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A globular cluster is a spheroidal conglomeration of stars that is bound together by gravity, with a higher concentration of stars towards their centers. They can contain anywhere from tens of thousands to many millions of member stars, all orbiting in a stable, compact formation. Globular clusters are similar in form to dwarf spheroidal galaxies, and the distinction between the two is not always clear. Their name is derived from Latin globulus. Globular clusters are occasionally known simply as "globulars".
Star formation is the process by which dense regions within molecular clouds in interstellar space, sometimes referred to as "stellar nurseries" or "star-forming regions", collapse and form stars. As a branch of astronomy, star formation includes the study of the interstellar medium (ISM) and giant molecular clouds (GMC) as precursors to the star formation process, and the study of protostars and young stellar objects as its immediate products. It is closely related to planet formation, another branch of astronomy. Star formation theory, as well as accounting for the formation of a single star, must also account for the statistics of binary stars and the initial mass function. Most stars do not form in isolation but as part of a group of stars referred as star clusters or stellar associations.
The Andromeda Galaxy is a barred spiral galaxy and is the nearest major galaxy to the Milky Way. It was originally named the Andromeda Nebula and is cataloged as Messier 31, M31, and NGC 224. Andromeda has a diameter of about 46.56 kiloparsecs and is approximately 765 kpc from Earth. The galaxy's name stems from the area of Earth's sky in which it appears, the constellation of Andromeda, which itself is named after the princess who was the wife of Perseus in Greek mythology.
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A dwarf galaxy is a small galaxy composed of about 1000 up to several billion stars, as compared to the Milky Way's 200–400 billion stars. The Large Magellanic Cloud, which closely orbits the Milky Way and contains over 30 billion stars, is sometimes classified as a dwarf galaxy; others consider it a full-fledged galaxy. Dwarf galaxies' formation and activity are thought to be heavily influenced by interactions with larger galaxies. Astronomers identify numerous types of dwarf galaxies, based on their shape and composition.
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Hercules, or Her, is a dwarf spheroidal galaxy situated in the Hercules constellation and discovered in 2006 in data obtained by the Sloan Digital Sky Survey. The galaxy is located at a distance of about 140 kpc from the Sun and moves away from the Sun with a velocity of about 45 km/s. It is classified as a dwarf spheroidal galaxy (dSph). It has a noticeably elongated shape with a half-light radius of about 350 pc. This elongation may be caused by tidal forces acting from the Milky Way galaxy, meaning that Her is being tidally disrupted now. Her also shows some gradient of velocities across the galaxy's body and is embedded into a faint stellar stream, which also points towards its ongoing tidal disruption.
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Kurt Ludwig Adelberger is an American astrophysicist and sustainability manager, who formerly worked at Google as a principal in energy and sustainability and was previously the Engagement Manager for McKinsey & Company.
TON 618 is a hyperluminous, broad-absorption-line, radio-loud quasar and Lyman-alpha blob located near the border of the constellations Canes Venatici and Coma Berenices, with the projected comoving distance of approximately 18.2 billion light-years from Earth. It possesses one of the most massive black holes ever found, at 40.7 billion M☉.
NGC 3311 is a super-giant elliptical galaxy located about 190 million light-years away in the constellation Hydra. The galaxy was discovered by astronomer John Herschel on March 30, 1835. NGC 3311 is the brightest member of the Hydra Cluster and forms a pair with NGC 3309 which along with NGC 3311, dominate the central region of the Hydra Cluster.
Dawn K. Erb is an American physicist. She is an associate professor in the department of physics at the University of Wisconsin–Milwaukee.
References
- 1 2 3 4 5 Dawn K. Erb; Steidel, Charles C.; Shapley, Alice E.; Pettini, Max; Reddy, Naveen A.; Adelberger, Kurt L. (February 3, 2006). "The Stellar, Gas, and Dynamical Masses of Star-forming Galaxies at z ~ 2*". The Astrophysical Journal. 646 (1): 107–132. arXiv: astro-ph/0604041 . Bibcode:2006ApJ...646..107E. doi:10.1086/504891. S2CID 14911369.
- ↑ Erb, Dawn K.; Steidel, Charles C.; Chen, Yuguang (May 21, 2018). "The Kinematics of Extended Lyα Emission in a Low-mass, Low-metallicity Galaxy at z = 2.3*". The Astrophysical Journal. 862 (1): L10. arXiv: 1807.00065 . Bibcode:2018ApJ...862L..10E. doi: 10.3847/2041-8213/aacff6 . S2CID 56389863.
- ↑ Mathewson, Samantha (26 July 2018). "Giant Gas Halo May Reveal How Early Galaxies Evolved". Space.com. Retrieved July 27, 2018.
- ↑ "Giant Gaseous Halo Surrounds Young Star-Forming Galaxy". Sci-News.com. 26 July 2018. Retrieved July 27, 2018.
- ↑ "Young Galaxy's Halo Offers Clues To Its Growth And Evolution". Keck Observatory. Retrieved July 27, 2018.
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