L.

AU - Suntzeff, N. B.

AU - Bechtol, K.

AU - Abbott, T. M. C.

AU - Abdalla, F. B.

AU - Allam, S.

AU - Annis, J.

AU - Benoit-Lévy, A.

AU - Bertin, E.

AU - Brooks, D.

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 - Davis, C.

AU - Desai, S.

AU - Doel, P.

AU - Eifler, T. F.

AU - Flaugher, B.

AU - Fosalba, P.

AU - Frieman, J.

AU - García-Bellido, J.

AU - Gaztanaga, E.

AU - Gerdes, D. W.

AU - Gruen, D.

AU - Gruendl, R. A.

AU - Gschwend, J.

AU - Gutierrez, G.

AU - Hartley, W. G.

AU - Honscheid, K.

AU - James, D. J.

AU - Jeltema, T.

AU - Krause, E.

AU - Kuehn, K.

AU - Kuhlmann, S.

AU - Kuropatkin, N.

AU - March, M.

AU - Miquel, R.

AU - Nord, B.

AU - Roodman, A.

AU - Sanchez, E.

AU - Santiago, B.

AU - Scarpine, V.

AU - Schindler, R.

AU - Schubnell, M.

AU - Sevilla-Noarbe, I.

AU - Smith, M.

AU - Smith, R. C.

AU - Soares-Santos, M.

AU - Sobreira, F.

AU - Suchyta, E.

AU - Tarle, G.

AU - Thomas, D.

AU - Tucker, D. L.

AU - Walker, A. R.

AU - Wechsler, R. H.

AU - Wolf, R. C.

AU - Yanny, B.

PY - 2018/1/11

Y1 - 2018/1/11

N2 - We present chemical abundance measurements of three stars in the ultrafaint dwarf galaxy Horologium I, a Milky Way satellite discovered by the Dark Energy Survey. Using high-resolution spectroscopic observations, we measure the metallicity of the three stars, as well as abundance ratios of several α-elements, iron-peak elements, and neutron-capture elements. The abundance pattern is relatively consistent among all three stars, which have a low average metallicity of [Fe/H] ~ −2.6 and are not α-enhanced ([α/Fe] ~ 0.0). This result is unexpected when compared to other low-metallicity stars in the Galactic halo and other ultrafaint dwarfs and suggests the possibility of a different mechanism for the enrichment of Hor I compared to other satellites. We discuss possible scenarios that could lead to this observed nucleosynthetic signature, including extended star formation, enrichment by a Population III supernova, and or an association with the Large Magellanic Cloud.

AB - We present chemical abundance measurements of three stars in the ultrafaint dwarf galaxy Horologium I, a Milky Way satellite discovered by the Dark Energy Survey. Using high-resolution spectroscopic observations, we measure the metallicity of the three stars, as well as abundance ratios of several α-elements, iron-peak elements, and neutron-capture elements. The abundance pattern is relatively consistent among all three stars, which have a low average metallicity of [Fe/H] ~ −2.6 and are not α-enhanced ([α/Fe] ~ 0.0). This result is unexpected when compared to other low-metallicity stars in the Galactic halo and other ultrafaint dwarfs and suggests the possibility of a different mechanism for the enrichment of Hor I compared to other satellites. We discuss possible scenarios that could lead to this observed nucleosynthetic signature, including extended star formation, enrichment by a Population III supernova, and or an association with the Large Magellanic Cloud.

KW - astro-ph.SR

KW - astro-ph.GA

KW - RCUK

KW - STFC

KW - AST-1560223

U2 - 10.3847/1538-4357/aaa01d

DO - 10.3847/1538-4357/aaa01d

M3 - Article

SN - 0004-637X

VL - 852

JO - The Astrophysical Journal

JF - The Astrophysical Journal

IS - 2

M1 - 99

ER -

Chemical abundance analysis of three α-poor, metal-poor stars in the ultrafaint dwarf galaxy Horologium I

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