The Hubble sequence is a morphological classification scheme for galaxies published by Edwin Hubble in 1926. It is often colloquially known as the Hubble tuning-fork diagram because the shape in which it is traditionally represented resembles a tuning fork. It was invented by John Henry Reynolds and Sir James Jeans.
An irregular galaxy is a galaxy that does not have a distinct regular shape, unlike a spiral or an elliptical galaxy. Irregular galaxies do not fall into any of the regular classes of the Hubble sequence, and they are often chaotic in appearance, with neither a nuclear bulge nor any trace of spiral arm structure.
The American Astronomical Society is an American society of professional astronomers and other interested individuals, headquartered in Washington, DC. The primary objective of the AAS is to promote the advancement of astronomy and closely related branches of science, while the secondary purpose includes enhancing astronomy education and providing a political voice for its members through lobbying and grassroots activities. Its current mission is to enhance and share humanity's scientific understanding of the universe as a diverse and inclusive astronomical community.
Virginia Louise Trimble is an American astronomer specializing in the structure and evolution of stars and galaxies, and the history of astronomy. She has published more than 600 works in Astrophysics, and dozens of other works in the history of other sciences. She is famous for an annual review of astronomy and astrophysics research that was published in the Publications of the Astronomical Society of the Pacific, and often gives summary reviews at astrophysical conferences. In 2018, she was elected a Patron of the American Astronomical Society, for her many years of intellectual, organizational, and financial contributions to the society.
A barred spiral galaxy is a spiral galaxy with a central bar-shaped structure composed of stars. Bars are found in about two thirds of all spiral galaxies in the local universe, and generally affect both the motions of stars and interstellar gas within spiral galaxies and can affect spiral arms as well. The Milky Way Galaxy, where the Solar System is located, is classified as a barred spiral galaxy.
NGC 2997 is a face-on unbarred spiral galaxy about 40 million light-years away in the faint southern constellation of Antlia. It was discovered March 4, 1793 by German-born astronomer William Herschel. J. L. E. Dreyer described it as, "a remarkable object, very faint, very large, very gradually then very suddenly bright middle and 4 arcsec nucleus. This is the brightest galaxy of the NGC 2997 group of galaxies, and was featured on the cover of the first edition of Galactic Dynamics by James Binney and Scott Tremaine.
Kenneth Charles Freeman is an Australian astronomer and astrophysicist who is currently Duffield Professor of Astronomy in the Research School of Astronomy and Astrophysics at the Mount Stromlo Observatory of the Australian National University in Canberra. He was born in Perth, Western Australia in 1940, studied mathematics and physics at the University of Western Australia, and graduated with first class honours in applied mathematics in 1962. He then went to Cambridge University for postgraduate work in theoretical astrophysics with Leon Mestel and Donald Lynden-Bell, and completed his doctorate in 1965. Following a postdoctoral appointment at the University of Texas with Gérard de Vaucouleurs, and a research fellowship at Trinity College, Cambridge, he returned to Australia in 1967 as a Queen Elizabeth Fellow at Mount Stromlo. Apart from a year in the Kapteyn Institute in Groningen in 1976 and some occasional absences overseas, he has been at Mount Stromlo ever since.
NGC 4323 is a lenticular or dwarf elliptical galaxy located about 52.5 million light-years away in the constellation Coma Berenices. The galaxy was discovered in 1882 by astronomer Wilhelm Tempel and is a member of the Virgo Cluster.
Martha Patricia Haynes is an American astronomer who specializes in radio astronomy and extragalactic astronomy. She is the distinguished professor of arts and sciences in astronomy at Cornell University. She has been on a number of high-level committees within the US and International Astronomical Community, including advisory committee for the Division of Engineering and Physical Sciences of the National Academies (2003–2008) and Astronomy and Astrophysics Decadal Review. She was a vice-president of the executive committee of the International Astronomical Union from 2006–2012, and was on the board of trustees of Associated Universities Inc from 1994 until 2016, serving two terms as board chair and one year as interim president.
A flocculent spiral galaxy is a type of spiral galaxy. Unlike the well-defined spiral architecture of a grand design spiral galaxy, flocculent galaxies are patchy, with discontinuous spiral arms. Self-propagating star formation is the apparent explanation for the structure of flocculent spirals. Approximately 30% of spirals are flocculent, 10% are grand design, and the rest are referred to as "multi-armed". The multiple-arm type is sometimes grouped into the flocculent category.
Claudia Megan Urry is an American astrophysicist, who has served as the President of the American Astronomical Society, as chair of the Department of Physics at Yale University, and as part of the Hubble Space Telescope faculty. She is currently the Israel Munson Professor of Physics and Astronomy at Yale University and Director of the Yale Center for Astronomy and Astrophysics. Urry is notable not only for her contributions to astronomy and astrophysics, including work on black holes and multiwavelength surveys, but also for her work addressing sexism and sex equality in astronomy, science, and academia more generally.
Bruce Gordon Elmegreen is an American astronomer.
Neta Bahcall is an Israeli astrophysicist and cosmologist specializing in dark matter, the structure of the universe, quasars, and the formation of galaxies. Bahcall is the Eugene Higgins Professor of Astronomy at Princeton University.
Laura Ferrarese is a researcher in space science at the National Research Council of Canada. Her primary work has been performed using data from the Hubble Space Telescope and the Canada-France-Hawaii Telescope.
NGC 5238 is an irregular galaxy in the constellation Canes Venatici. Located at a comoving distance of 4.51 Mpc, it is 64.4 arcseconds in diameter. It has sometimes been classified as a blue compact dwarf galaxy. Although some authors have hypothesized it to be a member of the M101 Group of galaxies, it is currently believed to be an isolated galaxy.
NGC 4294 is a barred spiral galaxy with flocculent spiral arms located about 55 million light-years away in the constellation Virgo. The galaxy was discovered by astronomer William Herschel on March 15, 1784 and is a member of the Virgo Cluster.
NGC 4298 is a flocculent spiral galaxy located about 53 million light-years away in the constellation Coma Berenices. The galaxy was discovered by astronomer William Herschel on April 8, 1784 and is a member of the Virgo Cluster.
NGC 4299 is a featureless spiral galaxy located about 55 million light-years away in the constellation Virgo. It was discovered by astronomer William Herschel on March 15, 1784 and is a member of the Virgo Cluster.
Deidre A. Hunter is an American astronomer at Lowell Observatory. Her primary research area is tiny irregular galaxies — their origins, evolution and star production, and the shapes that are formed. She uses many parts of the electromagnetic spectrum, and includes spectroscopy in her approach.
NGC 4393 is a spiral galaxy about 46 million light-years away in the constellation Coma Berenices. It was discovered by astronomer William Herschel on April 11, 1785. It is a member of the NGC 4274 Group, which is part of the Coma I Group or Cloud.
