The Pristine Dwarf-Galaxy survey - III. Revealing the nature of the Milky Way globular cluster Sagittarius II

Nicolas Longeard; Nicolas Martin; Rodrigo Ibata; Else Starkenburg; Pascale Jablonka; David S. Aguado; Raymond G. Carlberg; Patrick Côté; Jonay I. González Hernández; Romain Lucchesi; Khyati Malhan; Julio F. Navarro; Rubén Sánchez-Janssen; Guillaume F. Thomas; Kim Venn; Alan W. McConnachie

doi:10.1093/mnras/stab604

The Pristine Dwarf-Galaxy survey - III. Revealing the nature of the Milky Way globular cluster Sagittarius II

Nicolas Longeard^*, Nicolas Martin, Rodrigo Ibata, Else Starkenburg, Pascale Jablonka^*, David S. Aguado, Raymond G. Carlberg, Patrick Côté, Jonay I. González Hernández, Romain Lucchesi, Khyati Malhan, Julio F. Navarro, Rubén Sánchez-Janssen, Guillaume F. Thomas, Kim Venn, Alan W. McConnachie

^*Corresponding author for this work

Astronomy

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Abstract

We present a new spectroscopic study of the faint Milky Way satellite Sagittarius II. Using multi-object spectroscopy from the Fibre LargeArray Multi Element Spectrograph, we supplement the dataset of Longeard et al. (2020) with 47 newly observed stars, 19 of which are identified as members of the satellite. These additional member stars are used toput tighter constraints on the dynamics and the metallicity properties of the system. We find a low velocity dispersion of SgrII v = 1.7 +/-0.5 km s-1, in agreement with the dispersion of Milky Way globular clusters of similar luminosity. We confirm the very metal-poor nature of the satellite ([Fe/H]_SgrII = -2.23 +/- 0.07) and find that the metallicity dispersion of Sgr II is not resolved, reaching only 0.20 atthe 95% confidence limit. No star with a metallicity below -2.5 is confidently detected. Therefore, despite the unusually large size of the system (rh = 35.5 +1.4-1.2 pc), we conclude that Sgr II is an old and metal-poor globular cluster of the Milky Way.

Original language	English
Pages (from-to)	2754-2762
Number of pages	9
Journal	Monthly Notices of the Royal Astronomical Society
Volume	503
Issue number	2
Early online date	5-Mar-2021
DOIs	https://doi.org/10.1093/mnras/stab604
Publication status	Published - May-2021

Keywords

Astrophysics - Astrophysics of Galaxies

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10.1093/mnras/stab604

The pristine dwarf-galaxy survey – III. Revealing the nature of the Milky Way globular cluster Sagittarius II Final publisher's version, 1.23 MBLicence: Taverne

http://adsabs.harvard.edu/abs/2020arXiv200505976L

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Longeard, N., Martin, N., Ibata, R., Starkenburg, E., Jablonka, P., Aguado, D. S., Carlberg, R. G., Côté, P., González Hernández, J. I., Lucchesi, R., Malhan, K., Navarro, J. F., Sánchez-Janssen, R., Thomas, G. F., Venn, K., & McConnachie, A. W. (2021). The Pristine Dwarf-Galaxy survey - III. Revealing the nature of the Milky Way globular cluster Sagittarius II. Monthly Notices of the Royal Astronomical Society, 503(2), 2754-2762. https://doi.org/10.1093/mnras/stab604

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title = "The Pristine Dwarf-Galaxy survey - III. Revealing the nature of the Milky Way globular cluster Sagittarius II",

abstract = "We present a new spectroscopic study of the faint Milky Way satellite Sagittarius II. Using multi-object spectroscopy from the Fibre LargeArray Multi Element Spectrograph, we supplement the dataset of Longeard et al. (2020) with 47 newly observed stars, 19 of which are identified as members of the satellite. These additional member stars are used toput tighter constraints on the dynamics and the metallicity properties of the system. We find a low velocity dispersion of SgrII v = 1.7 +/-0.5 km s-1, in agreement with the dispersion of Milky Way globular clusters of similar luminosity. We confirm the very metal-poor nature of the satellite ([Fe/H]_SgrII = -2.23 +/- 0.07) and find that the metallicity dispersion of Sgr II is not resolved, reaching only 0.20 atthe 95% confidence limit. No star with a metallicity below -2.5 is confidently detected. Therefore, despite the unusually large size of the system (rh = 35.5 +1.4-1.2 pc), we conclude that Sgr II is an old and metal-poor globular cluster of the Milky Way.",

