Astronomers discover new almost dark galaxy

By analyzing deep optical imagery from the IAC Stripe 82 Legacy Undertaking, a global workforce of astronomers has serendipitously found a brand new nearly darkish galaxy. The newfound galaxy, dubbed “Nube,” has a really low floor brightness and is as large because the Small Magellanic Cloud (SMC). The discovering is reported in a paper revealed October 18 on the pre-print server arXiv.

Galaxies with central floor brightness fainter than 26 magazine/arcsec² are generally called “nearly darkish galaxies.” They lack an unambiguous optical counterpart and they’re often missed within the optical catalogs of extensive discipline surveys. Nonetheless, these faint galaxies could showcase extraordinarily faint optical emission when imaged extra deeply.

Now, a workforce of astronomers led by Mireia Montes of the College of La Laguna, Spain, has detected one other galaxy of this uncommon kind. They recognized it throughout a visible inspection of one of many survey fields of the IAC Stripe 82 Legacy Undertaking—a wide-area survey for faint floor brightness astronomy. The survey investigates Stripe 82—a 2.5 diploma extensive stripe alongside the Celestial Equator within the Southern Galactic Cap.

Nube is situated some 350 million light years away and has an efficient floor brightness of roughly 26.75 magazine/arcsec². The galaxy is assumed to be 10 billion years previous and its metallicity was measured to be at a stage of -1.1.

On the subject of different elementary parameters of Nube, the research discovered that it is extremely prolonged, with a half-mass radius of twenty-two,500 gentle years. The galaxy has a stellar mass of about 390 million solar lots and its total halo mass is estimated to be 26 billion solar lots. These outcomes level to an efficient floor density of some 0.9 solar masses/parsec².

Based mostly on the findings, the authors of the paper concluded that Nube is essentially the most large and prolonged galaxy of its sort to this point detected. The galaxy turned out to be additionally 10-times fainter and its radius is three-times bigger than typical ultra-diffuse galaxies (UDGs) with comparable stellar lots. Usually, UDGs are extremely-low-density galaxies with sizes corresponding to the Milky Way, however have solely about 1% as many stars as our house galaxy.

Making an allowance for the intense properties of Nube, the researchers talk about the origin and nature of this galaxy. They investigated whether or not these properties are a results of the unique formation of the galaxy, or whether or not they’re resulting from a later evolutionary course of brought on by the surroundings through which it’s discovered.

“To this finish, and beneath the speculation that the distribution of stars in Nube is consultant of the distribution of the dark matter halo, we discovered {that a} soliton-shaped profile (typical of fuzzy dark matter) reproduces the noticed distribution of stars very properly,” the authors of the research concluded.

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