Additionally, the magnitude limits for SEGUE-2 use SEGUE-1 as a test case to achieve the optimal balance between survey depth, sky coverage, and data quality. Of these, 7 have been found to be in the red giant stage of their life. Using the combined power of the twin 10 meter Keck telescopes perched on top of Mauna Kea in Hawaii, researchers were able to determine the weight of over a dozen of the most massive stars within this tiny galaxy. The upper limit with 90% (95%) confidence is sigma_v < 2.2 (2.6) km/s, the most stringent limit for any galaxy. Its small radius—of about 2.1 pc—is typical for the galactic globular clusters. The corresponding limit on the mass within the three-dimensional half-light radius (46 pc) is M_(1/2) < 1.5 (2.1) × 10^5 M_☉. It is difficult, however, to estimate the mass of such faint objects due to significant foreground contamination, which inflates the velocity dispersion. Astronomers have found a dwarf galaxy so surprisingly small it’s like “discovering an elephant smaller than a mouse.” The tiny and faint collection of 1,000 stars called Segue 2 orbits the Milky Way 35 kilo-parsecs (114,170 light years) away from our Sun. The cluster has a slightly flattened shape and shows some evidence of the tidal disruption. We identify Segue 2 as a galaxy rather than a star cluster based on the wide dispersion in … 3/15 Segue 2 pushes the low-stellar mass limit of galaxy formation. The velocity dispersion is too small to be measured with our data. Whereas SEGUE-1 matched shorter exposures of bright targets with long exposures of faint targets, SEGUE-2 obtains only deep pointings, as it focuses on the far reaches of our Galaxy. Segue 2 is the least massive galaxy known. That’s miniscule compared to the Milky Way, which shines 20 billion times brighter. ApJ 770, 16; doi: 10.1088/0004-637X/770/1/16, © 2011-2020. We identify Segue 2 as a galaxy rather than a star cluster based on the wide dispersion in [Fe/H] (from −2.85 to −1.33) among the member stars. The corresponding limit on the mass within the three-dimensional half-light radius (46 pc) is M 1/2 < 1.5 (2.1) × 10 5 M ☉. Since one light year is about 9.5 x 10 12 km, so the diameter of the Milky Way galaxy is about 9.5 x 10 17 km in diameter. Specifications for Galaxy Watch Active2, a Samsung smartwatch in 1.4" and 1.2" display, 44mm and 40mm size, 240mAh and 247mAh battery, LTE and Bluetooth. In this video, we will talk about the smallest discovered galaxy in the universe. Segue 2 is a dwarf spheroidal galaxy situated in the constellation Aries and discovered in 2009 in the data obtained by Sloan Digital Sky Survey. Segue 2 is notable because it is such a small galaxy, holding only about 1,000 stars that orbit the Milky Way. We present Keck/DEIMOS spectroscopy of 25 members of Segue 2--a threefold increase in spectroscopic sample size. (2009), is a galaxy with a luminosity of only 900 L_sun. “Finding a galaxy as tiny as Segue 2 is like discovering an elephant smaller than a mouse,” said co-author Dr James Bullock from the University of California Irvine. Segue 2 is the least massive galaxy known. Segue 2’s presence as a satellite of our home galaxy could be “a tip-of-the-iceberg observation, with perhaps thousands more very low-mass systems orbiting just beyond our ability to detect them,” he added. The name is due to the fact that it was found by the SEGUE program, the Sloan Extension for Galactic Understanding and Exploration. 2009, MNRAS, 397, 1748 ΔRA Δ D e c ΔRA Δ D e c g – r g – r r r SDSS III/SEGUE CFHT/Megacam The least massive galaxy known to science is a collection of 1,000 stars, held together by dark matter, orbiting the Milky Way called Segue 2. The upper limit with 90% (95%) confidence is sigma_v < 2.2 (2.6) km/s, the most stringent limit for any galaxy. Segue 2, discovered by an extension of the Sloan Digital Sky Survey in 2009, is putting out about as much light as 900 suns, Bullock said. Their inability to find any has been a major puzzle, suggesting that perhaps our theoretical understanding of structure formation in the universe was flawed in a serious way.”, “Segue 2’s presence as a satellite of our home galaxy could be a tip-of-the-iceberg observation, with perhaps thousands more very low-mass systems orbiting just beyond our ability to detect them.”, Segue 2 is located in the constellation of Aries (Roger Sinnott / Rick