keywords = "Astrophysics - Astrophysics of Galaxies",

author = "Nicolas Longeard and Nicolas Martin and Rodrigo Ibata and Else Starkenburg and Pascale Jablonka and Aguado, {David S.} and Carlberg, {Raymond G.} and Patrick C{\^o}t{\'e} and {Gonz{\'a}lez Hern{\'a}ndez}, {Jonay I.} and Romain Lucchesi and Khyati Malhan and Navarro, {Julio F.} and Rub{\'e}n S{\'a}nchez-Janssen and Thomas, {Guillaume F.} and Kim Venn and McConnachie, {Alan W.}",

year = "2021",

month = may,

doi = "10.1093/mnras/stab604",

language = "English",

volume = "503",

pages = "2754--2762",

journal = "Monthly Notices of the Royal Astronomical Society",

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Longeard, N, Martin, N, Ibata, R, Starkenburg, E, Jablonka, P, Aguado, DS, Carlberg, RG, Côté, P, González Hernández, JI, Lucchesi, R, Malhan, K, Navarro, JF, Sánchez-Janssen, R, Thomas, GF, Venn, K & McConnachie, AW 2021, 'The Pristine Dwarf-Galaxy survey - III. Revealing the nature of the Milky Way globular cluster Sagittarius II', Monthly Notices of the Royal Astronomical Society, vol. 503, no. 2, pp. 2754-2762. https://doi.org/10.1093/mnras/stab604

TY - JOUR

T1 - The Pristine Dwarf-Galaxy survey - III. Revealing the nature of the Milky Way globular cluster Sagittarius II

AU - Longeard, Nicolas

AU - Martin, Nicolas

AU - Ibata, Rodrigo

AU - Starkenburg, Else

AU - Jablonka, Pascale

AU - Aguado, David S.

AU - Carlberg, Raymond G.

AU - Côté, Patrick

AU - González Hernández, Jonay I.

AU - Lucchesi, Romain

AU - Malhan, Khyati

AU - Navarro, Julio F.

AU - Sánchez-Janssen, Rubén

AU - Thomas, Guillaume F.

AU - Venn, Kim

AU - McConnachie, Alan W.

PY - 2021/5

Y1 - 2021/5

N2 - We present a new spectroscopic study of the faint Milky Way satellite Sagittarius II. Using multi-object spectroscopy from the Fibre LargeArray Multi Element Spectrograph, we supplement the dataset of Longeard et al. (2020) with 47 newly observed stars, 19 of which are identified as members of the satellite. These additional member stars are used toput tighter constraints on the dynamics and the metallicity properties of the system. We find a low velocity dispersion of SgrII v = 1.7 +/-0.5 km s-1, in agreement with the dispersion of Milky Way globular clusters of similar luminosity. We confirm the very metal-poor nature of the satellite ([Fe/H]_SgrII = -2.23 +/- 0.07) and find that the metallicity dispersion of Sgr II is not resolved, reaching only 0.20 atthe 95% confidence limit. No star with a metallicity below -2.5 is confidently detected. Therefore, despite the unusually large size of the system (rh = 35.5 +1.4-1.2 pc), we conclude that Sgr II is an old and metal-poor globular cluster of the Milky Way.

AB - We present a new spectroscopic study of the faint Milky Way satellite Sagittarius II. Using multi-object spectroscopy from the Fibre LargeArray Multi Element Spectrograph, we supplement the dataset of Longeard et al. (2020) with 47 newly observed stars, 19 of which are identified as members of the satellite. These additional member stars are used toput tighter constraints on the dynamics and the metallicity properties of the system. We find a low velocity dispersion of SgrII v = 1.7 +/-0.5 km s-1, in agreement with the dispersion of Milky Way globular clusters of similar luminosity. We confirm the very metal-poor nature of the satellite ([Fe/H]_SgrII = -2.23 +/- 0.07) and find that the metallicity dispersion of Sgr II is not resolved, reaching only 0.20 atthe 95% confidence limit. No star with a metallicity below -2.5 is confidently detected. Therefore, despite the unusually large size of the system (rh = 35.5 +1.4-1.2 pc), we conclude that Sgr II is an old and metal-poor globular cluster of the Milky Way.

KW - Astrophysics - Astrophysics of Galaxies

U2 - 10.1093/mnras/stab604

DO - 10.1093/mnras/stab604

M3 - Article

SN - 0035-8711

VL - 503

SP - 2754

EP - 2762

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 2

ER -