XX Tauri (Nova Tauri 1927) was a

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

, which appeared in the constellation Taurus in 1927. It was discovered by Arnold Schwassmann and Arno Arthur Wachmann at

Hamburg Observatory Hamburg Observatory (german: Hamburger Sternwarte) is an astronomical observatory located in the Bergedorf borough of the city of Hamburg in northern Germany. It is owned and operated by the University of Hamburg, Germany since 1968, althoug ...

on an objective prism

photographic plate Photographic plates preceded photographic film as a capture medium in photography, and were still used in some communities up until the late 20th century. The light-sensitive emulsion of silver salts was coated on a glass plate, typically thi ...

taken on 18 November 1927. Subsequent examination of pre-discovery photographic plates taken at the

Harvard College Observatory The Harvard College Observatory (HCO) is an institution managing a complex of buildings and multiple instruments used for astronomical research by the Harvard University Department of Astronomy. It is located in Cambridge, Massachusetts, United S ...

showed that the peak brightness, magnitude 5.9, occurred on 1 October 1927, at which point it may have been faintly visible to the naked eye. By 1988 it had faded below magnitude 19.8. XX Tauri faded three magnitudes from peak brightness in just 43 days, making it a "fast nova". Its post eruption light curve shows small amplitude (~0.1 magnitude) variations of timescales of days, hours and minutes, which makes the determination of the orbital period of the binary system comprising the nova difficult. The orbital period may be 0.136±0.002 days. In 1984 a small (radius 2.2 arc second)

nova remnant A nova remnant is made up of the material either left behind by a sudden explosive fusion eruption by classical novae, or from multiple ejections by recurrent novae. Over their short lifetimes, nova shells show expansion velocities of around 1000& ...

surrounding XX Tau was discovered using the

Hale Telescope The Hale Telescope is a , 3.3 reflecting telescope at the Palomar Observatory in San Diego County, California, US, named after astronomer George Ellery Hale. With funding from the Rockefeller Foundation in 1928, he orchestrated the planning, de ...

. The expansion of that remnant has been used to derive a distance estimate of 3500

parsec The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to or (au), i.e. . The parsec unit is obtained by the use of parallax and trigonometry, a ...

References

{{DEFAULTSORT:XX Tauri Novae Taurus (constellation) 1927 in science Tauri, XX