V Aquilae
Star in the constellation Aquila
From Wikipedia, the free encyclopedia
V Aquilae (V Aql) is a carbon star and semiregular variable star in the constellation Aquila. It has an apparent magnitude which varies between 6.6 and 8.4 and is located around 400 parsecs (1,300 ly) away.
 | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Aquila |
| Right ascension | 19h 04m 24.155s[1] |
| Declination | −05° 41′ 05.44″[1] |
| Apparent magnitude (V) | 6.6 - 8.4[2] |
| Characteristics | |
| Evolutionary stage | AGB[3] |
| Spectral type | C5,4-C6,4(N6)[2] |
| B−V color index | +4.32[4] |
| Variable type | SRb[2] |
| Astrometry | |
| Radial velocity (Rv) | +37[5] km/s |
| Proper motion (μ) | RA: 6.243±0.407[6] mas/yr Dec.: −1.379±0.318[6] mas/yr |
| Parallax (π) | 2.4779±0.2320 mas[6] |
| Distance | 1,300 ± 100 ly (400 ± 40 pc) |
| Absolute magnitude (MV) | −5.19[7] |
| Details | |
| Mass | 2.5[8] M☉ |
| Radius | 234[9] R☉ |
| Luminosity | 6,500[10] L☉ |
| Surface gravity (log g) | −0.108[9] cgs |
| Temperature | 2,800[10] K |
| Metallicity [Fe/H] | 0.10[11] dex |
| Other designations | |
| BD−05 4858, HD 177336, HIP 93666, HR 7220, SAO 142985[12] | |
| Database references | |
| SIMBAD | data |
V Aquilae is a type of star with a spectrum that is dominated by strong absorption lines of the molecules C2 and CN, hence known as carbon stars. The enhanced levels of carbon in the atmosphere originate from recently nucleosynthesized material that has been dredged up to the surface by deep convection during temporary shell burning events known as thermal pulses. Published spectral types for the star vary somewhat from C54 to C64, or N6 under an older system of classification.[2][13] The subscript 4 refers to the strength of the molecular carbon bands in the spectrum, an indicator of the relatively abundances of carbon in the atmosphere.
V Aquilae is a variable star of type SRb.[11] Its variability was first announced by George Knott in 1871.[15] It has a published period of 400 days, but other periods are found including 350 days and 2,270 days.[16]