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

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

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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 & 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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@article{d2a7086663dc45ac97d9d6fa93d9d4d1,

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.\}",

year = "2024",

month = jan,

day = "1",

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

language = "English",

volume = "681",

journal = "Astronomy \& Astrophysics",

issn = "0004-6361",

publisher = " EDP Sciences",

}

TY - JOUR

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

UR - https://www.scopus.com/pages/publications/85182910269

U2 - 10.1051/0004-6361/202348554

DO - 10.1051/0004-6361/202348554

M3 - Article

AN - SCOPUS:85182910269

SN - 0004-6361

VL - 681

JO - Astronomy & Astrophysics

JF - Astronomy & 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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