| Right Ascension | 09 : 47 : 33.4 (h:m:s) |
|---|---|
| Declination | +11 : 25 : 43 (deg:m:s) |
| Distance | 600 (ly) |
| Visual brightness | 4.4 .. 11.3 (mag) |
| Period | 312.43 (days) |
| Spectra type | M8IIIe |
R Leonis is an extremely red long-period variable star, a typical Mira variable. This star varies over a period of 313 days from mag 4.4 and spectral type M6 near its maximum to mag 11.3, spectral type M8III, so that it is a factor 575 more luminous (and a bit less cool) in its maximum than in its minimum. It is about 600 lightyears away (this value - from Robert Garfinkle's "Star Hopping"-is all but certain, as sources vary), and is receding from us at 13 km/s. Therefore, its absolute magnitude varies from about Mag -1.9 to +5, and its luminosity from about 440 to 0.7 times that of our sun.
Its variability has been discovered in 1782 by J.A. Koch in Danzig; this was the fourth recognized Mira variable. It can be found about 5 degrees west of Regulus (Alpha Leonis), and slightly NE of Subra (Omicron Leonis).
Recent and forthcoming maxima: May 2000, March 2001, December 2001, November 2002, September 2003, July 2004, May 2005; January 2008, November 2008, September 2009; April 4, 2012; February 8, 2013; December 15, 2013; October 21, 2014; September 16, 2015; April 13, 2016; February 17, 2017; December 24, 2017; October 30, 2018; September 5, 2019; July 11, 2020; May 17, 2021; March 23, 2022; January 26, 2023; December 02, 2023.