R Lyrae on:
[Wikipedia]
[Google]
[Amazon]
R Lyrae, also known as its Flamsteed designation 13 Lyrae, is a 4th magnitude semiregular variable star in the constellation Lyra, approximately 350 
The variability is not consistent and regular, but periods of 46, 64, 378, and 1,000 days have been reported, with the 46-day period being the strongest.
It is calculated that R Lyrae was a star on the main sequence. It is considered an oxygen-rich
R Lyrae, also known as its Flamsteed designation 13 Lyrae, is a 4th magnitude semiregular variable star in the constellation Lyra, approximately 350 light year
A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...
s away from Earth. It is a red giant
A red giant is a luminous giant star of low or intermediate mass (roughly 0.3–8 solar masses ()) in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius large and the surface temperature around or ...
star of the spectral type M5III, meaning it has a surface temperature of under 3,500 kelvins. It is much larger and brighter, yet cooler, than the Sun. In the near- infrared J band, it is brighter than the nearby Vega.
R Lyrae is unusual in that it is a red star with a high proper motion, greater than 50 milliarcseconds a year.
The variability is not consistent and regular, but periods of 46, 64, 378, and 1,000 days have been reported, with the 46-day period being the strongest.
It is calculated that R Lyrae was a star on the main sequence. It is considered an oxygen-rich asymptotic giant branch
The asymptotic giant branch (AGB) is a region of the Hertzsprung–Russell diagram populated by evolved cool luminous stars. This is a period of stellar evolution undertaken by all low- to intermediate-mass stars (about 0.5 to 8 solar masses) lat ...
star, with both hydrogen and helium shells fusing.
References
{{Stars of Lyra Lyra Lyrae, 13 Lyrae, R Semiregular variable stars 7157 175865 092862 Durchmusterung objects M-type giants