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.

Polaris (novel)

Polaris is a Nebula Award-nominated science fiction mystery novel by Jack McDevitt. It is the second book of his Alex Benedict series. Antiquities dealer Alex Benedict and his employee, Chase Kolpath, become involved in a mystery involving the disappearance of the passengers and crew of an interstellar yacht from 60 years earlier.

References

Polaris (train)

The Polaris was a design of locomotive-hauled train designed in concept form by CSRE Ltd. The train was inspired by the British Rail InterCity 125 (HST), and was intended to have a top speed of 140 mph (225 km/h). The loco hauled trains would have had two power cars and been compatible with British Rail Mark 3 coaches. The power cars would have either been Diesel electric, electric and electro-diesel, making the design suitable for use across the whole British railway network. CSRE also proposed an Electric multiple unit (EMU) type of Polaris called the Polaris E.

The Polaris concept will now not be taken to market.

Potential orders

According to the Managing Director of CSRE, David Shipley, there was interest from a number of train operating companies, and the Polaris were planned to be operating in the UK by 2012. This will now be no longer happening. Grand Central Railway planned to introduce some Polaris trains in 2010, but did not announce an order; presently it operates a mixture of British Rail Class 43 power cars with British Rail Mark 3 coaches and British Rail Class 180 multiple units.

UGM-27 Polaris

The UGM-27 Polaris missile was a two-stage solid-fuel rocket nuclear-armed submarine-launched ballistic missile (SLBM) built during the Cold War by Lockheed Corporation for the United States Navy.

It was designed to be used for second strike countervalue (CEP not good enough for first strike counterforce) as part of the Navy's contribution to the United States arsenal of nuclear weapons, replacing the Regulus cruise missile. Known as a Fleet Ballistic Missile (FBM), the Polaris was first launched from the Cape Canaveral, Florida, missile test base on January 7, 1960.

Following the Polaris Sales Agreement in 1963, Polaris missiles were also carried on British Royal Navy submarines between 1968 and the mid-1990s.

Plans to equip the Italian Navy with the missile ended in the mid-60s, after several successful test launches carried out on board the Italian cruiser Giuseppe Garibaldi. Despite the successful launching tests, the US never provided the missiles, due to political convenience. Instead the Italian Government set to develop an indigenous missile, called Alfa, with a successful program, officially halted by Italian Nuclear Non-Proliferation Treaty ratification and failure of the NATO Multilateral Force.