New KiDS in town: Sextans II: A new stellar system on the outskirts of the Milky Way

Massimiliano Gatto; Michele Bellazzini; Crescenzo Tortora; Vincenzo Ripepi; Massimo Dall'ora; Michele Cignoni; Konrad Kuijken; Hendrik Hildebrandt; Shiyang Zhang; Jelte De Jong; Nicola R. Napolitano; Simon E.T. Smith

doi:10.1051/0004-6361/202348554

New KiDS in town: Sextans II: A new stellar system on the outskirts of the Milky Way

Massimiliano Gatto, Michele Bellazzini, Crescenzo Tortora, Vincenzo Ripepi, Massimo Dall'ora, Michele Cignoni, Konrad Kuijken, Hendrik Hildebrandt, Shiyang Zhang, Jelte De Jong, Nicola R. Napolitano, Simon E.T. Smith

Astronomy

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Abstract

We report the discovery of a significant and compact over-density of old and metal-poor stars in the fourth data release of the KiDS survey (DR4). The discovery is confirmed by deeper HSC-SSP data revealing the old main sequence turn-off of a stellar system located at a distance from the sun of D = 145_-13⁺¹⁴ kpc in the direction of the Sextans constellation. The system has an absolute integrated magnitude (M_V = -3.9 ± 0.4), half-light radius (r_h = 193_-46⁺⁶¹ pc), and ellipticity (e = 0.46_-0.15^+0.11) values that are typical of ultra-faint dwarf galaxies (UFDs). The central surface brightness is near the lower limits of known local dwarf galaxies of a similar integrated luminosity, as expected for stellar systems that have escaped detection until now. The distance of the newly found system suggests that it is likely to be a satellite of our own Milky Way and we have thus tentatively named it Sextans II (KiDS-UFD-1).

Original language	English
Article number	L13
Number of pages	7
Journal	Astronomy and Astrophysics
Volume	681
DOIs	https://doi.org/10.1051/0004-6361/202348554
Publication status	Published - 1-Jan-2024

Keywords

Galaxies: clusters: general
Galaxies: dwarf
Galaxies: photometry
Galaxy: halo
Hertzsprung-Russell and C-M diagrams
Surveys

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New KiDS in townFinal publisher's version, 1.15 MBLicence: CC BY

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title = "New KiDS in town: Sextans II: A new stellar system on the outskirts of the Milky Way",

abstract = "We report the discovery of a significant and compact over-density of old and metal-poor stars in the fourth data release of the KiDS survey (DR4). The discovery is confirmed by deeper HSC-SSP data revealing the old main sequence turn-off of a stellar system located at a distance from the sun of D = 145-13+14 kpc in the direction of the Sextans constellation. The system has an absolute integrated magnitude (MV = -3.9 ± 0.4), half-light radius (rh = 193-46+61 pc), and ellipticity (e = 0.46-0.15+0.11) values that are typical of ultra-faint dwarf galaxies (UFDs). The central surface brightness is near the lower limits of known local dwarf galaxies of a similar integrated luminosity, as expected for stellar systems that have escaped detection until now. The distance of the newly found system suggests that it is likely to be a satellite of our own Milky Way and we have thus tentatively named it Sextans II (KiDS-UFD-1).",

keywords = "Galaxies: clusters: general, Galaxies: dwarf, Galaxies: photometry, Galaxy: halo, Hertzsprung-Russell and C-M diagrams, Surveys",

author = "Massimiliano Gatto and Michele Bellazzini and Crescenzo Tortora and Vincenzo Ripepi and Massimo Dall'ora and Michele Cignoni and Konrad Kuijken and Hendrik Hildebrandt and Shiyang Zhang and {De Jong}, Jelte and Napolitano, {Nicola R.} and Smith, {Simon E.T.}",

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doi = "10.1051/0004-6361/202348554",

language = "English",

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T1 - New KiDS in town

T2 - Sextans II: A new stellar system on the outskirts of the Milky Way

AU - Gatto, Massimiliano

AU - Bellazzini, Michele

AU - Tortora, Crescenzo

AU - Ripepi, Vincenzo

AU - Dall'ora, Massimo

AU - Cignoni, Michele

AU - Kuijken, Konrad

AU - Hildebrandt, Hendrik

AU - Zhang, Shiyang

AU - De Jong, Jelte

AU - Napolitano, Nicola R.

AU - Smith, Simon E.T.

PY - 2024/1/1

Y1 - 2024/1/1

N2 - We report the discovery of a significant and compact over-density of old and metal-poor stars in the fourth data release of the KiDS survey (DR4). The discovery is confirmed by deeper HSC-SSP data revealing the old main sequence turn-off of a stellar system located at a distance from the sun of D = 145-13+14 kpc in the direction of the Sextans constellation. The system has an absolute integrated magnitude (MV = -3.9 ± 0.4), half-light radius (rh = 193-46+61 pc), and ellipticity (e = 0.46-0.15+0.11) values that are typical of ultra-faint dwarf galaxies (UFDs). The central surface brightness is near the lower limits of known local dwarf galaxies of a similar integrated luminosity, as expected for stellar systems that have escaped detection until now. The distance of the newly found system suggests that it is likely to be a satellite of our own Milky Way and we have thus tentatively named it Sextans II (KiDS-UFD-1).

AB - We report the discovery of a significant and compact over-density of old and metal-poor stars in the fourth data release of the KiDS survey (DR4). The discovery is confirmed by deeper HSC-SSP data revealing the old main sequence turn-off of a stellar system located at a distance from the sun of D = 145-13+14 kpc in the direction of the Sextans constellation. The system has an absolute integrated magnitude (MV = -3.9 ± 0.4), half-light radius (rh = 193-46+61 pc), and ellipticity (e = 0.46-0.15+0.11) values that are typical of ultra-faint dwarf galaxies (UFDs). The central surface brightness is near the lower limits of known local dwarf galaxies of a similar integrated luminosity, as expected for stellar systems that have escaped detection until now. The distance of the newly found system suggests that it is likely to be a satellite of our own Milky Way and we have thus tentatively named it Sextans II (KiDS-UFD-1).

KW - Galaxies: clusters: general

KW - Galaxies: dwarf

KW - Galaxies: photometry

KW - Galaxy: halo

KW - Hertzsprung-Russell and C-M diagrams

KW - Surveys

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DO - 10.1051/0004-6361/202348554

M3 - Article

AN - SCOPUS:85182910269

SN - 0004-6361

VL - 681

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

M1 - L13

ER -

New KiDS in town: Sextans II: A new stellar system on the outskirts of the Milky Way

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