U Orionis
Encyclopedia
U Orionis is a Mira-type variable star
in the constellation
Orion
. It is a classical long period variable
star that has been well observed from the United Kingdom for over 120 years. It was discovered on 1885 December 13 by J.E. Gore and initially it was thought to be a nova in the early stages of decline (Gore's Nova and NOVA Ori 1885 as still listed in SIMBAD), but a spectrum taken at Harvard showed features similar to that of Mira. Thus U Orionis became the first long period variable to be identified by a photograph of its spectrum.
's orbital zone (about 1.7 astronomical units), and, to be habitable with water at liquid state and a comfortable temperature, a planet would have to be located within 85 AU, within the Kuiper belt
's orbital zone.
Mira variable
Mira variables , named after the star Mira, are a class of pulsating variable stars characterized by very red colors, pulsation periods longer than 100 days, and light amplitudes greater than one magnitude in infrared and 2.5 magnitude in visual...
in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
Orion
Orion (constellation)
Orion, often referred to as The Hunter, is a prominent constellation located on the celestial equator and visible throughout the world. It is one of the most conspicuous, and most recognizable constellations in the night sky...
. It is a classical long period variable
Long period variable
A long period variable is a type of variable star in which variations in brightness occur over long timescales of months or years. Long period variables are giant stars and brighter, from spectral class F and redwards, but most are red giants and AGB giants, meaning spectral class M, S or C...
star that has been well observed from the United Kingdom for over 120 years. It was discovered on 1885 December 13 by J.E. Gore and initially it was thought to be a nova in the early stages of decline (Gore's Nova and NOVA Ori 1885 as still listed in SIMBAD), but a spectrum taken at Harvard showed features similar to that of Mira. Thus U Orionis became the first long period variable to be identified by a photograph of its spectrum.
Stellar parameters
The star has a very low effective temperature (roughly 2700 K) but a very large and bloated radius of 370 solar radii and a high luminosity, 7,000 times higher than the Sun. If our Sun were replaced with U Orionis, its radius would extend beyond MarsMars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...
's orbital zone (about 1.7 astronomical units), and, to be habitable with water at liquid state and a comfortable temperature, a planet would have to be located within 85 AU, within the Kuiper belt
Kuiper belt
The Kuiper belt , sometimes called the Edgeworth–Kuiper belt, is a region of the Solar System beyond the planets extending from the orbit of Neptune to approximately 50 AU from the Sun. It is similar to the asteroid belt, although it is far larger—20 times as wide and 20 to 200 times as massive...
's orbital zone.