KiDS in the sky: New stellar system discovered by the Kilo-Degree Survey

Astronomers have found a brand new stellar system within the outskirts of the Milky Way as a part of the Kilo-Diploma Survey (KiDS). The newfound system, named Sextans II, is most definitely an ultra-faint dwarf galaxy. The discovering is reported in a paper published November 10 on 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). Though KiDS is targeted on the meeting of large-scale constructions within the universe, it might additionally detect low-surface brightness extragalactic stellar techniques.

That’s the reason a crew 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 techniques with KiDS. For this goal, they regarded for low-luminosity stellar overdensities within the KiDS newest information launch (DR4), which introduced promising outcomes.

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

The crew recognized a extremely promising overdensity of stars within the Sextans constellation with an absolute built-in magnitude of -3.9. Comply with-up observations of this overdensity with the 8.2-meter Subaru Telescope confirmed that it’s a stellar system positioned some 473,000 light years away.

The astronomers initially designated the newfound system KiDS-UFD-1 and dubbed it Sextans II. The collected information point out that Sextans II is comparatively small, with a half-light radius of about 629 gentle years, whereas its mass is estimated to be 4,910 solar lots. The system has a metallicity at a degree of -1.5 dex, ellipticity of 0.46, and is no less than 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 crew concluded that the newly detected stellar system is a faint spheroidal satellite of the Milky Way, most definitely an ultra-faint dwarf (UFD) galaxy. Basically, UFDs are the least luminous, most dark matter–dominated, and least chemically developed galaxies recognized.

Nonetheless, the researchers don’t exclude the likelihood 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 may be supplied solely by a correct spectroscopic observe up of an affordable pattern of member stars, which may be difficult, given the magnitude vary spanned by candidate RGB members,” the scientists wrote.

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