[63] The Milky Way may contain ten billion white dwarfs, a billion neutron stars, and a hundred million stellar black holes. However, the observed curve is relatively flat, indicating that there is additional mass that cannot be detected directly with electromagnetic radiation. Similarly, with the discovery of the Canis Major Dwarf Galaxy, it was found that a ring of galactic debris from its interaction with the Milky Way encircles the Galactic disk. [124] Estimates of the pitch angle of the arms range from about 7° to 25°. The stream is thought to have been dragged from the Magellanic Clouds in tidal interactions with the Milky Way. The Milky Way's spiral structure is uncertain, and there is currently no consensus on the nature of the Milky Way's spiral arms. But in this stunning vista, the Spitzer Space Telescope's infrared cameras penetrate much of the dust, revealing the stars of the crowded galactic center region. [126][129] This observation suggests that the Milky Way possesses only two major stellar arms: the Perseus arm and the Scutum–Centaurus arm. Galileo Galilei first resolved the band of light into individual stars with his telescope in 1610. [37][38] The light originates from the accumulation of unresolved stars and other material located in the direction of the galactic plane. [154] The distance between the local arm and the next arm out, the Perseus Arm, is about 2,000 parsecs (6,500 ly). Brighter regions around the band appear as soft visual patches known as star clouds. Alternatively, a minority of astronomers propose that a modification of the law of gravity may explain the observed rotation curve. | last4 = Howard | first4 = C. D. | last5 = De Propris | first5 = R. | last6 = Kunder | first6 = A. The smallest dwarf galaxies of the Milky Way are only 500 light-years in diameter. [142] The globular clusters can follow rosette orbits about the Milky Way, in contrast to the elliptical orbit of a planet around a star. The Crew Dragon spacecraft carrying Crew-2 lifted off early Friday aboard a SpaceX Falcon 9 rocket from Kennedy Space Center in Florida. The oldest stars in the Milky Way are nearly as old as the Universe itself and thus probably formed shortly after the Dark Ages of the Big Bang.[35]. Pan (28 kilometers, or 17 miles across) orbits in the Encke Gap, which runs through the center of th... Titan presented this face as the Cassini spacecraft approached for its second very close flyby of the mystery moon in December 2004. [111] However, RR Lyrae-type stars do not trace a prominent Galactic bar. [114] X-ray emission from the core is aligned with the massive stars surrounding the central bar[107] and the Galactic ridge. [167] Nonetheless, these stars and clusters now comprise the stellar halo of the Milky Way. [191], The Milky Way and the Andromeda Galaxy are a binary system of giant spiral galaxies belonging to a group of 50 closely bound galaxies known as the Local Group, surrounded by a Local Void, itself being part of the Virgo Supercluster. These estimates are very uncertain, as most non-star objects are difficult to detect; for example, black hole estimates range from ten million to one billion. Most younger stars, including the Sun, are observed to be in the disk. [52] A recent mass estimate for the Milky Way is 1.29×1012 M☉. [5][6][54] Recent studies indicate a range in mass, as large as 4.5×1012 M☉[55] and as small as 8×1011 M☉. Away from the central bulge or outer rim, the typical stellar orbital speed is between 210 ± 10 km/s (470,000 ± 22,000 mph). Explain the observed curve is relatively flat, indicating that there are SMBHs located near the center our! Too distant to be in the Milky Way 's center structures of.. 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