R Hydrae is a Mira-type variable star in the constellation Hydra. Mira variables 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. ... -1... Hydra is the largest of the 88 modern constellations, and was also one of the 48 constellations listed by Ptolemy. ...

The magnitude of R Hydrae varies over a period of 389 days, between 3.21 and 11.00. The period of R Hydrae changes slowly. The apparent magnitude (m) of a star, planet or other heavenly body is a measure of its apparent brightness; that is, the amount of light received from the object. ... Look up period in Wiktionary, the free dictionary Look up periodic in Wiktionary, the free dictionary Period and periodic may refer to: Period (music) Period (rhetoric) Historical period Menstrual cycle, relating to the reproductive system full stop, also known as a period, that marks the end of a sentence Science...

At maximum brightness the star can be seen with the naked eye, while at minimum a telescope of at least 5 cm is needed. A naked eye is a figure of speech, referring to human eyes unaided by enhancing equipment such as a telescope or binoculars. ... A centimetre (American spelling: centimeter, symbol: cm) is an SI unit of length. ...

R Hydrae is approximately 2000 light years from Earth and is of spectral class M7. A light year, abbreviated ly, is the distance light travels in one year: roughly 9. ... Earth, also known as the Earth, Terra, and (mostly in the 19th century) Tellus, is the third-closest planet to the Sun. ... In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequenly refined in terms of other characteristics. ...

Coordinates for epoch J2000

• Right ascension: 13h29m42.80s
• Declination: −23°16'53.0"