NO Apodis

NO Apodis is a solitary,^[15] red hued variable star located in the southern circumpolar constellation Apus. It has an average apparent magnitude of 5.86,^[16] allowing it to be faintly seen with the naked eye. The object is relatively far at a distance of 790 light years^[1] but is drifting closer with a heliocentric radial velocity −18.3 km/s.^[7]

A light curve for NO Apodis, plotted from Hipparcos data. The data has been folded with the 24.9 day period listed in the International Variable Star Index.^[2]

NO Apodis

location of NO Apodis in red
Observation data Epoch J2000      Equinox J2000
Constellation	Apus
Right ascension	17h 31m 27.4667s[1]
Declination	−80° 51′ 32.876″[1]
Apparent magnitude (V)	5.71-5.95[2]
Characteristics
Evolutionary stage	AGB[3]
Spectral type	M3 III[4]
U−B color index	+1.80[5]
B−V color index	+1.67[5]
Variable type	Semiregular[6]
Astrometry
Radial velocity (Rv)	−18.3±0.6[7] km/s
Proper motion (μ)	RA: −3.662 mas/yr[1] Dec.: −43.943 mas/yr[1]
Parallax (π)	4.1479±0.0741 mas[1]
Distance	790 ± 10 ly (241 ± 4 pc)
Absolute magnitude (MV)	−1.32[8]
Details
Mass	1.63[9] M☉
Radius	107[10] R☉
Luminosity	1,408[11] L☉
Surface gravity (log g)	1.7±0.1[12] cgs
Temperature	3,521±122[10] K
Other designations
59 G. Apodis[13], NO Aps, NSV 8609, CD−80°638, CPD−80°828, FK5 1455, GC 23550, HD 156513, HIP 85760, HR 6429, SAO 258769[14]
Database references
SIMBAD	data

NO Apodis has a stellar classification of M3 III,^[4] indicating that it is a red giant. It is currently on the asymptotic giant branch,^[3] fusing hydrogen and helium shells around an inert carbon core. At present it has 1.63 times the mass of the Sun^[9] and an enlarged radius of 107 R_☉.^[10] It shines with a bolometric luminosity 1,408 times that of the Sun^[11] from its photosphere at an effective temperature of 3,521 K.^[10]

NO Apodis is classified as a semiregular variable of unknown subtype. Observations from Tabur et. al. (2009) reveal it to have two periods, both lasting 26-7 days.^[17] During this timeframe, the star flucates between 5.71 and 5.95 in the visual band.^[2]

Periods of NO Apodis^[17]

Period	Days	Amplitude
1	26.2	0.04
2	26.6	0.092