Astronomers have found a beforehand unknown pair of potential satellite tv for pc galaxies orbiting the Milky Way. The placement of those dwarf galaxies means that lots of of different unknown mini-galaxies may very well be hiding round us — probably difficult our understanding of the galaxy’s edges.
A satellite tv for pc galaxy is a clump of stars, both in a round blob or a halo-like form, that orbit the Milky Method independently from the remainder of the galaxy. Our galaxy’s largest-known satellite tv for pc is the Large Magellanic Cloud, which holds round 30 billion stars and could be seen with the bare eye. Different identified satellites solely include just a few hundred thousand or a few million stars.
A 2020 census of identified satellite tv for pc galaxies suggests scientists have discovered a most of round 60 satellite tv for pc galaxies orbiting the Milky Method. Nevertheless, there may be some uncertainty concerning the true variety of satellite tv for pc galaxies, largely as a result of scientists disagree over how massive these star clusters ought to be and the way far they need to lie from the galactic middle to be counted as true satellites, in line with NASA.
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However most astronomers agree that there ought to be many extra, at the moment unknown, satellite tv for pc galaxies on the market. Based mostly on our present understanding of dark matter — which does not react with mild however interacts gravitationally with seen matter and makes up around 27% of the universe’s mass — researchers have lengthy assumed that the Milky Method ought to have round 220 satellite tv for pc galaxies. Our lack of ability to identify many extra of those is sometimes called the “lacking satellites downside.”
In a brand new research, printed June 8 within the journal Publications of the Astronomical Society of Japan, researchers found two new potential satellite tv for pc galaxies, Sextans II and Virgo III. The satellites are situated round 411,000 and 492,000 light-years from Earth respectively and are doubtless each ultra-compact dwarf galaxies (UCDs) — collections of previous stars clumped tightly collectively, making them brighter than different satellite tv for pc galaxies.
Nevertheless, the discoveries don’t assist clear up the lacking satellites downside. As an alternative, the placement and orientation of those potential satellites hints that there are much more satellite tv for pc galaxies than scientists initially realized. This raises a brand new downside, which researchers have dubbed the “too many satellites downside.”
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Researchers found the UCDs utilizing the Hyper Suprime-Cam (HSC) connected to Japan’s Subaru Telescope at Mauna Kea Observatories in Hawaii. This instrument has spent the previous couple of years looking out a area of area round 33 light-years throughout. Based mostly on the estimated 220 satellite tv for pc galaxies postulated by the lacking satellites downside, an space of this measurement ought to have round 4 satellite tv for pc galaxies on common, Universe Today recently reported.
Nevertheless, the newest discoveries deliver the entire variety of satellites discovered by HSC on this space to 9. If this focus of satellites is constant across the Milky Method, it might imply that there may very well be not less than 500 satellite tv for pc galaxies across the Milky Method, researchers wrote in a statement.
Previously, scientists have proposed a number of options to the lacking satellites downside, together with that some satellite tv for pc galaxies are hiding behind larger satellites and that others are so diffuse they are almost impossible to detect with present know-how. Nevertheless, these elements are unlikely to have the ability to clarify an overabundance of stars, leaving scientists with no actual solution to clarify the brand new outcomes.
“The subsequent step is to make use of a extra highly effective telescope that captures a wider view of the sky,” research co-author Masahi Chiba, an astronomer at Tohoku College in Japan, stated within the assertion. This could assist make clear how widespread satellite tv for pc galaxies actually are, he added.
One such telescope is the upcoming Vera C. Rubin Observatory — a state-of-the-art facility geared up with the world’s largest digital camera, which is anticipated to come back on-line in 2025, Chiba stated. “I hope that many new satellite tv for pc galaxies might be found.”