Polaris

Polaris (α Ursae Minoris, α UMi, commonly the North Star or Pole Star) is the brightest star in the constellation Ursa Minor. It is very close to the north celestial pole, making it the current northern pole star.

It is a multiple star, comprising the main star, α UMi Aa, which is a supergiant; two smaller companions, α UMi B and α UMi Ab; and two distant components, α UMi C and α UMi D. α UMi B was discovered in 1780 by William Herschel.

The revised Hipparcos parallax calculates the distance to Polaris at about 434 light-years (133 parsecs). Many recent papers derive distances up to 30% closer, particularly by assuming that its pulsation is in the fundamental mode. Deriving an accurate distance is especially important because Polaris is the closest Cepheid variable to Earth, so its physical parameters are critically important to the whole astronomical distance scale.

History of observations

Polaris in stellar catalogues and atlases

Star system

α UMi Aa is a 4.5 solar mass (M_☉) F7 yellow supergiant (Ib). This is the first classical Cepheid to have a dynamical mass determined from its orbit. The two smaller companions are α UMi B, a 1.39 M_☉ F3 main-sequence star orbiting at a distance of 2400 AU, and α UMi Ab (or P), a very close F6 main- sequence star with an 18.8 AU radius orbit and 1.26 M_☉. There are also two distant components: α UMi C and α UMi D which have been shown to not be physically associated with the other three stars.

Polaris (convention)

Polaris (formerly Toronto Trek) is an annual science fiction and fantasy convention held in Toronto, Ontario, Canada in the past and now held in Richmond Hill, Ontario, Canada.

It began in 1986 as a relaxacon as Toronto Trek Celebration. Two years later, in 1988, Toronto Trek Celebration 2 took place. In 1989 it dropped the word "Celebration" and became simply "Toronto Trek". For its twenty-first convention in 2007, the name was changed to "Polaris". At Polaris 26, held July 5–7, 2012, it was announced Polaris had come to an end and that a new convention would replace Polaris in 2013.

The convention had a focus on media guests from science fiction, fantasy movies and television series and novel authors such as Star Trek, Babylon 5, Stargate, Doctor Who, Buffy the Vampire Slayer, Jericho, Lost and Battlestar Galactica. Photo opportunities, autographs and Question & Answer sessions feature the media guest, who sometimes come to other programming and after hours events.

USS Periwinkle (1864)

USS Periwinkle (1864) was a steamer procured by the Union Navy during the final months of the American Civil War. She served the Union Navy’s struggle against the Confederate States of America as a patrol gunship.

After the war, this ship was retained by the U.S. Navy to support the Hall Scientific Expedition to the Arctic Ocean, and during this voyage – under her new name Polaris – she proceeded into Arctic waters, only to have her hull crushed by the ice.

Construction

America, a heavy screw tugboat built at Philadelphia, Pennsylvania, in 1864, was purchased by the Union Navy 9 December 1864 from John W. Lynn; renamed Periwinkle; and commissioned early in January 1865, Acting Master Henry C. Macy in command.

Assigned to river patrol in the Potomac River

The two-masted, schooner-rigged, white oak tug joined the Potomac Flotilla 15 January 1865 as a gunboat, and operated primarily in the Rappahannock River.

In mid-March, a fleet of oyster schooners operating in the area was threatened by a Confederate enemy force, and Periwinkle with USS Morse, blockaded the mouths of the Rappahannock and Piankatank rivers to protect them. The Flotilla also interrupted contraband business between lower Maryland and Virginia, and cleared the rivers of mines, and fought guerillas ashore.

Unknown

Unknown or The Unknown may refer to:

Mathematics

Film

Music

Other uses

Placeholder name

Placeholder names are words that can refer to objects or people whose names are temporarily forgotten, irrelevant, or unknown in the context in which they are being discussed.

Linguistic role

These placeholders typically function grammatically as nouns and can be used for people (e.g. John Doe, Jane Doe), objects (e.g. widget) or places (e.g. Anytown, USA). They share a property with pronouns, because their referents must be supplied by context; but, unlike a pronoun, they may be used with no referent—the important part of the communication is not the thing nominally referred to by the placeholder, but the context in which the placeholder occurs.

Stuart Berg Flexner and Harold Wentworth's Dictionary of American Slang (1960) use the term kadigan for placeholder words. They define "kadigan" as a synonym for thingamajig. The term may have originated with Willard R. Espy, though others, such as David Annis, also used it (or cadigans) in their writing. Its etymology is obscure—Flexner and Wentworth related it to the generic word gin for engine (as in the cotton gin). It may also relate to the Irish surname Cadigan. Hypernyms (words for generic categories; e.g. "flower" for tulips and roses) may also be used in this function of a placeholder, but they are not considered to be kadigans.

Unknown (1988 anthology)

Unknown is an anthology of fantasy fiction short stories edited by Stanley Schmidt, the fifth of a number of anthologies drawing their contents from the classic magazine Unknown of the 1930s-40s. It was first published in paperback by Baen Books in October 1988.

The book collects nine tales by various authors, together with an introduction by the editor.

Contents