| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquila |
| Right ascension | 20h 05m 26.54594s[2] |
| Declination | +15° 30′ 01.5408″[2] |
| Apparent magnitude (V) | 6.34[3](6.36 to 6.60)[4] |
| Characteristics | |
| Spectral type | M2.5III[1] |
| U−Bcolor index | +1.76[3] |
| B−Vcolor index | +1.64[3] |
| Variable type | Candidateeclipsing variable[4] |
| Astrometry | |
| Radial velocity (Rv) | −111.7±0.3[5] km/s |
| Proper motion (μ) | RA: 33.899[2]mas/yr Dec.: 24.023[2]mas/yr |
| Parallax (π) | 4.1626±0.1069 mas[2] |
| Distance | 780 ± 20 ly (240 ± 6 pc) |
| Absolute magnitude (MV) | −2.6±1.0[6] |
| Orbit[7] | |
| Period (P) | 198.716±0.038 d |
| Semi-major axis (a) | ≥ 35.39 ± 0.76 Gm (0.2366 ± 0.0051 AU) |
| Eccentricity (e) | 0.048±0.016 |
| Periastronepoch (T) | 2,443,721.1 |
| Argument of periastron (ω) (secondary) | 99.3±29.7° |
| Semi-amplitude (K1) (primary) | 12.97±0.27 km/s |
| Details | |
| Radius | 104±56[6] R☉ |
| Luminosity | 1,100[6] L☉ |
| Temperature | 3,670[8] K |
| Rotational velocity (v sin i) | 10[8] km/s |
| Other designations | |
| V1472 Aql,BD+15°4040,HD 190658,HIP 98954,HR 7680,SAO 105663[9] | |
| Database references | |
| SIMBAD | data |
V1472 Aquilae is atriple star system in theequatorialconstellation ofAquila. It is avariable star that ranges in brightness from 6.36 down to 6.60.[4] The system is located at a distance of approximately 780 light years from theSun based onparallax. It is ahigh-velocity star system with aradial velocity of −112 km/s.[5] When it is at its brightest, it is very faintly visible to thenaked eye under excellent observing conditions.
The binary nature of the main component was announced byP. B. Lucke andM. Mayor in 1982, who found it to be a single-linedspectroscopic binary with anorbital period of 198.7 days and aneccentricity of 0.05. At the time of its discovery, it was the shortest known binary period of any class M giant.[7] The primary is an agingred giant with astellar classification of M2.5III.[1] It has a diameter104±56 times and luminosity 1,100 times that of the Sun.[6] The star is a fast rotator with aprojected rotational velocity of 10 km/s, possibly due to interaction with its companion.[8]
The variability of this star was discovered from Hipparcos data and, in 1997, it was classified as asemiregular variable with a period of 100.3727039 days. However, a plot of the light curve better matches that of aneclipsing binary orellipsoidal variable. The 198-day orbital period produces alight curve with a primary and secondary minimum which, together with possible variations due to ellipsoidal rotation, produces the observed semiregular 100-day photometric variation.[1] Later observations show that it is less luminous than expected for a pulsating star with its amplitude, being more typical of ellipsoidal variables, and that it has a 200.05-day period with primary and secondary minima.[10]
A co-moving companion some 4.0 magnitudes fainter than the primary lies at anangular separation of2.7 arcseconds.[1]
