T Aurigae (or Nova Aurigae 1891) was a

nova A nova ( novae or novas) is a transient astronomical event that causes the sudden appearance of a bright, apparently "new" star (hence the name "nova", Latin for "new") that slowly fades over weeks or months. All observed novae involve white ...

, which lit up in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The first constellati ...

Auriga Auriga is a constellation in the northern celestial hemisphere. It is one of the 88 modern constellations; it was among the 48 constellations listed by the 2nd-century astronomer Ptolemy. Its name is Latin for '(the) charioteer', associating i ...

in 1891. Thomas David Anderson, an amateur astronomer in

Edinburgh Edinburgh is the capital city of Scotland and one of its 32 Council areas of Scotland, council areas. The city is located in southeast Scotland and is bounded to the north by the Firth of Forth and to the south by the Pentland Hills. Edinburgh ...

, 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 Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), ...

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 Cope ...

(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 a British astronomer best known for his pioneering work in astronomical spectroscopy together with his wife, Margaret. Biography William Huggins was born at Cornhill, Middlesex, in 1 ...

, 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 plate Photographic plates preceded film as the primary medium for capturing images in photography. These plates, made of metal or glass and coated with a light-sensitive emulsion, were integral to early photographic processes such as heliography, d ...

s 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, the organization focuses on coordinating, analyzing, publishing, and archiving variable star observations made largely by amat ...

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 and 2010, and was donated to the observatory by Edward Crossley, its namesake. It was the largest glass ref ...

showed that it is an

eclipsing binary A binary star or binary star system is a Star system, system of two stars that are gravity, 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 ...

, 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 Compact star, stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very density, dense: in an Earth sized volume, it packs a mass that is comparable to the Sun. No nuclear fusion takes place i ...

. 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 emission n ...

(

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 Science Biology * Seashell, a hard outer layer of a marine ani ...

) 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 {{DEFAULTSORT:T Aurigae Novae Auriga 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 ...

Durchmusterung objects