LP Andromedae

LP Andromedae (often abbreviated to LP And) is a carbon star in the constellation Andromeda. It is also a Mira variable^[7] whose mean apparent visual magnitude is 15.12 and has pulsations with an amplitude of 1.50 magnitudes^[3] and a period of 614 days.^[8]

LP Andromedae

A near-infrared (L band) light curve for LP Andromedae, adapted from Jones et al. (1990)[1]
Observation data Epoch J2000      Equinox J2000
Constellation	Andromeda
Right ascension	23h 34m 27.5216s[2]
Declination	+43° 33′ 01.2996″[2]
Apparent magnitude (V)	15.12 variable[3]
Characteristics
Spectral type	C8,3.5e[4]
Apparent magnitude (G)	16.9041[2]
Apparent magnitude (J)	9.623[5]
Apparent magnitude (H)	6.355[5]
Apparent magnitude (K)	2.71[6]
Variable type	Mira[7]
Astrometry
Proper motion (μ)	RA: −21.313±0.532 [2] mas/yr Dec.: −22.058±0.453[2] mas/yr
Parallax (π)	2.5002±0.3626 mas[2]
Distance	approx. 1,300 ly (approx. 400 pc)
Absolute bolometric magnitude (Mbol)	−5.21±0.26[8]
Details[8]
Mass	0.8 M☉
Radius	340 – 420 R☉
Luminosity	2,900 – 16,200 L☉
Temperature	2,100 – 3,350 K
Other designations
2MASS J23342752+4333012, IRAS 23320+4316, RAFGL 3116
Database references
SIMBAD	data

In 1974 LP Andromedae, known then as IRC+40540, was identified as a carbon star and also shown to be variable.^[9] It had previously been suspected of variability during the 2 Micron All Sky Survey (2MASS). A detailed study of its spectrum showed an unusually cool star with a basic class of C8, and Swan band strength of 3.5. It also showed strong C¹³ isotopic bands.^[4] The period was narrowed down to around 614 days, one of the longest periods known for a Mira variable.^[10]

This star has a dusty envelope with an estimated mass of 3.2 M_☉, fueled by the star itself which is losing mass at a rate 1.9×10⁻⁵ M_☉/yr. Such a high mass loss rate should place LP Andromedae close to the end of its asymptotic giant branch evolution. The envelope extends to a distance of 3 parsec from the star, and is mainly made of silicon carbide and carbon particles.^[8]

See also

• List of largest known stars