New stellar system found by the Kilo-Diploma Survey

Astronomers have found a brand new stellar system within the outskirts of the Milky Approach as a part of the Kilo-Diploma Survey (KiDS). The newfound system, named Sextans II, is almost certainly an ultra-faint dwarf galaxy. The discovering is reported in a paper published November 10 on the pre-print server arXiv.

KiDS is an intensive 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). Though KiDS is concentrated on the meeting of large-scale buildings within the universe, it might additionally detect low-surface brightness extragalactic stellar programs.

That’s the reason a staff of astronomers led by Massimiliano Gatto of the Astronomical Observatory of Capodimonte in Naples, Italy, determined to conduct a large-scale seek for unknown faint stellar programs with KiDS. For this goal, they appeared for low-luminosity stellar overdensities within the KiDS newest knowledge launch (DR4), which introduced promising outcomes.

“We report on the invention of a major and compact over-density of previous and metal-poor stars within the KiDS survey (knowledge launch 4),” the researchers wrote within the paper.

The staff 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 confirmed that it’s a stellar system positioned some 473,000 mild years away.

The astronomers initially designated the newfound system KiDS-UFD-1 and dubbed it Sextans II. The collected knowledge point out that Sextans II is comparatively small, with a half-light radius of about 629 mild years, whereas its mass is estimated to be 4,910 photo voltaic lots. The system has a metallicity at a degree of -1.5 dex, ellipticity of 0.46, and is a minimum of 10 billion years previous.

Based on the authors of the paper, the outcomes point out that Sextans II is a faint, previous and metal-poor system. Gatto’s staff concluded that the newly detected stellar system is a faint spheroidal satellite tv for pc of the Milky Approach, almost certainly an ultra-faint dwarf (UFD) galaxy. Typically, UFDs are the least luminous, most darkish matter–dominated, and least chemically developed galaxies recognized.

Nonetheless, the researchers don’t exclude the chance that Sextans II could also be a disrupting globular cluster, including that additional investigation of this method is required to substantiate its true nature.

“The ultimate phrase on the character of the system might be offered solely by a correct spectroscopic observe up of an affordable pattern of member stars, that could be difficult, given the magnitude vary spanned by candidate RGB members,” the scientists wrote.

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