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Colour-magnitude diagram of stars positioned inside of 5′ from the newfound stellar overdensity heart. Credit score: arXiv (2023). DOI: 10.48550/arxiv.2311.06037
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Colour-magnitude diagram of stars positioned inside of 5′ from the newfound stellar overdensity heart. Credit score: arXiv (2023). DOI: 10.48550/arxiv.2311.06037
Astronomers have came upon a brand new stellar machine within the outskirts of the Milky Manner as a part of the Kilo-Stage Survey (KiDS). The newfound machine, named Sextans II, is perhaps an ultra-faint dwarf galaxy. The discovering is reported in a paper revealed November 10 at the pre-print server arXiv.
KiDS is an in depth multi-band photometric survey using the VLT Survey Telescope (VST) at ESO’s Paranal Observatory in Chile. Since 2011, the survey has been mapping 1,350 sq. levels of the evening sky in 4 broad-band filters (u, g, r, i). Even supposing KiDS is targeted at the meeting of large-scale constructions within the universe, it may additionally stumble on low-surface brightness extragalactic stellar programs.
This is the reason a group of astronomers led by way of Massimiliano Gatto of the Astronomical Observatory of Capodimonte in Naples, Italy, made up our minds to behavior a large-scale seek for unknown faint stellar programs with KiDS. For this goal, they regarded for low-luminosity stellar overdensities within the KiDS newest knowledge unencumber (DR4), which introduced promising effects.
“We file at the discovery of a vital and compact over-density of previous and metal-poor stars within the KiDS survey (knowledge unencumber 4),” the researchers wrote within the paper.
The group recognized a extremely promising overdensity of stars within the Sextans constellation with an absolute built-in magnitude of -3.9. Observe-up observations of this overdensity with the 8.2-meter Subaru Telescope showed that this can be a stellar machine positioned some 473,000 gentle years away.
The astronomers to begin with designated the newfound machine KiDS-UFD-1 and dubbed it Sextans II. The accrued knowledge point out that Sextans II is somewhat small, with a half-light radius of about 629 gentle years, whilst its mass is estimated to be 4,910 sun plenty. The machine has a metallicity at a degree of -1.5 dex, ellipticity of 0.46, and is no less than 10 billion years previous.
In line with the authors of the paper, the consequences point out that Sextans II is a faint, previous and metal-poor machine. Gatto’s group concluded that the newly detected stellar machine is a faint spheroidal satellite tv for pc of the Milky Manner, perhaps an ultra-faint dwarf (UFD) galaxy. Generally, UFDs are the least luminous, maximum darkish subject–ruled, and least chemically advanced galaxies identified.
Alternatively, the researchers don’t exclude the likelihood that Sextans II could also be a disrupting globular cluster, including that additional investigation of the program is had to verify its true nature.
“The last word at the nature of the machine will also be equipped best by way of a right kind spectroscopic apply up of an affordable pattern of member stars, that can be difficult, given the magnitude vary spanned by way of candidate RGB contributors,” the scientists wrote.
Additional info:
Massimiliano Gatto et al, New Children in The town. Sextans~II: a brand new stellar machine within the outskirts of the Milky Manner, arXiv (2023). DOI: 10.48550/arxiv.2311.06037
Magazine knowledge:
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