T Aurigae (or Nova Aurigae 1891) was a nova, which lit up in the constellation

Auriga AURIGA (''Antenna Ultracriogenica Risonante per l'Indagine Gravitazionale Astronomica'') is an ultracryogenic resonant bar gravitational wave detector in Italy. It is at the Laboratori Nazionali di Legnaro of the Istituto Nazionale di Fisica Nuclea ...

in 1891.

Thomas David Anderson Thomas David Anderson (6 February 1853 – 31 March 1932) was a Scottish amateur astronomer. Life He was born at 28 Saxe-Coburg Place in Stockbridge, Edinburgh, the son of John Anderson. When he was five years old, his father showed him Com ...

, an amateur astronomer in

Edinburgh Edinburgh ( ; gd, Dùn Èideann ) is the capital city of Scotland and one of its 32 council areas. Historically part of the county of Midlothian (interchangeably Edinburghshire before 1921), it is located in Lothian on the southern shore of t ...

, reported that he was "almost certain" he saw the nova at 02:00 UT on 24 January 1892, when it was slightly brighter than χ Aurigae (

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's ...

4.74). He mistook the star for 26 Aurigae, although he noted to himself that it seemed brighter than he remembered it being. He saw it twice more during the following week. On 31 January 1892 he realized his mistake, and wrote a note to

Ralph Copeland Ralph Copeland FRSE FRAS (3 September 1837 – 27 October 1905) was an English astronomer and the third Astronomer Royal for Scotland. Life Copeland was born at Moorside Farm, near Woodplumpton in Lancashire, England the son of Robert Copela ...

(the Astronomer Royal of Scotland) reporting his discovery. Professor Copeland immediately reported the discovery via telegram to

William Huggins Sir William Huggins (7 February 1824 – 12 May 1910) was an English astronomer best known for his pioneering work in astronomical spectroscopy together with his wife, Margaret. Biography William Huggins was born at Cornhill, Middlesex, in ...

, who made the first spectroscopic observations of T Aurigae on 2 February 1892, when the star was a magnitude 4.5 object. T Aurigae was the first nova to be observed spectroscopically. TAugLightCurve

Strope and Schaefer report that the peak brightness of T Aurigae was magnitude 4.5,. Pre-discovery images on photographic plates allowed the a light curve beginning in late 1891 to be constructed.

AAVSO The American Association of Variable Star Observers (AAVSO) is an international nonprofit organization, founded in 1911, focused on coordinating, analyzing, publishing, and archiving variable star observations made largely by amateur astronomers ...

data shows that T Aurigae's quiescent magnitude is 15.3. In 1958 observations of the stars forming T Aurigae with the

Crossley telescope The Crossley telescope is a reflecting telescope located at Lick Observatory in the U.S. state of California. It was used between 1895 to 2010, and was donated to the observatory by Edward Crossley, its namesake. It was the largest glass refle ...

showed that it is an

eclipsing binary A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in w ...

, with a period of 4.9 hours, and an eclipse depth of 0.18 magnitudes. T Aurigae was the third nova that was discovered to be a short period eclipsing binary, and that discovery led to increased speculation that the nova phenomenon was connected to close binary star pairs. Today it is believed that all novae are binary stars, with a "donor" star orbiting a

white dwarf A white dwarf is a stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very dense: its mass is comparable to the Sun's, while its volume is comparable to the Earth's. A white dwarf's faint luminosity comes ...

. The stars are so close to each other that matter is transferred from the donor star to the white dwarf.

Nebula

T Aurigae is surrounded by an

emission nebula An emission nebula is a nebula formed of ionized gases that emit light of various wavelengths. The most common source of ionization is high-energy ultraviolet photons emitted from a nearby hot star. Among the several different types of emissio ...

(

shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses ** Thin-shell structure Science Biology * Seashell, a hard o ...

) which is roughly elliptical (25 arc seconds by 19 arc seconds in size) and resembles a planetary nebula. Its 3-dimensional shape is similar to a prolate ellipsoid, but it has a central waist, making it shaped somewhat like a peanut. Santamaria ''et al.'' obtained images of this shell from 2016 through 2019 and by comparing those images to archival images dating back to 1956, they were able to determine that the shell is expanding at about 0.01 arc seconds per year, corresponding to an expansion velocity of about 350 km/sec.

References

External links

* https://web.archive.org/web/20050912175943/http://www.tsm.toyama.toyama.jp/curators/aroom/var/nova/1600.htm Novae Auriga (constellation) 1892 in science Aurigae, T 036294

1841 Events January–March * January 20 – Charles Elliot of the United Kingdom, and Qishan of the Qing dynasty, agree to the Convention of Chuenpi. * January 26 – Britain occupies Hong Kong. Later in the year, the first census of the i ...

Durchmusterung objects {{var-star-stub