Fienberg / IAU / Sky & Telescope magazine / Sci-News.com). (2009), is a galaxy with a luminosity of only 900 L ☉ . Segue 2 is the least massive galaxy known. Segue 2 is located in the constellation of Aries about 114,000 light-years away. [6], The stellar population of Segue 1 consists mainly of old stars formed more than 12 billion years ago. We present Keck/DEIMOS spectroscopy of 25 members of Segue 2—a threefold increase in spectroscopic sample size. SEGUE 2: THE LEAST MASSIVE GALAXY. Segue 2 is a dwarf spheroidal galaxy situated in the constellation Aries and discovered in 2009 in the data obtained by Sloan Digital Sky Survey. The stars are held together by a globule called a dark matter halo. [2][4] This elongation may be caused by the tidal forces acting from the Milky Way galaxy if Segue 1 is being tidally disrupted now.[6]. (2009), is a galaxy with a luminosity of only 900 L_sun. What sets Segue 2 apart from a star cluster is the dark matter halo that acts as the galaxy's glue, another study researcher, Evan Kirby, explained in a statement. 2013. Segue 2 is located in the constellation of Aries about 114,000 light-years away. Researchers, in a NAOJ release, informed that the measurement accuracy of the galactic objects and the Earth achieved with interferometry technique helped study details with the same resolution as the 2300 km diameter telescope. Segue 2 … It is located at a distance of about 23 kpc (about 75,000 light years) from the Sun and moves away from the Sun with the velocity of about 206 km/s. Whereas SEGUE-1 matched shorter exposures of bright targets with long exposures of faint targets, SEGUE-2 obtains only deep pointings, as it focuses on the far reaches of our Galaxy. 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Segue 2, discovered by Belokurov et al. Kirby and his team used the powerful Keck II telescope, in Hawaii, to measure the metal content of the stars in Segue 2, and found that they vary a lot. [2][4] Observations indicate its mass is about 600,000 solar masses, which means that Segue's 1 mass to light ratio is around 3400. [6] The metallicity of these old stars is also very low at [Fe/H] ≈ −2.5 ± 0.8, which means that they contain 300 times less heavy elements than the Sun. The galaxy consists of just 1,000 or so stars with a bit of dark matter holding them together. We identify Segue 2 as a galaxy rather than a star cluster based the wide dispersion in [Fe/H] (from -2.85 to -1.33) among the member stars. It may once have been a globular cluster of the Sagittarius Dwarf Elliptical Galaxy, which was later stripped from it by the tidal forces acting from the Milky Way galaxy. [8][9][10][11][12], Segue 1 is located in the middle of the Sagittarius Stream and at approximately the same distance from the Sun. The upper limit with 90% (95%) confidence is σ v <; 2.2 (2.6) km/s, the most stringent limit for any galaxy. We present Keck/DEIMOS spectroscopy of 25 members of Segue 2--a threefold increase in spectroscopic sample size. It was discovered in 2009 as part of the massive Sloan Digital Sky Survey. The corresponding limit on the mass within the three-dimensional half-light radius (46 pc) is M 1/2 < 1.5 (2.1) × 10 5 M ☉ . Segue 1 is a dwarf spheroidal galaxy or globular cluster situated in the Leo constellation and discovered in 2006 by Sloan Digital Sky Survey. NAME Segue 2 -- Galaxy The astronomical object called NAME Segue 2 is a Galaxy: Origin of the objects types : (Ref) Object type as listed in the reference "Ref" (acronym) Object type linked to the acronym according to the original reference It is also one of the faintest known galaxies with light output just 900 times that of the Sun. Segue 2 is the least massive galaxy known. “Astronomers have been searching for years for this type of dwarf galaxy, long predicted to be swarming around the Milky Way. We identify Segue 2 as a galaxy rather than a star cluster based on the wide dispersion in [Fe/H] (from –2.85 to –1.33) among the member stars. According to the findings of a study published online in the Astrophysical Journal, a dwarf galaxy named Segue 2 is the least massive galaxy in the known Universe. The velocity dispersion is too small to be measured with our data. [7] There is an estimate of roughly 1000 stars within the object. Puny or not, Segue 2 is a galaxy. 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