V1291 Aquilae
Variable star in the constellation Aquila
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V1291 Aquilae is a single[10] star in the equatorial constellation of Aquila. It has a yellow-white hue and is dimly visible to the naked eye with an apparent visual magnitude that fluctuates around 5.65.[3] Based on parallax measurements, it is located at a distance of approximately 278 light years from the Sun. The star it is drifting closer with a radial velocity of −22 km/s.[2]
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Aquila |
| Right ascension | 19h 53m 18.73574s[2] |
| Declination | −03° 06′ 52.0653″[2] |
| Apparent magnitude (V) | 5.65[3] (5.61 to 5.67)[4] |
| Characteristics | |
| Evolutionary stage | Main sequence[5] |
| Spectral type | F0VpSrCrEu[5] |
| U−B color index | +0.10[3] |
| B−V color index | +0.20[3] |
| Variable type | α2 CVn[4] |
| Astrometry | |
| Radial velocity (Rv) | −21.850±0.0005[2] km/s |
| Proper motion (μ) | RA: +21.578[2] mas/yr Dec.: +14.186[2] mas/yr |
| Parallax (π) | 11.7248±0.1011 mas[2] |
| Distance | 278 ± 2 ly (85.3 ± 0.7 pc) |
| Details[6] | |
| Mass | 2.26±0.05[7] M☉ |
| Radius | 2.32±0.19 R☉ |
| Luminosity | 25.7+2.3 −1.8 L☉ |
| Surface gravity (log g) | 4.03±0.08 cgs |
| Temperature | 8,770±30[7] K |
| Metallicity [Fe/H] | 1.00[8] dex |
| Rotational velocity (v sin i) | 6.7±0.5 km/s |
| Age | 670±210 Myr |
| Other designations | |
| V1291 Aql, BD−03°4742, HD 188041, HIP 97871, HR 7575, SAO 143883[9] | |
| Database references | |
| SIMBAD | data |
In 1962, Helmut A. Abt and John C. Gloson published data showing that the star's brightness varied.[11] Based on that publication, the star was given its variable star designation, V1291 Aquilae, in 1972.[12]
This is a magnetic chemically peculiar star, or Ap star, with a stellar classification of F0VpSrCrEu,[5] matching an F-type main-sequence star with abundance anomalies of strontium, chromium, and europium in the spectrum. It is a variable star of type Alpha2 Canum Venaticorum that ranges in visual magnitude from 5.61 down to 5.67[4] with a period of 223.826 days. This is most likely the mean rotational period of the star.[1] V1291 Aquilae was one of the first Ap stars discovered with a period of more than 100 days.[13] It shows a surface magnetic field strength of 3.6 kG.[7]